Performance deterioration based on in-service engine data: JT9D jet engine diagnostics program

TABLE OF CONTENTS Section 1.0 SUMMARY I 2,0 INTRODUCTION 3 ....

3,0 DATA COLLECTIONAND ANALYSIS METHODOLOGIES 5 i 3,1 Data Collection 5 3,1,1 Engine ConditionMonitoringData 5 3,1,2 In-FlightPerformanceCalibrations 6 • 3,1,3 Plug-lnConsoleTesting 8 3.1.4 Test Stan_ t'esting 16 __ 3.2 Pan American Tes_cStand Instrumentation and Test_Data Uncertainties 18 3.2.1 Expanded instrumentation 18 3.2.2 Test Stand Instrumentation Calibrations 18 3,2_3 MeasurementUncertaintiesof the Pan American Test Stand Instrumentation 20 3,2,4 MeasurementUncertainties Due to Data Samplingand Engine Configuration Dif.Zerences 21 _ 3,2,5 Test Stand.Correlations 22 3,3Mai ntenanceData Collection 23 3,4 AnalysisTechniques 25 3,4.1 Flight Data and P . lug-ln Cosole Data 25 3,4,2 Top-Down Analysis.ofPrerepairand Postrepa!rTests 26 4,0 RESULTSAND DISCUSSIONS _ 37 4.1 Overall Engine PerformanceDeteriorationResults 37 4,1,1 Engine ConditionMonitoring (ECM) Data 37 4,1,2 In-Fl_ight CalibrationData 46 4,1,3 Prerepairand PostrepairData 47 4,1,4 Plug-lnConsole (P.IC) Data 55 4,2 Overall Engine PerformanceDeteriorati.on Comparison 57 _' 4,3 Module PerformanceDeterioration 68 4,3,I Fan 72- j 4,3,2 Low-PressureCompressor 75

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4,3,3 High-Pressure Compressor 79 4,3,4 High-Pressure Turbine 82 4,3,5 Low = _- ressureTurbine 82 T ABLE OF C ON TE N T S (Cont'd.)

Secti on 5.0 REFINED MOD E LS OF JT9 D ENGINE_PERFORMANC E DETERIORA T ION g l 5.1 Refinementof PerformanceDeteri orati on Models 91 : 5.I.1 Fan 91 5.1.3 High-Pressure CompressQr 94 .

i 5.1.2 Low-PressureCompressor 91 5.1.4 High-Pressure Turbine 96 5.1.5 Low-Pressure Turbine g7 5.2.EnginePerformance . Trends . ._Modelversus Data 102 5.3 Model Predictions 104 6,0 RECOMMENDATIONS 109 6 .1 EngineOperating Prodedures 109 6 .2 PerformanceMonitoring 112 6.2.1 PerformanceTrending and Management 112 6.2.2 Engine ConditionMonitoring 114 .

6.2.3 OperatingHistory and Repair Data Collection 114 6.2.4 Analysis of Performanceand Repair Data 114 6.2.5 Test Stand Instrumentation and Calibration 114 6 . 3 MaintenancePractices_ 115 6. 3 .1 Ean . 115 6.3.2 Low-PressureCompressor 1151 6.3.3 High.Pressure Compressor 116 6.3.4 Combustor System 116 , 6 . 3 .5 High-Pressure Turbine 117 6.3.6 Low-PressureTurbine 117 6.3.7 Rebui l dStandards 118 6.4 Design Criteria 118 6.4.I _Introducti on 118 _ _ 6.4.2. FIight-Load-lnduced Losses 118 6.4.3 PerformanceLoss Due to Erosion 119 6.4.4 Thermal Di s tortionEffects 120.

6.5Recommended Programs 121 6..5..1 Introduction 121 6.5.2 F light LoadsTest Program 122 6.5 . 3 F an Engine Test : at ,Altitude 123 _ 6.5.4 EngineDiagnosticsProgram for Use by Airlines 123 vi

T AB LE OF CON T ENTS (Cont'd.)

Section 7.0 CONC L USIONS 125 7.1 Overall Engine PerformanceDeteriorati.on 126.

7.I.i Short-TermDeteri orati on 127 7.1.2 Long-TermDeteri orati on 128 7.2 F light PerformanceData !28 7.3 Performance Recoverabil_ity 129 7.4 Deterioration Models 12 9 APPENDIXA . EffectsofBleeds-On versus Bl e eds.OffOperation on F 1 ightLoads - 131 APPENDIXB E f fectsof F an andLow-PressureCompressorFlow .

CapacityLosses on EnginePerformance 135 APP E NDIXC MaintenanceData Collection 1 3 9 APPENDIXD. Test Stand and Ins.trument Calibration 151 APPENDIX E Quality Assurance 165 APPENDIXF . Acronyms and Symbols 16.7 REFERENCES ._ 171 DISTRIBUTION . LIS T 173 vii ;.! " .... .. . , , ", • , ,, , - .......... i'-,'- LIST OF ILLUSTRATIONS Number Title _ o I Typical Corrected Engine Condition Monitoring _ __ (ECM) Data 7 2 Location of Major Components of_ the Plug-ln ._ Console System 11 3 Installationof . the PIC System Instrumentation Harness_ 11 4. P.IC System InstrumentatiorL 12 51 PIC Sys_m Data AcquisitionUnit 12 .

6 Typical PIC Data System Print-Out 13 _.

7 Typical Plot of. On-Wing PIC Calibration of ' J-TgD-7(SP) Engine P-695745 14 8 Data Processing F low for Prerepair and PostrepairTest Stand Testing . 17 .............

9 Flow Di_grem for "Top Down" Analysis. 27 10 , _M Plot of Change _n Euel Flow with UsabLe 38 .

11 ECM Plot of Change in EGT wi.th Usage . . 39 12 747SP Airplane Average Wf Perf orma_ , ,ce Deter.ioration Trends Based on ECM Data 40 __.

13 747SP Airplane Average- E GT Performance I Deter_ioration Trends Based on ECM Data_ 41 14 ECM Data from Pan American Airplane .N534PA on.

Change in Fuel Flow with Usage. 42 15 ECM Data from Pan American Airpl_aneN534PA on Change in EGT with Usage 43 J L j _ . - .

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tx ILLUSTRATIONS(Continued) Number Titl_..._e pa__.el 16 _Aircr aft-Del.i vered versus Spare Engine Performance Deterloration for South African Airways, JTgD-7F Engines 44 17 Aircraft-Delivered versus Spare -- Engine .

Performance Deterioration for Iraqi Airlines JTgD-TFEngi nes 44 ....

18_ Aircraft-Del ivered versus Spare Engine.

Performance Deterioration for Northwest O_ient Air]ir, es JTgD-20 Engines 45 19 PerformanceDeterioration_ (Fuel Flow Change) for 28 Pan American Airplane.DeliveredJTgD-TA(SP) Engines versus 16 Spare £ngines from Eight Airlines -45 ] 20. Performance Deterioration (EGT Change) for _ 28 Pan Ameri can Airplane.Del ivered JTgD-7A(SP) Engines versus 16 Spa_e Engines from ELght Airlines 46 21 In-Flight Calibration Fuel Flow and Exhaust Gas TemperatureData as Functions of Engine Pressure Ratio for Engine P-695738 on Airplane N536PA Taken on May 21, 1977at 155 Hours / 23Cycles. . 48 22 In-Fl.ight Calibration Low. and High-Pressure Rotor Speed Data as Functions of Engine Pressure Ratio for Engine P-695738 on. Airplane N536PA Taken on May 21,.1977 at 155 Hours / 23Cylcles. 49 23. Fuel Flow and Exhaust Gas Temperature.Data at EPR of-1,40 as Functions of Cycles for All_ In-Flight Calibrations of Engin=. P-695738 on Airplane N536PA 50 24 Low- and High.Pressure.-Rotor-Speed -Data as.

Functions_ of- Cycles f-or AlI In-Fl.ight Calibrations_of Engine P-695738.on ..Airplane N536PA 50 _ LIST OF It.LUSTRATIONS (Continued) Number Titl_..__e 25 Comparison of Four-Engine Averages of Gas GeneratOr Rarameters as Functions of Cycles as.

Determined_ by In-Flight Calibrations and Engir_ Condition Monitoring.of Engines on Air.planes N536PA and N537PA 51 26 Long-Term TSFC Deteri orati on, Measured at ConstantThrust, as.a Function . ofFlight Cyc'Les 52 27 Long-Term EGT Deterioration, Measured. at Take-Off EPR, as a Function of Flight Cycles 52 28 Long-Term TS F C Deterioration,. Measured at.

Constant Thrust, as.a Function_)fLFlight .Cycles _ 53 29 Long-Term EGT Deterioration, Measured .at Take-Off EPR, as a..Function of Flight Cycles 54 30 Long-Term TSFC. Deterioration, Measured at Constant Thrust, as a Function of Flight.Cycles; Comparison of Average P_rere_air to___Average PostrepairPerformance 55 31 Long-Term EGT Deteriorati on, Measured at Take-Off EPR, as a Function of Flight Cycles; Comparison of Average Prer___eepair to Average_ Postrepair.-Perf ormance 56 32 Typical Gas .Generator Plot 58 33__ Typical.GasGenerator P.lot 59 34. T.ypical Gas Generator . Plot 60 35 Typical Gas Generator;P_Iot 61 36. Typical Gas Ge r ler_ : tor Pl.ot 62 37 TypicalGas Generator Plot 63 .

38 EstimatedSea.LevelStatic TSFC Deterioration_ 64 39 EstimatedSea Level Static EGT Deterioration 64 xi L IST OF ILLUSTRATIONS(C o ntinued_ Numb e r Tit l_._.._e 40 C o mpari s on of Ga s . . . G enerator Param e ter s a s F uncti o n s . o f Cycles a s . D e ter m in e d by Altitude Synthesi s of PIC .Data, In- F light Calibrati o n Data, and ECM Data. 65 I 41 Pr e repair Sea L eve l Static TS F C Performance of _ ] JI_ g D Engin e s at C o n s tant T hrust _ 66 .

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42 Prerepair Sea Level Static EGT Performance of JTgD.En g inesat Constant EPR 67 4 3 Postrepair - -Sea Level Static TS F C Performance of JT 9 D En g ines.atCon s tant-Thrusts_ _ 67..

4 4 Po s trepair Sea Level Static £GT Performancefor JT g D Engines at Co n stant EPR 68 45 Fan Module 2 erformance Deteri orati on 74 .

46 Estimated F an Module_Deterioration with Usage 75 47 Comparison of PIC, o'TgD-7A(SP) Prerepair, and__ _ Histori cal Fan Perf o rmanceDeteri.orati on Data_ 76 t' 48 Low - Pre s sure Compr e s s o r Module Perf o rmance Deteri or . at ion . 77 I 49 Estimated Lo w-Pressure Compress o r- Module '_ Deteriorationwith Usage . ......................... -- -7 8 50 Comparison of. PIC, .O TgD-7A(SP) Prerepair _ and . ..

Postrepair, and Historical Low,Pressure Compre s sorPerformanceDeterio c _at . ion Data 80 51 High-Pr es s ure C om pr es sor M od ule _Ea r _ f_m an ce Deter.J.orati on. 81 52_ Estimated High,Pressure Compressor Module Deterioration wit h Usage_ 81 53 C o m p arison. o f PIC,. J T gD-7A(SP) Pr e repair and Postrepair,, and Historical High-Pressure Compre s sorPerformanceDeterioration Data 83.

xii {'4 LIST O F ILLUSTRATIONS(Continued) Nu m b e r Tit le 5 4 High-Pre ss ure T urbine Module Performance Deterioration 04 55 E stimated High-Pressure Turbine .Module Deteriorat_ton with Usage 85 _ 56 Comparison of PIC, JTgD-7A(SP) Prerepair and. .

Po s trepair,and HistoricalHigh-Pr ess ureTurbine PerformanceDeter.ioration Data. 86.

57 Low-Pressure tur_b ine__ -Module. Performance Det eriorati on 87 58 : Low-Pre s s.ure Turbine Module_Deterioration with Usage _ 88 59 Comparison of . PIC, JTgD-7A(SP) Prerepair and _ _ Postrepair,_ and . Historical Low-Pressure Turbine Perf . ormance Deteri orati on. Data. 89 60 Development of F an Perfor_ n anceDeterioration Refined Model 92 ...............

61 Fan Performance DeteriorationRefined Model.and 1 Variation . Band 93 . ' 62 Devel opmemt of Low-Pressure Compressor PerformanceDeteri orati on Refi necL Mode] 94 63 . . . Low-Pressure Compressor Performance. 1 Deteri orati on Refined Model . and Var_tati on Band 95 i 64 Development of High-Pressure Compressor I Perf:ormance Deteri orati on R e fined Model.. _ 96 65 High-Pressure Compressor Performance Deteri orationRefined Model and Variati on Band 97 | 66 Developmentof High_-Pressure .TurbinePerformance 1 Deteri orati on Refined Model 98 ' 67 High-Pressure Turbine•Performance _Deteriorati on.

Refined Model and Variation Band 99 ,_ xiii ...............................................................................................

I LIST OF ILLUSTRATIONS (Continued) .__ Number Title 68 Development Of Low-Pressure .Turbine Performance Deteri oratl onRefi ned Model 100__ 69 Low-Pressure Turbine Performance Deterioration.

Refi ned Model I0_ 70 Prerepair TSFC Performance Data, Measured at Constant Thrust, as a Function of Usage 102.

71 _Prerepair EGT Performance Data, Measured at Constant EPR, Bs a Function of .Usage 103 72 Postrepair TSFC Performance Data, Measured at ConstantThrust, asa Function of Usage 104_.

73. Postrepair EGT Performance Data, Measured at Constant EPR, as a Function of Usage 105 74 Module Performance Deterioration, at Constant UndeterioratedSea Level Static Take-Off Thrust, Bas.Ed on thE_RefinedEngine Deterioration Model _ - 105 75 Module Performance Deterioration, at Constant.....

UndeterioratedSea Level Static Take-Off Thrust; Refined Model Results Compared to Preliminary Model Results 107..

76 . Major Causes for Module PerformanceDeterioration _ 108 77 Contribution of Major Causes._..to _O_erall Engine Performance Deteriorati on - 108 78 Hot Rotor / Rub-Str_ p Interacti on _ 112 A-I In-Flight Calibration of Fuel Flow_Change as a Function of Cycles at_ Mach 0.85,_35,000 feet Altitude,EPR_: 1,40 131 A_2_ Bleeds-On / Bleeds-Off Comparisonfor the Position I Engine on Airplane N537PA 1.33 B-1 Effects of-_Fan Flow Capacity___LossozL_ . JTgD Performance. Parameters 136 B-2 ,-Effect of Low-PressureCompressor Flow Capacity Loss on JTgD PerformanceParameters 137 xiv / LIST_OFTABLES Table Titl_... P_a_._ I Sampl.e Print-OutOf In-]:..light Calibrat.ion.Co_ect.ed Data 9 II Engine . Performance ParametersRecorded by the Plug-ln _ ConsOle System I0 Ill Chronologyof-On-.Wing PICTesting.;747SP Airplane. N536PA; Engines P-695743 and P-695745 15...............

IV Chronologyof On-Wing P.IC Testing; 747SP Airplane N537PA; Engines P-695760 and P-695763 15 V Summary of Engine PerformanceData Obtainedfrom Test-Stand Testing 19.

VI .Summary of Total . Parameter UncertaiFLties 20 VII Engine. SimulationIterationLog!c for.T . op Down. Approach 28 VIII Modified Engine.Simulation IterationLogic_Usedf-or Analysis 29 IX History of JTgD-7A(SP)Engine P-695745 31 X ObservationsDuring Teardown.of JT9D- ] J£(SP) Engine P- . 695745 31 XI DetailedResult_ of PrerepairTop Down Analysis;JT9D-7A(SP) Engine P-695745 at Sea.Level. Static Take-Off Conditions, Engine PressureRatio = 1,455 .. 32 XII Summary of Repairs on.JTgD-7A(SP) Engine P-695745 . 33 XIII DetailedResults of PostrepairTop Down Analysis; JTgD-7A(SP) Engine P-795_745 at. Sea Level. Stat,ic Take-Off. Conditions, Engine.Pressure Ratio.= 1,455 34 XlV Comparisonof Prerepair-to-Postrepair Module Performance Improvements;JT9D-7_ S.P_) _EngineP-695745_ 35 XV Summary. of.EngineCycles / Timefor Each Source of Performance Data 37 1 !

XVl Engine . Comparisonsfor the_First . Approach; Spare versus ....................

Aircr aft-Del ivered Engines 43

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XVll Typical Gas GeneratorAnalySis Based on PIC Calibrationsof .

Engine P-695743 on 12-4-78ReLative to 4-18-78 69 XV LIST OF TABLES (Continued) Table. Ti t1____._e Page XVIII Module Contributionto Short-TermDeterioration. Based on Analysis .(at 14g Cyc]_es) of HistoricalData 7 0 I XIX Module Contributionto Short,TermDeteriorationBased on I Measured Performanceof Engi.ne P-695 7 43 after Cleaning, Retrimming..(at I_4_I Cycles), __nd Parts Inspection 7.1 _' XX. Average Module Contributionto TSFC Deterioration Using PIC Dat_ 72 _ XXI Comparisonof Module Contributionto Short-TermTSFC Deterioration _ 73 C-I. Pan American 747SP / JTgD-TA(SP) Engineswhose Repairs were Anal yzed 140_ C-II Pan American 7 .47SP / JTgD-TA(SP) Engine Prerepair._nd_ PostrepairTesting;. Summary of Engine Repairs 141 I_ D-I _ Pan . American-TestStand CalibrationResul.ts 153 D-II Summary of Pan American Thrust System Calibrationsby Pratt & Whitney.Aircraft 155 D-Ill CalibrationResults for Cox.Meter.-No. 23275 156 D-IV Cal.ibration Resu]tsfor Cox Meter No. 23276 157_ D-V Summaryof Fuel Flow Meter CalibrationResults 158 xvi SECTIONi,O_ SUMMARY This.report presents the results of an investigationconducted fr_n F.ebruary 1977 to February 1979 of. in-service JTgD engine-performance deterioration under the NASA JT9D Jet.Engine Diagnostics Program.. The primary purpose.of this effort .was to generate new data .under known.

conditions, to permit a. more . accurate _ definition of JTgD engine performancedeterior.ation tre n ds and levels, The in-servicefleet of 32 JTgD engines utilized in Pan American's fleet of 74" / .Special Performance aircraft was selected for this purpose. The selection of .

this engine, fleet provided the_ opportunity of obtaining engine performance data starting before the first, flight and. continuing through initial service such that the trend and levels of engine.

deteriorationrelated to both short- and long-term deter.ioration could be.more carefully defined. The performancedata col.lected and analyzed included flight, speCial ground.testusing a Plug-ln Console (PIC), and test stand prerepair and postrepair performance calibrations, The results of . the analyses of.thesedata wer_ used to: o R e fine preliminary models of performance deterioration, established in an earlierstudy conducted, under the_NASA JT9D Engine Diagnostics Program by filling in gaps and augmenting.

previouslyobtained historiCaldata, o Establ . ish an.understandingof the relationshipsbetween ground and altitudeperformancedeterior_at L on trends,. .

0 Refine preliminaryrecommendations . co n cer_ n ing means to reduce and control.deterioration, and ....

o Identify areaS, where-additionaleffor.t is required to develop an understandingof complex deterioration mechanisms.

The engine performance deterioration levels and trends were primarily determinedfrom two data sources. Short-termtrends were obtained from the analyses of the Plug-ln ConsOle (PIC) test results which c_osely monitored four engines from first flight to beyond_500 (cyCles),The longer term deterioration was establishedfrom Sea level_ facility tests.

of engines,with 700 to 2100 flight cycles before and after engine repair (overhaul). TheSe.data _,howedthat the prerepair performance " deterioration increased from.l.0 percent loss in TSFC* at 50 flight _mThroughout this report, performance-values in_Thrust SpecifiC Fuel Consumption(TSFC) and Exhaust . Gas Temperature (EGT) are referenced to sea level,static conditions..Engine - Condition Monitoring (ECM) data in Fuel .Flow (Wf).and EGT are referenced-to altitude..

co n di_ ions.

O , ycl e .S t :o3.0-perce n t at I000 cy t, les and .3._ perceF_tat._000 cycl_,s, The corre,_pon_:ling incre;_s_. - in- average EGT. was 5 to 33oc. Th e - pos t , re.palr .pe!_ i ot_1_ar i c o . . _I E _t_r! o!"ati Oilincreasedfr_-_11. 2.2 . perce n t al . I(!0!!.

cycles , to . 2.8.percent at 2000 cyc_les. C.orrespo n dif i g i n creases in EGT were ll_-to 21oC.

Models of performancE_.-deterioratio n were derived for the fan low- al_d k ' " , high-presSLire C_xl_presSor,. a n d,high- and.low-pressureturbine modul o S....

T, hese models--Include both module efficie n cy_nd flow capacitychanges.

, The TSFC deterioration at, 1500 fligh t Cycles as predicted from the module deterioration models wer_e: fan, 0.2. percent L low-pressure- Compressor, 0.6 percent; high-pressure aompressor, 0.6 perce n t; " high.pressure turbi n e, 1.2 percent; and low-pressure turbine, 0.8 percent., The Sun11_ t _tion of 3.4 percent e n gine TSFC deterioration i.s slightly below the average JTgD,7A(SP)measureddeterioratio n ......

The effect of , airpl.a n e acceptancetesting on_early engi n e perfonu;_nce deterioration was evaluated.from four Sets of data, each , of which. .

compared airplane-delivered , e n gines (which were, flight tested) and spare engines (which. were not f , light tested). No noticable , di.ff e re n ce_s in early reve n ue perfo_llance or deterioration trends wer e observed.

I I c) L_ 4 1 , ....... _.... a..w_,II ' i III SECTION2,0 INTRODUCTION The rapid rise in .tlie cost of_oil si.nce the OPEC_oil embargo in 1973_.

haS. resulted in a national effort to increase the availability of domestic oil, dev e lop alternate sources of energy, and develop near-• and.. long-term means to reduce fuel consumption•. To counteract the adverse impact of the world.wide fuel crisis-on the aviation industry,.

NASA has initiated the Aircraft E nergy _ Efficiency (ACEE) program.

Included in this program are major propulsion.projects'which are.

addressingboth near-termand long-termgoals. The long , term activities are directed toward developing propulsion technology to reduce fuel consumptionby at least 12 percent in the late 1980,s and an additional 15 percent,in the-early 1990's. the near-term activiti.es are a part of the Engi.ne Component Improvement(ECI) ProjeCtwhichuis directed toward ' improving the fuel consumption of selected current high bypass ratio.

• . turbofan engines and their derivatives by 5 percent over-the life of- these engines. The ECI project is divided into two subprojects, (I) Performance ._Improvement and (2) Engine. DiagnOstics. Performance Improvement. is directed at developingfuel saving component, technology for existing engines and thei_ derivativesto be introducedduring the 1980 to 1982 . time period. Engine Diagnostics is_ directed toward identifyingand quantifyingengine performancelosses that occur-during the engine's Service life and developingcriteria for minimizingthese losses.

The.first phase of.-tlie_ Engine Diagnostics project was the gathering,_ 1 documentation and anal#sis of historical._ data. The resulting informationwas used to establish performance.-deterioratiOn trends at

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the over.all engine and module level, estabtish probable causes contributi.ng to per.formance deterioration,, and identify areas and / or compon.ents_h . er e correctiveaction . couldbe taken. I i That effort was completed in 1978, and the results.are reported in....

Reference I. The-eff.ort reported in this doc_ne h t was directed towar, d expanding the understandingOf engi.nedeterioration by acquiring new ] in-service engine performance data from a-selected sample•, of . ,JT9D engines. This investigation was conducted during _ tlle period fr.om February 1977 to February 1979. The main source ofl data has been the i Pan American .World•AirwaysJT9D-7A(SP)engines which are installed in i their,i_leet of 747 Special Perf . ormance JT9D-7A(SP)aircraft which, were i introduced tn. service in March 1976. Data were. obtained •from , On-the-wing ground tests using expanded engine instrumentation, i prerepair and pos..trepair test stand, data, and. in=flight cockp . it__ mor L i tored data.

The data analyzed from these sources was then used to fill in and.

refine the analyticaldeteriorationmodels for the engine _andeD_gine modules e_tabl ished from the.earl.ier effort.

These refinements to the p_eliminary deteri.oration models considered, in particular, first, the results of the-analysis . effort of these studies, andthen the-models developed during the previous historical studies. It also, considers the resu.lts oflthe short-termservice engine test, as reported in . Reference 2, .

The following secti.ons ofthis report describe . thedata collection and analytical effort, the results of the analysis, deteriorationmodel refinements,recommendations, and conclus.ions. Supporting. documentation.

is included in AppendicesA through F.

SECI_ION 3.0 DATA COLLECTI ON_ AND ANALYSIS METHODOLO C II ES 3.1 DATACOLLE C TION_ __ The .objective of collecting per.formance and repair-type engine data was to provide an insight, into tbe_.trends and. levels of performance deter.ioratio11 with usage.

Engine performance data were collected on 32 Pan American JTgD-7A(SP) ranging from zero to more than 2000. engine flight , cycles. These- performance-data along w . itli the pe r tinent r epair data were used to.

doc_nent tl_-perfo_ance, history o f each engine. These data-covered both_short-, and long-term deterioration.

The data gatllered incltlded the foll owing: o Engine Condition Monitoring. (ECM) Data - These data consisted of the basic-cruise fl.ight performance data recorded by the .

flight cr.ews for . . ever,,y fl ight._ ECMdata were gathered for the full 32 eng!ne data base, starting from the-first revenue fl ights. .

o In, Flight Perfo r mance . Calibrations .- These calibrations were additional, engine _ and aircraft flight d_ta, recorded _ periodically,, on.specific engines by the Pan American (PA) Engineering Staff,.starting with the fir_ f.lights.

o Plug, ln Console (PIC) Testing - These tests were a series .of controlled instal,ted-engine_ground tests conducted by Pratt & ._ Whitney Aircraft (P&WA) and Pan American personnel with expanded i nstr _nent ati on. The PIC tests we r e conducted . concurrently with the in-flight calibrations to achieve g r ound / fl_i_gbt, perl_o_nance ca1_parisons.

o Prerepa.ir and-Post r epair Test Cel.l Testing - A series of prerepair and postrepai_ tests with, expanded instrumentation were. conducted by Pan American in conjunction witli repairs of the sample engineS. Engine.tear.down and repair data we r e also ...................

collected for these engines.

3.1.1 Engine Condition Monitorin 9 Data The Engine Condition Monitoring (ECM) data for 32- Pan American JTgD-7A(_S_P) engines in 747SP-airplanes were collect6d i_rom the fi r st 5 I revenue flight (when it was first recorded) through the first engine overhaul, or to December 15, 1978 when the data collection was completed, The ECM data included exhaust gas temperature (EGT), fuel flow (Wf), engine pressure ratio (EPR), low-and high-pressurerotor speeds (NI and N2), Mach number (Mn), air temperature, bleed valve position, aircraft gross weight, and altitude, The data are recorded by the flight ,crewon every revenueflight at steady state_cruiseconditions.

The measured data were compared with a set- of engine base-line performance data, and the changes .or deterioration in exhaust gas __ temperature,fuel flow, and high- and low-pressurerotor speeds at the measured engine pressure ratio were determined.These data _wereplotted as.functionsof calendar time, and the trendswere used by Pan American• to monitor any changes in engine performance.This collectionof_data.

provided_the data base for establishing 747SP fleet and individual airplane in-flight performance deteriorationtrends..A sample of ECM i_lJ.ght data relative to the base, line perfo_ance is shown in Figure I.

3.1.2 In'FlightPerformanceCalibrations In-flight engine perfomance data were obtained from a seri e s of in-fl.ightcalibrations performed by Pan American on selected 747SP flights.These calibrations, which were conductedconcurrentlywith the ground test _]ug-ln C onsole program, established:engineinitial flight performance, shor.t- and medium-te_m flight performance deterioration trends, and. a_.r e lationship,between installed flight and ground performan ce.

The performancecalibrationswere conductedon each ofthe four engines in two of the Pan American 747SP airplanes starting with the first....

flight, the delivery flight, and subsequentrevenue flights spaced to establish perfo r mance tr.ends. Calibrations were made by Pan American_ Engineering personnel_ using normal flight deck instrumentation.

Calibration conditions, were standardi.zed to the extent possible by 1 conductingthem at steady state.cruiseconditionwith the fuel heating and anti-icingsystems shut off-. One or two calibrationswere made at altitudes between 35,000 and 41,000 feet. The engine and airplane parameters that were recorded at each .calibrationpoint are listed below. I PressureAltitude P amb 1 !

Inlet airtotal temperature Tt2 Inlet air static temperature Ts2

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Mach number Mn Low-pressurerotor speed N1 High,pressurerotor speed N2 High-pressureturbine exhaust gas temperature EGT Fuel_flow Wf Engine pressure ratio EPR..

Numberofair-condition_ng packsiin use Aircraft gross weight _ TOGW A calibrationconsisted.ofat least four complete data. point sets where EPR on each engine was varied between 1.2 and 1.5. This variation, while holding total average thrust constant, was accomplished by increasing EPR on the inboard engines and decreasing EPR on the outboard engines; after dat_ were recorded at this condition, EPR was again varied by decreasing EPR on the inboard engines and increasing.

EPR on the.outboard engines and repeating the calibration.Steady state condi tions were establ is hed by watchi ng aircraft and engine instrumentation until stabil ization was achieved before._ manually recordingeach set of data points. In addition, a fuel sample was taken at the eno ofthe flight to establishthe fuel heating value. _ The recorded in-flight calibrationdata and fuel sample were delivered to Pratt & Whitney Aircraft and were processed in the same manner as.

for the ECM data. Changes were noted f o r exhaust gas temperature., fuel i flow, and high-and low-pressurer o tor-speeds versus engine pressure ratio at standard, conditions with the air-condi.tioning., bleed requirement factored out. Table I pres e nts a sample print-out.of the correcteddata which were then used in the subsequentanalyses.

3.1.3 Plug-lnConsole Testin_ ..

The Plug-ln Console (PIC) system was developed and operationally 1 checked out by__Pratt & Whitney Aircraft as a quick and accurate system i!

f o r measuring on-wi_nginstalled engine performance.A series of PIC _ tests, c o nducted by Pratt &.Whitney Aircraft personnel,were performed _ _ on two engines_of two Pan American 747SP aircraf_t. The first P. IC tests were conducted prior to the-first flight of each aircraft. The data !

from PIC tests combined with in-flight calibration tests were used to establ ish the initial and oarly engine pe_rformance deteri orati on. i This PICsystem provided high quality data on 15 engine performance i parameters.With the--exception of engine thrust, the PIC system records all test data that were normally obtained in an engine test stand..The _.

engine performanceparametersobtained are shown in Table If.

_ mr_...j, _ _ " __ , , , " "li i I'll IIi i I I ] i I II " I " I ° TABLE I SAMPLE P RINT O UTOF IN-FL I GHTCALIBRATION CORRECTED DATA RECORDED DATA CORRECTED - CORRECTED TO STANDARD AIR_ QNDITIQ N ING A PERFORMANCE FL e OH1 E P _ CONDITIONS _ REFERIENCE , CABIN BE ED RELATIVE TO C ONDITIONS t _ PERFOR M ANCE CORRECTION REFE R EN C E _ ..

.-- , , L,,, y T ' I t / C. A|R FL T ¢ONV' ER S|L'IN TO SEA LEVEl. |NSTALLE O C4tS GENERATOR (ShEE n COI _ I;tECTI (1 N [I§V|AT|L ' ?N TST| - | 6 / T -19,0 3 _ 9 0,8k? l,Tfl 1 7t 2 6, 9 6, 4 - 9_ , 3 |089 , . tT4 3 4 , 94,6 9 3 ,0 1 097, -|3|* 0,0 0,4 -5, . -1 , 0 l e T. 0,9 -3, "2 1,37 9 1T01|, 9_ ,4 9 _ ** 2 ]0 _ |TS _ 6 , q4 *B "93 , 8 l| O0, . - 1 3 2 , 0 , 0 0 , 4- '_ * .- - 2*4 0 , 5 Oe b -It, "3 1, 3 6 6 17115, 96,0 9 3 ,8 Y .084, X 7340, 94*4 9 3*0 I09 5 , - |3 0, 0,0 0,4 - _ , - 0,4 • |, 6. 0,4 - b e " 4' | , 5 02 3. 7 04.0, 96,0 93*S .1086, . 2? _ 64 , 96 , _ i 92 ,9 2094* "PI Z 9 * 0 , 0 0, 4 -S, " 0,4. ]; ,7 0 ,_ . - _ , TSTI J - _ 6 4 ? -- | 9*0 3 S4 O*S b ii 1* 3 3S 17146 * 9& , 4 94* 3 |0 _ * . _ 16, ¢)4*7 "3, _ .|O Q 8* --1 3 1, O*O 0,4 -- _ * . --|,2 |* / _ n, 8 -J, "2 | * 3Lqo 17059, 9 fl*S 94, 2 |084, 176 | 0, 9 4,9 9 3, 2 1|00, --132, 0 *0 0,4 - _ * -- _ , Z 0 , _ _ , 6 - 1 _ . L -3 | ,368 | 7| 31 , 9 5 ,9 93*7 |OBS. | 7 _ 8 _, 9 S**3 . 9 3,0 | 09 b , - |3 0, 0,0 0*4 -* _ , - O, b t * 4 . 0* 3 - S* " _ _ *J64 |7074,. 9 6,0 93,3 ]; 01i6, | 720?, 9 4, _ , 93,0 ]LOqS* - | 30 * 0 , 0 0,4 "S, . - 0,6 | ,6 0, 0 -_ , .

TSTI['| 6Z.7 " _ 4,0 3 ST 0 , 11 _3 2, 3 46 26 3 66* 9 5*9 9 4,0 _ 017 , Z696 _ . 93,8 9 Z , 6 !01)9, - ] | 27* 0,0 0,4 "_ * . "2 * 6 1-6 .1.0 -7 , " . i -2 ][ *3 47 _ 6; _ 4 | , _ ,2 _ 4. 0 1032, t6980..9 _ ,8 q _ *6- _ 0 _ 0,- - 2 2 7, 0 ,0 0*4 _ 3. . _3, 6 0 , 3 0, 9 "1 _ .

"3 Z,349 1166]L? , 93, 3 93*8 ] _ o' r ?.. | 70)8, 9 3 ,9 92 , 6 _ 09(1, -128, 0,0 0,4 - s, - ],6 1,3 9,7 - _ '% •".4 . |.34.$ 10443, 95.| 9 _ .0 .|O T _ . |6947. 9 3, 8. 9_ ,6 |OSq, -12 7. 0.0 0.6 -3. -2,; _ |.2 0 , 0 . -?* TSTE _ ] _ _ ? . _4, 0 _ 0 , 3|3 |,3 _ 7 ]; 641 _ , 93, 3 q 3, q 1077, 16 9 94, q _ * q 9 _ ,6 . | 090 , "!27, _ 0,0-0,4 - 3, "2*( _ - |*& 0 * 8 - _ * •"4 |*_ / *7 _ 6476, 9 _, 2 93,0 I0 7 8 ,_ |6 9 9 _ . .. 9 3 ,9 9 Z , 6 1 0 90 , . --| 27 , 0,0 0,4.-q, . - Z *2 |, 3 0,0 - 7 " ; _ | *_9 0 ] _ 6 5 49 , 9 _*_ 9 3 *9 |O ? Z, 210 _1 . 9 _ *0 9 Z , 7 I091, -12 _ * 0,0 0.4 - 3* -- 3*2 0,3 U*P . -1 _ ..

" 3 _ . _ .* _ $1 _ .6T09. _ 5,4 9 3 *7 lO T ?* 1T0 7 0, q A ,O 92.7 2093* . - | 28, O*O-O*4 _ * a _ * .-1 , ? _ . _ * / _ .. _ ), 6 -.q.

T STE-| 6 / _ r - _ q,o 3s7 0 , 818 !,34 6 |6 3 78. 95,6 9 4,0 |o' r ?, . . _ 6968, 93,8 92,6 | 089,. -127, 0,0 o,4 . - J J, - z ,6 1 .. . _ 0.9 -7 , -z | , 348 _ .6 8 84,.94.3 94 , 0 |071, . | 7 006, 9 3 , 9 92.6 _ 090, ,-|28, 0,0 0*4 -. _ S, --3 , 4-Q,4 0.9 * _ -*.

- 3 1, 38 0 ];6674, 9 _ ,4 9 3 ,? ]; 077. ]; ?044. 9 3 *9 92*7 ]; 09|, -- | 28 * 0,0 0 * 4 -- 5. --| ,4 | * _ O*b _ .

• 4 | * * _ 44 ]; 6473.*-93*2 9_ *0 107" / , |6 9 29. 9 3* 8 9 2* 6 |089, * | 27* O*O 0 , 4 * _, --|;* IS 1, 3 0.0 -7 , J TSTI['I 6 / 2 * _ 4 , 0 _ SST 0,8 _]; ];* _ k8 ]; 6309, 99* 3 94, 1 1 07 _ . 16999. *9 3 * ¢ _ 92*6. 1090, -| ; _? * 0,0 0.4 _ r _ , -? * _ 1 .4 I _ ,0 - _ .

- :_ ]; * 3 5 "_ | 6 3 39* . 9 4 , 2 9 _ .0 ! 012, 1707S, 94,0 _ 9:_.T _ 09 |, -]; 2 8,-0,(1 0*4 _ 5,- - 3 , _ O*? O* q "1 _ . _ .- - 3 1* _ 32 166 7 0 * 93.4 93 ,T 1077, 17075. 9 _ *0 92,T |09|, --128, 0.0 0,4 -.S, --]; ,6 ],3 0 *3 -q* • 4 ];,344 . 164b 2_ 93.1 q: _ .O _ 073 , 16961, 9 . 3,8 9? * 6 ];089* - ]; Z ? * 0,0 004 .-S _ - Z * Z 2.? 0,0 -70 , 7STE*I 6 /- 9 - "10 , 0 4 _ 0 - -0,3 _8 1.37 _ _ 3222. 96,]; 9 / *02 10 _ ) * 1 37 / _ 0, q _ *7 9 3 *1 1108 , -- 1 33 , 000 0,_ * _ * -- 2 * 0- _,3 0.0 -_ * " * 2 I,. _ TS ];6993, 93, 3 9 k ,4 ?0 _ * • 17 7 40. 94, T _ .2 ] _ 0 _ . . -1 _ , 0.0 0 , _ . _ . 11_ .3 , & L 0 . _ 0 . B * _ , - 3 1,376 ITTS?, 96,]; o _ .q _ 2 03 , I L T ? _ 8 , 94,8 9 3,_ 110 8 . - |_ 3, 0,O 0, _ " * ., 0,6 - 1 , 3 0.3 0,.

"4 1,37| 17184** 95.9 93,3 1100, 17 6 6'_, 94*6 93*0 1107, -13 Z * 0,0 0,3 -_ , _ l* / t- |* Z _ )*( _. - 1 , TST|'| O / 9 - ]; 6,0 4 _ 0 0,8 _ , _ 2,306 13185, 9 b . | 9 &,2 |098. 17 3 32. 94, _ 92, 9 _| 0 _ , -| 3 3 . 0,0 0,3 "_ * -_*_ ) _ * b O .T - | .

•" 2 | * . _ 7 _ 169 7 6* 9 _ *3 94.3 | 0 9 S* _ | 770?, .9 4.7 _ '3.1 !|0 7 . . - _ ? _3 , 0,¢) 0 , _ -_ , - 3 ,2 O*.q 0 ,7 -?, ....

• 3 | *3?3 176 3 3*96 , 0 9 _ .9 1. _ 0 ; , ] 7 ( _ 3, 9 ., ,6 98. ! |1 07. -_ 3 3 , 0,00*S - q, "-0*6 |.3 0 ,3 0 , .

" * 10369. _ 1T183*.9 _ *8. 9 3 , S 20W* 13608 * .94*S.9 3 ,0 1 106, - 13 2* 0,0 0*3 "So . -- 1,6.. _ . , Z O*O " ! *-- TSTE'I 6 / 9 "3Z*O- 4 3 0 0,85 Z !*503 202g 8 *101* ]; 9 _,? 1 163 , _ 0 _ 44.. _8 07 _ .,2 _ .| _ q. ( _ , n , _ ) 00 3 O* -2 . ; _ _,3 0*6 f . .

"Z 1 , 203 _3 702, - 9 0 ,4 91*8 | 00 _ . | L4 _ 5 _ , ..8 9,]; 9 0,8 10 _ 4,- O * O. 0 0 * 8 0 * r _ " 8 -- 2* _ 0 * Z " _ * - 3 l*_ O] l _ ll?, ql, 5 92. 2 1 02S, 14S17. 89,0 90,7 10 _ 4, O, (1,0 0,8 O, - _ ,6 _ . * *, 0*6 - _ * "4 .... |, 4118 Z O] _ ?* _ O0*O 9 * ,*6 ];1 6 4, ---20|7 _ * qB* ? -94,1 || _3 , O* 0,0 0, _ t O, .- _ 0 , 2 1, _ " _ ,3 . |1, _ ST S * _ 0 _ .9 -3 Z *O _ 30 .0 ,8 31 |*; _ ; _| | 4 8 0 7* 9 _ ) *? 9 3 *2 | 03 3 * |41t q A. R9,7 9_ ,0 | 060* O * 0 , 0 0.9 O * -3 , 8 2,&--0. 3 - _ .?* .

" _ 1, _ 1 _ 0061, 1 00, 0 e3,8-11 _ 6, . 206 _ *,,.* _ 8, _ _ , 3 1161, O* (1,00*U O, ., 3_ .9 t*X 0,6- - _, - 3 |, 5 1 8 20864, 1 00, fl 9 _* $ _ |69, _ 2 073 _ |. 9 _ ,9 94. 3 _ .62 , O, _ 1,r) 0 ,_ O . --0, _ |,R (1.2 _ *. .

|*_ |8 - 1 4363,. 9_ 38 19 1 , _ * ] _33, ... _ . _ 1 _ 31 _o 89,6 90*q 1 059* O* 0,0 U* 8 O* -3* & 1 , 8 _ 0. 1 -_ , T A BLE II E NGI NE PERFORMAN CE ? A RA MET E R S - RECORDED B Y THE - PLUG -IN- CO N SOLE SYSTEM Temper atures Pres sures Other T arab P arab N I ....

T t 3 Ps3 . N 2 Tt4 _ P t3 Fuel Fl o w. .

T t6 avg, P s 4 Vane Angle Tt6 indiv, (6) P s 5 Tt7 avg,. Pt7 .

Tt 7 indiv. (6)_ . _ Total 5 6 4 15 Total Data Parameters The PIC system is schematically shown in F _ tgure 2, The system consistedof: o an engine , interface harness . , including electrical cables and tubing t o the pre ss uretransducers; !

o_ a modified trim mast to guide cables and tubing through the fan stream; o. a temperature-controlled pressure . transducer box;_ o a data rec o rding...S_ystem (da / ; a logger)_ and o a Hewlett P . ackard 9825 minicomputerfor reducing the data to engineering units, applying standard day._, correction s , and calculating pr e limi nary module performance, The installationof the interface harnes s is shown on F igure 3. The trim . mast, transducer box, and leads into the cabin,are shown on F ig u re 4, The recording system and, J _i J _computer on board the aircraft are shown on Figure . 5, During the PICtesti . ng, all c o rrected parameters were calculated by the m inicomputer and plotted, f o r - data validation and compared with data from previous te s ts., F igures 6 and . 7 s h o w a ty.pical _data p_int and p_]_Qt s _pr__ 9 _pa)t e dH, dqri._{)g a PlC te s t.

I

" ' : ..... , ," " , "* " l " Ii .... i* i _ " -r ' " ]_1i " i i lii I i II I I I I I l / ,-Data recor d er a nd minicomputer / . _ loc a ted in a ircr a ft .

Forward f I_/ [ _ % Modi fi e d _ .Trln L M a st" e l ec t r o nl c , // - - ' _ -- " _ e - / - _

J J r ' ' " ' , w '' ' - )

Transducer. box-- _ Figure 2 Location of MajorComponents of the, P]ug-lnConsole System -_ The instrumentation lines are. cOnn e ctedvia the modified trim mast to the tranSducer box or: dir e ctly to aircraft to . the _pecial data recordingsystem loCated.inside the aircraft.

F.Igure 3 Installationof the-PIC Sy , stem Instrumentatio_ Harness.- T he .

instr_nentation harnesswas instal.led prior to each test, _._ ..... ,- ,,,, - _ , , - , , , - . , :, ::...... . - _ ,_ m , w ,_ Figure 4 PIC System. • Instrumentation - The transducer.,-box and instrumentation, leads into the cabin are_shown .....

.... y- ) " I

I

Figure 5 PIC SyStem Data Acqui_.ition Uni.t-The recor, ding equipment i and the HP9825 minicomputerare shown.

!

_ .i. _ ,-. __ _ __ " , • , "_ ,r i ill li II flail l II I , ,I I i -i II I II IIII III ' r - .............

, * w F l g ur.e 6.. T ypical PIC Data System Print-Out - Tabular data in strip chart form is output from the minicomputerfor plotting and p, reliminar.y analysis, o O, I I l l ' _ _ ll l l • " - i i ..... i i 41_ " 'd I!

._ • | I.... _ , ; . _ . . . _ . I ...... ! . _.... t , I......................................

, . ..... _ _ , . , . _ _ I _ i , .,' . .._| ........ I , _ * I , . , ' ..... _ _ ..... _.I ....... , .... , .......... ! ',:: :::: . ::: :' .'. : '.: ' . ' . : ' , ' ,' • _ ; _ 'J' ' I _" _ : ; _ : ' : _ ; _ ; _ : i : .' .... ! ; ;: if :; _ i ' . _ ' _ : .... ' i ' i' i il "J;; :';: ' :; .. : _ ; ,' _ . .i i : " ; ..... :' . "' ; ; " '" : i :: *' : • . _ _ ; _ • Z " _ _ " : : .' _I .... _ ! Il l Z _ , , . ' : .':: , .: ' . . : ...... : :' : " : ::.: :, , : ' , ........ : l_._li_,II , . . h,_.h , ,ll_i,,l_Jh,, J _.i , Ii!!_l,.._ll , ,, i ,, I!!!l._,i , , _,_ , .l .. ,li._i l ,, ,, l ,i , . J ,_,il, , ..l, , . l,, , , l i : i_l i : _li_il _, l , , . ,l ., , . l .. I ,_i i_l_l : i!!l!,!ilii' :l .......................... l!,_ll!.I F ig u r e7 T y p i c alP l ot o f O n -Wi n g PI C Cal i b rati o n o f , .T T g D-7 ( S P ) E ng i ne _, P - 695745 - P l o t s of the d ataw e r e m a d e t o pe r m it c om p ari s o n withpreviou s calibrati o n s and to check on d ata q uallty.

( 0188 5 9-8 ) T en s et s of P I C calibrati o ns werema d e o n the Pos ition I an d 2 engine s o n Pan American74 7 SP air pl aneN 536 PA st artin gp r lo r t o the fir s t fligh t . T he date s ,engi n e a g e, a n d t e st lo cati on are l i st ed o n T able i Ill.No t e that engineP- 695 74 5 wa s rem o ved , r epai re d , and rein s talled. -- o n a different - airplane pri o r t o t he las t_ t e st . S_x s e ts o f P I C calibra t i o n s weremade o n t he P os iti o n I and 2 en g ine so n P an American _ 747SPairplane . N 53 7PA. The da t e s , e n g ineage,and loca t i ons are li s te d o n Table IV.

1 4 • , 6 'E ._ "= TABLE Ill CHRONOLOGYOF ON-WING P;IC TESTING 747SP AIRPL A NE.N536PA; ENGINES P-695743 AND P-695745 Date _ Hour___E _ Test Locati on 5-09-77 -743, -745 18 11 JFK - NY i 4-21-77 - 7 43, - 7 45 0 0 .......... Boeing- Seattle 5-16-77 -743,.-745 110 19 JFK- NY 5-19-77 -743, - 745 155. 23. JFK - NY ! 6_-20-77 " -743, -745 614 91 _ - JFK - NY 7-18-77 -743, -745 1021 133 JF.K,- NY 11-02-7 T -743 1081 141 SFO, 11- 02-Z7 -745 2486 365 SF0 2-11-78 -743 2473 360 JFK . NY 2-11-89 -745 3878 584 JFK - NY 4.13-78 -743 3415 475 . SFO 4-13-78 -745 _ 4820 700 . SFO .

12-04-78 -7.-43 6903 1078 .................................. LAX TABLE.IV CHRONOLOGYOF ON-WING. PIC TESTING 7 _ 4.7SP AIRPLANE N 5 37PA;ENGINES P-6 9 5760AND P-695763 Date -- Hour_ _ Test Location 5-04-78 0 0 TBC 6-07-78 52 15 TBC.

6-27-78. 297 54 SF O .

7-20-78 .............. 609 II0 LAX .

Ii-05-78. 2224 331 JFK --NY 1.04-7. 9 3165__ 510 SF0 3.1,4. Test Stand Testing_.

Prerepair and postrepair t e sting with.expanded test,instrumentation was conducted On JTgD-7A(SP) engines, from the Pan American 747SP.

fleet, as they came.into the ow_rhaul_shop for repair.. These tests,.

for the .most part, were-conducted by Pan American at their J. F, Kennedy maintenance center. However, for those engines which were repaired by Pratt & Whitney Aircraft, the tests were conducted at the P&WA Middletowntest_faci] ity.

The-engines were.tested in a partial.Quick.... Engine Change (QEC) ._ configurati on with bellmouth-type inlets, flight nacelles and nozzl es.

Test data were.taken at stabilizedsteady state operating conditions at a minimum.off.ive power settings between take-off power and idle-._ The expanded, instrumentationinstalled for these tests permitted the recording of the parameter data listed below at each engine operating.

conditi on: Bellmouthinlet total pressure Pt2 Low-pressure. compr e ssordischargetotal temperature Tt3 Low-preSsure .compressor dischargestatic pressure Ps3c__ Low-pressurecompressordischargetotal pressure Pt3c High-pressurecompressor__Z__ge total temperature Tt4

!

Burnerstatic pressure Ps4 High-pressure-turb._ine inlet statiC pressure Ps5 i High-pressureturbineexhaust gas temperature,average Tt6 High-pressureturbine exhaust gas temperature_,. 6 points Tt6 _ Low-.p_essure turbi.ne exhaust g_as temperature,7 points Tt7 Low, pressureturbine__exhaust gas temperature, , average - Tt7 i Low-preSsure_..turbine exhaust total pressure - Pt7 .!

Net thrust ..... Fn Euel flow Wf ---_ Low-preSsureroi_or, speed N1 High-preSsurerotor speed N2 Variable. stator _vane bell crank angle Barometricpressure P-bar_ Dry bulb temperature T,db Wet.bulb temperature - T wb '_ Test-stand_.pressure depression,front P cdf ; Test Stand pressure depression,, rear P. cdr .. ..... L J = Test data were recorded and . transmittedto Pratt & Whitney Aircraft .

for reduction and preliminary analysis. Adjustments were required to I!

correct the-test data from partial QEC engines in both Pan American and P . ratt& Whitney Aircraft test stands to permit comparisonswith test data from original production bare eng!nes in the P&WA test _ stands.Data processingflow is illustrated in Figure 8. __ L_" L L j . . { I : i '_ i I: I Executedon II • I ..... [..,,T ' , ! .... d a t a re d uc ti on_.

I i = , i .l .i 4_u . j storedon • p , 6 , etc cor r ec t ions li _ i _ l ; _ T' : ' _ i,:_ ; co m p u t e rfile • P r tssu re ratios "":'""':' ; ,.,. ,_ E_ _ [ _I I E_. p ros ra m: i " ' _L_ . . "i . ' • Testceil co r rec t ions L .;;t ' _ , - _ _ -; _ ; i " .

t;_ ' _' " ; ¢ _ Keypunch , - ° cr e at e plot file .

P r e and / or a s necessary _ PIot file ..............

post.repair _ ...._ . f los sheet : 1 Checkcomputtr dt l wn CUrVO$ .. 2 Rea dcu r v e sat fro m p'oduction Wf _ ' 3 inputcon st , E PR en 4 ine KC, _ T2 KH " . , pa r amete rs into Newen , neda t , _ ) , : _ EPR;const.

da t a base , .... module perfor ma nce r analys i sP r os ra m • : ' 4 R u n program, v e rify " _" reasonableness of r e sul t s -- . ..', • -- ...... i Pt7 / Pt _ Eigure8 Data. Processing Flow for Prerepair.-and P o strepair - Test Stand Testing -. The-steps in prccessing test cell data from test log sheets through prelim.inar.y module analysis are_shown schematically.

Ten sets of prerepair-and poStrepair tests,, two prerepair-only tests,.

and !2 postrepair-only tests were conducted on 19 . JTgD-7A(SP} engineS.

Table -.v presents a list of these engines with their removal dates, _ engine ages in hours and flight cycles, te_t dates, and test locations. The table also lists the engine prerepatr and postrepai.r changes in TSFCand E GT relative to the new engine acceptance test, ba sed O n th e analy s is ofthe te s t data w he re b o th pr e r ep air a n d po s trepairte s ts were completed.Yhe corrected te s t data, along with the engine tear d own an d repair bui'_ddata (Section 3 .3), were then use d as input to the detailed_top-down analy s i s (Section 3 .4,2).

3.2 PAN AMERICAN TEST STAND INSTRUMENTATION AND TEST DATA UNC E RTAINTIES 3.2.1 ExpandedInstrumentation The Ran American-test stand incorporate s visual instrumentation, and data was visually_ acquired and recorded on engine test log _heets by the test stand crew. The parametersnormally recorded were limited to_ those required for production engine performance testing and by the phy s ical dimensions of the instrumentationconsole. For thi s program, additionalinstrumentation was_installedin the-test stand and control room for the-additionalengine parametersrequired. The chromel-alumel temperaturesystem was expanded to include.oneTt3, one Tt4, and seven Tt7 readings. All of these temperatureswere recorded on the existing Doric Mode] 400 indicator-via ten-channel select switches. Provisions : were also made to record eight bellmouth Pt2 and two cell static_ pressure readings on U-tube manometers with a 30 inches of water capabil_ity that were alreadya.vailable on the Pan American test stand.

3.2.2 Test Stand Instrumentation Calibrations _, 1 The performance instrumentationon the Pan American test stand was calibrated in-place by the Pan Am Instrumentation personnel. The normal calibratio, . interval for the majority of the instrumentation is .....

six months. However, the calibrationof the test stand instr.umentation_ was dependent on the engine test requirementsso that the actual time intervals between calibrations varied. Whenever-possible, Pratt & _ Whitney Aircraft._ Instrumentation personnel were present for the calibrations.The instrumentationand calibration procedures utili z ed by Pan.American were developedlin accordance with the accuracies defined by the Pratt &. Whitney Aircraft Test Instruction Sheets (T.I.S.). No. special modifications were made to either the instrumentatiozL or to the proce d ures used in conjunction with this program.

ThekPan American thrust system (indicator,cable, and load cell . ) and the fuel flow meters were periodicallybrought to East Hartf o rd for _ M calibration.in the Pratt . & Whitney.Aircraft Instrume n tation Standards Laboratory. The master , thrust system was calibrated three times and the flow meters_(meter _numbers 23275 and 23276) were calibratedtwice. 1 The resul,tsof the flow meter calibrationswere compared to the Pan American results obtained using their Cox InstrumentsCalibrator. The.. i' master thrust system calibrations were compared to the primary Calibrati ons performedby the manufacturer(BLH).

I g Detailed discussi o ns o f th e Pan American test stand calibration standards, procedures and results, and of the thrust system calibrationsat Pratt & Whitney Aircraft are presentedin Appendix D, 3.2.3 Measur_ent Uncertaintiesof the Pan American Test Stand Ins trument ation There is a degree of uncertainty in all test stand performance measurementswhich must be considered in the subsequent analysis of the recorded performancedata. This uncertaintyis a function of the f.ollowing: (!) accuracy- of the installed instrumentation, (2) thoroughness and frequency of instrumentation calibration, and (3) accuracy of the reference or master instruments.A summary of the Pan American test stand instrumentationuncerta.inties is listed in Table VI.

TABLE VI SUMMARY. OF TOTAL PARAMETEIt: UNCERTAINTI ES Parameter _ . Total Uncertainty Pt2, "cd (% Reading) * +0.50 P breather (in. HgG) _.13 Pt7 (in. HgA) ¥0.35 Pt3 (in. HgA) T0.48 Ps3 (in.HgA) __0.052 Ps5_(in. HgG). +5,57 Ps4 (in.HgG) ¥3.10.

Barometer (in. HgA) _0.28 Tt3, Tt4, Tt6, Tt7 (oc) +6.3-to+13.0 Tt2 (OF) - +2.8_" I Thrust (Ib) +136._ NI. (rpm) - +5.

N2 (rpm) +I-0.

Fuel Flow (% Reading]_ -+0.46 TSFC (%) _0.55 •U-tubesemployed for eight bellmouth Pt2.pres.sures and one Pcd pressure.

A detailed discus s i o n o f the factors c o ntributing t o and the derivationof the above data. uncertaintiesis presentedin AppendixD, 3,2.4 MeasurementUncertaintiesDue To Data Sampling and Engine Configurati on D_fferences Analysis of test stand data was subject to other uncertainties in measurement hardware and calibration equipment which have just been i addition to the measurementuncertaintiesassociatedwith the physical.• discussed.One major source of this type of uncertaintywas sampling error. This error referred to..differences between measured parameters and true average parameters .... resulting from a limited number of measurement points in a flow field which had significant circumferential / radial profile variations.This uncertainty has been particularlynoticeable_in the measured values of Tt6 and Tt7 from prerepairand postrepair data, where repairs involved burner liner replacement. All.of the JTgD-TA(SP)engines for which prerepair and postrepair data were available,had burner liners _ replaced during I_ repair, (in most cases by liners of.a different design),Comparisonof -

I

prerepair, and postrepairdat_ for these engines• showed that while TSFC improved as a result,of repairs in near.lyall instances; thereby inferring reductions in both Ft6 and Tt7, the measured Tt6_and TtT values increased from prerepair to postrepair, in several engines..

Moreover, individual_ engines were not consistent,in trend, some , exhibiting increases in Tt6 but decreases in Tt7 as a.result of repair, others with increasing Tt7 but decreasing Tt6, etc. The conClusion is that the burner liner r.eplacement (and possibly other repairs) resulted in a shift in the temperature profiles at both locations. Since Tt6 and.Tt7 probes wer.e-atdifferent locations both circumferentially and radially, a profi.leshift could result in changes in magnitude and / or direction of,measur_ed values at the two locations (althoughanalysis shows that the average values of-the two.

should change in the .same.•direction and by nearly the same magnitude).

As an indication of the magnitude of this uncertainty, differences between thermodynamic(the true average value based on fuel flow) and measured temperatures of 20 to 30oc or more have been observed for individual JTgD-7A (SP) engines, with differences of 10oc or more common..Incomparisonto the instrumentation accuraciesshown.in Table.

VI, it can be seen that the sampling err.ordifferences can be_quite signifi cant.

Data sampling uncertaintieshave also been.observedwith.Tt3,.Pt3,and.

Tt4, but to. a far- lesser extent than with the hot_ section.....

temperatures.As. a result of Tt6 and Tt7 uncertainty,the analysis .

methodology had to be modified (in most instances)to disregaradthe -.

measured values of Tt6and TtT. The analysis_ methodology is discussed .

in more detail in Section 3.4.2 ..........................

There was also a minor area of hardware-relateduncertainty where.

engines have had retrofit part changes after introductioninto servlce (P-686 series of JTgD- I A(SP) engines). Production data for such engines were adjusted to reflect estimated performance changes associatedwith the part changes, In •other words, these eng!nes were treated as though they came off the production line in the retrofit configuration, These .retrofitchanges may have removed some part deterioration that was present,, thereby making the analyzed performancedeteriorationless than was really the case. This was not.

a significantproblem however, since the retrofit was accomplishedon most of these engines early in their service lives. Another uncertainty had to do with production tolerance variations for the retrofit parts; the data _djustment reflected a nominal part configuration.Because of the limited scope of the retrofit changes, this was not believedto be a serious problem.

3.2.5 Test Stand Correlations It was necessary to apply corrections to the_Pan American test stand data in order to make a direct comparison between engine test parameters recorded in Pan American'stest stand and parameters recorded at Pratt & Whitney Aircraft, during the prod uc.ti on test run of- a particular engine. Cell-to-cell corrections resulting from back-to-back _testing (at Pan American and P&WA) of_P-695745, were used. I These corrections represent the most recent back-to-back tests and I were believed . tobe_t_he best correlationavailable.

The uncertainties in airline test stand data analysis were caused. ] primarily by hardware differencesbetween the engineconfiguration as tested inthe PA stand and in the productionconfiguration. Generally, engines in the PA test stand are tested in the partial QEC configura- tion. The engine is tested with bellmouth inlet and .actual flight nacelle rearward of the inlet. For the productiontest, on the.other hand, the engine has a bellmouthinlet and special productionnozzles;- fan dischargeflow is manifolded and dischargedthrough two long ducts with convergentnozzles. QECcorrections were used to correct the data • for differences_between the two configurations. However, these corrections cannot account for physical jet area.differencesbetween differ ent_individualflight nozzles ands.individual productionnozzles.

These-, differences-can amount to +0.5 percent or more in jet area because of production tolerances.- Nozzle area_variations, of this.

magnitude can significantly affect measured_gas_generator parameter and, therefore,the analyzed component, per=nrmancechanges as .well as overall performanceloss.

J 3,3 MAINT E NANCE DATA COLLECTION The "top down" analyses of engine performance deteriorationon both engine and module bases were aided by knowingthe extent of chan_es in gas-path conditions, in each module, that contributed to the performancechanges,These conditionsinclude airfoilwear, changes in blade tip-to-seal clearances, and thermal distortion effects.

Likewise, the analysis of the postrepair performance restorationwas aided by knowing which gas-path components were replaced or rebuilt and the as_s_embled . dimensions and clearancesin the gas path.

Performancedeteriorationand restorationanalyses were made on the 19 engines listed on Table V. T]_eseanalyses included 12 prerePairtests and 22 p u strepairtests, The prerepair and postrepair engine condition data and the exte_t of repair was collected for each engine from Pan American (PA) and P&WA repair records, P&WA Servi ce Repre s entative Reports, and by measurementsand obser.va_tions by P&WAEngineeringspecial.ists.

Detailed prerepairinspectionswere_limitedto three engines since,the Pan American 747SP engine-repair schedule did not permit time for inspectionprior to each engine overhaul or repair. The three engines included serial numbers P-686060 and P,695745,which were repaired at - .__ I the Pratt & Whitney Aircraft (P&WA) Service. Center, and P - 686049, _!

which was removed after 11,663 hours of continual operati.on. The teardown i_ns pecti on . of the disassembl ed mQdul e s. included: o Blade.tip to outer air-seal (OAS) clearances and OAS rub depthmea su re m ent s ; o Inspection of airfoils and seals in disassembled modules incl uding.theextent and type .ofwe.ar_ and distortion; o Inspectionof.combustor includingwear, distortion, burni.ng, and cracking; and o Measurernent of sample fan blades from engine. P_-695745 irlcl udi ng surface roughness,wear, and distorti on.

In addition to the prerepair and / or, po s trepairtest performancedata, information was__collected for all_maintenance actions including the following: Eng_ine hours and cycle s since the last repair; Causes _of .current. and past engine removal s; Prior repair hi story; Comments on condition.ofdisassembled modules Modules replaced as part .of th e overhaul with repair history on each rep_lacement m o dule;. _ Partreplacement and rePair on engine; Gas-pat,h measurementsand clearanceson built-up engine; and .

Subsequentchanges and repairs if initial repair does not achieve required performancerestoration,.

The 23 JT9D-TA(SP) engine,repairs wh,ich were analyzed during the .

program are summarized in Appendix C, Information in this appendix includes: En g ine removal date, removal,cause, who repaired t.heengine, and the extent of the.repair; Prior operatingand..repair history; Identification of the variousmodules, their operating hours since refurbishment, and which were i_epl aced during this__epai r; Documentationof improvementsin thrust specif.ic fuel consumption (TSFC) and exhaust gas temperature-(EGT) resulting from this overhaul (.fore n gines which received a prerepair and postrepair test);and Sample teardown.and build.up data on. one oft these.23 engine repairs, .... • ......... + . + .......... + +-+. + , ++ .. : ....... _.,_,. . ,,,., r ,,,e,m_,., . _ .......... '' '"++........ _ .......... -+-.+-+ ..... +_m'_._,_ 3,_4 ANALYSISTECHNIQUES 3,4,1. Flight Data and Plug,ln Console Data During this investigation the flight data included, both Engine .

Condi ti on Moni t ori ng (ECM) data and i + n-fl i ght performance calibrations, Plug-ln Console (PIC) data were obtained from on-the-wing engine tests at sea level static conditions, These types of. data are di scusse.d_i n .the .fol+l owing paragraphs, The ECM data were corrected+to _tandard day conditions by a computer--- program, Additional corrections were applied for Re_olds number, Mach number, and aircraft service bleed.variations that normally occur-in revenue service in order .to.further normalize-the data. No corrections were made for +. variation in. fuel. lower _ heating value since this information was. not available. The normalized data were then compared .........

to a set of generalized engine, gas generator-curv.es and ten-day averages of the resulting deltas, were plotted versus cycles for --each engine, Since thes_ trends still exhibited erratic variations in. +_ engine performance, smoothed curves were drawn of ea_cch curve for comparison_f.all engines, The in-flight calibrationstaken on two aircraft (serial numbers N536 and N537) were_reduced to a usable form rsimilar to the ECM data, However, rather, than comparingthe data to a set of generalizedengine gas generator curves, each engine's data were compared to that.

engine's first in-flight calibration.Gas generator parameter deltas were then calculated_at constant,engine pressure ratio _EPR__] L . and p!.otted versus cycles to establ ish individualenginetrends, The PIC data taken on.-the-wing at sea . level, static conditions were corrected to standard day conditions with additional correcti.ons applied to correct for variations in fuel lower heating valve .and ........

water content of the air._An additional correctionwas made.to the data taken, at Boeing to account for the appar.ent presence, of a vortex being ingested into the inlet of-the engine, Analysis ofthe data for all four engines involved , in this part of the program exhibited +, improvements in fan and low-pressure compressor performance between..

tests at Boeing and subsequent tests elsewhere, These improvements were.not expected, Investigationof the manner in which these tests.

were-.run revealed that all Boeing tests were conducted with a_screen placed in front and partially to the-sides,ofthe-engines to reduce the.possibilityOf foreizjn object damage to the engine, Experi.ence at Pratt & Whitney Aircraft has indicated that the presenCe of .such a.

I

I

devi c e in ' relativelyclose proximity to the engine produced a w eak vortex _hat was ingested by the epgine,Thi_ resulted in losses in fan.

and Iow-pressure._compressor performance, The.performancedeterioration for each of the four enginesfollowed in the PIC program was determinedstarting with tJne. ProductionAcceptance Test data and _pplying corrections to it based , on other testing to synthesize_ the data , to , an outdoorflight nacelle configuration.These data were compared to the measured deltas between Production AcCeptanceTest data and on-the,wingPIC.data,and a comprehensivegas generatoranalysiswas performedto assess modular performance . , changes required to close the tw_ sets of . data._ These. losses were then removed for the subsequentdata analysis. . Each subsequentPICrcalibrationwas.

compared to the previous calibration, and an assessment . ofmodule performance changes_ based on. an analysis of the gas generator - parameter - changes was made, Finally, the accumulat.ivemodule performancelosses were plotted versus engine cycles to establish the modu]e and overall engine performancedeteriorationtrends relative.to the reference, base line. -- Based on comparisonsof the .threetypes of data, it may be concl_ded that ECM . data provided a broad data base, in-flight performance_ calibrations provided better-controlledflight data, and PIC data ..

provided accurate installed ground data in the-same time frame as the in-fl ight calibrati ons.

3.4._2 _ Top Down Analysis of Prerepair and PostrepairTests The top down data analysis approach has_been. previouslydescribed . in Reference I, NASA report.CR-135448, on historical- data studies. To summarize,this approach uses a computer simulat.ion of the JTgD engine which has been modified through the addition ofspeclal iteration balances.These iterationbalances were used to modify efficiency and fl . ow, capaci.ty levels for all components in order to match,shifts in measured data parameters relative to the base-line production values for-that particular-engine,The measured data parametershifts were obtained..... after correcting t ' _e engine .. testcell data,, first .for standard condi tions of temperature and humi di ty, then for airline-to-en.gine, manufacturer test . cell differences (t,: :, t cell corrections). The data were also corrected for differences in tes.t configuratioErel_tive to productionbase-.line (such as nozzles), and finally, for any retrofit part changes , that have been made to_the engine , since the original. , productionConfiguration. The test cell and_ configuration Corrections used represent revisions based on recent P-6957.45engine-correlation testing and Pratt & Whitney . Aircraft back,to-backtesting of productionand.flight nozzles. The result of the analysis was a simulation point for_--thedeteriorated engine, listing all the component performance shifts, requ.ired_ to match that particularset of data. The approach reduced the inherent inaccuracies of influence coefficient techniques that. had traditionally been employed in performancedeteriorationanalys.is and could not properly account for nonlinear sensitivities and. component interaction effects.The top.down analysis procedure is schematically illustrated in F igure 9.

Engine test Modify co m p u ter data@ X cycles engine si m ulation % A Fn % _ W f Adds p ecial % 6 N 1 , etc iterati o n balances Analy ! etest data Iteratesto m atch: % A Fn % AVVf % AN1 e t c Co m po n ent variatio n s calculated _ 7fan A f anFC A 7 7 LPC, etc Figure 9 FIow Diagram f o r - "T.op Down" Analysis - Top down analysis begins with measured engine performanceparameterchanges and utilizes the JT9Doengine simulation to analyze the module performancelosses-required to match the_performancedata. I L 1 In general, the test cell data analyst s of JT9D-7A(SP) engine performancechanges_includesmeasurement of Pt2, Tt2, Pt3, Tt3, Ps4, 1 Tt4, Tt6, PtZ, TtT, Nl, N2, thrus.t, and fuel flow. In theory, this was i a sufficientnumber - of parameterst o permit independent determination of efficiencyand flow capacity for all five componentmodules. Table ] VII illustratesthe top down iteration logicrequired. It should.be !

pointed out that although the. iteration balances were-specified in

I

' 1 '" d _ . . . ........... .... , ii i_ ]= • i i i i i i i i .... i I T ......... _ terms of variable pairs (for example, vary A6 to converge Tt6), the final solution incorporatesall variable interactions..(i,e,, effect-of..

A5 and other flow capacitiesand efficiencieson Yt6), TABLE VII.

ENGINE SIMULATIONITERATIONLOGIC FOR.TOP.DOWNAPPROACH._ Observed ParameterShifts ComponentVariable Iterate,d .

Percent_Changein NI. PercentChange in Fan F.1ow Capacity PercentChange in N2 Percent Change, in High-Pressure CompressorFlow_Capacity ..

Percent_Change in Pt3 / Pt2 Percent Change in Low-I)ressure Compressor..Fl ow Capacity; PercentChange in Ps4 / Pt7 Percent Change in High-Pressure Turbine .Inlet Area Change in__T.t3 Change in Low-Pressure Compressor Effi ciency _ L_ q Change in High-PressureCompressor 1 Change in Tt4 Efficiency Change in Tt6 Percent Change in. Low-Pressure Turbine Inlet Area_._. I Change in Tt7 Change. in..Low-Pressure .Turbine Effi ciency 1 Percent Change in Fuel Flow Change in . High-Pressure Turbine Efficiency PercentChange in Net_Thrust _ Change in Fan Efficiency In practice,_ however, because both .Tt6 and Tt7 for individualengines were subject to significantradial and circumferential, profile effects which masked, biased, or--otherwisedistorted the true .thermodynamic average temp_erature at these locations. Therefore, it. was generally found to be necessary to "couple"-fan efficiencyand flow capacity as.

well as tow-pressureturbine efficiency and flow capacity. Table VIII shows, the modified top down iterati,on logic required because of Tt6 and .

Tt7 accuracy lim,i.t_.at!ons, This iterationlogi.c.._wa_s . .....use.d_..for.an.a.!.ysis... .................

the test data, The concept Of Coupling was.developed in the historical.

data analysis efforts wlierethe numberof-parameters measured was not - adequate to. define the unknowns, Briefly, it involves using a known.

quantitative relationshipbetwee h efficienCy-and i_lowCapacity Cha r lge for a.given comp o nent,thus, the term "coupling."-wasused. Generally, this relatlonsI_ip-had been , Obtained from component rig _testingwhere- tip clearance was varied,, or from back-to-backtesting where module_ were "swapped."

I TABLE VIII MODIFIED £NGINE SIMULATIONITERATIONLOGIC USED IN ANALYSIS I Observed ParameterShifts CompOnentVariable Iterated PercentChange in N1 . Percent Change in Fan FIow Capacity (Coupledto Fan Efficiency.)

Per_cent Change in N2 Percent Change... in High-Pressur e .- Compressor_Fl ow Capacity PercentChange in Pt3 / _Pt2 _ Percent Change in Low-Pressure Compr e ssorFlow Capacity .

Percent C ha n ge in Ps4 / Pt7 Percent Change- in. High-Pressure Turbine InletArea Change in Tt3 C hange . in Low-P_essure . CompressOr Effi ciency Change. in Tt4 .......... Change in High - Pressure Col n pre_sor____ .

Effi ciency .

PercentChange in Fuel E.l-ow C i _ange in High-P.ressureTurbine Efficiency PerCentChange in Net Thrust Cl)ange i_ Low-Pressure- - llurbine- Efficiency (Coupled to.- Low.- PressureTurbine Inlet Area l 'i _e analysis of a single engine t_t. was Subject to uncertainty , for reason_ discussed previously under Section 3.2. Much of the .problem involves t i le inability` of the production instrument_ior_to ,_leaSure true average conditions as a result . of limited instr.umentation locations.Shii_.ting proi_iles as a result of.. . test cell interact.t o nS and

part cIianges during repair served to accentuatethis-problem. In 6taler ....

t o minimize error, an integral part o f the data _inalysis methodology was to perform both prerepairand postrepairtestingwhenever possibl_, and Obtain records of repairs performed and rebuild clearances, plus ....

any availableinformation , on part conditionat teardown.

The procedure then used was to vary the toleranc e s, or closure accuracy, of the computed , parameters with the test cell dat_.

parameters., so that the differences between prerepair and postrepair_ analyses reflected the known repairs performed._ In particular, those modules on which no .repair had been pcrformed should have the same computed performancelevels for both prerepairand postrepair analyses, while performance improvementswere .generally to be expected in those componentswhich had been repaired or replaced. Except for Tt6 and .TtT, the closure tolerances between analysis and the observed data were.

nearly alwayswell within the instrument_tion accuraciesdisCus_e_d for_ the measured . parameteY_s..

An example of how.the top down analysis was performedfOra, particular.

- engine is shown in Tables. IX through XIV. The JT9D-7A(SP) engine.

selected for the example is P-695745. The engine history is . shown .in Table IX. Following removal for high exhaust gas temperature (EGT), the.

engi . newas. prerepair tested at . P.ratt & Whitney Air¢raft, and an extensive teardown . was.perfor_ned prior to repair. The engine was then repaired.andpostrepair , tested at . Pratt & Whitney Aircraft. . The engine was.then shipped to Pan American and postrepairtested there. The test data analyzed .for . this engine:is from the prerepai.r: and postrepair testing at Pratt & Whitney Aircraft. Table.X presents t11eresults of the teardown_inspection following_prer.epair testing. Ean,rub and minor foreign object .damage (FOD) was observed,_ as well as low-pressure compressor rub-strip wear, burner diStress, and high-pr_eSsur.e turbine damage. The top-down analysis.of, the prerepair-data is Shown in Table XI. When the simu,lation was run, with all iteration.balances (Table.

VII), there, was no thermodynamic solution w hi c h matched the data with acceptable accuracy., Similarly., when the Tt7_balance was eliminated (low-pressure turbine efficiency iterated on thrust and ,fan efficiency..

coupled to fan flow capacity) there was no thermody.namic solution. The it e ration balance on Tt6 had to be eliminated .to o_ain a n analysis.

which.gav_ acceptable Closure-with the_data, because the measured Tt6 differed significantly from. the true average val.ue, ._The resulting analysis showed (I) e_ficiency and flow Capacity losses .in the r fan and low-pressure Compressor, (2) I_igh-- pressure.turbine efficiency loss and i_low capacity increase, and (3) minor__Iz_-preSsure turbine effi c iency los_ plus flow capacity increase, ., Table. XII sulllnarizes repairs perfomned On the _ engine. Fan foreign obj_ep_t da.m.a.g._..,.was blended and the rub Strip r_placed_.with a. different TABLE IX HISTORY_ F J T gD, 7 A(SP)E N GINE P_6 9 5 1 45 o In s talled o n air;_aftN5 3 6PA, p o sition_1_11 / 18 / 76 o Removed f or high EGT, 4 / 20 / 7 8 with484_,hours and 7 0 3 cycle s o Returned to P&WA o P[e_lep,air te s ted 4 / 29 / 78 o Repaired per JTgD ma_ntenamc e program in s tructions o _. Postrepairtested 6 / 10 - 6 / 13 / 78 o De_l__ered to PA o . P ostrepairtested6 / Ig - 6 / 20 / 78 Installedon aircraft_N534PA, position I, 7 / 7 / .78 TABLE X OBSEEVATIONSDURING TEARDOWN.OF_JT9D-7A(SP) , ENGINE P-.795745 Fan- Light erosion damage. 2 blades FOD damage. Avg rub depth 0.0 5 2".

LPC- Blades and vanes good___. Rubber OAS 'worn._3 ....... - 0.04"-rub depth . 3rd stage. - HPC - Not disassembled.Borescope _inspectionshowed slight feltmetal loss 9th stage. No other discrepancies. . _ , Combustor- Axial cracking in vicinityof 3rd lou_ers_ HPT--_,__ Slight leading edge blade eros , ion, Average blade tip erosion .

0.010". Slight twist 2nd stage vanes. Rub and some smearingon _ _ lstOAS. Knife edge rubs and microfin damage on.2nd_JOAS. Avg clearance 0.081" 1st stage; 0.043"-2ndstage.

LPT - Not disassembled.No observabledamage.

TAB L E Xl DETAILED RESULTS O F -PREREPAIR"TOP DOWN"ANALYSIS ....

JT9D-7A(SP)Engine P-695745 at Sea Level Static Take-Off Conditions,EPR = 1.455 ._ PrerepairTe s t; • Engine S!mulatlon 4-29-78; Rel. to ( E liminate (Eliminate Parameter--- Production* (All Balances) TT7 Balance) TT6 Balance) % _ Fn -0.8_ -0.9 % _Wf +0.4 +0..7 % _ TSFC i +I.2 +1.6 %_ N1 -0.4 -0.2 % A N 2 . +0.07. - 0..2 4.Tt 3 , oci +0.I N N -0.1 .

_ T t4, oc -5. 3 0 0 - 3 .5 Tt6, °C . +32.0_ +8.7 S S Tt 7 , oc +11.0 O 0 _ + 1 1.0 %a Pt 3 / Pt2 -0.4 L. L. -0.2 %APs4 / Pt7 -1.8 U . U -1. 7 T.... T I I _)Fan, pts ._ 0 0 -0.3 %_ F an,. FC- N N -0.4 ,)LPC, pts -0.2...........

% A LPC, F C- -0.3 _ HPC, pts ._ 7 )HPT, pts -0.9 % A.A5 +1.4 _ T t .LPT, p . ts -0.2_ %.A A6 +-1.5 - •Adjusted t o remove sm o ke probe and for + 1% P T3 / P T2 PKo.fi]e_, ............................

3 2 TABLE XII SUMMARY OF REPAIRS ON JT9D-7A(SP) ENGINE P-695745 L MQdule Repair Performed Ean - OAS replaced with axial skewed groove configuration. Repair FOD.

Avg clearanceO.138"_.

LPC - New OAS. Avg. Clearances - 2nd 0.067", 3rd 0.032", 4th 0._043_ HPC - No repair.

Combustor-__Repl ace with rood2 liners.

HPT - New ist stage blades and 2nd stage vanes. Replace 2__ - -2nd stage blades.

Rebuild 2nd OAS_.segmentswith_new honeycomb_ Avg clearance - Ist stage 0.0675". ._ - 2nd stage 0.041".

LPT - No repair TABLEXIII DETAILEDRESULTS OFPOSTREPAIR "TOP DOWN" ANALYSIS JTgD-7A(SP)Engine P-695745 at Sea Level Static Take- _ Off Conditions,EPR = 1.455 Po str e palr. T e s t; En _i ne Simul ation 6-13-78;; Rel.... (Elimlnate ( Eliminate '(El iminate T t6 Parameterto Production (All Ba lances)Tt7 Balance)Tt6 Ba lance)& Tt7 Balance) _ % A F n -0.7 -0. 3 -0.7 -0.9 %AWf -0. 5 -0.7- -0. 5 -0. 3 - % _ TSF ' C +0.2 - -0.3 _0.2 +0.6 % AN1 -0.4 -0.4 -0.4 -0.3 % _ N2 +0.8 +0.8 +0.,8 +0.8 Tt3, oc _ -0.5 N -0.4 -0.8 -0.2 Tt4, oc -- 0 -O.3 -2.2 -1.0 TT6, o _ c_ -1 3 .0 -9.7 +2.7 -2.2 S_ Tt7 +16.0.. 0.. - 6.9. +16.0- +I.I % A Pt 3 / Pt2 -1.1 - L -1.0 -I,1 -1.1 % &Ps4 / Pt7 -1.5 U -1.6 ............. 1.5" -1.2 T I _ Fan, pt s O_ +0.06 +6.0 -0.2 % _ Fan F C N +0.1 • +0.1 -0.3 _ LPC, pts -0.2 -0=5 --.

% _ LP C , F C +0.9 -0.8 .......

_ HPC, pt s ...........

n HPT, pts +2.0_---------1.0 ............

% _ A5 +2.5 +0.6 +1.2 A n LPT, 9 ts -0.4 .... 2.9 -- % _ A6, +2.0 +2. 3 _1.5 *Adjustedto remove sm o ke probe and for +1% Pt3 / Pt2 profile.

TABLE XIV COMP.ARISUN OF.PREREPAIR-TO-POSTREPAIR MODULE PERFORMANCEIMP_ I _O W EMENTS JT 9 D-7A(SP) E ngine P--6 9 57 . 45 _.

Change in Module Performance Modul e Repair Performed Pts % FC Fan New OAS (axial skewed rgr_oove); repair FOD +0.1 _ +0.1 LPC New.OAS +0.2 _ +0.32 . , HPC None .......

Combustor . ._Replace Mod 5 liners with Mod 2............

HPT New Ist stage b ] ades , and 2nd stage .vanes. +0.9 ............ _0.2 Rebuild 2nd OAS LPT None +0..2_ (Bu_rn er:. pro.f iIe ) type. Low-pressurecompressor outer airseals were replaced, the Mod. . 5 combustor liners replaced with Mod. 2, andthe high-pressureturbine.was.

rebuilt. No repairs were performedto the , high-pressure compressor-orthe low-pressureturbine. The analysis of the . postrepair-testdata is shown in Table XIII. When . all iterationbalances are used, tbere was again no .

solution to the data with acceptabl . e accuracy, If the Tt7 balance was eliminated, there was a. soluti on as_shown.. Howeverthe . solution was not believable since inspection of-high-pressur . e turbime build, clearances indicates that efficiencycould be at most 0.1 to 0.2 points , better , than _ _ productionlevels.Also, a low-pressure, compresso_flow capacity that was.

significantly _better than new was not credible.When the Tt6.iteration balance was eliminated, there was an approximate solution, but. the performancelevels of the_fan and low-pressurEturbine are not believable (fan much better than new, and low-pressur_-turbineconsiderablyworse than prerepair,even though no repairs were-performedon that module). In orderto obtain an acceptableanalysis of this data, both the Tt6 and Tt7 balances had to be eliminated, and the fan efficiencyhad to be coupled to its flow capacity as previously described. In other words, circumferential / radialprofile , changes have masked the true- average values•of.both TtE and Tt7 in the postrepair data. The resulting final analysis is shown in the rig_ ] t_. _ . _ i ].a._d_._GQ]._.n..,._ . _T.b_._f. _ an._s.ti. _ . _ .............

- , , , • " d It • I I I I I ' -- lo sse s, but low- p re s sur eco m p re ss orperf o rmance - had be en i mp r o v e d t o the original level. High-pre ss ureturbine efficiencyhad been recover e d, but.

s ome flow capacity increase was s till s hown (a portion of thi s increa s e.

was due to decreased burner pre ss ure lo ss , as described below). A minor - improvement in low-pres s ure turbine efficiency was noted relative to.

prerepair;this impr o vementwas explainablein terms of the burner-change from Mod. 5Lt o Mod. 2 (shifted radial temperature-profile inward,which resulted in tighter-low-pressure turbine clearances).It should be noted that.there was. a minor improvement in burner pressure loss associated with this change also. In this analysis, and those which follow, any change in burner-pre s sure loss has been combined with the_predicted _ high-pre s sure,turbine f]ow capacity, change as indicatedabove. Table XIV_ summari z es by module the repair s performed,togetherwith the analy z ed .....

prerepair , and po s trepairperformancechanges. Good agreement between the two is shown. The analy s es were felt to be credible because they show.

good agreement with observedpart condition and repairs-performed,even though s ome data parameter s had to be - rejected (Tt6 prerepair, Tt6 and..

Tt7 postrepair).In general, neither Tt6 nor Tt7 could be used for - most of th_ prer e pair and po s trepair-analy s es performed. In a few cases,_ low-pressurecompressor efficiency and flow capacity; were coupled (drop Tt3 balance),because of profileeffects at Station 3, .. d . _ . . , ,ira ,, " . i I . .i,-., , _ ._ SEC?ION4.0 RESUL?S AND DISCUSSIONS This section of the report has two primary parts: overall engine.• performancedeteri oration, and engine module performancedeterioration.

The deter.ioration_data were obtained and analyzed over the period from i February 1977 to February 1979. Overall engine, performance deterioration was acqu. ired .from four sources which are described in detail• in Section 3.0, Data Acquisitionand Analysis Methodology.Th e se sources were Engine Condition Monitoring (ECM), In-FlightCalibration, Prerepair and PostrepairTests, and Plug-ln ConsOle (PIC) . Tests.Engine.• module performancewas analyzed from only the Prerepairand Postrepair Tests and the PIC Tests inasmuch as the other data sources did not include-the instrumentationnecessary to determine, module performance.

Each of the sources ofdata cover , ed a range of engine cycles and times.

Table XV summarizes the engine cycles / times associatedwith the data from each source.

TABLEXV SUMMARYOF ENGINE CYCLES / TIME FOR EACH SOURCE OF PERFORMANCE. DATA ApprOx.R.angeof Data Source _,_. Time (hours)....

Eng!neConditionMonitoring 25 - 2300 100 --12000 In-F-light CalibratiOn 10 - 1000 20 - 6900, Prerepair-andPostrepair"Tests 700-- 2100-- 4800 -,12000 Plug-ln_Console Tests 1 - 1000 0 - 6900 4.1 OVERALL ENGINE PERFORMANCEDETERIORATION RESULTS The pr.esentation of the overall, engine•performancedeterioz_tion results are, in . general.,given,in the order of data quality•.The. ECM and In-FlightCalibrationdata results• are presentedfirst because the-data were subject to scatter-and variationswhich .rrecluded any substantive , Conclusions.Then the Prerepair and Postrepair and PIC_Test _data, the.

quality of wbich,_is consi_l e _ed very g_ood, are presented.

4.1.1 EngineoCondition Monitorin9Data 1 | A deta_iled deScriptio_of tile methods and proceduresfor obtaining the !

ECM data iS given in Section 3.0. As described in this seCtion, E C M !

J

i

!

3 7 _ data for an individual engine required statistical treatment of the data in order that para m eter plots, such as fuel flow or . : EGT versus.

engine flight cycles, yield reasonably smooth , trend variations. Even then, parametervariations wi.th, engine cycles is somewhat erratic as, shown in Figures 10 and 11 where the . changesin fuel flow (Wf . )in ..........

percent and the changes in exhaust gas temperature (EGT) in.,oc are,.

plotted as functionsof engine flight cycles for the 32 747(SP) : engines, studied and tested during this investigation.The base-line,or zero,• value representsthe JTgD-7A engine gas . generator_ values obtai ned .. from the Boeing PerformanceEngineersManual.

- ., im ll . 2 t , 4 I I I I 1 I J _ I 1 1 I I 200 400 600 8 0 (I. 1000 120 0 1400 1600 1800 . F li g h t cyc l es Figure 10 ECM Plot of Change in F uel F low.w, ith Usage . - Data . from 32 Pan American,JT9D-7A(SP)engines , through the - first removal results , in a relativelyconstant average fuel flow to about 75 0 cycles (averagedoes not includethe . last four,engines).

Dashed lines representingthe average,value s ar.e. shown on these two _ figures. These average wlue_ show a 1.3 percent and.a 20oc' increase in fuel flow_and exhaust gas temperature,respectively,over the first 1500 cycles (approx_imately two years) for-this particular group of JTgD-7Aengines.

Some of the variations s hown in, F igure 10 and 11 are believed to result from instrument error and nonuniform extraction of engine bleed air among the engine s . (A discussionof the nonuniformextractionof engine 'i i

I

bleed is given in Appendix A.) Averaging the result s from each_ airplane, which attenuate s these individual engine effects, yield s the re s ult s pre s ented in . figures 12 _nd. 13 where fuel., flow change in pe r cent, and .exhaust gas temperature-change in. oC-are plotted a s functions of engine flight cycle_, The-reason for the distinct, level s , which for example s how s air_plane s N531, 532, 534, and 658 g r ouped together-, i s that change s in the engi.ne configuration s over the period of airplane deliveryhad different level s of performance, In addition, the i.n s tallation of a Contro'( Differential Tran s former (that i s , CDX) unit, whic h , caused the indicatedengine, p_essureratio ( E PR) setting at.

which f.uelflow rate was being measured to be greater than .the actual.

EPR, has the eff.ect of reducing the.measuredfuel flow and exhaust gas temperature,The fewer flight_cycles for airplanes N531 and N532 are_ associated.withthe time when the engines were removed for their first shop vislt, u 4 0- -20 -'_ _ _ ' _ _ - - _ _-- ,_ ..................

• 4 C I 1 I I i J . I I I , J I [ . ] I I I [ I 0 200 40 0 S O0 BO O 10 00 12 00. 14 0 0 1600 180 0 F[ i gl ] .t cycles_ Figure 11 ECM Plot.of Change in . EGT wi_th. Usage . --Data from 32 Pan American JT9D-TA(SP) engines, through the first removal results , in. a s . lowlyincreasing average EGT to about 1000 cycles (averagedoes not _ inc_l_Jde the last four engines) Only data for 28 eng!nes . (sevenair . planes)_are shown in these , figures because the other_four _ engines . had too few f l ight cycles to be representative, One factor w1_iCh is_ often thought to have an effect on engine ...

deterioration is the effect of engine location (position) on. the I air p lane.An-example-ofthe-data, examined to see if such an effeCt were prevalent is shown in Figures 14 and 15 where changes in fuel flow and 39 '_ _ -- , i i i i i i i I I I l exhaust gas, temperature are p l o tted a s functions of en g ine.f_tight cycle s for each engine on one air r cr . aft, Th e s e_ and similar data .

(startingat 25 flight cyc l es and above) did not show any di s cernible differences in performance deterioration effects• between inboard (po s itions2 and 3) and outboard (position s 1 and 4).engines .................................

4 m 3 -- NI_34 1 747 _I _ _ ' _ _ 'm " ' _ , _ , _ ' ' _ , . N 632 _ . 747SP | _. N531 1747 _ P1 w W -- •1 .... -- _N_t7 47S P ) - i _ N S_c 747se l N_N 1 747S @1 j I i " '- I-. I l I J i I I 0 1 2 3 4 B 6 ? 8 9 10 ENGIN EFLIG H TC YC LES {1 0 0) Figure 12 747SP Airplane Average Wf Performance Deterioration Trends, Based on ECM Data - The four.engine average change in.fuel........

flow as a function of usage shows l_ittle change.at constant EPR between 100 and 1000 flights; the later configuration engines in airplanes N536PA and .._537PA show better .

performance,_.

Another situation, which could contribute to _ different engine deteri o ration levels, is whether_ the engine is installed on the aircraft prior to aircraft acceptancetests or as a spare engine_atthe beginning or during revenue service, Discussions of the. engine ...............

deterioration problem have- led to the hypothesis that aircraft.

acceptance tests might have a significant impact•on initial (or I short-term)performance deterioration, The reason for this is that the acceptance tests are generally believed to be more-severe than normal

L

revenue-service.The._ideal approach would have been to.compare . .a large I data sample of spare and aircraft-delivered engines of the same engine I model., o perating in the same aircraft, and flying the same flight )

'i

40 ' d • • _ : ...... ' .,•_ .... , ...... , .................. I"i - r ......... I I I II I I I cycles. Since-such a data sampl_ did not exist, the f o llowing two approaches were used to best. compare the available, data. In the first approach, the three comparisions shown in Tab]eXVl we r e made.

30 -- i N534 (747FJP) _ .... _.,. . .___.._ i 10 " _ - _ . -- N531 (747 =P ' ,< _ N( _ SQ(747 F ) _ _'_ u 4 0 " ' _ ". N 532 (747S P ) .......

, • '' _ ' ' " ' * N536(747SP) :> _ 10 -- - _ N537 (747SP) • 20 -- . .. , - " " uJ <_ • 3 o I I i I I I I I I I 1 2 3 4 5 6 7 8 9 _10 ENGINE FLIGHT CYCLES (100) Figure 13 747SP Ai r plane Average EGT P e rformance Deterioration Trends Based on ECMData -.The four-engine average change in EGT as a function of usage shows similar trends for the airplanes used in t h e study.

In each of these cases, the spare engines were operated in the same aircraft, thus on the same route structure as the aircraft-delivered.

engines. Comparable ECM performance data (changes in fuel flow and exhaust,gas temperature) from the earlier recorded revenue flight data out to the 800th .engine flight cycle were plotted. In all cases, the data were from the first engine installation and prior to _ any repair.

Comparative plots of changes in fuel flow and exhaust gas temperature versus flight cycles for the three individual airline comparisons are shown in Figures 16, 17, and 18. The aircraft-delivered engine data are plotted as solid lines and the spare engine data as dashed lines. As with. the data of the Pan American 747SP fleet p r esented in_Figures i0 and II, thes e data shown wide variations in performance levels and trends. The South African Airways and Iraqi Airlines data show the spare engine performance falling within the performance bands defined by the aircraft-delivered engines, the Northwest Orient Airlines data show the spa r es t o have poor e r initial pe r formance but less increase in fu e l flow with age.

4 1 2 _ ..... ' _ • I.u ENG I NE 5 / N _ . 0 I 6860 55 < . 2 68 0 048 3 686049 1 , 4 686O6O / .2 JAN. l , 1 0_ e 7 .... JU L Y ,1077 ' ; _" - _ JAN. l , 1 976 _ _ J J LY1, 1| 7 8_

1 I , 1

J ! ! J! I

2 000.o uns ,ooo HO U . S 6 ooo Ho u s 8 0o H O R 4 II I ; 1 1 I II I I I I ; I 0 100 200 300 400 500 600 700 , 800 000. 1000 1100 1200 1300 - 1400 1500 l_a n ! ? nn _ : _ 1 800 1900 Engine F [ i g ht Cyc l es , .... ii ] Figure 14 ECM Data from Pan . AmericanAirplane N534PA on Change in Fuel Flow with Usage --Early variationsin individualtrends are believed to be caused by airplane--induced effects; a__plane average closel.y follows the fleet..trend.

T he second appr..oach compared all of the available spare JTgD-7 engine ECM data with a representative sample of aircraft-deliveredJTgD-7 engine ECM data. The advantage in this approach was a large data sample. The disadvantagewas that the approach mixed engine models, aircraft, and airlines. Performance of 16 spare engines from eight airlineswere compared with the EC M performancerecor_ds of the first 28 Pan American 747SP aircraft-de-livered engines which were collected in i this s tudy. In the second approach, the.comparative plots for-the 16 spare engines and the Pan American 747SP-aircraft-delivered engines are i show n in F igures 19 and 20, The pl o ts of change in fuel flow and exhaust gas temperature f o r-the 16 spares generally fall - within the bands defined by the 28 Pan American JT9D-7A(SP_) engines and exhibit the same average.trendwith age. These bands were defined . bythe curve& s h o wn in Fig__11.

J

iii ¸¸ '......... , _ all _ lt #_ I h i l " ""=" I ] AVI I| A III " " I _I t) ........ ..... 4 6 B_ O OO - ..... I'_ " 4t) _ ...................... r ....... _ .....

] , B O 100 200 :K,I) 400 5L1 0 0{_ ?L.'O III X) - UO L) 1000 ...1il _ o 12 0 0 1 3 t10 14 0 0 1500 II , O0 I I 0(1 i l i 00 EnGint_Fl io hI C y eht s F . igure 15 ECM Data from Pan Ameri.can Airpl a ne N534PA on Change - -in EGT wit l _ Usage - The - shift_in the EgT trends of engines 1 and 2 coincideswith changes in the fuel flow slopes (Figure14).

TABLE XVI ENGINECOMPARISONS FORTHE FIRST APPROACH SPARE _ERSUSAII_CRAFT=DELIVERED ENGINES- Numberof Engines Ai r line A_irplane / Engine Sp.ar___ee. A rcraft. Delivered South .Ai_r_can .Air_ways 7 47SP I JT9D-7F 2. 6 .

IY-aqi Airlines 747 1 JT9D-7F 3 7 • NorthwestOrient Airlines DCIO-4O I JTgD_20 ? 6 .... • " _ " i iii i ii i i / i • _ _ Original : _ ....... Spare 30 - , 3 .

t . _ , EG T I A Wf

i °C .--

- 20 __ -30 -3 0 200 400 600 000 0 200 400 600 800

Engin e flight cycl e s

] Figure 16 Aircraft-Oel ivered versu s Spare Engine Performance..... _ Deterioration for South African Airways JTgD-7FEngines ....Based on these data, it would appear, that the EGItfor the ,two spare engines improved with usage re1.ative to the six air p lane -_ delivered engines while the fuel fl_ for the spares increased with usage relative to the airplane-deliveread en_gines; these apparent trends conflict..

' __ Original _ __ Spare 40' - 20 I - 2 | Q................. 2 0 0 400 ___60 0 800 0 2 0 0 400 60 0 800

E_ ne _ fli gh t cycl e s

Fi g ure 17 Aircraft-Del i v ered versus Spare Engine . Perf o rmance Deterioration for Iraqi Airlines. JTgD , ; 7FE n gines -,The.spare engine , performance trends generally fall within L he trends defined by the air.plane-delivered, engines; the performance for t_ese spare engines appears to deteriorate slightly more after 150 cy_ - Ie s .

44 - --Original -- - Spa _ re -- 40- , , " 4 | -- 3 0 -_ ....... : "_" a "_ - " 3

=

20 . . , ,, , , .

E

,o - 'L

A EGT o A Wf o .. .- -'_ - - " -- °C - I0 - 20 - 30 0 _200 400 000. 8 00 0 200 400 8 00 800 Engin e flig h t _ cycl e s Figure 18 _ Air.craft-.Del ivered versus Spare . Engine Performance Deterioration.for NorthwestOrient Airline ;, JT9D-20Engines - .

T.hespare engines, exhibit poorer initial performancecompar e d to the airplane-delivered . engines, . but the_..subsque n t f.uel flow trends are similar.

4 \ / / _ ._. _ __ - _. ., . _ \ 3 t,_J . zx / _ 2 _ . / / ' _ ' x _ / _ " -- " < - _ / 28 PA JT9D - 7 A (SP) . _ _ - _ , _ _ / ' / _ , I / . / e ngin e s

...... /

o _p_ ..... - / ....

- 2 - I 1 I l " 3 1 _ 200 4 00. 600 800 E ngin e flight cycl e s .

F . igure 19 Performance Deteriorati.on for 28 Pan Amer . icanAirplane- !

Deli.veredJT9D-TA(SP)Engines versus 16 Spare En_ L inesfrom . i Eight Airlines --The.spare engineS, operating over different.- i routes and . cycles, exhibit a simil&_ _ band of . fuel flow chang_ to that. deflned . bythe airplane-del ivered_ngines.

!

I

4 5 , , , i • i i i i " I I I I I 30.- . .--- "-- " - '-- " - . _ " 20 _ 28 PA JT9D-7A (SP . ) _ . _

4 o I

e n gi n es._ 10 " "

A EGT o \

°C _ _ .

- 10 . I.

-20 - 30 "_. .

-40 . a ........ ,. I ...........I o 200 . 400. coo._ coo .

Engin e flight cycles.

Figure 2 0. Perf o rmance Oeteri o rati o n for- 28 Pan American Airplane-Delivered JTgD-7A(SP) Engines versus-16 1- Spare Engines from Eight Airlines - The spare engines, operating over_ different - routes and cycles, exhibit a - - similar band of : EGT change to that defined by the airpl ane- delivered engines.

The limitedamount of.data and the variationsin the ECM are such that it would not support an accurate comparative , performance analysis of - spar e and aircraft-deliveredengines ; However, the available data, .

while- limited, shows no noticeabl ; difference in early revenue .

performance between engines which were and ._were not -part of . th e aircraft producti on . accept ance testi ng.

4.1.2 . In-Fli ghtTCalibration Data These. . data were obtained from the same instr_entation as the ECM data..

The only significantdifferences . inthe two types of data are that the in-fli g ht calibration data were recorded by : an observer specifically interested in. the results, and that the parameters were treated statisticallydifferentlyfor the two types of data. In the case of the ECM data, the data scatterwas - handled by amassing large quanti.ties of- data. F or the i . n-flight calibration data, engine-paramet e rs such as fuel flow_ exhaust gas temperature,and low-pressure-rotorspeed were recorded systematically over a ranger of power,settin g s and faired values of-the engine parameterswere then used. Typical data of this ....

type for-one . en_ne are pre sent ed _ i_D _F , Lgures 21 and 22 where fuel flow, exhaust gas temperature, and high-and IOw-pressure rotor-cOrrected - speeds are plotted as a functions of engine pressue ratio. Typical data ..

scatter amounts to about +.i / 2 _co+I percent for exhaust gas temperature and fuel flow and about "_0,2percent for high- and low-pressurerotor - - speeds. Cross plotting dat-a of this type at an engine Pressureratio of 1.40 yielded resul.ts similar to those shown in Figures 23 and 24. These figures show the same parameters as a function of flight cycles for engine P-695738 on airplane N536PA, In this instance,the data scatter was at most only slightly_reater than the base plots used to generate ...............

these figures, Using data derived by the.procedures just described, a comparison of ECM and in-flightcalibrationdata_for two airplanes,N536PA and,N537PA ....

is made in Figure 25 for the same four gas generator parameters previouslydiscussed.In this instance,the data were averagedfor the four engines on each airplane..Thedata have been normal.ized such.that all parameters for each data source and_airplane are equal at 100 cycles. These results show that the ECM and in-flightcalibration• data exhibit very similartrends. Variations.thatare . evident.are within .the acCuraCy• and repeatability of the.-data.

4.1.3 Prerepairand PostrepairData Prerepair data for JTgD-7A(SP)engines (12 tests) (see Table V) is presented in Figures 26 and 27. Changes in thrust, specific-fuel Consumption (TSFC) and exhaust gas temperature (EC._T) relative to.

productionbase-line values of each individual engine are plotted as functions of-engine _ fligh_tcycles. The last three_ digits of. each engine's serial number_-is shown b_side the•appropriatedata point. TSFC.

was measured at constant thrust, and . EGT at take-off engine,pressure.........

ratio (EPR). All eng!nes were-testedat Pan American with the exception of P-686060. and. P-695745 which were tested and repaired, at Pratt & Whitney Aircraft. Fuel flow, thrust, and•EGTmeasur.ed in the•test.stand.

have been corrected using standard•day_ test stand, and configuration corrected factors as described in Section 3.4, Analysis Techniques.

Additionally, the. data for the P . -686 • series of. engines have been adjustedc for a package of engineering retrofit changes incorporated after the engines wer.eflown in the certificationflight test program - .

prior to being intrOduced into commercial service. Data scatter _ is .......

limi.ted to about.+I percent in TSFC,.indicating that T-SFCdeterioration- for unrepaired e-ngines should be fairly predictable. The average prerepair TSFC _rangesfrom.abOut I percent above production levels at 700 cycles to about +.3.8 percent at 2000 cycles.

Figure 27 presents prerepair- exhaust gas temperature for the JT9D-7A(SP) engines, ..... Data . scatter is partly attributable to the 1 200 11 6 0 " A J I- 1 , 100 10 5 0 f 21000 i 20000 / , d "- ' o: 19000 / m l_ 18000 f LL .I 17000 . , u_ .- 16000 : _ ....

15000 / 14000 1 , 22 1.26 1.30 1.34 1.38 1.42 1 A 6 1 , 50 - - ENGINE P RESSURE RATIO Figur e 21 In- F light C alibrati o n Fuel Flow an d Exhaust Gas Temperature Data as Functions of Engine Pressure Ratio for Engine P-695738 on Airplane N536PA Taken . on May 21, 1977 at 155 Hours / 23 Cycles - The-data show very little scatter Over._the range Of power at which, data were recorded, -. 04 .... ,, _ . ... . _ , _ 93 - ' " ' : Z 92 _ ....

91 J ,,, IO0 e9 / _!

- g /

A.N 97 / _-" 95 Z I 93 j_ 1.22 1.26 1.30 1.34 1.38 1.42 1.46 __ 1.50 EN GINE PRE S SURE RATIO Fi g ure 22 In-Flight Calibrati o n Low- and High-Pres s ure Rotor Speed Data as F uncti o n s o f Engin e Pressure Ratio for Engine P-695738 on Airplane N536PA T aken on May 21 , 1977 at 155 i H o urs / 2 3 Cylcle s - T he data sho w very little scatter o v er the ran_ p owerat which data were recorded.

1140 - ' 113 0 _ " -- 111 o _ -_ , --. & ' 11 00 0 10Q 200 , 300 - 400 , § OO CO0 700 600 ENGI NE FL I GHT CYCLES • Figure 23 Fuel Flow,and Exhaust Gas Temperature. Data at,EPR of 1 . 40 as , Functions of. Cycles for All In-Flight- Calibrations of Engine P-695738 on Air, plane N536PA.- The data scatter-is only slightly greater than.the data scatter f_r- q ndividual en q _._ in-flightcalibrations.

94 " ' _

'L IIIIIII

03 , O 7 /x A A L " 0 1 _ 2 _ 300 4 _ _ 0 6 _ ?0O 8 _ ENG I NE FL I GHT C Y CLES Figure 24 Low- and High-PressureRotor Speed Data as Functions of Cycles for All .In-Fright Calibrationsof Engine P-695738 on Airplane N536PA.- The data scatter-is only slightly greater than,the data scatter for incLiNidual engine in-flightcalibrations.

I

J I I " ........ " ,, • i . " i I • I 1,0 - - - ,- _ ..

<3 •,-4.0 i i i i i 1,o N B36PA: ..... IN-FLIGHTDATA ECM DATA _. . _._.. " -= _ .,,_.. ,. ....

Z ..... N 537PA: <3 " - " -" "" IN-FLIGHT DATA 1 ....... ECM DATA -1.o A 1 .0 , ,,-I _ 0 _-- -- ,.wl ===.,__ =_ , __ = t # I, _ .

LL - " 1 . 0 '<] t O O---- -- 2 0 0 30 0 400 500 6 O 0 . 7 - 0 O -- E NG I N E I_ LI GHT C YC LES Figure 25 Comparis o n o f .F o ur-Engine Averages of Gas Generat o r . • Parameters as Functions Of Cycles as Determined by In-Flight Calibrations-and Engine Condition Monitoring of. - Engines -on AirplanesN536PA and N537PA - -T he f o ur-engine averages re d uce the data sCatter and i m pr o ve the agree m ent between the two d ata s o urces.

4 g b _ _ .' _ ..... - . ............. d 0 8 0 048 _ -" , _ 4 ., . , ,047 .. . T _ . .L.J7 3_ .. . : 0 8 3 _ - JT9D . 7A(SP) (%) 2 DA T A A V _ R A G S ' r ' L ITSFC " - _ 24--5 //' _ 1 ° 6 ° I 227-. 083 72 2: 0 I _ , 600 8 00 1000 1200 1400 1600 . . 1800. 2000. 2200 2400 2600 2800 . 3000 3200 3400.

ENGINE FLIGHT.CYCLES Figure 2 6 Long-Term . Prerepair TSFC Deteri o ration ,. Mea s ur e d. at .

Constant Thrust , as a Function of Flight Cycles - The prerepair data are similar in . trend and level .to the average of _ _ the historicaldata.

80; J 4 0 • [] 083 __ 7 4 3 I_ L 1 727 n 083 r !, _ 32 ..

AEG ' I ' 2° _ ' m IU O 4 8 I oC ) JT9D-7A i SP) BASED ON FUEL FLOW -20.

600 80 _ 1000 1200, - ,.,1400 ,. -. ,1 600 1800 2000 2200 2400 2600 2800- 3000 3200 34 00 .........

ENGINE FLIGHT CYCLES • Figure 27 L o ng-Term Prerepair EGT Deterioration, Measured at Take-Off EPR, as a Function of Flight Cycles -After .

temperature profile adjustmentswere made, the prerepair data agrees , well with the average of . the historicaldata.

in-serviceengine temperature profile shifts. Because of these profile s hifts and the limited data Sample, the least squares, i_itof the data.

is slightlydifferentfrom the true average obtainedfrom fuel flo_,- The po s trepair data are_presented ith. F igures 28 and 2 g where TSFC an d.

E G T are-shown as functions.of engine flight cycles for 18 engines (22 tests), Solid Symbols are used for those engines for-which prerepair data wer.eshown in figure 26 and 27, The postrePaJr TSFCdata relative to productionengine level varies from_about+0.5 percent at 700 flight- cycles tO about.+2.8 percent at 2000 cycles, Tl_ereiS somewhat more data scatter in the pO s trepairTSFC data than in the prerepair data.

Even if all repairs were the same at a given engine-cycjic : age and. if productionquality parts and.build standards were used, a small amount . .

of increased Scatter . -(less than 0,6.perce_t) could be attributed to productiontolerances.Howe v er, al.lrepairs are not thee. same at a given.

cyclic age. Swapping of_ deteriorated modules with other-used Or partially refurbishedmOdLLleS was common practice to expedite repairs. _ In addition,, part. quality differs from productionquality because only selected individual parts are replaced in a t module repair / refurbishment,and .some partsmay be repaired rather than replaced, finally, repair build clearance limits are generally broader than production clear.ances.All. of these, factors tend to cause increaseddata scatter in postrepairTSFC r.esults an_d_make it difficult_.

to constructpostrepairaverage trends.

LEGEND O E N GINE S WITHOUT PREREP A IR D A T A • E N GINES WITH PREREPAIR DATA • o4 ! , oe3 054] 727 ] 3 • , .o B 3 < I oJ _O o , 1 JT 9 D - , A(Sm

• oo- o, 2 o 6 O4, , : 22

D A T A A VERA, GE

' ; , J6 oEo

0 I 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 . 3200 3400 ENGINE FLIGHT C YCLES Figure 28 Long-Term Post_epair.TSFC Deterioration, Measured at Constant Thrust, as a F unction . oi _ FLight Cycles.- - The. _ postrepair-datascatter shows results Ofa wide-range-of repairs and broaderrepair - buildclearances ............................. .I ] . :. . _ ........ . , ....... , , , ,, , I II "_imm 'am • ".......................................................................................................................... :........... ;:+.;. . -;;: ; +'_7.':7"7 .'.7]:_,',;..,',]i{ .......... i.............. ".':'ll

'!

LE G END O ENGINES WITH O UT P I!E R E PAIR DATA • ENGINES WITH PRER E PAIR D ATA. _ 6 0 , i , , O . U . •_ s 0 070 l o - -1o.- _ . ... . _ _ ' 0 48 _ 0 49 060 727 llL - (_ L} . . __m I _ o7 + o 88- - "4-l;_ _i °S 3 "_' _l U " ' + C 1 732 .

L\ I I o 66 o 63\ • 83 Jim, • J T gD- 7 A (SP) BASEDON FUEL FLOW 716 -20 -7 4 5 050 0 0 727 600 800 1000 1200 1400 1600'_ 1800_2000 2200 2400 2600 - 2800 3000 3200 3400 .

E PI (31NE _E L I G H .T . . C. Y , + C , L ,ES Figure 29 Long-Term P o strepair EGT Deterioration, Measured at Take-Off EPR, as a Function of Flight Cycles - The_ postr.epair data agrees well, except for a degree of data scatter,with the average of the .hi.stori cal. data.

The results, of.the prer.epai.r / postrepair data are believed to.have more credibilitythan the r analysis.resultsof.the postrepair-<)nly data. The greater credibility occurs because instrumentation, test stand• correction, and data sampling uncertaintiestend to be reduced through.

the process of iterating the analyses of prerepair / postrepair, data __ until the results closely correspond to knowledge of actual_ part condition and repairs perf.ormedon the individual engines, . This procedure - is discussed in more detail in Section 3_4,. Analysis T_chniques.

T he p o strepair--a v erageex h aust gas temperature data (Figure.29) relative t o the individual, pr o duction engine level varies f_rom + 4oc_ at 700 flight cycles to about 21oc at 2000 cyc_les. Here-again, considerabledata s catter+dueto temperature _ profile- shifts is evid e nt, iI The profile changes are related t o repairs perf o rmed; in particular, 1 all engines had combust o r-l : nersreplaced, i+n almost all cases by liners of a different type (M o d. 5 Changed to Hod. 2). There is an _ average reducti o n in measured exhaust gas+temperature + of ab o ut 1 3 oc ' I !

ass o ciated with this burner liner change, based on Pratt & Whitney t ,I I i • ' , !

Aircraft productiondata. The faired Curve is the true average exhaust.

- gas temperature-determinedfrom fuel flow and_ is about 13oC higher than a least squaresFit of. the. measured data .....

The curves presented in Figures 30 and 31 use the faired curves s hown on the previous four figures to compare the prerepair-and postrepair results. Figures 30 and 31 show changes in TSFC and EGT as functionsof engine flight cycles. On average, repairs result in about a 1 percent reduction in TSFC and a 10oc reduct.ion, in EGT. As prev.iously noted for an individual engine, considerable variation in this I0oC reduction can occur because of data scatter - and the effect of temperature.profile shift resultingfrom the repair.

..... Ul PREREPAIR " / _ "PO S TREPAIR

/

1 / ....

600 80 0 10 0 0 12 0 0 • 1400 1600 . 18 0 0 200 0 2200 24 0 0 260 0 ENGINE FLIGHT CYCLES Figure 30 Long-Term TSFC Deterioration, Measured at Constant Thrust, as a Function of F light Cycles; Comparison of Average Prerepmirto Average PostrepairPerformance- The repair process did not attempt to maximize performance restoration.

4.1.4 Plug-lnCon Sole IPIC)Data PIC Data were obtained on four-engineson two 747(SP) airplanes,engine P-695743. and P-695745 on airplane N536PA and engines P-695760 and P-695763 on airplane N537PA. The method of and schedule for data acquisitionare discussed in detail in Section 3.0. In addition to the x ."_ .... • ,, , , • . , . ,, ' '_ . " | i i i i I lll n ll I I ' s tan d ar d RI C d ata a c q u i s iti o n, e ng in e P - 6 9 5 7 43 wa s g iv en s pe c ial trea t ment.After 1 0 8 1 fli g ht hour s (14 1 cycle s ), the engine wa s returnedt o Pratt & WhitneyAircraft' s pr o ducti o n te s t facility where, it wa s te s ted "as-received" in the o riginalproductionte s t s tand, After . water and detergentwa s hingt o rem o ve s urfacecontaminati o n from en g inepart s , and en g inevane c o ntroltrim, the en g inewasrete s ted, Next,the pr o duction en g ineca s eswerereplaced with fully-instrumented en g ineca s e s and a performance te s t wa s run. An analyti,cal t e ardownof the enginefollowedduringwhich the condition of all. s eal s and o ther- part s which might affectperformance was d o cumented, The engine, was then reas s embledand returned - to s ervice during which.PIC data c o llection wa s co r _ c tnu e d.

+60 I ,-4 0 I "' I .... r o +20 "----" - _ __. _ _,_ _ LP.OSTREP A IR ,_ 0 ' ,.............

-20 .- , 600 800 1000 1200. 1400 1600 1800 • 200 0 2200 2400 2600 ENGINE FLIGHT C Y CLES Figure31 L o ng-Term EGT Deteri o ration, Measuredat Take.-_Off EPR, as a F unction of F light Cycles; Comparison , of Average Prerepair to AveragePostrepair P erformance --An average of about10ocin EGT i s recovered as a_result.of repair.

rn terms of overal I engineperformance deteriorati on, the"as-recei red" enginehad a TSFC incr _ ease (l o s s) of . 1 . 5 per c ent. Water and detergent ..............

wash plus vane controltrimregained0.3 percentofthis . loss.Because _ thrusti s not measured-whi.le acquiring PIC.dataand EGTis subjectto .

measurement problem s associatedwith. temperatureprofile shifts, overallengineperformance deterioration basedon PIC data is obtained by using the gas generator measurements to determine individual module.

los s es,An exampleof gas . generator data is. shownin F igures32 through 37. These module losses in conjunctionwith module, influence coefficients can then be usedto calculate TS F Cand EGT,The resultsof this approachis shown in F igures " _ 8 _ _ .an d. 39 where TS FC and EGT are 6 ..............

I I I |I f i , M , .... ;* , ', , S ' plotted as functions Of engine flight-cycles. . TSFC increasesrapidly at a rate of about_one percent i n the first 25to 50 cycles and then more gradually__to2.2 percent_.at 1000 cycles, In a simila e -fashion, EGT increases 5 . .to7oC after 25 to_ 50 cycles and th_n to about _)oC at_ 1000 cycles, 4.2 OVERALL ENGINE PERFORMANCEDETERIORATIONCOMPARISON Now that the results of the various sources of. performance_ deteriorationdata have been.presented,a comparison Of these results.

with tl_ previouslyacquired historicalde.terioration data.is given in the. subsequent figur.es.. Figure_ . 40 shows a comparison of the. ECM, in-flight Calibration,and the.PIC data. Changes in.fuel.flow, exhaust gas temperature,and l.ow- and high-pressurerotor speeds are shown , as functions of engine._f.light cycles. All data have been non_lali.zed at 100 ...........

fl.ightcycles. The PIC data which were taken.on the ground.liave been analyticallycorrected .to altitude conditions, AgreB11entbetween the various data sources is reasonablygood, Prerepairperfonnancedeterioration data are-shown in . _igures 41 and 42 where the changes in TSFC in percent and EGT in oc are shown as functions, of engi . ne- flight, cycles. On these figures, . ..the data sources included:PIC data, shown cover.ing a range of flight cycles..fran I to 1000cycles; historical, data, obtained from a limited number of tests of engines returned to the manufacture r after - 5 to 300 cyc:les; the one special prerepair_ data point at 141 cycleS_ obtained on engine P-695743 and di s cussed in Sectton. A . 1.4; the prerepairdata fr(_nthe ,ITgD-7A(SP) fleet, covering a.range from 700 to 2100 cycles; and.the historical airline data, reported in Reference- , 1, over a range of engine i_light.

cycles frail 120 0 to 3500 cycles. Data fr a l l the Various data Sources - agrees quite well. The results show a rapid deterioration over the first i00 cycles where the change in TSEC_ increases over I-percent and EGT rises to 7 oc. The perfonnance continues to deteriorate so that at i000 cycles TSFC and EGT have increased 3 percent and 21oC, _ respective_ly, and at 2500 cycles these parmneters are.up 4.2 pe r cent and 36oc, respectively. The sources and causes of t l iis perfo r mance deterioration are discussed in. detail., in the next .-paragraphs w! ] e.r.e..

engine m_dule performancedeteriorationis discussed ....

The poStrepairperfoniLance deteriorationdata are preSe n ted.in.Fixtures 43 and_ 44 wher.e the changes in TSFC_ in percent and EGT. in oc are shown as functions,of engine,flight cycles. The data Sources are JTgD-7A(SP) fleet postrepair data and historical.airline. data fra;_ Reference 1.

....... i iilll I I ] 58 ........

.... ' , I I'll+'_ <, 4 _ 5 9 .41_ ....... . " "', '" - ill I ........... i i I I • I I I I I II ] " - -- I . .. 11 60 _- D 3 .0-

2.0-. a . o

1.0 " { % ..........

u _ N537PA ' I -- < o P - 695745,POS. 1 A P - 6 95 7 6 0,POS, I 0 - o P-6 9 5743,POS. 2 I_P-695763,POS. 2 -1.0, I- I- I- ,1 I . I I I I • I_ I I 100 200 300 400_ 500 . 600 700 .800 900 .-. I000 1100 .

ENGINEFLIGHT CYCLES-- Figure 38 EstimatedSea Level Static TSF C- Deterioration --Overall TSFC.

Prerepair deterioration,based on module deterioration and influence coef f icients, shows a rapid deterioration of 1 percent in the f_rst 50 cycles followed by l o ng-term_ deteriorationat.a much s l ower rate to 2.2 percent at 1000 cycles.

30 - N536PA . N537PA O P - 695745 , POS. 1 . A P-695760 , POS . 1 - rl r iP.695743 , POS . 2 I1 P-695763 , POS. 2

r, "

O -1 0 I I I I I I I I I I I 1 100 . 200 300 400 500 600 700 800 . 900 1000 1100 ENGINE FLIGHT C Y C LES Figure 3 9 Estimated Sea_ Level Static Prerepair EGT. Deterioration.- Overal l EGT deterioration, based_on module deterio r ation_nd influence coefficients, shows a.rapid deteriorationof 6oc in the first. 50 cycles fol l owed by a long-term deterioration._ at a slower rate to 22oc at 1000 cycles.

, ° , 5. .... _ .. ; ;, , , , r , , , . i B._._ a mwr_ I I _ 01 ......

ql l qm l qn Im l| m < I : I I ' ' -1.0 , , I 1 .0 A _ ...-..- - " I'-_' - ' -l.0 PIC ,,= .,.., .i, ECM .

_ - --,, _ I N-FL I GHT ..........................

1 0 _ . .

o. . ..

<a -lO .

1 .o. I : I

- -,.o J I

0 ................... 100 200 300 400- 500. 600 700 ENGINE FLIGHT CYCLES Figure 40 Comparison of Prerepair Gas Generator - Parameters as Functions of Cycles as Determined by PIC Data Corrected F or Altitude, In-Flight . Calibration Data, and_ECM . Data. - .

Agreement among the three trends , is. fairly good although ...........

wide variations , in fuel. flow . occurred in in-flight calibrationdata and ECM data for engine , P-695745 and thu_..

influencedthe averagevalues.

_, b ra d 5 ,0 ....... _ HISTORiCAI.

4,0 / _ , _ _ ,m A IR LINE AVERAGE '_ - 3.0 I _ . / TgD7AISP) PREREPAIR .

1 .o r i

I

J, 1 500 1000 1500 2000. 2500 3000 3500 E N GI N E FLIGHT CYCLES Figure 41 PrerepairSea Level Static TSFCPerformance of JTgD Engines • i 1 at Constant Thrust - JT9D-7A(SP)t e st stand data correlates ,

!

well with historicalairl.ine data; PIC data shows, a somewhat _ .

more rapid TSFC loss.

6 6 o . .... . . . _...... L_ HISTORICAL L _ ' - ' " f PREREP A IR f m c I B O O I_Q00 1 5 00 2000. .. 2500 3000 3 5 00 ENGINE FLIGHT CYCLES Figure 42 Prerepair Sea Level static EGT.Performance o f - JTgD Engines at Con s tant EPR - JI'gD. 7 A(SP)te s t s tand data correlates ....

well with historicalairline data; P IC data S hows a . somewhat steeperEGT •increase in the low flight cycle range.

4, 0 • HISTORIC # ,L • _ ' 3.0 .... _ AI RL I NE A VER A GE m W. . S - / J T 9D7A(SP) < _ / P O ST REP AI R 2,0 / f ,..

/

1, 0 / . / . .........

500 1000 . 1500 • 2000 2500 3000 3500 ENGINE FLIGHT CY C LE S Figure 43 Pos_trepa.ir Sea Level. Static TSFCPer f ormance of JT9D Engines at Constant ThruSt - JTgD-7A(SP) test stand data and historical airline data show similar trends- with the .

h iStoPi C al_ data slightly higher in level.

_ 0 ...... Z ......... : 4 0 _ " o . .

p..

L U HISTORICAL <I 20 __ _ r AIRLINE A VERAGE ,' JTOD7A(Sp) _ J POST.REPAIR ENGI N E , FLIGHT CYGt.ES - Fig.ure 4 4 Postr e pairS e a Le vel Static EGT Perf o rmancef o r - JT9D Engines at Constant EPR - JTgD-7A(SP). test stand data and historical airlJne__data are very similar i n both trend and level, 4.3 MODULE PER F ORMANCE.DETERIORATION As previously stated, module,performance deteriorationwas determined only when prerepair,postrepair,and PIC data were obtained. These were .

the only.sources of / data whi,ch, wer.eassociated with instrumentation suitable for module performance evaluation. A typical example of the PIC data being used to obtain module deterioratConis illustratedin Table XVII. The change in measured gas generator-parameters listed in.

the upper left column were obtained at an engine pressure ratio (EPR) of 1.43 from Figures 32 through 37, presented earlier. The change in gas,generator parameters in the Analytical, Results column represents the result of engine cycl.ecalculationsusing the module,performance changes analyzed to have occurred. The only significancediffer e nces- between the measured and-analyzed gas generator-parameter changes_were in turbine temperature, wher .e temperature profile variations make measurements unrepresentative of the average temperature in many instances., T.hevalues of-module performancechanges,in efficiency and flow capacityanalyzed to have occured are thereforereason,_.ble.

The analyses, of the - prerepairand postrepairdata were similar but used the J T gD engine simulation rather than influence coeff_icients i.nthe I analy s is procedue.Module efficiency and flow capacity were "coupled" in an attempt to more accuratelyreflect the effect .ofone component, or modul e on another. "Coupling" refers to using a known relatio n ship betv_een the . efficiency and flow capacity o f a gi v en component,f , ._o_h e r i feature o f prerepair and p o strepair analyses is th.e-re!atingof the t 8 ......................................................................

known module., repairs with the te s t data obtained before and a?ter repair. T_ details of these proceduresare discussedin Section 3.0 TABLE XVII TYPICAL GAS GENERATORANALYSISBASED ON PIC CALIBRATIONS OF ENGINE P-695743 .......

ON 12-4-78 RELATIVETO 4-18-78 Change in Engine Measured Anal ytica l Paramet ers Paramet er Results Low-Press_reRotor Speed (%) +0.21 +0.23 High-Pressure Rotor Speed (%) +0.29 +0.29 HPC DischargeTotal Temperature (OR) +1.0 +2.0 HPT DischargeTotal Temperature (OR) +28. +21. ' LPT DischargeTotal Temper_ture (OR) +11. +-17. 'I Pt3 / I_t2 (%), +1.41 +I.44 Ps4 / Pt7 (%). -0.65 -0.67 Engine Air. Flow (%)-- -0.41 -0.63 Fuel Flow (%) +1.07 +0.99 Analyzed Module Parameters ....

Fan Efficiency(points) -0.80 Fan Flow Capacity (%) -0.50 Low-PressureCompressorEfficiency(poi nts) -0.65 Low-Pressure Compressor Flow Capacity (%) -0.40 High-Press , ure CompressorEfficiency(points)_ -0.60 High,PressureCompressorFlow Capacity; (%) -0.45 High-PressureTurbine Efficiency (points) -0.40 High,Pressure Turbine Flow Capacity (_) +0.40 I Low-PressureTurbine, Ef#iciency (poi nts) O. i Low-PressureT, urbine Flow.Capacity(%) O. i S om e typical tabularresul.tsusing the approachesmentioned above are given in Table XVIII which shows the modular breakdown from an analysis of historiCal.datafr( x nReference 1. This analysis was done-- _' ......... .... , . ,, , ii • "11 "ii" ii i i I I at 149 engine flight cycles and, as such, represents short-term deterioration.It should be noted that the estimated contribution, of the individualcomponents / modules to the overall perfOrmanc_1oses may be somewhat inaccuratebecause ofthe.lack of detailed instrumentation.

for a more Complete analysis.However, the breakdown between the high- and low-pressure-spool_ performance.lossesis reasonably accurate, As shown in. the table, this analysis indicates that the low, pressure ...

spool contributes55 percent to the overall engine-deteriora_;ion while ._ the _b £ gh-pressure spool contributes45_percent, TABLEXVIII MODIJLE CONTRIBUTION TO SHORT-TERMDETERIORATION BASED ON ANALYSIS (AT 149 CYCLES)OF HISTORICAL .DATA _.

Effi ciency F1ow Capacity TSFC.

Change {%) Chan_e (%) Change .(%), Fan -0.25 -0.25 +0.15 Low-PressureCompressor _ - 0.5 - 0.5 +0.15 High-Pressure Compressor -0.5 -1.25 +0.30 High-Pressure Turbine -0.5 +(3.25 . . +0.35.

Low_P.. ress.u_e_.T_.ur_bi he. -O. 5 O. 0 +0 .50 Total +I.45 Measured +I.45 Low-PressureSpool +0.80.

High-PressureSpool +0.651 Table XIX shows the short-term performance deterioration of engine P-695743 which was one of the four engines subjected to PIC Tests.

These results are based o_ the test stand data after the engine had been washed and the engine vane control(EVC) trimmed. These procedures improved, the.overall engine TSFC loss front1.5 to 1.2 percent. After these__ests,the , engine was subjectedto a complete analyticalteardown . .

where the condition of all the seals and other parts which affect performancewere documented.Based on this information,the performance of each module was estimated.These estimates correlatedwell with the....

performance data shown in the table and other historical short-term deteri.ortion data (Reference 1). The details._)fthis specific test efformare describedin detail in Reference 2.

As discussedin Section. 4.1.4 (Plug-lnConsole-Data)., the-gas generator- data and component influencecoefficientswere used to derive the TSFC _ation shown in Figure 38. A detailed breakdownOf each module's ContributiOn to the TSFClOss is , given in Tahla:sXX for-50, 150, a_d !_00 engine f, ligllt. Cycles,.At 50: C ycles, the TSI_C IZ_ss is dominated by-tlie.

Kigll-pressure L urbine. d _ .teri O ration witl_l_.sse e impacts.byi:h e , fan and low-pressurecompressor, At GO0 cycles, tile. l_igh-pressure turbin_ and low-pressureCompressor are equal in their contributionto tiletotal loss; the impa_,t.ofthelow-pressure turbine is pra_ticallynegli_lible ........

Over-the short term, tIIe-TSFClo s _es . . are nearly equally split between tilehot Settion._ and cold,._ection as well as between tlie_hlgh-pr.essure spool. , and._the low-pressure , spool, At 500 Cyc = les,tile cold seCtiOn dominates the - TSFC -10s . _es; the - low-pressure _i)6ol eXh . _bitsmore deteriorZ_tion tllan doe._til e high_pre_sur e spool, TABLE XIX..

MODULE CONTRIBUTIONTO SHORT-TERMDETERIORATION: BASED ON MEASURED. PERFORMANCEOF ENGINE P-69574 3 AFTER CLEANING,.. . _T_F.!I_lMM_NG_EZ.(AT 141 CYCLES),. AND PARTS INSPECTION Chang e in .TSFC . - _Iodule S.ince New (%)_ .

Fan +0.15 Low.Pressure Compressor +0.35 High-P_ressure Ccm]presor +0.12 High-Pr e ssure Turbine. +0.47 Low-P_._.essure T_Lm.bine +0.I0 T.otal +I,19 A.comparison of the tl_ree sources.of• short-termdata is presented on Table XXI in. terms of module. Contribution to TsFC. loss at _ approximately 150 cycles, In general, a!l three sources are in ._ agreement,The low-pressureturbine loss_based on.historical data is ] considerablyhigher than.that for the Other a_alyseS, but tliis.re . _ul.t could be due to the lackof Suitable inst_:umentation to accurately assess the diStribution.o¢Iow-.pre._sure spool loss__s, That.is, part of tl_is- loss• could easily be assigned to the i_a n or low.presSure compres_)r.with no ._ignificant effec L on the analysiS, 1 Tlleshort-term losses are due largely to high-pressure turblne and. I 1ow-p.resSure com_nre . _Sor deterioration with tt_e low-pres . _ure turbine • . . • • .... •

Contributing very little-to,the total los s . The-losses are evenly s plit, between the high.pressure and low-pres s urespool modules. Cold section deteriorat_ion seems te be slightly greaterthan that for the hot section, T AB L E XX _ - - AVERAGEMODULE CONTRIBUTION TSFC DE T CRIORATION .....

USING PIC DATA Change in TSFC { ) .

50 1"5'0 %500 F an O. 20 O.25 O.30 Low-PressureCompressor 0.25 0.40• 0.60 High-Pressure Compres or 0.10 0.20 0.30• High-Pressure Turbine 0.40 0.50 0.60- Low-Pressure-- T ur bine O. O.05 O. 15 Total O.95 __1.40 Io95 High-PressureSpool O.50_ O.70 O.90 Low-_P_ess ure Spool ........... O.45 O.70 1..05 Cold Section 0.55 0.85 1.20 Hot Section 0.4 0 0.55 0.75_ , Figures. 36 thru 50 show the._performanCe _ losses for each major componentwhich directly affects the.loss in TSFC (that is,fan, low- 1 and • h igh--pressur.e, compressors,and high ..... and . low-pressureturbi n es).

i

T hese < Jataare based on.PIC-tests,pr(,repair and postrepairtests, and 1 previously acquired historicaldata. The PIC data.show no discernable ,!

effect of engine location on the airplane (that . is, inboard versus_.

outboard)forany of the engine modules.

4.3.1 Fan The_efficiency and flow capacity losses due..todeteriorationof the.

fan . are shown in Figure 45 for the PIC tests. The fan performancefor all engines deteriorates rapidly at first. The enginLs-of airplane.

N536A mhow a highh,er, initial f.an_modul e loss.

The same fan performanceloss parametersare shown in Figure 46 using prerepair and postr_pair data. The data covers a range- of. flight cycles from 700 to 2100 and representsthe deterioration for the 72¸ unrepairedmodule s . Los s e s in fan efficiencyand flow Capacity due to deteriorationare predicted by "top down" analyses of the JTgD,7A(SP) engine prerepair data. This figure also shows module losses predicted from analyses ofpostrepair data in those cases when no changes or refurbishmentwere accomplishedon that particular module during the repair, The.prerepair-basedloss estimates are believed to have better Credibilitythan the pOstrepair-based estimatesfor reasons previously discussed in Section 3.4, Analysis Techniques. Module cyclic age is I identical with engine name-platecyclic age if no repairs have been I perfon_ed on that particul.ar module previously,which is generally the case for these prerepair data. Where there has .been prior module repair, module..age is .engine fl.ight cycles since the module was last repaired.

TABLE X_ ' , I COMPARISONOF MODULE CONTRIBUTION TO SHORT-TERMTSFC DETERIORATION Data Source P-695743 HistoricalData P&WA Testing Analysis of Anal ysis (A_-Recei ved PICData 1149 Cycles) with 141 Cycles.) 1150 Cycles)_ Change in TSFC (%) Fan +0.15 +0.05 +0.25 Low-Pressure Compressor- +0.15 • +0.40 +0.40 High-PressureCompressor +0.30 +0.35. +0.20 High-RressureTurbine +0.35 +0.60 +0.40 L ow-Press ure._T_ur]_i ne +0.50 +0.10. +0.05 T,_t. :! +I.45 +1.50 +I.30 Low-PressureSpoo'i +0.80 +0.55 +0.70 High-Pressure Spool +0.65 . - +0.95. +0.60 Cold Section ._ +0.60 +0..80 +0..85 Hot Secti on +0_,_85__ +0.70 . _ +0.45 Figure _7. is presented.toshow fan deteriorationusing data from all_ - available sources, that is, PIC.tests., prerepair and postrepairtests, and the previously acquired historical data. There is very . good agreement between the prerepair and postrepairdata and the histor.i c al data. The PIC data show a more rapid short-termdeterioration(that is,

!

7 3 • . , • , , i i m i i i I llll | ! I I I' the first.lO0 c ycles), T he sl o pe of the PICdata cu rve at about 100 ¢ ycle_ would seem to indicate similar deterioration levels for. all three dat_ sources by the time 2000 to_3000 cycles are obt_aS n ed.

_ 1,0 - N536PA N537PA L o P - 6 9 5745 , POS• 1 _ P - 695760,POS i . _- n P-6 9 5743,POS. 2 (_ .P -6 95 76 3 , POS 2

:: -i.0 o

o {IIL_ZL ._ j

,, 8_ o

-2.0 l £ l l I 1 I I I I [3]

>

I._l. C / ') .

-i.0"_ o 0 _ mn 0 " c) '. o- "2. 0 ' 1 l I I I ' I I I I I 1 I I OI 1 100 200 300 .400 500 600 700 800 900, 1000 1100 FAN AGE , , FLIGHT CYCLES Fig u re 45 Fan Module PerformanceDeterioration- PIC cal.ibrations from four engines, on two airplanes, show very rapid initial deteriorationfollowed by long-term deteriorationat a much slower rate.

_nalyses of the-short-term fan flow capacity losses have received special attention because-their effect on engine performance is

J

appreciable and.because the effects are considerablydlffer.ent between take-off_ and cruise - conditions. The results of this analysisshows that .

for_a 2 percent fan flow capacity loss, which is.typicalfor high-tlme fan b|ades,the take-off TSFC improves about 0.5 percent, but there is a 0.6 percent TSFC_penality at maximum Cruise power at altitude.When the- - flow capacity loss_ is 4 percent (extreme deterioration),tLe take-off I'SFCis about 0.8 percent better than whe n _new, but there is a_ _ 2___per.cent penality at maximum cruise• 3 ......... • 2 m l FLOW 047 • 0 5 0 • db7 1 6 CAPACITY. _ . _ LO S S , (%) 1 JTgD-TA(SP)AVERAGE' - _ 727 745 • • 060 •_ 732 a • _ 722, WP • PREREPAIR / POSTREPAIR COMBINATION _ : POSTREPAIR TESTS ONLY EFFICIENCY-- L OSS (POINTS ) 1 047 • 050 • _ 716

" - . gD.TAC PI A V ERAGE

• 1 732

?45 0. • 060 727 0 = FANA GE-- - FLIG HI CYCLES Figure 46 Estimated_Fan M o dule Deterioration.with Usage•- -The average estimated losses in fan efficiency and flow capacity are show n ....

4.3.2 Low -Pressure.Compressor The efficiency and. fl o w capacity losses due to deterioration of. the.

low.preSsure compressor for the PIC tests are Shown in Figure,48. The low-pressure Compr . essorexhibits,a deterioration characteristic-similar to_t_be_ f _an.

3 i l HIS TORIC A L -- , -DA _ A PIC i JTgD _ A( _ ERAGE_ o _ I ,., I I J A Z i.

0 2-- o .

H I STO R IC A L >.- ¢J Z I.IJ PIC I u_ .

U .

w •JT9D-7AISP) AVERAGE , I I I I 0 1 1000. 2000 3000 4000 FAN AGE " _ .(F LIGH . T CYCLES) Figure4 7 Com p aris o n o f P IC, JT g D-7A(SP) P rore p air, and Historical Fan Performance Deterioration Data - The prerepair test stand • data sh o ws , go od . agr e ement whil e the PIC data sh o ws a higher level of loss.

N536PA N537PA I'0F o P - 6 957 4 5 ,POS. I A P -6 95 7 6 0,POS, I .. . _ - | C_P-6 9 5 7 4 3, POS. 2 (_P - 69576 3, POS. , _

o

o A O u . -_.U- Q <I -3.0 I I , I 1 1 1 I 1 I I _ _ _ 0 _ _ -1.0 -2.0 I I "l r I I 1 I I I l I IOQ. 200 300 400 500 600 700 800 900 1000 1100 LPC AGE~ FLIGHT CYCLES Figure . 48 Low-Pressure Compressor Module Performance Deterioration -- PIC calibrationsfrom four engines, on two airplanes, show .....

rapid initial deterioration (less-than that for the_fan) followed by long,termdeterior._tion ata much slower, rate.

The prerepair and postrepair data for the low-pressure compressor module are presented in Figure 49. 0nly prerepair results are shown, since, there were no available postrepair data for engines with unrepaired low-pressure compressormodules. It will be observed that most of the engines showing hizjhlow-pressurecompressorlosses also_ exhibit high fan module losses and vice versa. This observation leads• to the conclus.ion .that, white fan / low-pressurecompressor losses are variable (possibly because of the .differing flight experience of individual engines), the losses are interrelated.Fan deflections and 77" re s ulti n g rub s from f l i g ht m aneuver s an d l oads als o tend to caus e .- l o w-pr e ssurec o mpre ss ordefleCtionsand rub s , 3 ,- , - - 0 060 .

e o 4 7 . i FLOW Q' o4B C APACITY

Loss

8h : ( %) _ o 8 3 0 -- '_ 1 , 7 3 - JTSD - TA ( SP) 050 0 w 722 DATA AVERAGE I . & O 72 7 74B • 74 _1 "__ • FIXED STATOR ASSEMBLY • TRUNNION STATOR ASSEMBLY 060• • 047 EFFICIEI _ C Y m . o4 8 L O SS (POINTS) 083j"_"__ • 732 DATAAVERAG E • 050 . _ 722 745 • 743 _ 727 l o o o _ 2000 ....................................... : _ Ooo LP C AGE - FLIGHT CYCLES .

Figure 49 Estimated Low-PressureCompress o rModule Deteriorationwith Usage - The m agnitude of low-pressure compressor deterioration appear s • related to the magnitude of fan deterioration for-individualeng!nes,.Itis b e lived that the- data scatter is aggr.avated by the greater potential for leakage in the case of the _ tr _ unoi on stator.

Additionally,there are two different physical low-pressurecompressor configurations representedin the data: . 1) first=stage compressorfixed.

stator - (enginesP-6 9 o 745 and . P-695743), and 2) first-stage cump ressor trunion stator. W h ile there are ins_f_ficient . f.ixed stator data to be 7 8 conclusive, it is believed that the-physical differencescontributeto lower losses for the fixed stator low-pressurecompressor-becausethe trunnion stator low-pressure compressor is known to present-greater potentialfor leakage as a result of relative movement between the cask and trunion bearings during service use..

Figure 50 compares the data from the. three sources (that is, PIC, preprepair-and postrepair, and historical).The loss in efficiency is reasonablycomparablefor all sources of data, The flow capacity trends are similar but the levels of_loss are •highestfor the historicaldata and lowest for the PIC data.

As with the fan, the-low-pressurecompressor.wasanalyzed to determine how flow capacity losses affect performance.A detailed description of this study is__presenJzed in Appendix B.

The analysis showed that a 2 precent loss in flow capacity (that is, a _ typical low-pressurecompressorwith 2000 flight cycles) results in a I0oC increase in EGT at take-off and a_O,6 percent increase in TSFC at maximum cruise power at altitude. A..4percent loss in flow_capacity (extreme deter.ioration) increases the .take- . off EGT by 25oc and the.

maximum cruise TSFCby 1.5percent.

] 4.3.3 High-Pressure Compressor 1 The efficiency losses due to deterioration of the high-pressure compressorfor the_PIC tests are shown, in Figure 51. On airplan e N537A,.

the deterioration losses,show the characteristic short-term losses..

]

However, on airplane N536A the high-pressure compressor,short-term losses are relatively small. No explanation is known for this latter tr.end..

The pr_repair and postrepair data f.or the high-pressure compressor module-are shown in.Figure 52. Estimated loss in flow capacity for the .........

high-pressurecompressor-is not shown. While the "top down" analysis method predicts high-pressurecompressorflow capacity changes in order to match,the test data, the results are biased by variable stator indexing resultingfrom f._eld trim. Thus, the results include vane trim _ .

effects in addition to flow capacity,loss due to deteri.oration.

Additic_ally,engine performance, is.not strongly influenced by changes in high-pressurecompressorflow capacitychanges r.esulting from either deterioration or vane trim. For these reasons,,the -analytical flow .....

capacitychanges are not presented. . .

The losses in efficiency due to deterioration._ange-from about 0.5.

point at 700 cycles to I point at 2000 cycles.

HI ST ORIC A L B JT9D . ?AISP) AVERAGE , - I_lC

o I I I .... J

H I STORICAL

'F

1 .1 000 . . 200 0 3000 LPC AGE " _ (FLIGHT C Y CLE S ) EJgure 50 Comparison . of PIC, JTgD- 7 A(S P )Prerepair-andP o strepair,and Hi s toricalLow-Pre ss ureCompres s or PerformanceDeterioration- Data - -The .loss in.efficiency i s comparable for all data sources_ BQ. _ .. ..............................................................................................................

N536PA.. N537PA.

l.Or o P,6 9 _.745, POS, I A P-6 9 5760,P0S. I .

[_P-69 5 743,POS. 2 {_P-695763,POS,_2 > .

!

-^ - o

I_. _ , ....

f " -2.01 I I I ,I ,,I. / . ..I . l I 1__.1 i I 100 200 300 400 500. 600 ..700__ 800 900 1000 1100 HPC AGE , ,FLIGHT CYCLES Figu r e 51 High-PressureCompressor Module Performance. . Deterioration• PIC calibrations, from four engines, on two airplanes,show.

characteristic , initial deteriorationfor engines on one of the airplanes but a reduced initial deterioration, for engines on the other airplane,,followed by long-term.

deteri oration at a much slower rate.

O PRE , PO S T C OMBINATIONS _ PO S T REP A IR TESTS ONL Y LOSS 2 743 t "0 722 EFF I C I ENCY , 4 l" (P OI NT S ). t - I o 6o I 727 A 097 A I _ 1 L 727 "

I ------. A o s O -O o ;; TgD. , A( S P

0 _ l V V u = = J X D A T A A VER A GE 1000 2000 3000 HPC AGE - FLIGHT CYCLES Figure 52 Estimated High-Pr e ssure-Compressor Module Deteri o ratio n _wi.th ,- Usage - Results are shown for only efficiency loss since analyticalflow Capadty loss results include the e .f_Zect, of variabl e vane trim in additionto deterioration ..............................

Figur e 53 c o mpare s the data fr o m the thr.ee data so urc e s , Th e hi s t o rical data s h o wns . - a deteriorationlevel.ab o uttwice as great o n th e. PIC and prerepair and po s trepair-dataat I000 fli g ht cycle s . Po ss iblerea s on s for thi s . d ifference are: i) the relatively f e w and po ss ibly cleaner .

airp o rt s s erved by the Pan American 747(SP) aircraft,, which may hav e biased the data in so me fa s hi o n (i s le ss erosion), and 2 ) m o re careful c o ntrol in the . 7 47(S _ E) o f thru s t reverse u s age re s ulting in le ss dirt .......... _ .........

inge s ti o n.

4. 3 .4 Hi gh-Pressure Turbine T he efficiency loss es and flow capacity increa s e s, due to deteri o ration of the high-pres s ure turbine ba s ed om the PIC / te s tsare s hownin F igur e ....

54. M ost of the lo ss e s in the high- , pre ss ure turbine, o ccur in the first 50 to 100 flight cycles.

T he prerepair-and postrepair data for the high-pressure_turbineare shown in - Figure 5 5, Only prerepair •data_re s ult s are s hown, since there were no available postrepair data for- engines w_th unrepaired high-pres s ureturbinemodules. Rredictedefficiencyloss has relatively little data s catter , while considerablymore scatter - is seen for flow capacity i.ncrease, T he reason for this variation in scatter is.

attributed primarily to the. fact that predicted flow , capacity is stronglydependent .on the measured value of P s4 / Pt7, which, in turn,,is influencedby the condition of the high-pressurecompressor.moduleand the resulting exit tem p erature profile effect on measured Ps4. Also, burner pressure loss variations associated with burner liner configurationwill affect predicted flow capacity since burnerpress u re loss changes are not separatelyaccounted L or, as discu s sed in Section 3.4.

F igure 56 compares the data.fr o mthe three data sources.. The losses in efficiency are greater for the h_storical data than those fror : L the other source s , The.differencesare related to design improvementsthat were incorporated in the JTgD-7A(SP) engines evaluated during this program ....

4,3. 5 Low-PressureTurbine The efficiencylosses and flow_capacity lo s ses due to deteriorationof the low-pre s sureturbine based on the PIC tests are presented in Figure 57. The deteri o rationlosses of this module are negligble.

The prerepair-and postrepair data for the low-pr . e s sure turbine are shown in F igure 5 8. The average low , pressureturbine efficiency lo s s and flow capacity increase is greater than that . shownby the PIC-data.

on the previous figure. A point of interest is that the rate of HISTORICAL , _ Q u_ u_ 1 _ ul ( $ P) A VERAGE

o t f I I I

1 1 0 0 0 20 0 0 3 00 0 HPC AGE "_ (FLIGHT CYCLE S ) _.

Figure 53 Comparison of PIC, JT9D-7A(SP)Prerepairand Postrepair,and Historical High-Pressure Compressor Performance DeteriorationData - The PIC and test stand data indicate less high-pressurecompressor loss than does the historical data.

N536PA N537PA 2.0 I- o P-6 95 74 5 , P O S , 1 _P- 695 7 60 , POS . 1 - _. ;_ _ , | c: } P -695 7 43 , P OS. 2 (_ P- 695 7 63 , P OS . 2 /x < 3 .-1. 0 ] I I . ,J I I z ..... I ., I ....... z ., a I 3 Q, _.-I.0- - 2. 0 I I I. I I I .I i _ • l J 1 I00 200 300 400 500 600. 70 0 800 9 00 I000 II00 HP I AGE~FLIGHT CYCLE Figure 54 High-Pressure T urbine Module PerformanceDeterioration- PIC I calibrations i_rom f o ur engines, on two airplanes.,show . I characteristicinitial deteriorationfollowed by long-term deteriorationat a much slowerrate.

O5O 2,0 '" ' 0 - 74 0 ..... FL O W CAPACITY • INCREASE- .

(%) 1 .o ' _ L __ ' • 04 7 , , 73 2 JTgD.7A(SP) • 048 DATA AVERAGE D 0 W 083 • 727 3°0 " '" 2,0 .......... 743 • ' ' = EFFICIENCY , 04 0 q l (POINTS) 732 .._ LOSS __ . _ . _ - _ • .................. JTgD - 7A(SP) 1.0 ' 1 4 B _ _ 0: :0 DATA AVE R A G E 0 iO0 1000 ' 1500 2000 H P T AGE - I _ LIGHT CY CL ES Figure . 55 .EStimated High-P_ ' es s ure T . urbineModule , Deterioratim_ with Usage - - T I _ greater data scatter irz the case of fl(_ v

"

capacity increa , se is attributedto the-stro_g dependencyOf predicted flow ca_!acity on measured P.s4 / Pt7 and the associatedinfluence , of . compressor- (:o n _it i on . on e x it proFil and measured PS4.

,% w .................................................................................... HISTORIC A L 2-- 1- -- PIC ' HI S T O RI C AL _" o _ D " _ , o I i I ..... I !

HP T AGE _ (FL I GHT CY C LES ) . ' l Figur e 56.... Comparison of PIC, J'TgD-7A(SP). Prerepair and _ Postrepair, . . !

and Hist o rical H . i gh-Pres s ure T urbine Performance . _ Deter-ioration Data - The PICand test stand data indicate .I lower I tigh-pressure turbine losses than does the h.i , S L or.ical

J

data. i

!

8 6 _."_ N536PA N537PA _.

_. 1,0 _ o P-6 9 5 7 45,POS. I z_P-6 9 5760,POS. i F- 13P - 69 5 743,POS. 2 IXP - 695763 , POS, 2 CD ....I u_ - -_l.O -_=. _ ..... i ,.. t _1 ..,t ....,. I -- ,, I . 1 _ I ...... J N -l.O- (J IJ- b_ ,,,.-2.0 I I l I. I I. 1 I . I ... I I <I i i00 200 300. 400 500 600 700 800 900.. I000. II00 LPT AGE , , , FLIGHT CYCLES Figure 57 Low-PressureT u rbine Mod u le PerformanceDeterioration- PIC.

cal.ibratiOns from four engines, on two airplanes,show that.

both initial and long-term , deterioration is practically negl_g!b]e. _I low-pressuretur.bine-, deteriorationappears to be related-to_therate of _ fan / low-press ure. compressor det eriorati on. Engines with high fan / low-pressur.e-compressor losses tend to be . high in low-pressure.

turbi4qe los-_es and vi_:e, versa.

Figure 59 Compares_ the data_fromthe three data sources.. The,-e£ficiency, losses and fh;w capacity increases,are lowest for the PIC and historicaldata and greaterfor the prerepairand postrepairdata.

3,0 ' • 2 o 0 _.

FLOW CAPACITY JTBD,7A(SP) AVERAGE - 050 , .o , _ W =, : ' - INCREASE( % ) • 745 _W 3 _ -- • 048(J) . 048(11) 72]7(i) q_ l ) 732

• o s o 0 55 ..... •

727(11} 0,0 0 500 1000 1500 2000 • PRE , POST COMBINATIONS .

• POST . REPAIR TEST ONLY 3 . 0 ° 2 . 0 EFFICIENCY JTSD-T A ( S P)AVERAGE - _ • 050 .

(POINTS} . 048( I ) .

LOSS nAT 743 - V_ 1 .0 _ ' v " • .......... =n=7 2 W """"_ 7 _7 ,( ! ) 048(II) 732 727( 1 1) • 7 45 0,0 - 0 500 1000 . 1500 , 2000 AVERAGE LPT AGE _ , FLIGHT-..C.YCLES -- F igure58 L_-Pres s ure Turbine Module Deterioration with Usage - The rate of low-pressure turbine deterioration appears to be- related to the-rate of fan / low-pressure- compressor deterioration; engines, that are high, in f . an and _ _.

low , p ressure c o m p re sso r losse s also, tend to be high ,- in low-pressure turbineloss and viceversa.

• " -- , ; , , ' ,, ", I I I IIII i """1 i I I I I I - " i " " 3 m -.

.i ,I 2- - w mr Z m ).

M- a.

¢{ I -- O JT9D.T A (S P ) A V ERA G E HI S TO R ICAL EL DATA o _PI C

I I I [ , 1

A z _ 2 - o U Z JT 9D - 7 A (S P ) AV ERAGE I _1 1 n LL HISTORICAL I.U DATA 0 _ P JC '

I I I I I

1. 50 0 1 0 0 0 . 1 50 0 .2 00 0 LP T AGE " _ (FLIGHT CYCLES) Figure 59 Comparison of PIC, JT9D-7A(SP) Prerepair and P o strepair, and Historical Low-Pr e ssure Turbine- Performance Deterioration Data - The- test stand data Shows greater low-preSsureturbine losses than does either the PIC. or historicaldata.

!

........ J , , i ..........i........ i I ""_"" _ SECTION5,0 REFINEDMODELS OF JTgD ENGINE PERFORMANCEDETERIORATION 5,1 REFINEMENTOF PERFORMANCEDETERIORATION MODELS One of the end results of the initial,phase of the JTgD Engine _.

Diagnostics Program was the. establishment of preliminary performance deterioration models for the JTgD engine and its modules (fan, low- and high-pressurecompressors,and high- and low-pressureturbines),Thes_ preliminary models were based on the analysis of Pratt & Whitney Aircraft and airline historical and_used parts data. This section.of the.report discusses the refinement of these models as influenced by the in-service data gathered from the Pan American 747 JTgD-TA(SP) fleet. This latter data included PIC tests data and prerepair and post, repair test stand data, 5.1.1. Fan Figure 60 shows the refined fan efficiency and flow capacity loss model. The refined performancedeterioration model isan average curve fit through the thr e e curves (which were not weighted equally).

Prerepair test stand data analysis results have been favored over PIC analysis results. During.PIC tests, the presence, of the inlet cowl caused inlet flow field instabilitieswhich led_to_ low rotor speed variations.The predictionof the fan flow capacity and efficiencyfrom ' the PIC - data alone_is, t]qerefore,considered less reliable than predictions based on test stand data. Prerepair test stand data and historicaldata (preliminary model) are in fairly good agreement with each other.The refined mode] represents an average fit through these two.sources.

Figure 61 presents the refined fan model cur.ves with the scatter bands.

These bands represent the approximate scatter in the JTgD-TA(SP) data _ and thus represents the _ossible engine-to-engine variations for each model_.

5.I.21 Low-Pressure Compressor' Figure 62 shows the.Low-PressureCompressor refined models. The three data sources are in fairly good agreement with each other exceptthat the historical data shows somewhat greaterflow. capcity loss. The J T 9D-7A(SP)prerepairand PIC data has been favored over the.h.istor_ical data because the expanded instrumentati_on (include Tt3) used in .the JTgD-7A(SP) engine testing permitted more accurate analysis of low-pressurecompressordeter iorati on.

PRECEDI N G PAG___ _ E _E BLA N t( NOT FILMED 9 1 3 m

" M ° °E' CI

I /_" / TEST S TAND DATA

gZ

I l I I

A , .

2 - - o n. PRELIMINARY MODEL 1 -- , PI _ . M O DEL u J _ _ P) AVERAGE - R E F ' NED " V / TEST STAND DATA 0 --

I I I I

1 1000 2000 3000 AVEB AGE FAN AGE (FLIGHT CY C LES) Figure 6 0 Development of Fan PerformanceDe , terioration Refined Model.............

- The refined model is based, predominately on the JTgD-ZA(S)test stand data and the preliminarymodel....

F, . igure 63 presents the r.efined low-pressure-compres s or models w_±h the ............

scatter bands of possible_vari ations among individualengines.

31 m !

I .

I .I I I

3 l A oo F - Z O ,.d >.

Z __. l--- u= u .

uJ 0_

[ I I I

_o o o 2 o0 o 30 o 0 AVERAGE FAN AGE (FLIGHT CYCLES) Figure 61 Fan Performance-Deterioration-Refined.M o d e l and Variation_ Band - The v ar,iatio n _band represents, data,Scatter _ _among individual JTgD-7A(SP) engines.

9 3 "' .... • = _ , ,'i , i_ "" 'if ....... i " " I I I I f a_- PRELIMINARY M ODE _ JTS D , TA( S P)AVERAGE " 7 _ . _ FLOW , _ _ ', " , ........

CAPACITY. LOSS P _ i TE S T S T AN D DATA / . . . . _ .r /

l I I J

2 m EFFICIENCY LOS S PRELIMINARY MODEL--_ (POINTS) . _" PI c- _ _ .. _ ....

1 -- _¢ 4 __ _ 1 8 1 __ LREFINED --MODEL / _ - " JT9D-7A(SP)AVER_AGE 0 l TEST STAND DATA

L I I I

I 1000 2000 3000 AVER / , _ . ,.PC AGE (FLIGHT CYCLES).

Figure62 Devel o pmemt of : L ow-Pressure Compressor Performance.

Deteri o ration RefinedModel - T h e refinedm o del shows, les s flowcapacity Ipss thanthe prel im_nary model.

; 5 . L 3 High-Pressure Compressor I T he refinedhigh - pressure m o delis shown o nFigure 64. It i . s weighted_ toward the JTgD-7 A (S P ) engine d ata and i s s omewhatlower than the . 1 preliminary model,.TheJTgD-7A(SP) PIC and test standdata trendshave been fa v oredover the historical re s ult s becausethere is relatively i littleTt4 instrumentation datain the historical testresults, leading to uncertainty as to high-pressure c ompres s or efficiency lo s ses.The 9 4 ....................

; - .. " _ ' ; , "- *,- , " • • '_ i ....... r ,,, i i i i i 1 _F Jim'_ll refined model lies above., the JT9D- . 7A(SP) data based on engineering.

Judgment, The 747 JTgD-TA(SP) s erves Y'elatively few City pairs and the , exposure to dirt . ingestionis estimated to. be l e s S . than.would be -- experiencedon th_ av e rag e airline Operator aircraft or engine to.which .......

the model is addressed,No flow capacity deteriorationmodel i s shown.• for reasons pr e viouslydiSeussedin S e ction 4.0 2 m FLOW .

C A P A CIT Y LOS S __ ( % ) 1 - 0--

I i I J

3 _ .......................

_ E F FI C| E NC Y _ " / / LOSS (POINTS) 1 - // - ...................

I I J .I t . . . 1000 _ 2000 3000 I A V ERAGE LP c ,,.AGE ( ELIGHT CYCLES ) i Eigure 63 Low-Pressure Compressor Performance Deterioration Refined 1 Model and V ariatix)n. Band - The variation• band_repres en tS_ I scatter among individualJTgD-7A(SP)engines.

4 m P_R ELIM I N A RY M O DEL / EFFICIENCY f - LOSS 2 - - _ " . f ......... S EFIN ED ( POINTS) / / o . j MO DEL t _ . j i _ / .

o • I" ! I I .

1 • 1 0 0 0 2 0 00 3 00 0 . . 4000 AVERAGE HPC AGE (FLIGHT CYCLES) Figure 64 De v el o pm e nt of High-Pressure Compressor Performance .

Deterioration Refined Model -The refined modet lies between the historical data and JT9D-IA(SP) data which indicate Iower . .deter-i orati o n . with respect to usage, The refined model with . t.be.perfor m ance scatter-band is shown on F igure 65.

5.1.4 ,High-Pressure Turbine The refined High-Pr . essureTurbi.ne models are-shown on Figure. 66. The efficiency loss ' for . the refined model is somewhat less severe than for the preliminary model. The flow capacity increase_is slightly greater.

The refined model represents an average fit of PIC, prerepair, and historical data, although PIC and prerepair-data are favor_edbecause of the h.igherqual . ityof the JT9D-7A(SP) data as discussed in Section 4.0.

9 ¢ | EFFICIENCY _.

LOSS ' , (POINTS) 1 l ooo 2000 300 0 AVERAGE HPC AGE(FLIGH T CYCLES) F ig u r e 6 5 H i gh - E c e ssu r e CompressOr , Pe rf o rma nce D e t e ri o rati on R e fi ned .

Model and Variation Band -The variation band represents data scatter among individualJT9D-7A(SP)eDgines.

The flow capacity increase for both the prEliminaryand refined models may be partly due to, high-pressure- compressor discharge pressure profile changes resulting from tip clearance losses in the low- and high-press_recompressors. Measured P_s4strongly influencesanalys_s of high-pressureturbine flow capacity as discussed in Section 4.0. The refinedmodels with their_ possiblescatter baFLds are shown on Figure 67.

5.1.5 Low-PressureTurbine The refined low-pressureturbine models are shown on Figure 68. Both efficiency losses and flow capacity increases are greater-than the preliminary models. Again, the-JTgD-7A(SP) test stand data analysis results were favored over the historicaldata because the JTgD-7A(SP) _ data are believed to be more credible. The_r.efined model trend was weightedtoward the test Stand (700 to_ 2000 cycle , )analysis results.

The PICanalysis of Iow- . pr.essure spool loss split between the fan.and low-pressurecompressor is considered less reliable because of inl e t instabilities as previouslydiscussed in the fan section (5.1.1).

J g7 !

d 2 m• FL O W CAP_ CITY PRELIMINARY MODEL ' -' _ INCREASE ..-, . "_ REFINED ..-- _ 1 - _j . ,mm .-

( O / o ) .O OEL \ _

/

TEST S T AND DATA _ JTgD-7A(SP) AVERAGE.• 0 --

I i I I I

REFINED EFFICIENCY ._ , . _ _ ' _'_ P R ELIMIN A RY MODEL LOSS _- (POINTS) . _ . - ' JTgD-7A(SP) AVERAGE TESTSTAND DATA 0--

I I I [ I

1 E00 1000 1500. 2000 AVERAGE HPT . AG E (FLIGHT CYCLES) Figur e 6 6 D eve lopm e nt of High- P ressure Turbine Perf o rmance Deterioration Refined Model - JTgD . 7A(SP) engine data showed lower efficiency deterioration and slightly higher flow_capacit_ increase than that for the historical data.

q FL O W INCREASE C APA C ITY _ L I I I 3 _ 2 _ (POINTS) EFF I CIENCY LOSS o 4

L I L I

1 10 00 200 0 300 0 AVERAG E H P T AGE (FLIGHT CYC L ES) . .

Fig u re, 6 7 H i gh -Pr e ss u re Tu rbine Pert_ o rma n ce D e t e ri o rati o n Refi ned Model_ .and V ariationBand - The v ariationband represents , - datascatter _11ongindividual JTgD-7A(SP) engines.

The refInedm o del s with_ the .possibl e scatterm bandsare_.sh o wn o n Figure _ 9o 9g .

_ : _ , --; ........ , n ,i ..... in i i ' " i i I I I a ! - IA I 14 , 1 N U <U 1 - - . JTgD.TA (SP) AVERAGE. _ TEST STAND DATA_ .. , . , "_ MO D=_ _ " _ _ - -- PnE UM,N A . Y --- M O O S L .r- PIC . / 1 " _ J 0 m _ , .m,.. _ _ ,m . Jr_ , t I I I I 3 mm m.

JT gD - 7A{ S P) AVER A GE m 1 TEST STAND DATA -- REFINED _ -- ' M oo,= ,. _ _ . / --P , E,. , , V , NARY MO DE,. _

o

._ 6 00 l ooo 1_ oo ..... = o o o AVERAGE LPT AGE (FLIGHT CY C LES) Fi g ure 68 Devel o pment of Low-Pressure Turbine Perf o rmance DeteriorationRefined Model - JTgD-7A(SP) engine data shows increaseddeterioration relative to historicaldata trends.

I00 _ . 3 - - b - Z O Q .

_ J O0 < 2 n Z > - Q .

. J EL O

I I I l

3 m .

Z

o

31 " 1 • • ' L u , /

I l I l

t l o o o • 2 o o o 3 0oo AVERAGE LPT AGE (FLIGHT CYCLES_)_ .._ F i gu r e 69 Low -Pr es s u r e Tu r b i ne P e rf o r m anc e De t e ri o rati on Re fi ned Model - The v ariation band •inCludes- all datacollected to date.

5, 2 E N G I NE PE RF ORMA N CE T R E NDS_MO DEL VER S U S . DA T A The refined m o del s o f c o mponent d eterioration have been combined to pre d ict overall engine s ea level take- o ff TS FC deterioration (at c o nstant thrust) and . EGT increa s e (at con s tant EPR). Stabili z ed high-pre s sureturbine performance beyond 1000 cycles;and low-pre ss ure_ turbine,performance beyond 2000_cycles are a s sumed, The result s are s hown in F igures 70 and 71.

HIS T ORICAL 5 . 0 , - AIRLINE A VER .

JTgD(7A ) (SP) PREREPAIR 4 . 0 - - - "_ REFINED --" MO D EL 3. ( - --- A TSFC .

( % ) t _ " , # 1.0 PIC o I I I I I I I 1- 500 1000 1500 2000 , 2500 -- 3000 3500- FLIGHT C YCLES Figure 7 0 Prer e pair TSF.CPerformance Data , Measured at Constant Thrust, as . a F uncti o n of Usage -The refined model of engine performance loss shows good agreement with historical . data and 7 4 7S P engine , test stand and PIC _ data.

F igure 70 shows engine TS F C deterioration at three usage , intervals o btai J 1ed by curve fit s t h rough JTgD-7A(SP)engine test stand data, PIC data, and the hi s toricaldata. The refined model shows good correlation with the various data sources. Prerepair TS F C deterioration for- unrepaired engines, as .pre d icted by the m o del, ranges from nearly 1 i percent in 5 0 cy c les t o a b out 3 .7 per c ent in 2000 cycles, The historical data (en g ine s. _._nerally having had s ome prior repair) and

I02

k L_ the_ model (with stabilized turbine damage) show_TSF___deterioration increasingto abo u t4.4 percent in 3000 cycles.

S 0 !"

m HISTORIC A L AIRLINE AVERAGE ,_, EG T 4 0 (o c ) -- REFINED '" MODEL , _ ..

20 JTgD7A(SP)PRER E PAIR TEST STAND D _ ,TA PIC o' I I I . - 1 1 5 00 1 o o o 1 500 2 0 00 250o 3o 00 3_ oo FLIGHT.CYCLES Fig_uz_e_71 Prerepair EGT Peri_ormance Data, Measured at Constant EPR, as a Function of. Usage -The ref.i n ed model of engine.

performance loss shows good agreement with historical data and 747SE.en g ine tes.t _ stand and _ PIC data_ Figure 71 presents prerepair EGT increase for unrepaired engines, relat.i.ve to production EGT level, as predicted by the models, This deterioration tm_nd is compared to the trends from JTgD-7A(SP)engine test stand data (based on fuel flow) and from P.ICdata, as well as to the. historical, test stand data. The model, with stabilized_ high-p r essure tur.bine damage assL_ed, shows good Correlation with the various data sourceS. Prerepair (unrepaired) EGT increase is about 30oc at 2000 fl ight cycles .... ii I There are no m o dule . loss models for postrepair-data because Of the compares postrepairTSFC_deter-ioration trends from JI_9D-7A(SP) engine test Stand data with t . he-trends of the historical data.. An average fit. !

of the data is Shown. A v erage-postrepair-TSFC deteriorationrelative to i the_production.level ranges from about 2 percent at I000 flight cycles i to..abozL_ercent at 3 000 cycles, i ............ i 4 , 0 m, HISTORICAL AIRLINE ¢J LL AVERAGE POSTREPAIR I-- PERFORMANCE JT9D-7A(SP) POST REPAIR < :] TEST STAND DATA 2 . 0 ............................................

1 , 0 i

o I I I I I I

1. 50 (I -- ......... ! I000 1E 0 0 . 2000 . 2 " 5 0 0 300 0 FLIGHT . CYCLES Eigure 72 Postrepair TSFC Perf o rmance Data, Measured at Constant Thrust, as a Function of Usage - The- average postrepair_ performance shows good correlation with .the 7_47SPengine test s_and _ dataand the historicaldata.

Similarly, Figure 73 shows postrepair-EGT trends, relative to the .......

productionlevel, for the various data sources. An average fit of the data is shown. Average postrepair EGT deteriorationis about 20oc at 2.000 cycles.

5.3 MODEL PREDICTIONS The indiv.idualmodule loss models have been used in the engine simulationto estimate losses at gi v en flight cycle periods, by module and by damage mechanism. These TSFC predictions, are_at sea level static constanttake-off thrust.

The bar chart shown in Figure 74 compares the individualmodule.losses estimated using the models at 50, 500, 1000, 200(i,and 3000 flight . _ ' cycles. No cold section repair was assumed for-the preparationof the comparison in Figure 74. H owever, high-pressure turbine damage was assumed to be stabilizedat 1000 cycles and low-pre_sureturbine_ damage at 2000 cycles to reflect typical prerepairengines.

E

J

I

10.4 . . . o _. _ . ; . , ,., " r " " i-" i i i i i d _ m,if_ + 60 -" HIS T ORICAL . - . +40 - / " AIRLINE AV E RAGE A VERAGE POSTREP A IR ./ " _ JTgD-7AIEP) POST REPAIR TEST S TAND DATA 0-- -2_ I I I , I t I I e oo . m oo le oo 2 ooo z5 oo 3 000 3e oo FLIGHT CYCLES Figure, 7 3 . Postrepair EGT PerformanceData , Measured at Constant - EPR, as a Eunction of-Usa g e- The average postrepairperfor m ance shows, good correlation with . the . 747SP engine test stand data and the historicaldata, + 3 .01 -

/

+ 2 .0 _ " A TSF C " (% ) _ - -- _ _ _ 5 0 FLI GHT S 50 0 FLI GHT S 1 00 0-,EL L GH T S 2000 FLI GHT S 3 000 ..FL I GH T S TOT A L * %TSFC D ETERIOR A TION. +1 . 0 +2.0 +2,9 +3.8 +4.4 Figure 74 M o dul e Performance D e terioration,ate_ConstantUndeterior- - ated Sea Level Static Take-Off Thrust, Based on the Refined .

Engine DeteriorationModel -Early perfor m ance lo ss es are most significant f.o_the - low-pressure compres s or and the high-pressure.turbine; as flight cycles _ncrease, high- pressure compressor - and . low pressure turbine become increasinglyimportant.

105 i F igure 7 5. pre se nts a m o dule-by-modulec o mpari s on betw e en the refined mo del and the preliminarymodel which r es ultedfro m the hi s toricaldata study. The refined model total TSFC lo ss at a given cyclic age i s s o m ewhat le s s than that_predictedby the preliminarymodel through. 1000 .

cycle s , and s imilar-to-thatpredicted by the preliminarymodel at 2 000 and 3000 cycle s , However, the di s tribution of losses by m odule i s different,The refined m o del s how s le s s high-pre ss urecompre ss or, lo ss at a given cyclic- age, and more low-pre s sure turbine lo s s, Fan.

low-pre ss urecompres s or and high-pre ss ure.turbinelo s ses are s imilar.

These differencesare attributed.primarily to increased data quality in this s tudy relative to the data from the hi s torical study, permitting more rigorous analy s i s (earlier data had greater test s tand correction uncer_t aint3_) • F igure 76 presents the refined model showing the revised estimates of the contributionof the three major _ cau s esof performance deterioration to module performance losses, Early performance losses,are due primarily to tip clearance increase s .

and are mo s t s ignificantf o r th e low-pre s surecompres s or and the high pressure turbine. As flight cycles increase,cold _s_cti on erosion and thermal c Us tort L onbecomes increasinglyimportant.

Figure 77 presents the refined model showing the estimated relative contribution of the three major causes to engine performance deterioration versus flight cycles. Comparison wilththe preliminary model would show minor changes in the_overalllevel and distr3butionby cause in the 500 to 1500 fl . ight, cycle period resulting from the improvedquality of the .J /g D-Z__(SP) data.

_, O _" E _ F AN 4 .0 -- _ LPC H P C _ I_ H P T IIT TU LP T , 3 ,0 " - A TSFC (° 1 4 ' ,,..

PR E L IM IN A RY MO D E L -- RE F I NI=D F_ 1. o 7!

:. : ::: o il 50 _ EL I GHTS , 5 0 0 FLIGHTS . 1 000 FLIG H TS 2 _ L I GHTS 3 00 ( 1 FL I GHTS ......11_ F ig u r e 7 5 M odu l e P e r . f o r m a n c e De t e ri o rati o n , at C o nsta n t Unde .t e ri o r ,- ated Sea Le v el Static T ake,0ff Thrust; Refined Model Resul t s Compared to PreliminaryModel Results ..... The refined model , shows slightly less sh o rt term_loss; as flight cycles .....

increase,the refined model loss is similar to the prel4m- inary model, but the distriJ3ution of los s es by.modu]e.,is somewhat different.

;4 107 !'

r--i _ CLEARANCE - FLIGHT LOADS AIRFOIL AND S EAL ERO S ION - _ RI .THERMA L DISTOR T ION 1000 FLIGHTS 200OFLI G HT S 3000 FLIGHTS . _ + 2'0 F " +1.5 I-- 6 0 FLIGHTS 600 FL I G HT S 3: _'

(%)

=' =l =

TOTAL % T S FC +1 . 0 +2.0 . +2 . 9 +3.8 _ . +4.4 DETERIORATION Fig u re 76 Major Cau s e s for Module Perf o rmance Deteri o rati o n - The estimated contribution of flight loads, erosion, and thermal , distorti on to module performance1osses are shown.

EROSION +4 , A T S FC (O _ ) . ' T HE RM A L DISTORTION .- + 2'F CLE A R A NCE CH A NGES (F L IGHT L OADS)_

l

0. I 1 1000 2000 3000 40 00 , FLIGHT C Y C LES F i gu r e 77 Con tri bu ti on o f Major C a use s t o 0ve ra ll Eng i ne Pe rf o rma nce Deterioration - The refined model shows negligable difference to the preliminary model with respect to the proportion of overall engine performance loss due to each cause.

i08 .

SECTION .6.0 RECOMMENDATIONS Based on the analysis of the data collected dur.ing the current, efforts..

of_ the NASA JTgD Engine Diagnostic.Program,.and considering the prel iminary recommendations presented in NASA CR-135488__(Ref.1) a number of refinedrecommendations can be made._ - o Action that. the - airlines could•take now to improve fleet_ average perfermance, o Areas where design and de.velopmentof improvements___are required,and o Areas where .additional diagnosticsefforts are required.

Recommended engine operating procedures, discussed in Section 6.2, lists operating do's and don'ts for the airlines to minimize deteri orati OF L during transientengine opera_ti on.

A simple and accurate system of performancemonitoring and maintenance documentati_on would permit each airline to optimize maintenance_ procedures and minimize fuel consumption and operating costs. Section 6°2 discusseswhat the airlines can do now and what addit.i_ona] tools are required ......

Section 6.3 recommends• maintenance actions and frequenciesby module to.

minimize performancedeteriorationand to achievethe maximum practical performance restoration. The recommendations,based on the historical data and.the Pan American 747SP engine prerepair and postrepair.data and analyses,may be put-into practice no_. I ] Section 6.4 discusses the four generic per f ormance deterioration mechanisms and.the design_and development, criteria that_should be investi gated to reduce the• tnfl uence_ofthese mechani sms.

Finally, Section 6.5 discusses.experimental and analytical efforts needed to better understand the complex_ causes of specific deterioration phenomenon and permit identification of potential solutions to.engi.ne performancedeteri orati on.

6.1 ENGINE OPERATINGPROCEDURES Production acceptance testing of new engines at Pratt & Whitney i Aircraft has shown very little deterioration(10.2percent TSFC change

t

109 . I maximum) from the initial data point to, the-final calibration. This running includes all of the various types,of operation. (includingsnap accelerationand .deceleration transients)that are required in customer test stands or during ground test operation in the aircraft. The followi.ngguidelines have been developed,to minimize deterioration• during this type of post, repAir engine operation:.

i. Operate at idle.power- for.a minimum of 5 minutes after start before acceler.ating_a_bove idle.

2. The initial acceleration from idle on a res . tored.engine should consist of gradual incrementalpower increases.

3, Unnecessaryh_ot, fastacceler__atio n s_ n r decelerationsshould be avoided: a. Whenever.possible, accelerations or declerationsshould be slow., that is, at a rate equivalentto a minimum of 60 seconds for a full power-leverexcursionbetween idle and take-_ . off power.

b. Following more.than one minute of.operation at.or above bleeds•closed power, the engine should be operated at - idle for: (1) 7 minutes prior to a slow acceleration(that is, 60 seconds minimum, idle to.take-off); ......

(2) 15 minutes,prior-to a snap acceleration,which is defined as . a power lever-movementof _ one.second or less for a full excursion.

c. When snap., d_celerations are required, they should be performed as soon as possible after reaching.high power (0 to 10 secorLds preferred,30_secondsmaximum) d. Engine calibrationsshould be performed in a decreasing power direction so that the engine will be "cool"- at.the end of. the calibration prior to shutdown or _.

operati on.

e. Run at idle for a minimum of 5 minutes before shutting down.

Adherence to these procedureswill minimize blade to rub-strip contact by allowingthe contact to.occur graduallyratherthan abruptly. Abrupt - contact in high-pressure turbine stages can cause localized metal transfer and build-uLon the rub strip which would result in excessive blade tipwear,_.

Suf_Zic_ent "Cool down"-timeat idle _after being at.high power and prior- to an acceleration to high power. (as prescribed in 3.b.above) is required to prevent excessive blade to rub-stripcontact resulting.from a hot rotor acceleratingin a relativelycool case. Similarly, if snap decelerations are to be made, they should be performed as soon as.

possible aft e r - reachinghi(_hpower (3.c above) to minimize the,amount of_ thermal growth nf the rotor disk which can potentially rub the "cool" case after the-deceleration is made.. F, igure 78 gr.aphically presents the interactionof a typical hot rotor and rub strip•(that is, tip clearance)during an acCeleration / deceleration cycle. Revised test stand proceduresthat are consistentwith the above recommendationsare soon.to be released for re_ision of: the JTPD engine manual.

An unfortunate incident during the postrepair testi.ng , of JTPD-TA(SP) engine P-695745 showed the-effects of inadvertentlynot following._ the above operating guide_lines.Following the April 1978 repair and postrepairtest of this JT9D engine by Pratt. & Whitney Aircraft, it was ret.urned to_Pan American for their testing. On.June 19th, the engi.ne was run in the_test stand for the purpose of.correlating their stand wit_ the.Pratt & Whitney Aircraft MiddletowneF_gine test.stand. During the second calibrationrun, after stabilizing for 3 to 5_minLttesat .......

take-off power-level,the engine was accidentallyshutdown. The-engine was restarted within 2 minutes, and the test was continued.There.was no indicati.on of rotor seizure; however, subsequent analysis of the test data indicated that there was a performance deteriorationof 1.2 percent in_Wf and a 12oc increase,in EGT relati.ve_ to the prior calibrati on run.

The ei_fectof this shutdown and restart was similar to the transient shown in.steps 3, 4, 5, and 6 on Figure 78. The - aCc.i.dental shutdown removed the centrifugal forces on the disk, allowing the disk to shrink, and opening the clearances(point 3 -,-4). The turbine-case, and outer, rub str_ip then started cooling and shrinkingat a more rapid rate I than the disk, causing.the blade tip / rub-stripclearance in the slowing down . engine,to close (point 4 -,- 5). The engine was restarted before t.he high-pressure turbine disks had cooled and the clearances h_d sufficientlyreopened. T h e resultingce n trifugal, force on the hot disks caused them to expand, closing the.gaps between the_ blades and the relativelycool rub strips (point 5 -,-6)..The-rubwhich ensued w . asnot ......

sufficientlysevere to cause a seizure but did open blade tip / rub strip Clearancesenough to cause the measured_performanCe loss......

Thus, the failure to ObServe . , the recommended , operating procedures during test stand or installed engine operation can result in IIi : '.-4Jr' .................. ,J , • , , _ _ _ r II ' '; ' '- ' # ' = '_ il s i g nificant, l oss o f perf o rmance.If the re s ultin g rub o c c ur s during a p os trepairtest, the re s t O red perf o rmance . froma careful refurbi s hment . _ Can be lost bef o re the engine i s returned to s ervice, and the benefit o f the refurbi s hment , will. be . ob s cured t o airiine maintenance and operati ng per so nnel.

_ 1 I F : _l N 2 h i I _ _<1 SI It - _'1 _)O R UBB T R I P EX PAN DS (_ RUB S T R I P COO L S i F I RST : _ DOWN F A S TER DISK COOLS .p 1 6 MINUTES , GAP / % ROTOR Di S K _ THAN DIS K _ / OK FOR -- _ I ' % , _ , D IS K S T I LL -_$ N A PACC E L

___o, -

• m (mml _ (Imm (tomb n (mmml gIw)m mmm (Immll m (mmmm _III' Im.m.dlmml i S . S . S . S. S.S .

IDLE , S LTO ( _ IDLE I RE - ACCEL ._ H OT A CCEL RUB .

I I I T I ME . I _ - - - _ A C CE L = I DECEL . = . .

(3 ) - _ S NAPACCEL=-INITIALCLEARANCEDECR E ASEDUETOCENTRIFUGALGROWTH AND BLADE T HE RMALS ( _ ) ,-- _ HOTSNAPDECEL. -- INITIALCLEARANCE I NCREAS E DUETOCENTRIFUGALRELAXATI O N AND REDUCED BLADE TEMPERATURE it ( _ ) _ IF S NAPACC E L P E RFORMED BEFORE D I S K COOLS , C EN T RI F UGAL GROW T H AN D BLADE T- H BRMALSON HOT ROTOR WILL CAUSE ABRUPT BLADE / RUBSTRIP CO N TACT \ F i gu r . e. 7 8 Ho t Ro t o r / Rub -Stri p I n t e ra c ti o n - Be c a use t he t he r m al ex pa ns i on a n d con tra c ti on rat e o ft he _ c as e ( a nd t he r ub s tri p ) i s fa s t e r t h a n t h at o f t he rot o r d i sk, an a b r u pt blad e / rub - strip c o ntact .will o ccur if a snap acceleration _ .

is per . formed before the disk c o ols.

6._2.PERFORMANCE - BD J _ ITOR ING 6,2.1 PerformanceTrendin_ and Management Efforts during the historical and current in-ser v ice data collection activities highlighted the need for improved management information Concerningindividualengine and fleet deteriorationif improvementsin 112 !

fuel bur.nelL and operatiIiO _osts are tb b_ achl_.ved, it has been clearly identified tl_at large variations ex:i._t betw e . en operator practices that have an i llpAct On ave_age• e_gi ne. perfbrmanOe Ievel, A_t operat o r' s fl_et fuel Consumpt , ion. is _pendent. on tw_ factors:-perfonllanCe r6.tenti . on while on the .wing, and $_ : rformance recovery whilo., in the shop, To.

effecti . vel.y manage tlmF , e factors, ccwnplete racm_ds of indivi.dual engilie performance histories and repairs are- . r.equired.These. data should i_cl _tde: _I nitlal engi ne performancedata; o Periodic installed engine perfon_anee data.to define trends, inCluding £ _uelcosts and range / payl . oad l imi tati ons; o Repres enta£ive airplaneoperatin g cycle-.data;_ o Accurate performancerestoration and engine modif, ication data., includ L ngcost .andshop t u rn-a_ounddata; and o Expanded instrt_nentation .testing _fore and after major refurbisl_nent actions ....

A computerizedmanag.ement tool could then be used by L . each.airline to--_ optimize engine own._ngand operating costs for its fleetand route.

structure..lhis , tool could provide .eaCh airline'S management with a means to evaluate effect L veness of shop visits and.could assist in contro.lling those factors , that increasefuel. ¢onsLmmd. To.developsuclx a managm_ent, tool, s_eral steps are _ecessary, including: o Performance data .collection_andprocessingShould be.revised .

to provide., more a . ccurate tracking of individual engine _ perf _ian ce.

o Accurate repair rebuild and operational, hiStories should be maintained,for engines, modules, and _oi,_lance sensitive components.

o A reliable and s:imple-systL_n, for measuring and analyzing engine p.erfonnance before and-after repair is-necessary, o A rigorous instrtnnent calibration syst_n is required to ensure _ test measur._nent accuracy.

Eacll of these requirementsis discussedi.n the following paragraphs.

6.2.2 Engine ConditionMonitorin _ The existing flight performance Engine Con d ition Monitoring (ECM) SystBn does not. provide data of suZficient.accuracy for precise performan_.e monitoring _f individual engine s . It is. desirable to develop a standardized, Simple, and-sufficiently accurate system for ' determinat.ion of engine flight performance deteriorationtrends. The AID'S.systBII, whicliis.available,may be the answerto this problem.._ AID'S is an aut a nated data System which monitors in-flight p e rformance more directlythan tI_ Current ECM approach.

6.2,30perating.Hist.oryandRepair Data Collection This basic information exists in various forms at all operators..It would be desirable.todevelop a uniform program with the capabilityof l comparison of operator characteristics.Such a com n on program would permit identification, and Comparison of "relative .deterioration rates for. 'operators.in adverse operating environments, such as. mid-East deserts, with operators in clean climates. A program of. this nature.

would provide the tool each operator needs to -assess thetr___OWL performanceretention and restoration..

6.2.4 A.nal_,sis of Performanceand Repair Data.

The NASA JT9D Jet Engine. DiagnosticsProgram has produced a.preliminary analyticaltool forisolating performancedeteriorationby module as.a.

function of test stand testing and Plug-lnConsole (PIC) testing data...

Further refinements will be.necessary before such a diagnostic tool would be available to each airline to determine what repairs should be made on an engine_ and to measure the performance improv e ment, by ._ module, of a repair action. See Section 5.4.

6.2.5 lest Stand Instrumentation and Calibration Based On the observations made during visits to the airlines'- test facilities during the historical and JTgD-7A(SP) data collection.

activities, Several. areas, we_'e noted where improvements could be made in the inStrmnent calibration procedures. The reconlnendations are not - directed toward anyone airline, but to the test facilities in general.

The reCom_endat.ions f . allinto_fivecategoriesas . _hown below: o . C alibrati on. standards, o Written calibrationproc.edures, o Data retention,

o Cal ibrati on . teChniques, and o Cal.i brati On-analys_s.

l_he problBns and recommended• solutions are discussed in detail in SeCtion 6.2.2 of the report on h.istoriCal data Studies, NASACR-135448 .......................

(Ref.. i) and will, therefore, not be . repeated in this document. The general problem.is that the errors which can develop in the. test Stand instr_nentation system are of the Sm_e magnitude as the peri_ormance..

Changes which need .to be. measured.. Thus, a rigorous program of.

instrument calibration is required to. accurately assessthe magnitude of a specific performance problem and to provide an indication of the most 1ike]y cause Of_ the problem.

6.3 MAINTENANCE PRACTICES i This section presents recommendations for the retention of engine _- performance which are based on the results of the earli.er, study, effort.

with refinements resulting from the later data analysis. A principal _ result of. these analyses is the knowledge that t_he , relative influence of low-pressure spool module deterioration , is greater on flight cruise performance than. on sea level performance. Thus, greater emphasis Should be placed on.low-pressure spool module performance restoration than g r ound testing would suggest.

6.3.1 F_an Fan performance deterioration is caused by the increased tip clearances which result from flight, loads and which appear to stabilize after I000 f.lights. Sur.face roughness .increases with usage and then also appears to Stabilize. F.an blade leading edge bluntness, however, Continues to increase and the pe_f.ormance penalty gr_w_, Based on these damage mechanisms, periodic hand cleaning of the fan blades and Stator vanes when the engine-is in the-shop and res.toration_ of leading edges are-the _two recommended maintenance actions. As long.

as the fan rub strip is mechanically sound and-the tip clearances are within Overhaul Manual limits, no restoration of fan blade clearance is recomF_ended due tu the short-term rub-out from the effect of fligh t _ loads. The recommended refurbishment p_eriOd is-between 2000 and 3000 cycles with strong .preference given to the.shorter_interval because ol_ rapidly increasing fuel priceS,___.___ 6, 3.2 Low-Pressure.Comp.ressor- The mechanisms that reduce _peri_ormance• in the low_pressure-compressor- arc tip clearance, roughness, and airfoil leading edge shape. Surface roughness inCreases-and then appears to stabilize. Tip clearances,.

however,cOntinue to increa s efrom the effect s of erosion on the rubber outer airseals, Airfoil leading edge shape or. bluntness i s not judged to be significant up to the current level oi _ u s age (4000 .to 5000 cycles ).

The low-pre s sure compre s sor Should.be Chemically cleaned at every exposure and the rub strips.replacedbetween 2000 and 3000 cycles when the engine is.in the shop.. The first-stagetrunnion stator-vane s hould be replaced with a fixed first-stage stator vane to reduce-fl.ow Ios s .._ The effect of airflow losses, particularly on EGT, as-well a s I'S F C,..

suggest that more attention should be placed on this module. The.- _ airfoils inspected showed signs of thinningfrom the samples inspected with 5000 cycles usage. Consideration should be_given to replacing• these airfoils between 5500 and 6500 cycles, depending on their condition at that. time. The rapidly increasing cost of fuel will.

increasingly, favor _ refurbishingat the louver end of the recommended interval 6.3.3 Hi_h-Pressure Compressor High pressur.e , compressor._performance losses caused by erosion are initially due to blade length reduction, loss of outer, airseal material, and increasedroughness.The ef.fects of blade Camber-change, based on analysis, become important, at usage levels beyond 3000 cycles in the blades.

The-performancelosses in the high-pressurecompressorsuggest that the compressorshould be refurbishedbetween 2500.and 3500 cycles with long bl.ades and new / refurbished rub strips in all stageS.The stators should also be chemicallycleaned at this time. Based on stator thinning, the stators, as well as.the blades, and outer airseals should be replaced ..............

at the next interval or 5000 to_.ZO00 cycles.

The •correlation of compressor blade- length to EGT impro_vement is strong. The measured EGT improvementdue-to reduced blade / OAS clearance.

appears greater than the expected,average. EGT improvement.T.hus,it appears that reductions in. compressor blade clearances improve combustor_temperature profile and, . hence, the EGT 9rofiles and measured val.ues.

6.3.4 CombustorS_stem Even after,repair, the combustor should have 100 percent efficiency, Whi.l_e. the direct effect of c om bustor deterioration on-performance_ is , insignificant,the - indirect effects - are major. Changes in radi.aland circumferentialtemperature patterns in the combustor exit gas._affe_ct 116 i clearances, and_ a host Of other- mechanical shape changes in the _ .....

turbine, as well as tur.bine durability.

When the combustor is repaired, the. dimensions, and particularly the con_ angle, should be restored. The fuel nozzles should also be r_emov_d and cleaned, The potential that.cumulative damage even with repair._will reduce the structural stability ofthe co_bustor front end suggest that the combustor not be i_sed beyond the third installation. Turbine durability and performance losses can be traced to variations in.

combustor repair practices. More precise definition of which dimensions are the most critical .must await further testing.

I, 6.3.5. Hi,h-Pressure Turbine _ - The deterioration of_the- performance of the high-.pressure turbine appears to be dominated by tip clearance changes and the second-stage vane inner shroud leaJ<age.

Blade tip wear of first-stage turbine blades cor.relates with initial build clearances and build standards with respect to blade length..

Control Of first-stage - bladelength by hand selecti.On ordrum grinding to a cOnstant diameter is recommended. The outer airseals should be offset ground to the requirement set forth.in the Overhaul Manual. The tip clearance should be Set to 0.073.+0.002 inch. The second-stage.

blade- clearances should be set to the- nominal dimension, and the Second-stage . vaneinner . footdimensionsshould be Set to the tight side of.the toleranceband.

6.3.6 Low-PressureTurbine _llade tip clearances ar.e a major cause of low-pressure turbine deterioration.Rebuild Standards which allow larger tip clearances . , cause an increase in postrepair , performance deterioratio n . , The ring seals of the low-.presSure turbine are , very responsive tO temperatur.e.

changes. . Hot shutdowns will cause rubbing and performanceloss due to the rapid contractionof-theseseals. , The , performancepenaltiesfor increasedtip clearance are larger in the- t . hird stage (first low-preSsure turbine stage) than in. the sixth stage.

The tip clearances should be kept to nominal dimensions,particularly in the third and fourth stages , during rebuild, and platform soldering _ should be eliminated by vane repair when , the ,low-pressureturbine is opened for otherreasons.

6.3.7. RebuildStandards Rebuilding an engine to the manufacturer's recommended standards is.

essential,to achieving optimum performance recovery. The historical data study indicated that the TSFC recovery was-less than that which was posslble with recommendedrebuild standards.Sim.ilarly with the Pan American engine repairs analyzed in the current study, there were numerous cases, where shop production schedules required module _ "swapping!'and did not-allow time for modules, and engines to be completelyrestored.This procedure is ill ustrated in Appendix C.

The Pratt & Whitney Aircraft JTgD Overhaul Manual and Repair Manual were originallydeveloped with the objective of prolongingthe useful life_of parts to reduce maintenance costs on the basis of structural .

and safety criteria. The .changingrealities of higher fuel costs suggest the need to revlse, the manuals to provide information concerningthe impact of various repair practices on fuel consumption, such that each , operator can determine the. trade-offs between fue.l.

consumpti on increasesand maintenancecost increases.

Thus, it is recommendedthat the operators follow the current Pratt& Whitney Aircraft recommendedrepair practicesuntil the results of this D_tagnostics Program ar_e used to revise and refine those practices.

6.4 DESIGN CRITERIA 6.4.I Int, oduction The resul.tsof the analysis of the historical data, in particular - the_ parts inspectionresults, and the Pan American 747SP in-service engine data have provided detailed informationfrom which recommendationscan be made for specific design , and development actions.. These recommendationsare presented in this s e ction, and are grouped below according to the three operati_n-rel ated generic causes of deterioration.These causes are: the.effect of flight loads on_engine clearances,erosion and impact, damage, and thermal distortion.

6.4.2 Flight-Load-lnduced Losses The increased diameterand tighter running clearances of current high, bypass ratio turbofan,eng!nes have increased the. sensitivity_ to the. .

effects of flight.maneuver-loads. Historicaland current enginestudies have shown that . there is_a performance loss during the first, few flights relative to productionengine final acceptancetest levels. The most likely Cause of this performanceloss is change in engine, running.

Clearances caused by either thermal or flight load conditions not experienced in the test stand environment.Analytical stucLtesof the effects of flight loads have indicated.that the typical flrst-flight load conditionsCould cause a loss of I percent in TSFC. Projection of the increased level of flight loads that might be experienced as service time increases suggests that the initial level of loss could increase another i percent in TSFC by the time 3000 flights have been completed.The results of these analtyicalstudies are reported in NASA CR-135407 (Ref. 3). The initial I percent TSFC loss may occur in the airplane acceptancetesting and delivery flightand, thus, may never be.

seen by the airlines. However, from a technical standpoint, this initial loss representsa real loss of engine performancethat might be avoidable if the causitive factors were addressed during the original engine and installationdesigns and might be recoverable or avoidable in currentengines by deyel opmentof appropriate modificati ons.

The flight-load-induceddeteriorationoccurs in all of the modules;- however, the major impact is in the fan, low-pressurecompressor,and high-pressureturbine. The increased gas, path clearances are caused by a combinationof mechanical effects,namely, steady state and transient aerodynamic_loads, gravity forces, gyroscopic effects, and engine transients, all ofwhich tend_to move the rotating blades and seals relative to the stationary case-mountedseals. The resulting rubs open_ the gas-path clearances _.The losses for the most part are estimatedto occur •early in the engine life and shortly after-engine rebuilds.

Future engines and engine installationsshould address these flight load effects.

Further effort is in order to determine how engine thrust and externally induced florcescan be more effectively transmitted through and around the engine. This achievement would permit retention of running clearancesand lower rates of deterioration.

A Simulated_Aerodynamic Load Test program has been initiatedto measure.

and evaluate the effects of simulated aerodynamic loads on gas-path clearances. This program will significantlyimp.rove the understanding of the short-term deterioration• problem and. pro . vide guidance for eval uati on of potenti al sol utions.

6.4.3. PerformanceLoss Due to Erosion Erosion is .the wearing away of airfoil and seal surfaces by the..

impingement of foreign matter., in the gas path, and thus, occurs primarily during ground and near-ground operation. The extent of erosion damage is,. ther.efore, a function of the number of.take-offsto which the engine is subjected and the conditions at the airports.

served. Erosion reduces engine performance in two ways. It blunts and wears down .airfoils,thereby reducing their efficiency, and it wears.

away blade_ends and seal surfaces, resulting in increased gas-path Ieakages.

T h e do c u mented e ffect s of er o sion o n c o mpre s s o rairfoil s and se a ls s upp o rt the need t o impr o ve the er o si o n re s istance of these part s . T he rubber o uter air s eal s s hou l d be replaced with a more erosion resistant material.Nickel graphite, nicromp o lyester, or sintered m etal materia ls are all candidatesthat s hou l d be as s e sse d.E l iminationof the squealer cut on the s ixth- s tage c o mpres s or blade s h o u l d be examined to deterimine if it can be done without s tructurallife loss. . In the l ong term, either airf o il material change s or the development o f ero s ion_ resi s tant coatingsfor applicationto both static and rotating airfoils are required,The developmentof" suitable erosion resistant coating s is i estimated to have the most ...... likelihood of early success within I _ reasonable level s o f cost, Based on the . damage rates and esti m ated i performance losses, coatings for-the high-pressurecompres . sor airfoil s are the most critical need, followed by application in the fan and i ! I ow- p re ss urec o mpre sso r., -- T he se l ection and s creeningof candidatec o ating s will take s ome period - of time, and service evaluation testing i s required prior to wide _ spread use of airfoil coatings for performance retention. Active programs , currently exist in both areas on other-Pratt & Whitney.

Aircraft engines (JT 3 D and JT8D) and have been initiatiedon the JT9D..

T hese coatingswill not eliminate the need to periodicallyrefurbish, replace, or recoat airfoils and seal materials. The potential improvementfrom coatings and new seal materials is.... at least-a..50.

percent increase in the performance life of these parts, with an optimistically 100 percent : increase. - .

The control of the. quantity of erosive material that enters the .

compressor through the use ofpassage shaping is a_ possibility for foreign object damage control'. The_size of ; the partic.les _that cause the bulk of the erosion damage ar e estimated to be such that passage .

shaping may have little eff.ect. The use of boundary layer'bleeds to remove the - erosivematerial at positionswhere it . tends to concentrate.

may have a somewhat higher probability of success. These areas wil l require extensive research and should _be investigateduntil sufficient technical information is available to evaluate both feasibility and cost effectivenessof such concepts. For current in-service engines, the condition of compressor •hardware_ sh o uld be monitored and airfoil s should be .replaced in accordance with a planned engine maintenance schedule.

6.4.4 ThermalDistortionEffects Thermal . distortion effects are primarily twisting, bowing, and soldiering of turbine,vanes whic h results fr_ r nthe basic temperature and stress environmentof the.turbines and changes to that environment.

These turbine environmental change s are caused by changes in the ........ m i - i • i i i i compre s s o r performance,combu s t o r dimen s ional c han g e s , and fuel no zz le coki r ig with usage which produce change s in combu s tor exit temperature levels and profiles. The resulting increa s e - in turbine airfoil los s e s and increased leakages reduce high- and 1ow-pre_sure ,turbine effici enci es.

Ba s ed on turbine part mechanical condition s , compre ss or and combu s t o r -- deterioration appear to cause radial and circumferentialchanges in temperature pattern s into the turbine and cau s e elevated metal temperaturesabove the design level s , resulting in thermal di s tortion, o f turbine parts. Turbine vane , bow result s in flow area changes which and. vane twist increase _ the secondary flow losses and reduce _- I_ control the operating lines of the compression, system._. Platform curl .....

efficiency.Higher , temperatures nearthe annul us walls increase running.

clearances due to the cases_and seals running warmer than .plannedand increase clearances due to d.lfferential growth of_,r.otors, seals, and cases, Fundamental to corrective action,isran understanding of the causal_ factors that produce combustor temperature profile shifts. The data collected and analyzed during the program,showthat such changes occur and arerelatable to clearancechanges in the high, pressure compressor,.

fuel nozzle, clogging (coking_, and combustor dimensional changes.

Component and engine,testing is required to quantify the relative importance of- these variables prio_ "_ to making definitive_ recommendations for design criteria changes. The impact of nozzle coking can,be minimized by periodic on-wing Zuel nozzle cleaning. This procedure is. very effective for removing fuel nozzle coking when periodiccleani.ng is per.fOrmed at periods..less than 2000 hours.

6..5 RECOMMENDEDPROGRAMS 6.5,_I Introduction The completed efforts in the NASA JT9D Jet.Engine Diagnostics Program have- accompl i_shed the , f-ol Iowing: o Defined the four major causes of performance deteriorationand estimated the magnitude of each cause as a f-unction of engine usage, o Identifiedthe pr.obable cause of engine short-termperformance deterioration as flight, load-induced increases-in gas-path.

clearances and established that the losses,caused by flight._.

loads most likely increasewith usage.

o Identified the relative importance of. each deterioration mechanism in each module as a function of usage.

o Developed analytical models for use in predicting and understanding the deterioration of the engine and engine ...............

modules as a function of usage.

o Identified deficiencies in. the current_ understanding of specific deterioration issues.

On the basis of these findings,several additionalefforts or tasks are .

recommended. . These recommen d edtasks are discussedin this secti on.

6,5.2 Flight Loads Test Program The estimated flight-load-inducedeffectson gas-path clearances are a .

significant cause_ of increased fuel consumption with usage. The .

SimulatedAer o dynamic Load Test program has been initiatedto increase our knowledgeof these effects by measuring the.influencesof.simulated aerodynamic loads on the gas,path clearances. This pr.ogram, however, cannot-measurethe influence of transient loads which would be caused by wind gu=ts,_hard landings, and flight maneuvers. To thoroughly understandthe effects offlight-induced loadson the engine / nacelle structure and on the various running clearances,a_flight test program -- is needed and recommended.This program would require - instrumentation .........

of JTgD engine s on a 747 airplane in inner and_outer, wing.-positions using,instrumentation concepts investigated during the . " F easi.bility Study ofMeasuring In-Service F light Loads" (see NASA CR-135395) (Ref.

4) and derived from the Simulated Aerodynamic Load Test program. This instrumentati on woul.d include: o F an, four.th, stage low-pressure compressor, and f . i.rst-stage high-pressure turbine tip .clearance instrumentati_onL o Expanded PIC engine-performancE instrumentation; o Velocim e ters and accelerometers on engines, pylons, and .

airplane center of gravity (CG); o _. Pressure transducersin the engine inlet cowls.

Thus, forces, accel erati ons, clearance changes,and performancechanges could be measured.

This program would supplement the Simulated Aerodynamic Load Test.

program and provide the°necessary informationto fully quantify cause and effect relationship s .

, I 6.5. 3 Fan___ Engi ne Test at Altitude A number of performance deterioration effects appear to be significant based on the analytical efforts to date but cannot be accurately quantified with the availab l e data. T hese performance deterioration effects include' o T he specific effects of erosion induced roughness and / or bluntnesson.fan airfoil efficiencyand flow capacity.

o The roughness effect on fan / low-pressure compressor flow ch o kingin th e .l o w- p ressurecompr e ssor, inlet gui de vanes, o T he precise effect of fan and low - pressurecompres s ormodule deteriorationat altitude.

o T he effect of specific deteri o rationmechani s m s o n off-design performance.

For these rea s ons, it is , _ , uggested that a fan-engine altitude test program be conducted.The program wou l d include . ase_ . ,ies of tests in an altitude test stand at cruise conditions as well as at sea level. , Modules with specific representativelevels of deteriorationwould be tested to measure the effect on the performanceof that module and its influence on the . performance, of the other engine modules. This test program would be . very helpful in quantifyingthe effects of different damage mechanisms on,component deteriorationand engine performance at cruise a ] _t_tude. .

6.5,4. EngineDiagnosticsProgram for Use by Airlines The earlier s tudies andthis study program,haveshown that with their current performancemonitoring, diagnostic, and repair practices,the .

airlines are not achieving optimum performance recovery. Use, of the "JTgD Module Performance Analysi s Program,, available from Pratt &_ Whitney Aircraft, could improve the airlines! engine diagnostic capability. This computer program is currently being revised to __ _- incurporate data. validity checks to reduce analysis uncertainties .

caused by test data scatter..Still fur.ther-refinements in airline diagnosticcapabilitycan be achieved based on the knowledge . gainedand to be gained from this JTgD Jet Engine Diag.nostics Program.

Furtherrefinement of the engine and module deteriorationmodels, as presented in Section 5.0, is planned fo ll owing the completion of the current and proposed JT9D Engine DiagnosticsProgram tasks_ These final models will aid in refining the_",lTgD Module Performance Analys.is Program" for use by ai . rlinesto plan engine maintenance based on performancecalibrationsand . historlcal data on each engine.

S E C T I ON 7,0 CONCLUSIONS The in-service, engi.ne , performance deteriortion investigationwas the.

second phase of the - NASA JT g D Engine Diagnostics Program to be completed.The performancedata collected and analyzed__inc l uded fl.ight, special ground test using a Plug-I_nConso l e (PI_C),and test stand prerepair and postrepairperformance,calibrations, The in-service fleet Of 32 JTgD,7A (SP) engines in Pan American's fleet of 747 Specia l Performanceaircraft were selected for this investigation. Analysis Of these improved data resulted in a refinement of the preliminary_ perf o rmance, deterioration models and concl usions. It wou l d be 4mproper, however, to concludethat.a simple direct analysis of the data from arLv one of these three data systems would provide a Sound bas.is'For a comprehensive underst . anding of performance deterioration levels and trends in an engine. Therefore,further refinements of the mode l s and recommendations are planned upon completion of other current and on-going program efforts.

There are a number of major points.thatcould not be resolved from the availabledata. These.pointswere: First . - The necessary data accuracy in individual engine flight perf_ormance deteriorationlevels was not and cannot be achieved with the. installed a.irplane measurement system. There are several reasons for this limitation. The insta l led performancemeasuring system and.

instrumentation is not sufficientlyprecise to permit identification of individual eng!ne performance changes. N o nuniform airplanE-related effects on the four engines, and.possible deteriorat . ion in airplane systems , affecting the ettgine, appear to influence the fl_ight performancedata.

Second - The _ analyses of the _historical and in-ser. v Jce JT9D-7A(SP) engine data suggest that the various deterioration mechanisms may influence _rformance_.differently at al.tit_de than at sea level. Thus,.

the effect of changes in module condi_tion on the cruise performanceof a new . or deteriorated._ngine may have a different influence than on the s . ealevel performanceof that engine. The centralquestion that applies to deterioratedengines is the effect of . efficiencyand flow capacity changes in deteri - orated fan and low-pressure compressor modules on cruise TS E C. .

Third - Since.reduction in fuel.flow at c_uise, where - most fue l is burned, is the obvious goal, f.ur.ther efforts are required to develop an .....

understanding of the cause and effect relationships in. module ...........

deterioration, and their relationship to engine cruise performance deteriorati on, ._ I i q ' PREC ED ING PA G E i _LAN I ( NO T F I L MED

!

The in-serviceengine study was conducted concurrentlywith.the normal flight Operation. and maintenance of the Pan AmeriCan 747SP airplanes.

In-flight data were collected with airplane-installedinstrumentation and with various airplane systems influencing engine operation. PIC testing was conductedwhen and where the. airplane was available between.

scheduled flights, Expanded instrumentation prerepair tests , were conducted.when a repair schedule permitted and when the engine was .

still in satisfactory condition prior to repair. Engine repairs involved extensive-swapping of refurbished and partially refurbished modules to minimize the engine repair "turn-around" time, lhus, the program was conducted in a realistic• operating environment, However, there were many factor_ that influencedthe data obtained.. In general, the flight data was useful in defining airplane average engine performance _ trends but was the least accurate data source in identifying individual,engine deterioration, trends and levels. The test-standtesting provided themost accuratemeasurement of engine and module perf.ormanceand performance changes, However, the accurate measurement of small changes in engine and module performance with _ usage was inhibited by the accuracz of the test-stand instrumentation ..........

and callbrati on processes, Thus, to obtain the desired understarLding of engine performance.

deter.ioration .requiredin-depth.analyses of the three data systems,• knowledge of their limitations, and, finally, a comparison_of the results with the historical data study results, with the prop_er judgementalweightingof each.

From these analyses, it can be concluded_thatthere is no single prime .

cause of per£ormancedeteriorationin the JTgD engine.The results have shown the relative domi nance of Iow- pressure compressor and high-pressureturbine deteriorationin the short term. However, fan, high-pressure compressor, and Iow-pressure turbine deterioration increase at a_steadyrate with. usage.

Furthermore,it would appear, that flight testing of the_airplaneby the manufacturer,prior to delivery to. the operator does not have a significant influenceon performance deterioration of the engines. The results indicate that if there was sommeengine deteriorationdue-to _ productionairplane testing, it was no more tha_ a spare engine might incur in the first few revenue.f.light cycles.

741 OVERALLENGINE PERFORMANCEDETERIORATION Engine performance deterioration• results_from the degradation of the .

mechanical , condition_ofengine parts. T1_e causes for the.degradationin mechanicalcondit.iz)n may be Categorizedinto four areas: o F l ight load s , which c au s e d ls torti o nin th e . e n g ine ca ses and produce chang es in r o t o r m o ti o n s with re s pect t o the ca s e s , the s um of which cau s e s the r o tating blade s to rub again s t the - s eal s . The re s ulting wear. o n both blade s and sea l s opens ga s - path clearance s .

o Ero s ion of airfoi l sand outer air .s ea ls , causing increa s ed roughne ss and bluntnes s , l o s s of camber, and los s of blade .

length in airfoi ls plu s the . lo ss of seal materia l . These effects result in reduced airfoil efficiencyand increased _ _ blade-to-sealclearances.

o Thermal distortion_of turbine airfoils and case s , caused by extended operation in a high temperature environment p l us increases in average _temperature. and temperature profil e with use. This distortionresults in flow.area change s , increased s econdaryf]ow Ieakage,and .increased gas-pathclearances, _ o. Operator repair practices and rebuild standards, which influence the degree of. . per,_.ormance restoration achieved. .

during repair and the rate of subsequent performance deteri orati on.

!

The probable role . of each cau s e of performance deterioration as a.

function of usage has been quantified at both the o:erall engine and the module Ievel.__ 1 7.1.1 Short-TermDeterioration

I

-_ Es.timation of engine performance loss . based on sea level . PIC_data indicatesthat significantlosses occur . veryearly, followed by a more gradual loss over-the longer term . A TSFC loss of I percent occurs within the first 50 cycles,, increasingto 2.2 percent by . 1000 cycles._ T . he _ rapid early loss is due t o wearing-in of seals and resulting operating clearances; - the longer term lo s s results from c o ld . section erosi on, further clearance , increases,and thermal distorti on .

TSFC " loss. in the - Ti r _t 50 cycles , is dominated,by low, pressure_ compressor and high-pressure turbine deteriorationwith smaller, but _ ....

signficant, contributionsfrom the fan and.high-pre s sure compressor. .

Over - the short term, TSFC losses are near.ly equally split between_the __ hot and cold sections and between the-high- and Iow-pres s urespools. No sign . ificantdifference i.n engine deteriorat , i.on trends due _to wing positi.oE_i__ apparentfrom the data obtained.

7.1.2 Lon g-TermDeterioration Tile747SP / JTgD-7A(SP) engin e •prerepair te s t- s tanddata "fills the gap" betwQen , the PIC data for short-term deterioration re s ult s and the airlin e hi s tori c test. s tandprerepair data for l on g -term deteri orati on.

These test- s tand data al s o repre s ent a better controlled data so urce a n d o ne in which there is le s s uncertainty as t o m o dule age,.__since .

almost all prerepair data represent s module s that have had no prior - repair. The in,service engine data s how an average-prerepair TS F C deterioration at 1500 cycle s of 3 ,7+.0.7p.ercent,relative to new producti on engine _ l evel..

Postrepair- data for in-service en g ines • s how an average TS F C .

deterioration at 1500 cycle s of 2.7+0,7 percent, relative to new _ prx)duction engine..level.The. 1 percen_ average TSFC;recovery during repair representsmostl.yhigh, pressure turbine performance improvement for these moderate time engines. The balance.ofunrecoveredperformance_ losses represents residual unrepaired module damage, particularly in the cold section modules. In some cases, modules have been "swapped"- from one _ngine to another. In many cases where module refurbishment has been performed,previous . ly refurbished modules from o ther • engines have been incorporated.In some cases, postrepairTSEC for individual engines is.worse than for prerepairas a result of deteriorated modules from other engines being incorporatedduring the repair . . As a result of these practices., pl.usthe varying l evels of rework performed during repair and brx)aderbuild .clearances, optimum performance recovery was not ach_ eyed.

7.2 FLIGHT PERFORMANCE DATA In-flight cal ,i brat ion and ECM data .haveproven to be of limited value.

in evaluating engine deterioration.ECM_trend curves start at about 50 cycles, and in-flight calibration_.data begins at about 20 cycles, s o ..

neither-type of data provides any informati o nabout short, term engine .- deterioration.Nor can any conclusions be drawn concerning individual .

engine, deteriorationtrend s aver the long term because - of appreciable s c atter in ECM and _n-flightcalibrationdata, Deterioration averaging for the.four engines on an airplane eliminatesa considerable-am o unt of scatter, suggesting that airplane systems (for.example, nonuniform bleeds) may be influe n cing individual engine trend s . T hus, the . __ usefulness of ECM and in-f . light data is limited to indicatin g gross averagelon g , term deteriorat£on trends.

An avenage altitude cruise-deteriorationtrend synthesized from PIC data shows good agreement, with.average ECM and in-flight trends over the long-termwhen ECM data are referencedto a lOO,cycle base line, In addition, since PIC data are collecte d from zero time, it shows .the l abs o lute magnit_de Of___ deteriorati(}n which cann o t be Obt ; _Inedfr_l} flight data alone....

7,3 PERFORMANCE. RECOVF._A B ILITY Analysis. of. in-serviCe JTgD-7A(SP) engine data indicates that a s tabilizedaverage long-termp os trepairTSFC le.vel slightly_bettertl_an i _ the historical.data .results is being achieved, In-serviCe. engine data at 1500 cycles show a po S t_epairTSFC relative to newtproductionengine.

performance level of about +2, 7 percent Compared_to a level o f about +3,0 p_ercen.t For-the historicaldata study r.eSul.ts_ Analysis conducted previously with, "best" airline postrepair module historical levels suggested that awerage postrepair TSFC relative to new production engine performance level, of Something less than.2.

percent could be achieved on a stabilized long-term fleet average bas_s, Achievement of this level of performancerecovery would require that attention, be given to periodic Cold section rework, consistent with the performancelife of cold section parts. The fan leading edge .

must.be r . eworkedperiodically, and considerableatt e ntilon must be given also to the . high-pressure turbine tip . clearances , during rebuild, High-pressure vane class must. be car.efully controll.ed_and the second-stage -vanemust be rew]_zk e __ t_LcOntrolleakage.

7.4 DETERIORATION MODELS _ The "average JT9D" deteriorationmodel presented in Section.5.0 has been shown to agree well w i th average sea level test data trends from PIC data anal.yses and htstor.ical and JTgD-7A(SP) engin e airline test stand, data , analysis,When consider.ing individualengines, of individual airlines, considerable,variance from the model can be expected.

Individua.l engine initial build, clearancesvary, resulting in different.

production_ performance level s and rates of deterioration. Individual engine Service experience-alsodiffers. Once.engine r e work has begun,,.

the . extent of individual module rework varies, resulting in greater prerepair _ perfonnance , variations and.. making it difficult to project _ "equ.ivalent unrepair.ed module cyclic age", upon which t l iemodel is _ based. It should be noted that themodel will continue to be refined as additional_informationbecomes available. In particular,further_work.

with the model to reflect the.r.esults , of the_SimulatedAerodynamic.L o ad Test program wi . th respect to f . light _load e££ects and shor_t_£erm deterioration trends is planned.

APPENDI X A E FF ECT SOF BLE E DS- O N VERSUS B LE EDS - O F F OPERATION ON F LI G HTI TR E NDS It ha s been previou s ly, indicated that airplane sy s tem s may influence the repeatability of data obtained during crui s e operation on a flight- J _y-flight basi s . Thi s was particularly evident with airplane N5 3 6PA where wide varlation s in fuel flow were noted in individual engines over a given period of: time while the total fue l .flow being used by all four engine s .remained fairly constant. This i s shown on.

Figure A- I which presents change in fuel flow_ at constant EPR versus usa g e in flight cycle s .. The ba s e fuel flow used i s the average fue l flow of the four engine s at go flight cycle s . It can be seen that a l l four engines maintain the s ame r e lative position o ut to _ gO cycle s . By 37(Icycle s , shifts have occurred with the po s itions I and 2 engines exhibitinga decrease in fuel flow of approximatelyI percent while the positions 3 and 4 engines exhibited an increase of about the same amount. Howev P _t_ _;h_e aye rage fuel flow across the wing does not change_ signifi cantly.

_F 2 ....

0 P-695745 , POS.1 _ P .696 744 ._ s . 3 .

I 1 I l I I I O. 100 200 300 - 40 0 500 600 709 ENGI N E FI.IGHT C Y CLES I Figure A-1 In-FlightCalibration of Fue l Flow_Change as a Function o f Cycles at Mach 0.85, 35,000 F eet Altitude, E PR = 1.40 - Wide. variations in fuel f l ow are. shown f_r individual.

engineswhile the total.fuel flow for a]_l__ _ f_Q jJ r___ P _Egines remainsfai r ly constant.

.; A_, 131 P R E C ED INGP ; ,G E L .., , _ . NO ; LEI L N i E ;_ Since these large var.iations were not noted during the sea .levelPIC_ testing which was accomplished with bleeds closed, one possible explanation for fuel flow variations is bleed hogging by one Or two .._ engines_, that is, most or all of the service bleed air is being.

extractedfrom one or two engines with very little air being bled from the remaining engines, Bleed hogging by one engine or the englnes, on ....

one side of the airplane, can be caused by one or a combination of effects. These_ef_f_ects include: o Differences _in engine perfprmance.

o Improper_ oper_n of one of four pylon-mounted bleed control valves. ..

o Improper operation of: one 1of two wing-mounted bleed isolation valves.

o Leakageanywhere in the bleed system or pneumaticsystem.

The "differencesin performance"-effect was the.only one of the above- effects which we were able to investigateduring this program. As part...

of-the, in-flight calibrations on both airplanes N536PA and N537PA, additional calibrationswere conducted with the pylon-mountedcontrol valve c]osed on.toneengine at a time such.that it would provide no.

bleed air Over-the full power range. A typical comparative plot of.

fuel flow versus EPR for engine P-695760 (position 1_ on airplane N537PA) for bleeds-on and bleeds-offoperatiOn is . show__in Figure A-2.

In the bleeds-on condition, the engine is sharing.. the bleed air .........

requir.ement with the-other three engines,. As seen at low EPR values,.

there is no fuel penalty due to bleed, inferring that the - engine is providingno bleed air. Conversely,at the hizjhEPR settings,the fuel _.

flow penalty due to bleed air is greater than 3 percent. D_ring these.

calibrations,, when the.. . positions I and 4 engines oper.ated at low EPR settings the positions 2 and 3 engines operated at high._EPRand vice versa._ Therefore, when the position 1 engine_ran. at low EPR.with ble.=ds on, and apparently, provided no bleed air., the_positions 2 and.3 engines ran at high EPR and provided all of the bleed air. From this nonuniform bleed sharing effect, it can be concluded that when operating four engines,_all.withbleeds on., those which are developing the highest, pressure at the eighth-stage_bleed_position are delivering the higher proportion of_ the bleed, flow. That is_____b_eth___b e btter per_forming engines take the greaterfuel flow penalty.

When the effects, of uneven pressure drops across the two sets of valveS.

and. pressure . , drops caused by local leakage are added.to the nonunifOrm bleed Sharing ef.fectdesCribed above,_the wide fuel flow vari.at_ionS shown in Figure A-1 are understandable, 2 0,000 " BLEEDS ON-.-- - - _ _ 9 _ _ - _ 111,000 _ ' u_ _ l S ,O 0 0 . " " 15,000 , 1 . 2 1.3 1.4 1.5 ENGINE PRESSURE RATIO • Figure A - 2 Bleeds-On / Bleeds-Off Compari s on f+orthe P os J tion 1 Engine on Airplane N537PA - Bleed flow penalty is a functio_ _i_ rel+ative pressureat the eighth-stagebleed port.

_ PE NDIX B EFF E CTS OF FAN AND LOW-PR E SSUR E COMPR E SSOR FLOW CAPACITYLOSS E S'ON ENGIN E P E RFORMANC E • INTRODU CTION This appendixpresent s the res.ults of anal_ical studies of the effects.

of. flow capacity losse s in the fan and low-pre s sure compressor-on engine performancelosses at both sea level and altitude conditions.

FAN ._OV L CAPACITYLOSSES .

Early fan deterioration_occursbecause of increasedtip clearance due to flight load-induced., deflections and involves a loss in fan flow..

capacity and_efficiency. Fan flow capacity loss is of interest, because the.effects on engine performance _re appreciable, and these effect s are considerablydifferentbetwe e ntake-off and cr_ulse CorLditions. .

Reduction in fan flow capacity means that:reduced corrected flow is.

available from the fan at a given correctedrotor speed. In order, to_ match higlt-pressure compressor- corrected flow demand, the low-pressure.

compressor is forced to_ a higher operating line. This requirement, plus the lower fan flow, results in a decreased bypass ratio (BPR)..

The core engin e does not have to "work.as hard", and turbine inlet.

temperature is reduced_to hold constant engine pres s ure ratio (EPR). i . . Reduced turbine inlet temperature results in decreased exhaust_gas 1 , temperaure (EGT) and decreased fuel flow (Wf). Figure B-1 shows t_e 1 changes, in EGT and .fuel flow at rated EPR. For a given l.ossin flow capacity, there is . a greater EGT reduction at r.ated EPR at.maximum " cruise and maximum climb power--thanat take-off power._ This varying J EGT reduction results from.a greater BPR decrease for a given flow.._ capacit.y loss at cruise aQd climb conditi_ons than_attake-off, i At constant thrust conditions, which should be used for meaningful !

evaluations of . thrust specific-fuel consumption (TSFC), the_ BPR .._ decrease which results from loss i . n. fan flow . capacity results in. a ..

slight decrease in fan airflow. At sea level s tatic take-off,there is essential.lyno resulting,change, in fan efficiency (tip clearance .......... !i increase,by itself,will.cause fan.efficientyloss, but this analysis_ considers flow capacity effects only). There is._a low-pressure" I compressor efficiency improvement.as a result of the high e r operating 1 line, and TSFC decreasesslightly,as shown , in Figure B-I. However, at_.

maximum cruis e and climb power (constantthrust) at altitude, the fan I operates closer to choke than at take-off even in an undeteriorat e d _.

condition due to higher operating., corrected airflows at these conditions. When flow capacity is lost as a, result of clearance increases,the fan is _ ' iven even-furthert o ward .chok e ,_The r.esult is .............. ;" " .M[[') a s i g nificant l oss in fan efficiency. Alth o ugh low-pre ss ur e. c o mpre ss or efficiencyimproves .at crui s e and climb power-as a re s ult of a lo ss in fan flow capacity, the los s _ in fan efficiency i s much greater in .

importance. The.re s ult i s a s i g nificantpenalty in crui s e,and climb.

TSFC fora los s in fan flow capaci.ty, a s shown in the T S F C compari s on.

of F igure B--I. For - 2 percent fan. flow capacity los s (typical_ deteriorationfor high,time fan blade s ), there is about 0.5 percent improvementin sea level. , take-off TS F C, about O.6percent TS F C . penalty at maximum crui s e power , at altitude,and about O,8percent TS F C p enalty_ at maximum climb power. For 4 percent, flow capacity lo s s (extremefan deterioration),the TS F C penalty at maximum cruise and maximum climb power-ismuch greaterthan twice the penalty for a 2 percent l.os s . In other words, the penalty is nonlinearwith flow capacity loss.

MAX CRU I SE P OWER (MCR) ._ I- " MAX CLIMB P OWER (MCL) I A T M A CH 0.84.38,000 FEET Q TAKE O FF POWER (T / O) A TS E A LE V EL STATIC I- +3 < ,I " MCL *20 4 1 _. ,_ I "

/ MCL ' ,_ : L,-_J _ ' T / O

-4 _ <: _ -4 --.

I 1 I _ i I 2 ......... 4 2 - 2 .... 4 .

FLOW C A PACI TY L O SS (%) Figure B-1 Eff e ct o f - Fan Flow . Capacity Loss on JT g D Performance Parameters -- Increasing flow capacity loss.re s ults in a _ significantpenalty in cruise and climb. ,. ...TSFC, although fuel flow at constant EPR decreases _ , LOW-PRESSURE .COMPRESSOR. FLOW .CAPACITY LOSSES F low capacityfor-t h e low-pressure-compressor of the JTgD engine has an i m portant influence on engine performance,especial.ly, at rated power (cLimb / cruise) at altitude. The importancestems from the sensitivity of the low-pre s surecompressoroperating line to flow capacity change.

Low-pressure compressor-flow capacity is influenced by tip clearance changes that occur during service use. Deflections an.d-resulti.n g rubs - from the application o f flight l o ads, together with erosion, .... c.a.u_e ..................

ru b - s trip wear and t ip clearance i n cr e a ses . T hi s c ond i t i o n, in turn, cau s e s 1ow , pre ss ure compre ss or flow . capacity l oss , L oss in ' low-pressure c o mpressor fl o w capacity causes the compre s sor operating line (pre ss ure ratio at a given corrected f l ow) to dro p in ord e r-to match the high , pre ss urec o mpre ss orc o rrectedflow demand.. T hi s -I owered operating line re s ults,in le s s core flow, higher bypa ss ratio (BPR), incr.eased exhaust ga s -temperature. ( EG T), and per.f _ ormance lo ss becat!se of compressor- efficiency, lo ss . E fficlency los s re s ults from unfavorableincide n ce ang! e changesand hig h er internalMach numbers.

The importanceof low-pres s urecom p re ss orflow capacity Ios s .i s greater at alti t ude rated power - than at t a ke-off power becau s e - the compre ss or ..........

operates at higher _ specificflows, an d internal Mach . numbers at.altitude tharLat take-off. A s low-pr ess urecom p r esso r fl o w ca pacity i s los t, the compressor i s driven further toward choke.... The re s ult is severe .

depression of the . operatingline and efficiency loss, particu l arlyat b climb p_er ....

Figure B-2 shows the estimated effect, of 2 and 4 percent low-pressure compresssor flow capacity loss at. s ea level static take-off, power and.

at Mach 0.84, 35,000 feetalti.tude maximum cruise and maximum climb powers. The computersimulation of the . JT9D engine,which was used for all of the test stand deterioration analy s e s of the historical and J T gD . -7A(SP) data, was used to est_,ate the effects of the flow capacity losses. The method of modeling the low-pressure. , compressor flow capacitychange s is pre s entedt n Reference I.

MAX C RUISE POWER (MCRL | AT M At ' _ n _ " m nt m FEET MAX CLIMB POWER (MCL) | .................

TAKE4)FF POWER (T / O ) AT SEA LEVEl.

5 . 0 . " 5.0 M C I _ , Z "

,.o / -- '. °

e_ I// ' ' Z e L w l _ | I / / m ® = 4o - MC ,, _ 2_ '/ / ° i u _ 2' 0 I- , c , .r -- " l • a" , //# ,. : ' T I _ ,c. T r o o -, o 11] .

o. o _ o.oL I _ _1 o ,0

L l I I I I, 2 4 2 4 2 4 .__ FLOW C A PACITY LO _ (%) .

F igure B-2 E ffect - of Low-Pr e ss JJ r e. C ompr e ssor F low Capacity Los_ on .

JTgD Performance Parameters . - The. s ensitivity of t I Iow.-pressure compre s sor rf lowcapacity los s is not constant' but Increaseswith the magnitude of the flow capacity loss.

A s s hown i n F i g ur e B - 2 , a 2 pe r ce nt f l ow c a p a c ity loss (c o rr espo ndin g to typical low-pre ss urecompre sso rtip clearance increa s e=atab o ut 2 000 flight cycl es ) r es ults in ab ou t I0oc E G T increase at take-off EPR, 0. 3 percent TS F C increase at con s tant take- o ff thrust, and 0. 6 percent TSFC increa s eat con s tantmaximum crui s e p o wer. Note that fuel flovl at maximum cruise power i s up about 1.7 percent, much great e r than the magni . tudeof the T S F C increa s e at maximum cruise power. The rea s on.

that the fuel flow increa s e i s much greater than the T S F C increa s e is that th e flow capacity los s re s ult s in a thru s t increase at con s tant E PR. It is w o rthwhile noting again that altitude fuel flow measurements-wouldbe a poor indicatorof engine-TS F C .in this ca s e, becau s e the fuel flow change would indicate an engine T S F r , deterioratlon level nearly three time s a_ great a s the actual deteriorati on.

If the low-pressure c o m p re sss orclearance increase is wor s e than average, as indicated by the 4 percent flow capacity loss bar in F igure B-2, the performance losses are-more than twice as great as for-the 2 percent flow capacity loss.. In . other words, the sensitivity of the low-pressure compressor to flow capacity loss is not constant, but increaseswith the magnitude of the flow__capacity l o ss.

SUF]MARY It s hould be .notedthat in-flightfue l flow measurements at rated power setting are a very poor indication of changes in TSFC at constant thrust, for fan deterioration as well as for low-pressure compressor-.

deterioration. Inthe case of fan flow capacity loss, not only are the magnitudes of - the two parameter.c h angesdifferent,but the directions are reversed.

1 3 8 APPENDI X C BAINT E NANC E DATA CO LL EC T I O N T hi s appendix summari z e s the malntenance_datawhich wa s col l ected on.

the 22 Pan American JTgD-TA(SP) engine repalrs-for_ which prerepair and / or po s trepair test s and detailed analyses were conducted, It also I'i pr.esents a typical descriptionof one of these . 22repairs.

Table C-I lists the maintenance actions by engine serial number and engine removal date. It al s o liststhe removal number, when the engine wa s repaired,whQ didthe re p air, and.thetype of repai . r. _ These en g ines received eithera Standard 1 or Standard 3 repair. A.

Standard I repair involves all major engine modules includingthe.fan and diffuser / combustor.. The individualmodules may be r.efurbished-per Standard 1 requirementsduring the repair action or may be replaced by other modules which have previously been. refurbished. Module refurbishment generally includes replacement of air seals. Blades and.

vanes are either re.t_stalled_a s is, repaired, or replaced with _ew airfoils, depending on the observed condition and / or -age. T he reassembled modules must meet a set of build standard measurements .

prior to acceptance.A Standard3 repair is.essentiallya hot section repair with limited inspectionof the fan and low-pressurecompressor,.

Table C-If summarizesall of_the repairs with_total time on the engine, time s ince the last repair,_ and prior removal cause. It also identifies the modules in the engine at the time.of .repair__.the type of repair, and _bich modules were repaired.

Attachment C-1 is a description of a typical mai.ntenance., action includinga listingof pertinentbuild-up clearances.

TABLE C-I PAN AMERICAN 747SP / JTgD-TA(SP) ENGINES WHOSE REPAIRSWERE ANALYZED Engi ne Serial. Removal Removal.. Repai r - Repaired Repair Number .... Number Date Completed by Class 686047 1st. 11-6-77 12,8-77 PA Std. 3 w 686748. Ist 12-21-77, 2-15-78 PA. Std, ].

2nd 8-12-78 9,15-78 PA. Std, 3: 686049 Ist 9,21-78 i-3,79 PA . Std. 1 68605 0 Ist. 5 , 17 - 78 8-18- 7 8 PA Std. 1....

- 686053 4th 9-21-78 11-22-78. PA Std, I 686054 2nd 5,1-78 5-15,78_, PAr S_d, 3, 686055 2nd 8-31_-78 9-19-78 PA Std, 3 686060 3rd 2-9-78 4-25-78 P&WA Std, I 4th 8-1-78 8-15-78 PA ]st GV * 686068 2nd.... 9-12--78 11,13-78 PA .. Std, I 686070 2nd 5_-28- 78 8-18-78__ PA Std. I.

686071 3rd 10-6-78 11-8-78- PA. Std, 3- 686083 .Ist 5-17-77 6-30-77 PA .... Std. 3 2nd 7-12-78 8-30-78 PA .. . Std. 3.

3rd 11-13-78 11-22-78 PA Ist GV * 686097 3rd 10-8-78 _I 0 -25-78 PA_ Std. I .. I 695716- 4th 7 - 6-78 9-2 9 -78 PA. Std, I !

695722 3rd _ 10-23-78 1-30-79. PA Std. . 1 695727 Ist 12-13-77 I-6-78 P . A Std. 3 2nd 8-14,78 9-16-78 PA Std. 3 1 695732 Ist_ 7-10-78 8-31-78 PA Std. I 695745 1st 4-20-78 6-13-78 __ P&WA Std, 1 • Refaced First-StageGuide Vane, : __ ...... , , "i , " , ,i ii i -_ i I I r i_ '_ ''_'' /_m_ " -- " .... i_ " " "" II E I I 1 i I

r J

• p .. . ' ...... ," , ...... , In I H I / ATTACHMENTC-I TYPICAL. MAINTENENCEACTION - ENGINE P-695722 Standard 1 Repair, November 1978 ].2,!02 T_ours; 2135 C,vc_l_es _ INTRODUCTION _ Engine P-695722 was removed f_ Position 3 on Pan American 747SP airplane N532PA on October 23, 1978 for combustor liner.distress.It had operated i2,102total hours and 2135 flight Cycles.

HISTORY Engine P-695722 was delivered to Pan American installed on 747SP-- airpl'.ne-N533PA with 41 hours_and 16 cycles in March 1976..In October 1977 the engine was removeddue. to turbine blade erosion. The.Mod 5 combustor,fuel nozzles, and high-pres_ure turbine were replaced_witha-- Mod 2 combustor, new fue.l nozzles, and refurbished high-pressure turbine module C95715. The.engine was installed on airplane N533PA where 4t operated 4768 hours and 848 flight cycles until this__r_moval.

The f an, lOw-press_re compress or, high- pressure compress or, and l . ow-press_Jre t u rbt n e were the.Original .modules at the-October 23, 1978 removal.

PREREPAIRTEST AND TEARDOWN Before teardown, the engine was.prerepair : tested at-the.Pan American Jet Center in the partial QECco n ditiL_ and, aS a result, a.Standard i repair-was ordered. The engine - was Completely disassembledand all modules were changed.

The Mod 2 inner-and outer l . inersexhibited burn-throughof louvers.

Heavy carbon depositswere noted_in theair caps directly downstreamof the swirl vanes. I ] The_ first-stage nozzle guide vane (NGV) assembly exhibited airfoil trailing edge Cracks adjacent to the outer platfo r m along with burning of the inner butt.resses. .. 1 i The high-pressureturbine was , removed, and the first-stage_bladeswere retired.dueto time.

The low-pressure turbine was in generally good condition. The third-stage_ n ozzle guide vanes showed evidence of rub and metal buildup on six.vanes.

BUILD-UP: The Standard I rebuild included refurbishedfan, Iow- and high-pressure.

compressors,combustor,and turbines,The recorded build-up results are as fol]_c_.s : Fan -- Refurbished blades and new outer air seals (OAS) were i . nstalled..The blade tip / OASclearance__as0.108 inch. _ Low-PressureCompressor - Refurbished module A95731 was installed w ith new OAS's. The blade and vane ages were not availabl e , however, , this module was first removed from engine P-695731 on.

December 8, 1978 with 9824 hours and 2239 cycles onthe engine and "A" module. The bl_ade / OAS:clearances were as.follows: Stage Clearance (inch) 2 O.086 - 3 O.052 4 ............... O.042_ Hi g h.Pr e ss u r e C ompre s sor . - R e f u rbis h ed mod u le. B86 0 54 was i n stall e d wit h ne w OAS's a n d repaire . d .. _.!)lades. T he blade tip l O AS cleara n ce s were: Clea_r_ance(inch) ................. _ (Clearance (inch) ...............

5 O.037 II O. 021 6 O.060 12 O. 029 7 O.059 13 O.037 8 0.045 14 0.027- 9 O.047 15 O.031 I0 O.039 Combustor- The combustormodule was rebuilt with a new Mod 2 outer .........

liner, repaired inner liner, new. cokeless fuel nozzles, and _new first-stage nozzle guide vanes. The inner / outer liner fit and engagementwere.O.O08 inch . tightand 0.388 inch, respectively.The first-stageNGV NCA = 29.5. The TOBI flow was 1.319 percent.

High-PressureTurbine - Re furbi s hedmodule C62962 was installed.It .

had a mixture of three different part numbers in the first-stage blades who s e ages were not avai l able,It had new second-stageNGV, with NCA : 23.0, and new s econd- s tage b l ade s . The blade tip / OAS clearance s :vere as follows: Stage C1earance (in cl]., ) 1 . 0.0715 2 O.030 (front) 2 0.0415 (rear) Low-PressureTurbine- Module D95738, which was removed from Engine- P.-695738on. January 2, 1979 with 8740 original,hours and 1395 cycles was instal Ied without being disassembted. | The engine was postrepair tested and failed due to a faulty fuel.

J

contr.ol. The engine was then successfullyretested wi.tha replacement fuel_c__n J__ary 30, 1979 and accepted as a serviceable spare.

• • o APPENDI X D TEST STAND AND INSTRUMENTCALIBRATION This appendix presents a detailed discussionof the calibrationof the Pan American expanded-instrumentation te s t. stand as to calibration standards,procedures and.results. It also discusses the uncertainties in recorded dataand how the uncertaintyvalueswere determi.ned.

D.I CALIBRATIONSTANDARDS Press ur es Wallace . andTiernan,Model_65-120,. O to 100 in. HgA calibratorfor , Pt7, Pt3c, and P s 3c. .

Wallace and Tiernan O.to 1000 in. HgG. gage for Ps4 , and PsSi.

Wallace a r , d Tiernan 26 to 3 1.5 in. HgA gage for barometer and Pcd (.cell depression . ) , A compressed-air _ regulated pressure source is used f . or calibrations.

The 30 in..water U-tubes used . for Pt2 and cell_static.measurements are zeroed and checked prior to each engine test.

T.emper a.t ures The chromel-alumelthermocouple system (Tt 3 , Tt4, Tt6, and Tt7) was calibratedwith a Leeds and Northrup Model 8686 mill;ivolt, source. All temperatureswere recorded.througha Doric Model 400, digital indicator and Doric _ ten-channel select , switches. The Tt2 - inlet temperature resistance.probes. and Doric DS-IOO-TS indicatorwer e calibratedwith a decade box and resistance harness. The probes, were also.checkedwith . a glass-bul b mercurjt_tberFn_eter. ) ]e!_ , d n.ext t. O the probes.

Thrust The Baldwin Lima Hamilton (BLH) 50,000 Ib working load cell was calibratedagainst an identicalmaster load cell in the thrust system. _ A hydraulic ram supplies the necessary force to the load cell system_ for calibrations, All calibrations were_ conducted with an engine mounted in the test s tand. T hemaster load cell is removed_from the load cell system during engine testing. The. master load cell and indicatorwere also crosscalibrated at BLH and Pratt & Whitney Aircraft.

Erequency The NI and N2-speed and fuel flow Hewlett Packard HP5214L varaibletime base counters were calibr-ated using Hewlett Packard master counter frequency generators.(Note: the speed counters were Jchanged to Digitec Madel 8151 units in September1978.)

Fuel Flow The Cox ANC-16 flow meters were calibratedat Pan American, using_the ....

Cox Instruments Calibrator, and at Pratt & Whitney Aircraft. Pan American. has two Cox flow meters available;one is normallyemplpyed in the _teststand, and the second is retained as a back-up. _ .............

Euel Density .

The specific gravity,measurements were obtained from an in-line hydrometerin the f ; uelline as well as with a second hydrometer and a fuel sample drawn from the fuel _ line. No cal_brations of. the__ hydro m eterswere availablE.

D.2 CALIBRATIONPROCEDURES Pan American does not employ any written proceduresor calibr.ation data recording forms for the test,stand instrumentationwith the exception .....

of the Cox fuel flow meters. Typically, the calibration procedures consistedof comparingthe working instrumentto a.reference instrument of equal accuracy and adjusting the working instrument until it is within the desired tolerance. T he reference instruments , are kept in the.

Instrumentation Laboratoryand brought to the test stand when required..

The master thrust load cell remains at the test stand, and the Cox Instruments £al ibratorremai ns.in thE l nstrumentati_on Laboratory.

The absence of-written calibration procedures, particularly with respect to .data retention, was the most difficult area of the _ evaluation. Pan American personnel perform the instrument calibrations and report any abnormalities for corrective action. They are. very conscientious, concerningthe maintenance of the equipment on the test stand and in the . calibration laboratory. However,.the procedures involving the cal.ibration results are essentially verbal. Written records of the calibrationsare not normally retained beyond the _date_ of calibration. Thus, developing uncertainty estimates_ for the perf o rmance measurements was dependent upon data recorded by Pratt & Whitney Aircraft._personnel, who were .present during the calibration proces s ...................................................

!

I ,!

D.3 CA L IBRA T IONR E SU LT S During the program, the Pan American test stand instrumentationwas ....

subjected to four.complete calihtations.On three occasions, Pratt & Whitney Aircraft personnel,observed the calibration procedures and - recorded the data. On one calibration-by Pan American personnel, no data were recorded. For - that calibration, it was assumed that the -- instrumentation was within the . Pratt& . Whitney Air,aft T.I.S. accuracy I imi ts.

The results of the calibrationsare summarizedon Table D-I. The errors presented are the average deviations_from the calibration standard over the range of calibrationfor each _instrument.

TABLE D- I PAN AMERICAN TEST STAND CALIBRATIONRESULTS Instrument ation, May Feb. June Jan.

Parameter - Range_ or Units 197___2_71978 197___88 197.___99 P breather . 0to . 40 in. HgG -0.44. +0.41 -0.05 Pt7 0 to . 100 in.HgA -0.08 -0.05 +0.11 Pt3c O.to 100 in. HgA. -0.11 -0.10 -0.31 Ps3c 0 to 70 in. HgA -0.02 0.00 Not +0.02 Recorded Ps5 0 to 1000.in.HgG -0.55 +2.00 +1.00 Ps4 0 to 1000 in. HgG -0.80 +1.00 +1.00 Barometer 26 to 31.5 in. H_IA -0.015 -0. . 01 -0.02................

(All above.pressures on Wallace & Tiernan_Gages) Tt3, Tt4, Doric Model 400 Not Tt6, Tt7 Indicator,. oc -3 +I Recorded +6 * Tt2 Resistance Sens ors, Not Doric Indicator,OF +I +2 Recorded +1 Thrust BLH 50,000 Ib Load Cell,_Ib force- -60 -30 ,50 -50 N1, N2 Hewlett Packard Not Speeds Counter, rpm . +I +1 Recorded + I Fuel FlOw Hewlett Packard Not Counter (only),pph +1 +I RecordecL +1 • Zero offset..corrected - o_ ....

cal ibrati on.........

15 3 Actual calibrations were not performed on the Pt2 or cell static pr.essures which were recorded on.3O-inch water U-tubes, The U-tubes were- zeroed and checked prior to engine testing. The chromel-alumel thermocouple system records-all Tt3, Tt4, ?t6, .and Tt7 measurements._ through the same Doric indicator. The individual temperatureparameters can be calibratedfrom the enginelocation or-at the back of the Doric unit. The Pan American. procedure has--generally been to apply the calibrations_signals at the back of the Doric unit over the range of_ exhaust gas temperature (EGT) (Tt6). Any adjustmentsare then applied_on.

the.basis of the EGT calibration.This .procedureis valid, since all of..

the indicated parameters ar:erecorded through one Doric unit, but can .....

miss any errors that might be introduced by the stand wiring for each parameter.

During the period of thisprogram,. Pan American. completed modifications to the test stand,.to accomodate RB211 engine parameters. The speed_ measurements systems, which had.employed Hewlett Packard HP5214 counters, were changed to Digitec Model 8151 variable time base counters in September 1978. Problems were encounteredwith the new.systems due to_ wiring malfunctions which caused a +60 rpm error in N1 and N2 measurements. This error_existed during__September to October 1978 and_ agai n in January 1979.

D.3.1 Thrust System Calibratons The Pan American BLH 50,000 Ib thrust system was calibrated_versus a 60,000 Ib transfer standard InterfaceForce Measurement System, traceable- to the National Bureau of Standards.Multiple calibrationswere performed during the three occasi.ons that the thrust system was available to Pratt & Whitney Aircraft in order to assess the system's repeatability.Al.l calibrationswere performed as-is, that is, wi.tbno adjustments except_ for electrical checks of the system's zero and R-cal (span) values. A summary of the calibration errors (thrust system,output minus applied calibrationload_ are presentedon Table D-II. The er.rors are averaged at .........

each calibrationpoint over the total number , of calibrationsperformed.

The overall average error and the maximum _observed error .are also presentedfor each calibrationperiod.

The last primary calibration of this thrust system performed by the._ manufacturer_(BLH) was dated September 1.976 and indicated a maxim_n.5 l_ error. The thrust calibrations conducted at Pratt& Whitney Aircraft ......

indicatedthat in March 1978 the master-load cell errors relative to the Interface Standard were negative,while.the other two calibraionsshowed positive errors. The Interface Standard was checked f_ ppssible shif . ts, .

but nonewas found. , 154 1 !

T ABL E 0-II..

• SUMM A RY O F PAN AM E RICANTHRUST SYS TE M CALIBRATIONS BY PRATT & WHITN E Y AI RC RA F T.

E rror , (Ib) _ . E rror (]b) E rr o r (Ib) Calibratl on June 1977 March 1978 January1979 Load (l..b) 12 calibration s)_(12 calibrations) (5 calibrations) I 0 2 0 2 __ , 10,000 20 7 24 20,000 35. 6 - 44 ............ _.

30,000 42 i 56.- 40,000 45 -12 61 5 0 ,000 3 5 ....... 3 3 59 30,000 ..... 18 54 i0,000 ..... 12. 18.

0 .... 7 -3 Average. Error.. (l b) 30. -7 35 Maximum Error (Ib_ 50. -33 95 i D,3.2. Fuel Flow Meter Calibrations Two Pan American Cox turbine flow meters, serial numbers 232 7 5 . and 23276, were calibrated in the Pratt & Whitney Aircraft Fuel Flow : Laboratoryagainst a Cox ANC-16 11596 reference meter as a secondary standard. The calibrations, we r e conducted with two fluids(Jet A and 9041) to compensatefor vi s co s ity effect s , The cal._ibrations produc e d curves of cycles per gallz)n (CPG) versus cycles per second divided by viscosity _ (CPS / ) f_r each meter. (Pan American does not use a viscositycorrection.)The average CPG values over the_120 to 1200 CPG range were used as a basis, of comparisonsince.it , is the average C PG values that are used to determinethe preset values for. - ..the Hewlett Packard variable time base counter s in the Pan American test stand.

The results of;the fuel flow.meter calibrat__ons are shown,on Table ...........

D-III for meter, number 232 75 .

Formeter number 232 7 5, the calibrationsat Pratt &.Whitney Aircraft , indicateda.shift of -O,06percent of reading forJet , A fuel and -0.03 percent-of reading for9041, fuel. The - 1977 comparison of. the Pan American calibrations, showed a differenceof +O.065percent of reading from the Pratt & Whitney Aircraft resul.ts, llhe19 7 8 / 19 7 9.compar , ison indicated that the Pan American results were higher.-by _+0.16 percent .

of reading. The Pan American calibration s -alone showed a +O.05- A _Rrcent of reading increase.

15 5

i

_T" .... f, ,i , TABL E Q-Ill CALIBRATIONRESULTSF £ R . COX ME_R.NO, 232 2 5 AverageCPG TyP'eII Je_-A- ...... 9_41 Calibrati on Date Fuel Fuel F ue _ __!l April 1977 (Pan Am) 1518_4, May 1977 (P&WA) 1517.0 1517.8 December 1978 (Pan Am) 1519.2 January 1979.(P&WA) 1516,1 1517,.3 Cox Meter number 23275 has been utilizectby Pan American as the primary performance measurementinstrument .....

The results of the fuel flow meter calibrations for meter number.

23276,which was used as a back-upfuel meter, are shown on Table D-IV.

TABLE. D-IV CALIBRATIONRESULTSFOR COX.METIZR NO, 23276 Average CPG Fue'l Type-II ' Oet- / _ '90411 Calibrati on Date Blen____dd Fuel Fuel _ Fue __ ]l August 1975 (Cox)* 1514.8 November 197 5 (P&WA) * 1513.2 April_1977(Pan Am) 1510.4 April. 1977 (P&WA) 1506. 5 1507.8 i March 1 9 78 (P&WA) 150 9 .7 _ 1508.5 • Conductedpriorto t h e current pr-ogram. I i C_mparison of the 1975 and 1977 calibrations indicates that a I significant , shift had occurred in this meter. The magnitude of the_ ,_ shift ranged from -0.29 percent of reading, based on.the P.an American__.

cal.ibration, to -0.55 percent of reading based on the 197 7 P&WA.

calibrationversus the original Cox Instrumentscalibratio n . T he shift in the average CP G introudceda correspondingincraease in the fuel flow.measurements_J_ith this metez:. 1 Comparison of the .1977 Pan American and P&WA ca.librations indicated that. Pan American _vas higher by of reading in t h e.

average CPG value. The 1978 P&WA calibr.atio n sindicated a shift of 156 1 +O. 21 p e rc e nt of r e ading u s l_ 9041 fuel. T he se 1 9 7 8 re s ult s -w e r e cl o s e r t o the 19 77 Pan American re s ult s , +0,0@ p e racent of t_eadin go , n_ the avera g e. .... _ Difference s can exi s t between the Pan American and Pratt & Whitn e y Aircraft calibration s due-to the calibration s tandard s and techniqu es_ _ employ e d. Pratt & Whitney Aircraft employ s a Cox reference flow met e r in s erie s with the workin g meter.• T he_calibrationaccuracy for thi s techni q ue i s +0.1 percent of reading. The Coxlnstrument s Calibrator empl o yed by P_ American h a s a specified accuracy of +0.15 percent of i reading. E valuation of the Pan American calibrations-indicate s that_ there i s more scatter in the data, +0.5 percent of-reading over the 120 t o 1200 CPS range, than i s evid_-nt in the P&WA calibration s . T he larger scatter probably is related , tothe calibrationtechniques and _ c o uld re s ult, in variation s in the avera g e CPG value betwe e n calibrati ons.

L Table D-V present s a summary of the fuel flow meter calibration r_ .s ul ts...

D.4 UNC E RTAINTIESOF MEASUREMENTS.AT PAN AMERI=CA_LTES T STAND The developmentof the measurement uncertaintiesfor-the Pan , American te s t.stand relied upon the periodic on- s tand instrument calibrations and the laboratory calibrations at Pratt & Whitney Aircraft. T he_ di s acLvantage of cal.ibrations of .thesetypes is that instrument_errors • can be determined only over long time intervals. E ven if th e calibrationswere conducted in detail, recording all pertinent data,_ short-term errors which could occur between calibraionswould.,notbe.

identif_iableunless they were of extreme - magnitudes. It is the short-term errors which influence the perfor m ance measur , ements for ........ i!

engines passed through thete s t stand between_calibration interval s .

T,heanalyses of the instrumentcalibrationscan provide an estimate of 1 the error-bound s po ss ible but cannot account for .short-term excursions 1 beyond those bounds, i The avail abl e Pan American data, specif ically_ the o n -stand ca l ibrati o ns,were.not genera ll y recorded in detail.. T he instrument s were not adjusted if they fell within the Pratt & Whitney Aircraft.

•T. . I.S.tolerance s ;, when the de_iatlon s relative .• to the calibratio n standard were not recorded, the , l ong-term uncertaintieswere assumed, based on the calibration tolerance s . Where actual calibration data . were avail able, the uncertal nties were calculated. Another ,probl,em is re l ated to.the measurement of as-is errors before the - instr_ents are adjusted to the pre s cribed tolerances. The a s -_s errors provide an indication . of how m uch drift has occurred s ince the last calibration date. Not recording the a s -i s error s • e l iminate s informationthat__is u s eful in assessingthe total mea s ur_ent uncertai n ties.

TABLE D-V SUMMARYOF_FUEL FLOW METER CALIBRATIONRESULTS METER SERIAL NO. 23275: C ycl es per Gall on _CP G ) Ran Am P&WA_Ma x _IgZ7 Pan Am P&WA_ Januar), 1979 CP___S April 1977 Jet-A 90_..__.i Dec. 1978 Jet,A 9041 120 151 9 . 7 1522.3 15 2 2.2 151 7 .5. 1520.9 1520.1 180 1515.8_ 1518. 9 151 9 .8 I_15.2 1518.6 1518,5 240 1518,9 1516.1 1517.9 1519.8: ].516.2 1517.6 360 1523.5 1515_8 1516.4 1519.8_ 151.4.9 1516.6 480 1520.4 1515.4 1516.6_ 15],9.8 1514.9 1516.4 600 1518.1 1515. 3 . 1516.2 1521..3 1514.6 1516.2 _I 1200 1517.4 1515.1 1515.7 1521.3 1513.8 ___1515.9 I Aver age CPG 1518,4 1517.0 1517.8 1519.2 1516.1 1517.3 METER SERIAL NO. 23276: C_cles per Gallon (CPG) i Cox P&WA Pan Am P&WA_ April 1977 P&WA, March 1978 CP__.SS Au_ 1975 Nov 1975 Apr 1977 Jet-A 9041 Jet-A 904.__.11 ,_ 120 1519..9 1514.0 1504.3 1507.2 1509.6 1512.9 1509.4 180 1514.3 1511.1 1509.9 1505.8 1508.4 1511.2. 1508.2 240. 1513.5_ 1512.6 1506.8 1504.7 1507.2 1509.3_ 1507.0 36 0 151 3 .1 151 3 .0_ 1 5 12.2 1505.2 1507.1 1508.6 150 7 .4_ 480, 151.3.9 1512.9 1510.4 1506..3 1508. 3 1508.4 1508.3 600 1514.3 i51 3 .2 1512.2 1506.9 1509.2 1508.6. 1508.9 _ 90 0 1515.1. 1514.1 1515. 3 1507.8 _ 150.9.2 1509.3 1.509.3 1200 1514.3 1514.9 1512.0 1508.1 1509.4 1509.4 1509.5 Average CPG, 1514.8 _ 1513.2 1510.4 1506.5 1507.8 _1509.7 1508.5 To develop the statistical estimates of the Pan American uncertainties, the calibrationperformedin June 1978.was included in the analysis.Since i!

no data were recorded, an estimate of the probable calibratlon_error was _ 1 made by calculating the mean of the three calibrationswhere data were 158 .....................

reCoraded and employing that value,as the Jun e 1978 error for- each instrument,Thi s method will not alter the.final bias error, but it will provide an._stim a te Of the possible preci s ion_errorover fourcalibralo n inter val s..

Bias error terms were calculated by s umming the observed calibration errors and _the.calibration tolerances, where necessary, over the four.

on-stand calibrations to produce an average bias for each parameter, as defined by Equation (1). Standard deviations were calculated using the calibration errors and calibration tolerances according to Equation (2), In order-to obtain a precision error e s timate, at the-95 percent confidence level, the results fr m Equation (2) were.multiplied by the t-statistic.

for a two-sided estimate (t.975)based on the.degrees of freedom involved.

For -this analysis, the degrees, of .freedom equalled the number- of calibr_Ltions (4) minus one.

n average bias. (_) : _"_- _ (xi-)n Equation (I) i =I. _.

n .

n- 1 Equation(2).

standar_d_d e _viation (s) = _'_ . - (xi - x-)2 i .=I where: n =-number-ofon-stand calibrations_and xi_=._ca_libration error (observederror or t_ol.eranCe) ...........

The total uncertaintyfor each param=.ter--is the arithmeticsum of the average bias and precision errors, Ine uncertaintiesfor the-measured ..

parameters are_then:, x + ts, where t is the t.975,statistic for tbe , degrees of-freedom invoTved._(For-four., stand calibrations, the t statis_tic for_n.- I = 3 . degre e sof freedom is _,182.)

The__Pan American uncertainties _re presented in the- following sections. Calibrationswhere no data were recorded are so indicated.

]59 D.2.1 Press u res May Feb. June* w Jan. Uncertai nt_ , Parameter 1 9 7.___7 1 9 7 8 1 97.._88 .. Ifl7.__._9 Bi_.__._ s Preci_d h P breather (0 - 40"HgG) -0.44 +0.41 -0.027 -0.05 -0.027 +I.] , 0 Pt710 IO0"HgA) -0.08 -0.05 -0.07 +0,11-0.07 $0.28 Pt3 ,_ " IO0,HgA) -0.II -0.i0 -0_17 -0.31 -0.17 TO.31 Ps3 IO- 70"HgA) -0.02 0.00 0.00 +0.02 0.00 +0.052 Ps5 (0 IO00"HgG) -0.55 +2.00 +0.81 +1.00 +0.81. _.34 Ps4 (0 - IO00!'HgG) -0.8(i +1.00 +0.40 +1.00 +0.40 _2.70 Barometer (26 - 31.5"HgA) -0.015 -0.01 -0.015 -0.02 -0.015 +0.01.3 m * No.data recorded. The estimatederror-is the mean of the three remaining caIJ_brations where data were available.

D4.2 Temperatures ....

May Feb. June* Jan. Uncertai nty Parameter 1977 1978 1978 1979 Bias Precisi on | Tt3, Tt4, Tt6, Tt7 (oc) -3 +I +1.33 +6 +1.33 +11.7 I Tt2 (oc) +I +2 +1.33 +1 +1.33 _¥1.5. _ * No data wererecorded. The June 1978 error is the mean of the three available calibrationerrors.

The high precision .error of the-Tt3,_ Tt4, Tt6, Tt7 temperature system is due primarily to the +6oc error exhibited during the- Januar.y 1979 calibratio n .The error was a zero shift, that is, a constant error from 0 to 1300oc. However, the temperature system was calibratedfor a Rolls Royce RB211 engine correlationprogram in December 1978, and, althoughthe data were not supplied to Pratt & Whitney Aircraft, it was indicatedthat the system was within +1oc at that time. The zer.oshift thus occurred within one month and s_ould have affected relatively few engines. The precision error of about +12oc is therefor__a pessimistic e._timateof the systems perf/ormance. LFsingonly the May 1977 error, based on the average of the two available calibrat.ions, the error__for the Tt3, Tt4, Tt6, and Tt7 measurementswould-b_: Bias = -2oc Precision= 44.3oC D4,3 Thrust The thrust uncertaintieswere derived from the_resultsof.the on-.stand calibrationsof the.worklng thrust system and laboratory_ calibrations of the master thrust system, The on-stand calibrations indicate the deviation of the working system from the master, and the laboratory calibrations, indicate the deviation of the master from a reference...

standard,The thrust system calibrationsare analyzed separately, and the resulting bias.and pr_ecision error terms are combined to yield t___tLe total , thrustuncertai nty.

Thrust May Feb. June Dec. Uncertainty System . 197.__7.7 197.___88 197____88 197._..._8 Bias . Precisio n Working System (Ib) -60 -30 -50 -50 . -48 _ .+40 June March Jan. Uncertai nty 1977 1978 1979 Bias Precision " Master Syst_em_ (Ib) +30 -7. +34 +19 ___.+99

- 1

Bias Precisi on Total Uncert ainty _ Total_ThrustMeasurement Error (lb] 29 +107 +136 The total uncertaintyalso contains an additional+5 Ib precisionerror due to the resolution of the thrust system, i.ndtcat_.

The uncertaintieswere calculatedbased on the_- a verage errors recorded during each,calibration period,_Also,the precisionerror ofthe-master systentwas calculated using a t.975 statis.tiCof 4.30 bacause only three.calibrations, (degrees of freedOm = 2), were involved.

D4.4 Speeds The-on-stand calibrations performed on the N1 and N2 speed counters have consistently shown• them to be.- within +l rpm of the input !

calibration signals. Based on the specificati6_sfor the Leeds and Northrup frequency generator used for calibrations,the . Hewlett Packard Model.5214L counter, and the engine rpm:transmitters•,, a more r.eal_istic..

estimate of the speed uncertainties would be: . NI Speed N2 Spee.d.

Instrument Blas _reci'si on BiaS' Pr ecision Leeds and Northrup Generator (rpn) +1. +i.

Hewlett PackardCounter (rpm) T4 ¥6 Speed Transmitters(rpm)_ - + , .1. - _+4 .

Total CrY) _. T* T . T* T , Total bias and precision errors are each determined by the root-sum-square (RSS) approach.

Pan American has changed to Digitec 8151 counters, and no accuracy sp#cifications for these units Jnave been received.

D4.5 Fuel Flow -- The fuel . flow uncertaintyis a function of the Cox meter, the frequency counter, and fuel specific gr_.v.ity measurementS.On-stand calibrations...........

have checked only the responseof the.frequency counter. The specif.ic .

gravitymeasurementswere. obtained from the on,line hydrometerand were cross-checked by Pan American on several_occasions using., a. separate fuel. sample and hydrometer. .

The laboratorycalibrations, of the two Cox meters,did identify a 0.55_ percent of reading shift in the serial number 23276 meter at the beginningof-the,program, However, this meter,is the_back-upmeter, and .

serial, number 23275 meter was used as the.-primary performance measurement i.nstr.ument. C alibraticnsof meter-23275.haveshown it to be very stable throughoutthe engine testiFLg conductedunder . thisprogram , Based on the available calibration data and observations of the Pan-- American fuel flow system,._ the estimated uncertainty in fuel £1ow..

measurementsis as--fol Iows: Bias Precisi on Working Meter (% Reading) +-0.10 . . +_.0,25 Pan American.Cox Calibrator (% Reading) 40,15 SpecificGravity (% Reading) ..... +0,15 N ,.

Total (% Reading). +0_18 +_0,28..

Total Uncertainty (%Reading) : +0.46 D The error contr A bution of the frequency counter is assumed to. be negligible. _.

The-fuel flow uncertainty, as.compared to the other parameters,was not developedfrom calibrationdata. Only two calibrationsper meter were ..

per.for_ned at Pratt & Whitney Aircraft which was not consideredto be adequate for developmentof rigorous statistical Conclusions.However, even considering the differences between Pan American and Pratt & Whitney Aircraft in calibrationtechniques and fuel_typ_s, the results.

were in good agreement. Therefore,. the fuel flow uncertaintieswere based on Pan Amer].can's ability to calibrate and utilize their fuel flow system.

D4.61 Parameter Total Uncertainties Table 3.2-I.is a summary of the total uncertaintiesderived for each performanceparameter.The total uncertaintiesfor .t h eTt3, Tt4, T_6, and Tt7.measurements_ of +6 to +13oc reflects the error-contribution of . the January 1979 cal1_ratio_of 6oc. The lower uncertainty does not , include that 6oc error, and the higher uncertai.qty._cto_.s include i that error.

D4.7 Comments The uncertaintiesquoted.in Section 3.2.4 are based_on the-calibration data acquired from the Pan AmeriCan test stand o_ver-a period of approxCmatelytwo years._As such, the uncertaint . i_s in.this document should notbe, compared to.those in the report on the historical data analyses, CR-135448 (Ref. 1), of the JTgD Jet Engine Diagnosti_:s Program which utilized instrument specif.ications as estimates for the ._- measurement uncertainties.One test stand instrument calibration was availablefor those, historicalstudies, but.it was not used to.estimate the total uncertainties.The uncertaintiespresented , in this document.._ represent the.long-term bias and precision, errors exhibited by the Pan American instrumentation. They are i.nteKLded to_provide realistic error bounds for.. estimatingthe most probable, er.rorof_ a given parameter . at any. point in time with 95 percent conf'.:dence.

APPENDIX E .

QUALITY .ASSURANCE Individualand Joint Pan American and Pratt & Whitney Aircraft quality assurance programs-providedthe policy and methodology for achieving validity in all the data gathering efforts in this.in-serviceengine performance deterioration_study.. These programs included_correlation of the Pan American. test stand, calibration• of performance instrumentati o n, , and .measurement of assembledgas-pathclearances.

Pan America_.standard procedureswere used for the followingtasks : - o Recording of flight performancedata; o Calibrati.on of installed . aircraft instrumentation; .

o Measuring and recording data relevant_toengine repairs atthe Pan American Jet Centerincluding: part and module histories;, part, module, and engine repair; part rep.lacement; and pertinent engine build-updimensionsand clearances.

These.procedures are all part of the Federal Aviation Admi_Listration (FAA) app.r o ved Pan. American MaintenanceProgram.

Pratt & Whitney Aircraft standard quality assura__ce programs were used.

for the folIowing tasks: o Measuring and recording,engine initial,production performance level s; o Measuring and recording data relevent to.engine repa.irs at P.ratt.& Whitney Aircraft including:part, module, and engine repair; part repl acement; and pertient engine bu.il d-up. dimensions and clearances; o The Plug-ln Console (PIC) installedengine performancemeasurement system and the periodic calibration of all components of this system (the PIC data components were calibrated to instrument standards_six..times - over the period of,this.p_rogram);_ _ o Correction of Engine Condition MonitorJng (ECM) data to standardized, values of.change in performa_Lce. _ o Reduction of/ in-fliz j htcalibration . data to a standard set of conditions.

P RE CED IN GPAGE BL AN K NOT R IMED 16 5 3" -- ....... - .... II I "l • I II I I I I I "1 I II I I "" " -- ilillPil/ Pratt & Whitney Aircraft and Pan American jointly c o nducted measurement and calibrati o n o f.sy s tem s in the f ol l o wing areas that were.unique to this pr o gram : o Calibrati o nof the expanded te s t s tand instrumentati o n(three sets of calibrations of the Pan American test stand were . _onducted dur_i n g. th e .period, o f thi s pr og ram) ; o Back-t o -back (Pratt & Whitney Aircraft, Middletown / Pan Americ a n.

,letCenter) engine test i ng t o e s tablish corrections between the ..... , differenttest stands used in the program (.Test Stand Correlation ' Te s ting), i The above combination of quality assurance procedures were used.to obtain high quality input data required.to detect the changes_in_ .[ L g ine and._engi ne,.module perf o rmance, with usage.

A P PENDIXF ACRONYMSAND SYMBOLS ACRONYMS (Organizatio ns) .

AA AmericanAirlines - BCAC . Boeing CommercialAirplane I?_ompany DAC DouglasAircraft Company NASA Nati ona I Aeronautics,an_Space Admini strati on NW . NorthwestAir lines PA Pan AmericanWorld Airways, P&WA Pratt & Whitney Aircraft TBC The Boeing Company TW Trans Wor l d Airlines UA United Airlines SYMBOLS A Area (squarefeet) ASG Axial skewed groove ATM Assumed temperature method.

BLH... BaldwinLima Hamilton Ithrustceil) .......

BPR Bypass rati o .

CDX Control differentialtransformer CPG -- Cycles per-gallon ECM Engine conditi o nmonitoring.

Elf Efficiency (percent) EGT Exhaust gas temperature(oc) EPR. Engine pressure, ratio F - Engine thrustL_ppunds).

FC F l.ow capacity FOD Foreignobject, damage _ FP F Iow parx_meter HPC., High.press ure compressor HPT High-pressure turbine___ IAS Inner air seal ID .Insi de diameter K K.i Io (10 3) LE Leading edge , LHV Lower heatingvalue LPC Low-pressurecompressor LPT Low-pressure turbine ..... : Mn Mach number 1 6 7 " .l_,,qi._ a iim4 m _. _ ..... i J T I _i . r" ill i " ii il i ii ii I I I I SYMBOLS (Cont' d.)

Mod Modifi cati on N Rotor speed (rpm) NASTRAN NAsa STRuctura , I ANalysis computer-program NCA Nozzle equivalent(flow)area NGV Nozzle guide vane OAS Outer air seal.

OD Outside diameter P Pressure (Ib / in 2) (psla) PIC, Plug-ln Console (testsystem).

PLA Power lever angle (degrees) PR Pressure ratio QEC Quick engine dlange (built-upengine / nacel l e) SLS Sea levelstatic SP SpecialPerformance (Boei n g747SP airplane_ .......

T Temperature (OF) {oc] , TE Tr . aiJing edge TIS Test. Informati on . Sheets T ! O Take-off TOBI Tangenti al onboard injectionsystem TOGW Take-off gross weig.ht (pounds) TSFC Thrust specificfuel .consumption (Ib / hr-lb) TSR Time since repair W. Mass flow (Ibm / s a c) W _low rate,(f_el)_ (pounds / hour)(%1 WC F I ow_capaci ty Vane angI e_,.( degree.)

A Change 6 -_P ressure c o rrection ... (in. _Ug / 29.92 ) . _, Efficiency(percent) (_ , Temperature.correction (OR / 519.)

Micro (10-6) SUBSCRIPTS* I Undisturbed_nlet (pressureand temperatures) 1 LOw-pressure. rotor (_otor. speeds) 2 Fan inlet (pressures. and temperatures).

2 High-pressurerotor (rotor speeds)__ _ 2.4 r. Fan..blade discharge * For simplicity,subscripts, may be written !'on the line"of type, especiallyin text.

SUBSCRIPTS(Cont'd.)* 2.6,. Fan,exit guide vane discharge 3 LPC discharge.

4. HPC dischar_ge 5 HPT inIet 6 HPT discharge 7 LPT discharge amb Ambient , b Burner bar Barometric F, f . Fuel JE Jet (primarystream) N, n Net s Static T, t Stagnation(total) •. . Fo_ simp . licity, subscriptsmay.be written "on the line" of type, especiallyin text.

.'I_9, RE F E R ENCES i Sallee, G. P.: RerformanceDeteri o rati o nBa s ed o n__ E xisting (Histor_ica . ]) Data. NASACR-1 3 5448, 1 97 B.

2 Bouchard,R. J., Beyerly,W. R,, and Sallee,G..... P." Sh o rt-Term P e rformanceDeterioration in JT 9 D- 7 A(SP)Engine 69574 3 . NASA CR-1 35 4 3 1, 19 7 8.

f

3 Jay, A and Todd, E. S.:. Effectof.Steady F lightLoad s on JTgD-7 Performance Deteriorati o n. NASA C R-1 3 540 7 , 19 7 8.

4 Sallee,G..P. and Martin,R. L.: ExpandedStudyof F ea s ibili.ty of Measuring I n-Flight 7 47 / u'I'9D Load s , Performance, Clearance,and.

T hermalData. NASACR-1 5 9717, 1979.

' _ E C . , E : DI Ne P AG £ BL A N K N O T F I L M E D