14 CFR Part 38 — Airplane Fuel Efficiency Certification

14 CFR Ch. I (1–1–25 Edition) Pt. 38 whichever is greater, above the reference Subpart A—General track and throughout the 10 dB-down time interval.

§ 38.1 Applicability.

K7.9 The tiltrotor altitude must not vary (a) Except as provided in paragraph during each flyover by more than ± 30 ft ( ± 9 (c) of this section, an airplane that is m) from the reference altitude throughout subject to the requirements of 40 CFR the 10 dB-down time interval.

K7.10 During the approach procedure, the part 1030 may not exceed the fuel effi- tiltrotor must establish a stabilized constant ciency limits of this part when original speed approach and fly between approach an- type certification under this title is gles of 5.5 degrees and 6.5 degrees throughout sought. This part applies to the fol- the 10 dB-down time interval.

lowing airplanes: K7.11 During all test procedures, the (1) A subsonic jet airplane that has— tiltrotor weight (mass) must not be less than (i) Either— 90 percent and not more than 105 percent of (A) A type-certificated maximum the maximum certificated weight (mass).

passenger seating capacity of 20 seats For each of the test procedures, complete at or more; least one test at or above this maximum cer- (B) A maximum takeoff mass tificated weight (mass).

(MTOM) greater than 5,700 kg; and K7.12 A tiltrotor capable of carrying exter- nal loads or external equipment must be (C) An application for original type noise certificated without such loads or certification that is submitted on or equipment fitted after January 11, 2021; K7.13 The value of V used for noise cer- CON (ii) Or— tification must be included in the approved (A) A type-certificated maximum Flight Manual.

passenger seating capacity of 19 seats or fewer; [78 FR 1139, Jan. 8, 2013] (B) A MTOM greater than 60,000 kg; and PART 38—AIRPLANE FUEL (C) An application for original type EFFICIENCY CERTIFICATION certification that is submitted on or after January 11, 2021.

Subpart A—General (2) A subsonic jet airplane that has— (i) A type-certificated maximum pas- Sec.

senger seating capacity of 19 seats or 38.1 Applicability.

fewer; 38.3 Definitions.

(ii) A MTOM greater than 5,700 kg, 38.4 Compatibility with airworthiness re- but not greater than 60,000 kg; and quirements.

(iii) An application for original type 38.5 Exemptions.

certification that is submitted on or 38.7 Incorporation by reference.

after January 1, 2023.

38.9 Relationship to other regulations.

(3) A propeller-driven airplane that Subpart B—Determining Fuel Efficiency for has— Subsonic Airplanes (i) A MTOM greater than 8,618 kg; and 38.11 Fuel efficiency metric.

(ii) An application for original type 38.13 Specific air range.

certification that is submitted on or 38.15 Reference geometric factor.

after January 11, 2021.

38.17 Fuel efficiency limits.

(4) A subsonic jet airplane— 38.19 Change criteria.

(i) That is a modified version of an 38.21 Approval before compliance testing.

airplane whose type design was not cer- 38.23 Manual information and limitations.

tificated under this part; A PPENDIX A TO P ART 38—D ETERMINATION OF (ii) That has a MTOM greater than A IRPLANE F UEL E FFICIENCY M ETRIC 5,700 kg; V ALUE (iii) For which an application by the A UTHORITY : 42 U.S.C. 4321 et seq., 7572; 49 type certificate holder for a type de- U.S.C. 106(g), 40113, 44701–44702, 44704; 49 CFR sign change is submitted on or after 1.83(c) January 1, 2023; and (iv) For which the first certificate of S OURCE : Docket No. FAA–2022–0241, Amdt.

airworthiness is issued with the modi- No. 21–107, 89 FR 12654, Feb. 16, 2024, unless otherwise noted. fied type design.

Federal Aviation Administration, DOT § 38.4 (5) A propeller-driven airplane— (7) Airplanes powered by recipro- (i) That is a modified version of an cating engines.

airplane whose type design was not cer- § 38.3 Definitions.

tificated under this part; (ii) That has a MTOM greater than For the purpose of showing compli- 8,618 kg; ance with this part, the following (iii) For which an application by the terms have the specified meanings: type certificate holder for a type de- Amphibious airplane means an air- sign change is submitted on or after plane that is capable of takeoff and January 1, 2023; and landing on both land and water. Such an airplane uses its hull or floats at- (iv) For which the first certificate of tached to the landing gear for takeoff airworthiness is issued with the modi- and landing on water, and either ex- fied type design.

tendable or fixed landing gear for take- (6) A subsonic jet airplane that has— off and landing on land.

(i) A MTOM greater than 5,700 kg; ICAO Annex 16, Volume III means Vol- and ume III of Annex 16 to the Convention (ii) Its first certificate of airworthi- on International Civil Aviation.

ness issued on or after January 1, 2028.

Maximum takeoff mass (MTOM) is the (7) A propeller-driven airplane that maximum certified takeoff mass, ex- has— pressed in kilograms, for an airplane (i) A MTOM greater than 8,618 kg; type design.

and Performance model is an analytical (ii) Its first certificate of airworthi- tool (or a method) validated using cor- ness issued on or after January 1, 2028.

rected flight test data that can be used (b) The requirements of this part to determine the specific air range val- apply to an airplane for which an appli- ues for calculating the fuel efficiency cation for a change in type design is metric value.

submitted that includes a modification Reference geometric factor (RGF) is a that meets the change criteria of non-dimensional number derived from § 38.19. A modified airplane may not ex- a two-dimensional projection of the fu- ceed the applicable fuel efficiency limit selage.

of this part when certification under Specific air range (SAR) is the distance this chapter is sought. A modified air- an airplane travels per unit of fuel con- plane is subject to the same fuel effi- sumed. Specific air range is expressed ciency limit of § 38.17 as the airplane in kilometers per kilogram of fuel.

was certificated to prior to modifica- Subsonic means an airplane that has tion.

not been certificated under this title to (c) The requirements of this part do exceed Mach 1 in normal operation.

not apply to: Type certificated maximum passenger (1) Subsonic jet airplanes having a seating capacity means the maximum MTOM at or below 5,700 kg.

number of passenger seats that may be (2) Propeller-driven airplanes having installed on an airplane as listed on its a MTOM at or below 8,618 kg.

type certificate data sheet, regardless (3) Amphibious airplanes.

of the actual number of seats installed (4) Airplanes initially designed, or on an individual airplane.

modified and used, for specialized oper- § 38.4 Compatibility with airworthi- ations. These airplane designs may in- ness requirements.

clude characteristics or configurations necessary to conduct specialized oper- Unless otherwise approved by the ations that the FAA and the United FAA, an airplane used to demonstrate States Environmental Protection compliance with this part must meet Agency (EPA) have determined may all of the airworthiness requirements cause a significant increase in the fuel of this chapter required to establish efficiency metric value.

the type certification basis of the air- (5) Airplanes designed with a ref- plane, for any condition under which erence geometric factor of zero.

compliance with this part is being (6) Airplanes designed for, or modi- demonstrated. Any procedure used to fied and used for, firefighting. demonstrate compliance, and any

14 CFR Ch. I (1–1–25 Edition) § 38.5 flight crew information developed for § 38.9 Relationship to other regula- demonstrating compliance with this tions.

part, must be consistent with the air- In accordance with certain provisions worthiness requirements of this chap- of the Clean Air Act Amendments of ter that constitute the type certifi- 1970 (CAA) (42 U.S.C. 7571 et seq. ), the cation basis of the airplane.

United States Environmental Protec- tion Agency (EPA) is authorized to set § 38.5 Exemptions.

standards for aircraft engine emissions A petition for exemption from any in the United States, while the FAA is requirement of this part must be sub- authorized to ensure compliance with mitted to the Administrator in accord- those standards under a delegation ance with and meet the requirements from the Secretary of Transportation of part 11 of this chapter. The FAA will (49 CFR 1.83). The fuel efficiency limits consult with the EPA on each exemp- in § 38.17 are intended to be the same as tion petition before taking action.

that promulgated by the EPA in 40 § 38.7 Incorporation by reference.

CFR part 1030. Accordingly, if the EPA changes any regulation in 40 CFR part The ICAO Doc 7488/3, Manual of the 1030 that corresponds with a regulation ICAO Standard Atmosphere (extended to in this part, a certification applicant 80 kilometres (262 500 feet)) (1993), ref- may request a waiver of those provi- erenced in sections A38.2.1.3.1, sions as they appear in this part in A38.5.2.2.1.9, and A38.5.2.2.1.10 of appen- order to comply with part 1030. In addi- dix A to this part, is incorporated by reference into this part with the ap- tion, unless otherwise specified in this proval of the Director of the Federal part, all terminology and abbreviations Register under 5 U.S.C. 552(a) and 1 in this part that are defined in 40 CFR CFR part 51. All approved material is part 1030 have the meaning specified in available for inspection at the FAA and part 1030.

at the National Archives and Records Administration (NARA). Contact FAA Subpart B—Determining Fuel at: Office of Rulemaking (ARM–1), 800 Efficiency for Subsonic Airplanes Independence Avenue SW, Washington, DC 20590 (telephone 202–267–9677). For § 38.11 Fuel efficiency metric.

information on the availability of this For each airplane subject to this material at NARA, visit www.archives.gov/federal-register/cfr/ibr- part, or to determine whether a modi- locations.html or email fication makes an airplane subject to fr.inspection@nara.gov. The ICAO Doc this part under the change criteria of 7488/3 is available for purchase from the § 38.19, a fuel efficiency metric value ICAO Store at 999 Robert-Bourassa must be calculated, using the following Boulevard Montre ´ al (Quebec) Canada equation, rounded to three decimal H3C 5H7, ( https://store.icao.int/ ). places: Where: § 38.13 Specific air range.

The SAR is determined in accordance with (a) For each airplane subject to this § 38.13, and the RGF is determined in ac- part, the SAR of an airplane must be cordance with § 38.15. The fuel efficiency determined by either: metric value is expressed in units of kilo- (1) Direct flight test measurements; grams of fuel consumed per kilometer.

or Federal Aviation Administration, DOT § 38.17 (2) Using a performance model that with the main deck floor and the for- is: ward and aft pressure bulkheads except (i) Validated by actual SAR flight for the crew flight deck zone.

test data; and (b) For an airplane with more than (ii) Approved by the FAA before any one deck, determine the sum of the SAR calculations are submitted. ∧ areas (expressed in m 2) as follows: (b) For the airplane model, establish (1) The maximum width of the fuse- a 1/SAR value at each of the following lage outer mold line, projected to a flat reference airplane masses: plane parallel with the main deck floor (1) High gross mass: 92 percent by the forward and aft pressure bulk- MTOM.

heads except for any crew flight deck (2) Low gross mass: (0.45 * MTOM) + zone.

∧ (0.63 * (MTOM 0.924)).

(2) The maximum width of the fuse- (3) Mid gross mass: simple arithmetic lage outer mold line at or above each average of high gross mass and low other deck floor, projected to a flat gross mass.

plane parallel with the additional deck (c) To obtain (1/SAR) as required to avg floor by the forward and aft pressure determine the fuel efficiency metric bulkheads except for any crew flight value described in § 38.11, calculate the deck zone.

average of the three 1/SAR values de- (c) Determine the non-dimensional scribed in paragraph (b) of this section.

RGF by dividing the area defined in Do not include auxiliary power units in paragraph (a) or (b) of this section by 1 any 1/SAR calculation.

∧ m 2.

(d) All determinations made under (d) All measurements and calcula- this section must be made in accord- tions used to determine the RGF of an ance with the procedures applicable to airplane must be made in accordance SAR as described in appendix A to this with the procedures for determining part.

RGF in section A38.3 of appendix A to § 38.15 Reference geometric factor. this part.

For each airplane subject to this § 38.17 Fuel efficiency limits.

part, determine the airplane’s non-di- (a) The fuel efficiency limits in this mensional RGF for the fuselage size of section are expressed as maximum per- each airplane model, calculated as fol- mitted fuel efficiency metric values, as lows: (a) For an airplane with a single calculated under § 38.11.

deck, determine the area of a surface (b) The fuel efficiency metric value of ∧ (expressed in m 2) bounded by the max- an airplane subject to this part may imum width of the fuselage outer mold not exceed the following, rounded to line projected to a flat plane parallel three decimal places: 14 CFR Ch. I (1–1–25 Edition) § 38.19 (1) The maximum takeoff mass; or § 38.19 Change criteria.

(2) The fuel efficiency metric value (a) For an airplane that has been by a percentage that is more than the shown to comply with § 38.17, any sub- following calculated thresholds.

sequent version of that airplane must (i) For airplanes with a MTOM great- demonstrate compliance with § 38.17 if er than or equal to 5,700 kg, the thresh- the subsequent version incorporates a old decreases linearly from 1.35 percent modification that either increases: Federal Aviation Administration, DOT § 38.23 for an airplane with a MTOM of 5,700 (mass) that is less than the maximum kg to 0.75 percent for an airplane with certificated takeoff weight (mass) used a MTOM of 60,000 kg. to establish the airworthiness of the (ii) For airplanes with a MTOM airplane under this chapter, the lower greater than or equal to 60,000 kg, the weight (mass) becomes an operating threshold decreases linearly from 0.75 limitation of the airplane and that lim- percent for an airplane with a MTOM itation must be included in the limita- of 60,000 kg to 0.70 percent for airplanes tions section of any FAA-approved with a MTOM of 600,000 kg. manual.

(iii) For airplanes with a MTOM A PPENDIX A TO P ART 38—D ETERMINA - greater than or equal to 600,000 kg, the TION OF AIRPLANE F UEL E FFICIENCY threshold is 0.70 percent.

M ETRIC V ALUE (b) For an airplane that has been shown to comply with § 38.17, and for A38.1 Introduction any subsequent version of that airplane A38.2 Reference specifications for SAR that incorporates modifications that flight tests A38.3 Determination of reference geometric do not increase the MTOM or the fuel factor (RGF) efficiency metric value in excess of the A38.4 Certification test specifications levels shown in paragraph (a) of this A38.5 Measurement of specific air range section, the fuel efficiency metric A38.6 Submission of certification data to value of the modified airplane may be the FAA reported to be the same as the value A38.1 I NTRODUCTION prior to modification.

(c) For an airplane that meets the A38.1.1 This appendix describes the proc- criteria of § 38.1(a)(4) or (5), on or after esses and procedures for determining the fuel efficiency metric value for an airplane sub- January 1, 2023, and before January 1, ject to this part.

2028, the airplane must demonstrate compliance with § 38.17 if it incor- A38.1.2 Methods for Determining Specific Air porates any modification that in- Range (SAR) creases the fuel efficiency metric value A38.1.2.1 SAR may be determined by ei- of the airplane prior to modification by ther— more than 1.5 percent.

A38.1.2.1.1 Direct flight test measurement at the SAR test points, including any correc- § 38.21 Approval before compliance tions of test data to reference specifications; testing.

or A38.1.2.1.2 Use of a performance model.

All procedures, weights, configura- A38.1.2.2 For any determination made tions, and other information or data under section A38.1.2.1.1 of this appendix, the that are used to establish a fuel effi- SAR flight test data must have been ac- ciency level required by this part or in quired in accordance with the procedures de- any appendix to this part (including fined in this appendix and approved by the any equivalent procedures) must be ap- FAA.

proved by the FAA prior to use in cer- A38.1.2.3 For any determination made under section A38.1.2.1.2 of this appendix, the tification tests intended to dem- performance model must: onstrate compliance with this part.

A38.1.2.3.1 Be verified that the model pro- duces the values that are the same as FAA- § 38.23 Manual information and limita- approved SAR flight test data; tions.

A38.1.2.3.2 Include a detailed description of (a) Information in manuals. The fol- any test and analysis method and any algo- lowing information must be included in rithm used so as to allow evaluation by the any FAA-approved section of a FAA- FAA; and A38.1.2.3.3 Be approved by the FAA before approved Airplane Flight Manual or use.

combination of approved manual mate- rial: A38.2 R EFERENCE S PECIFICATIONS FOR SAR (1) Fuel efficiency level established F LIGHT T ESTS as required by this part; and A38.2.1 The following reference specifica- (2) Maximum takeoff mass at which tions must be established when determining fuel efficiency level was established.

SAR values for an airplane. No reference (b) Limitation. If the fuel efficiency of specification may exceed any airworthiness an airplane is established at a weight limit approved for the airplane under this

14 CFR Ch. I (1–1–25 Edition) § 38.23

chapter. See section A38.5 of this appendix A38.2.1.3.2 Fuel lower heating value equal for further information. to 43.217 MJ/kg (18, ¥ 580 BTU/lb).

A38.2.1.1 Reference specifications at the A38.2.2 If any test conditions are not the airplane level: same as the reference specifications of this A38.2.1.1.1 Airplane at the reference masses appendix, the test conditions must be cor- listed in § 38.13(b); rected to the reference specifications as de- A38.2.1.1.2 A combination of altitude and scribed in section A38.5 of this appendix.

airspeed selected by the applicant; A38.2.1.1.3 Airplane in steady, unacceler- A38.3 D ETERMINATION OF R EFERENCE ated, straight and level flight; G EOMETRIC F ACTOR (RGF) A38.2.1.1.4 Airplane in longitudinal and lat- eral trim; A38.3.1 This section provides additional in- A38.2.1.1.5 Airplane gravitational accelera- formation for determining the RGF, as re- tion when travelling in the direction of true quired by § 38.15.

North in still air at the reference altitude A38.3.2 The area that defines RGF includes and a geodetic latitude of 45.5 degrees, based all pressurized space on a single or multiple on g (g is 9.80665 m/s , which is the standard 0 0 decks including aisles, assist spaces, pas- acceleration due to gravity at sea level and sageways, stairwells and areas that can ac- a geodetic latitude of 45.5 degrees); commodate cargo or auxiliary fuel con- A38.2.1.1.6 A reference airplane center of tainers. It does not include permanent inte- gravity (CG) position selected by the appli- grated fuel tanks within the cabin, or any cant to be representative of the mid-CG unpressurized fairings, crew rest or work point relevant to design cruise performance areas, or cargo areas that are not on the at each of the three reference airplane main or upper deck ( e.g., ‘loft’ or under floor masses; and areas). RGF does not include the flight deck A38.2.1.1.7 A wing structural loading condi- crew zone.

tion defined by the applicant that is rep- A38.3.3 The aft boundary to be used for cal- resentative of operations conducted in ac- cordance with the airplane’s maximum pay- culating RGF is the aft pressure bulkhead.

load capability. The forward boundary is the forward pres- A38.2.1.2 Reference specifications at the en- sure bulkhead, not including the flight deck gine level: crew zone.

A38.2.1.2.1 Electrical and mechanical power A38.3.4 Areas that are accessible to both extraction and bleed flow relevant to design crew and passengers are not considered part cruise performance, as selected by the appli- of the flight deck crew zone. For an airplane cant; that has a flight deck door, the aft boundary Note 1 to A38.2.1.2.1 —Power extraction and of the flight deck crew zone is the plane of bleed flow attributable to the use of optional the flight deck door. For an airplane that equipment such as passenger entertainment has no flight deck door or has optional inte- systems need not be included.

rior configurations that include different lo- A38.2.1.2.2 Engine stability bleeds oper- cations of the flight deck door, the aft ating according to the manufacturer’s nor- boundary is determined by the configuration mal schedule for the engine; and that provides the smallest available flight A38.2.1.2.3 Engines with at least 15 cycles deck crew zone. For airplanes certificated or 50 engine flight hours.

for single-pilot operation, the flight deck A38.2.1.3 Other reference specifications: crew zone is measured as half the width of A38.2.1.3.1 ICAO standard day atmosphere the flight deck.

(Doc 7488/3, 3rd edition 1993, titled ‘‘Manual of the ICAO Standard Atmosphere (extended A38.3.5 Figures A38–1 and A38–2 of this ap- to 80 kilometres (262 500 feet))’’) (incor- pendix provide a notional view of the RGF porated by reference, see § 38.7); and boundary conditions.

Federal Aviation Administration, DOT § 38.23

A38.4 C ERTIFICATION T EST S PECIFICATIONS A38.4.2 Flight Test Procedures A38.4.2.1 Before a Test Flight. The test A38.4.1 Certification Test Specifications.

flight procedures must include the following This section prescribes the specifications elements and must be approved by the FAA under which an applicant must conduct SAR before any test flight is conducted: certification tests.

14 CFR Ch. I (1–1–25 Edition) § 38.23

A38.4.2.1.1 Airplane conformity. The test air- A38.4.2.2.1.2 The engine thrust/power set- plane must conform to the critical configu- ting is stable for unaccelerated level flight; ration of the type design for which certifi- A38.4.2.2.1.3 The airplane is flown as close cation is sought. as practicable to the reference specifications A38.4.2.1.2 Airplane weight. The test air- to minimize the magnitude of any correc- plane must be weighed. Any change in mass tion; after the weighing and prior to the test A38.4.2.2.1.4 Changes in trim or engine flight must be accounted for. power/thrust settings, engine stability and A38.4.2.1.3 Fuel. The fuel used for each handling bleeds, or electrical and mechanical flight test must meet the specification de- power extraction (including bleed flow) are fined in either ASTM D1655–15 (titled avoided or minimized as practicable; and ‘‘Standard Specification for Aviation Tur- A38.4.2.2.1.5 There is no unnecessary move- bine Fuels’’), UK MoD Defense Standard 91– ment of on-board personnel.

91, Issue 7, Amendment 3 (titled ‘‘Turbine A38.4.2.2.2 Test Condition Stability. To ob- Fuel, Kerosene Type, Jet A–1, NATO Code F– tain a valid SAR measurement, the following 35; Join Services Designation; AVTUR’’), or conditions must be maintained during each as approved by FAA.

test flight, including the indicated toler- A38.4.2.1.4 Fuel lower heating value. The ances for at least 1 minute while SAR data is lower heating value of the fuel used on a test acquired: flight must be determined from a sample of A38.4.2.2.2.1 Mach number within ± 0.005; fuel used for the test flight. The lower heat- A38.4.2.2.2.2 Ambient temperature within ing value of the fuel sample must be used to ± 1 ° C; correct measured data to reference specifica- A38.4.2.2.2.3 Heading within ± 3 degrees; tions. The determination of lower heating A38.4.2.2.2.4 Track within ± 3 degrees; value and the correction to reference speci- A38.4.2.2.2.5 Drift angle less than 3 degrees; fications are subject to approval by the FAA. A38.4.2.2.2.6 Ground speed within ± 3.7 km/h A38.4.2.1.4.1 The fuel lower heating value ( ± 2 kt); may be determined in accordance with A38.4.2.2.2.7 Difference in ground speed at ASTM D4809–13 ‘‘Standard Test Method for the beginning of the SAR measurement from Heat of Combustion of Liquid Hydrocarbon the ground speed at the end of the SAR Fuels by Bomb Calorimeter (Precision Meth- measurement within ± 2.8 km/h/min ( ± 1.5 kt/ od)’’, or as approved by the FAA. min); and A38.4.2.1.4.2 The fuel sample may be rep- A38.4.2.2.2.8 Pressure altitude within ± 23 m resentative of the fuel used for each flight ( ± 75 ft).

test and should not have errors or variations A38.4.2.2.3 Alternatives to the stable test due to fuel being uplifted from multiple condition criteria of section A38.4.2.2.2 of sources, fuel tank selection, or fuel layering this appendix may be used provided that sta- in a tank.

bility is sufficiently demonstrated to the A38.4.2.1.5 Fuel specific gravity and viscosity.

FAA.

When volumetric fuel flow meters are used, A38.4.2.2.4 Data obtained at test points the specific gravity and viscosity of the fuel that do not meet the stability criteria of sec- used on a test flight must be determined tion A38.4.2.2.2 may be acceptable as an from a sample of fuel used for the test flight.

equivalent procedure, subject to FAA ap- A38.4.2.1.5.1 The fuel specific gravity may proval.

be determined in accordance with ASTM A38.4.2.2.5 SAR measurements at the test D4052–11 ‘‘Standard Test Method for Density, points must be separated by either: Relative Density, and API Gravity of Liq- A38.4.2.2.5.1 Two minutes; or uids’’, or as approved by FAA. A38.4.2.2.5.2 An exceedance of one or more A38.4.2.1.5.2 The fuel kinematic viscosity of the stability criteria limits described in may be determined in accordance with A38.4.2.2.2.

ASTM D445–15 (titled ‘‘Standard Test Meth- A38.4.2.3 Verification of Airplane Mass at od for Kinematic Viscosity of Transparent Test Conditions and Opaque Liquids (and Calculation of Dy- A38.4.2.3.1 The procedure for determining namic Viscosity)’’), or as approved by FAA. the mass of the airplane at each test condi- A38.4.2.2 Flight Test Procedures and Test tion must be approved by the FAA.

Condition Stability. An applicant must con- A38.4.2.3.2 The mass of the airplane during duct each flight test in accordance with the a flight test is determined by subtracting the flight test procedures and the stability con- fuel used from the mass of the airplane at ditions as follows: the start of the test flight. The accuracy of A38.4.2.2.1 Flight Test Procedure. The fol- the determination of the fuel used must be lowing procedures must be maintained dur- verified by: ing each flight used to gather data for deter- A38.4.2.3.2.1 Weighing the test airplane on mining SAR values: calibrated scales before and after the SAR A38.4.2.2.1.1 To the extent that is prac- test flight; ticable, the airplane is flown at constant A38.4.2.3.2.2 Weighing the test airplane be- pressure altitude and constant heading along fore and after another test flight that in- isobars; cluded a cruise segment, provided that flight

Federal Aviation Administration, DOT § 38.23

occurs within one week or 50 flight hours (at system is defined as the root sum of squares the option of the applicant) of the SAR test (RSS) of the individual accuracies.

flight and using the same, unaltered fuel A38.5.1.8 If the absolute value of the cumu- flow meters; or lative error of the overall SAR measurement A38.4.2.3.2.3 Other methods as approved by system is greater than 1.5 percent, a penalty the FAA. equal to the amount that the RSS value ex- ceeds 1.5 percent must be applied to the SAR A38.5 M EASUREMENT OF S PECIFIC A IR R ANGE value that has been corrected to reference specifications (see section A38.5.2 of this ap- A38.5.1 Measurement System pendix). If the absolute value of the cumu- A38.5.1.1 The following parameters must be lative error of the overall SAR measurement recorded at a minimum sampling rate of 1 system is less than or equal to 1.5 percent, no Hertz (cycle per second): penalty will be applied.

A38.5.1.1.1 Airspeed; A38.5.2 Calculation of Specific Air Range A38.5.1.1.2 Ground speed; from Measured Data A38.5.1.1.3 True airspeed; A38.5.2.1 Calculating SAR. SAR must be A38.5.1.1.4 Fuel flow; calculated using the following equation: A38.5.1.1.5 Engine power setting; SAR = TAS/W f A38.5.1.1.6 Pressure altitude; A38.5.1.1.7 Temperature; Where: A38.5.1.1.8 Heading; TAS is the true airspeed and W is total air- f A38.5.1.1.9 Track; and plane fuel flow.

A38.5.1.1.10 Fuel used (for the determina- tion of gross mass and CG position). A38.5.2.2 Correcting Measured SAR Values A38.5.1.2 The following parameters must be to Reference Specifications recorded: A38.5.2.2.1 The measured SAR values must A38.5.1.2.1 Latitude; be corrected to the reference specifications A38.5.1.2.2 Engine bleed positions and listed in A38.2 of this appendix. Unless other- power off-takes; and wise approved by the FAA, corrections to A38.5.1.2.3 Power extraction (electrical and reference specifications must be applied for mechanical load). each of the following measured parameters: A38.5.1.3 The value of each parameter used A38.5.2.2.1.1 Acceleration/deceleration (en- for the determination of SAR (except for ergy). Drag determination is based on an as- ground speed) is the simple arithmetic aver- sumption of steady, unaccelerated flight. Ac- age of the measured values for that param- celeration or deceleration occurring during a eter obtained throughout the stable test con- test condition affects the assessed drag level.

dition described in section A38.4.2.2.2 of this The reference specification is in section appendix. A38.2.1.1.3 of this appendix.

A38.5.1.4 For ground speed, the value is the A38.5.2.2.1.2 Aeroelastics. Wing rate of change of ground speed during the aeroelasticity may cause a variation in drag SAR test measurement. The rate of change as a function of airplane wing mass distribu- of ground speed during the SAR measure- tion. Airplane wing mass distribution will be ment must be used to evaluate and correct affected by the fuel load distribution in the any acceleration or deceleration that might wings and the presence of any external occur during the SAR measurement. stores. The reference specification is in sec- A38.5.1.5 Each measurement device must tion A38.2.1.1.7 of this appendix.

have sufficient resolution to determine that A38.5.2.2.1.3 Altitude. The altitude at which the stability of a parameter defined in sec- the airplane is flown affects the fuel flow.

tion A38.4.2.2.2 of this appendix is main- The reference specification is in section tained during SAR measurement. A38.2.1.1.2 of this appendix.

A38.5.1.6 The SAR measurement system A38.5.2.2.1.4 Apparent gravity. Acceleration, consists of the combined instruments and de- caused by the local effect of gravity, and in- vices, and any associated procedures, used to ertia, affect the test weight of the airplane.

acquire the following parameters necessary The apparent gravity at the test conditions to determine SAR: varies with latitude, altitude, ground speed, A38.5.1.6.1 Fuel flow; and direction of motion relative to the A38.5.1.6.2 Mach number; Earth’s axis. The reference gravitational ac- A38.5.1.6.3 Altitude; celeration is the gravitational acceleration A38.5.1.6.4 Airplane mass; for the airplane travelling in the direction of A38.5.1.6.5 Ground speed; true North in still air at the reference alti- A38.5.1.6.6 Outside air temperature; tude, a geodetic latitude of 45.5 degrees, and A38.5.1.6.7 Fuel lower heating value; and based on g (see section A38.2.1.1.5 of this ap- A38.5.1.6.8 CG. pendix).

A38.5.1.7 The SAR value is affected by the A38.5.2.2.1.5 CG position. The position of the accuracy of each element that comprises the airplane CG affects the drag due to longitu- SAR measurement system. The cumulative dinal trim. The reference specification is in error associated with the SAR measurement section A38.2.1.1.6 of this appendix.

14 CFR Ch. I (1–1–25 Edition) § 38.23

A38.5.2.2.1.6 Electrical and mechanical power A38.5.2.3.2 When an FAA-approved perform- extraction and bleed flow. Electrical and me- ance model is used, extrapolations to air- chanical power extraction, and bleed flow af- craft masses other than those tested may be fect the fuel flow. The reference specifica- approved when such extrapolations are con- tions are in sections A38.2.1.2.1 and A38.2.1.2.2 sistent with accepted airworthiness prac- of this appendix. tices. Since a performance model must be A38.5.2.2.1.7 Engine deterioration level. The based on data covering an adequate range of requirement in section A38.2.1.2.3 of this ap- lift coefficient, Mach number, and thrust pendix addresses the minimum deterioration specific fuel consumption, no extrapolation of an engine that is used to determine SAR. of those parameters is permitted.

Since engine deterioration is rapid when an A38.5.3 Validity of Results engine is new, when used for SAR determina- A38.5.3.1 A 90 percent confidence interval tion: must be calculated for each of the SAR val- A38.5.2.2.1.7.1 Subject to FAA approval, an ues at the three reference masses.

engine having less deterioration than the A38.5.3.2 If the 90 percent confidence inter- reference deterioration level in section val of the SAR value at any of the three ref- A38.2.1.2.3 of this appendix must correct the erence airplane masses— fuel flow to the reference deterioration using A38.5.3.2.1 Is less than or equal to ± 1.5 per- an approved method. cent, the SAR value may be used.

A38.5.2.2.1.7.2 An engine with greater dete- A38.5.3.2.2 Exceeds ± 1.5 percent, a penalty rioration than the reference deterioration equal to the amount that the 90 percent con- fidence interval exceeds ± 1.5 percent must be level in section A38.2.1.2.3 of this appendix applied to the SAR value, as approved by the may be used, and no correction is permitted.

A38.5.2.2.1.8 Fuel lower heating value. The FAA.

fuel lower heating value defines the energy A38.5.3.3 If clustered data is acquired sepa- content of the fuel. The lower heating value rately for each of the three gross mass ref- directly affects the fuel flow at a given test erence points, the minimum sample size ac- condition. The reference specification is in ceptable for each of the three gross mass section A38.2.1.3.2 of this appendix. SAR values is six.

A38.5.3.4 If SAR data is collected over a A38.5.2.2.1.9 Reynolds number. The Reynolds range of masses, the minimum sample size is number affects airplane drag. For a given test condition the Reynolds number is a 12 and the 90 percent confidence interval is function of the density and viscosity of air calculated for the mean regression line at the test altitude and temperature. The through the data.

reference Reynolds number is derived from A38.6 S UBMISSION OF C ERTIFICATION D ATA TO the density and viscosity of air from the THE FAA ICAO standard atmosphere at the reference altitude (see sections A38.2.1.1.2 and The following information must be pro- A38.2.1.3.1 of this appendix, incorporated by vided to the FAA in the certification reports reference see § 38.7).

for each airplane type and model for which A38.5.2.2.1.10 Temperature. The ambient fuel efficiency certification under this part temperature affects the fuel flow. The ref- is sought.

erence temperature is the standard day tem- A38.6.1 General Information perature from the ICAO standard atmosphere A38.6.1.1 Designation of the airplane type at the reference altitude (see section and model: A38.2.1.3.1 of this appendix, incorporated by A38.6.1.2 Configuration of the airplane, in- reference see § 38.7). cluding CG range, number and type designa- Note 2 to A38.5.2.2.1.10 —Post-flight data tion of engines and, if fitted, propellers, and analysis includes the correction of measured any modifications or non-standard equip- data for data acquisition hardware response ment expected to affect the fuel efficiency characteristics ( e.g., system latency, lag, off- characteristics; set, buffering, etc.). A38.6.1.3 MTOM used for certification A38.5.2.2.2 Correction methods are subject under this part; to the approval of the FAA.

A38.6.1.4 All dimensions needed for calcula- A38.5.2.3 Using Specific Air Range to De- tion of RGF; and termine the Fuel Efficiency Metric Value A38.6.1.5 Serial number of each airplane A38.5.2.3.1 Calculate the SAR values for used to establish fuel efficiency certification each of the three reference masses as de- in accordance with this part.

scribed in § 38.13, including any corrections A38.6.2 Reference Specifications. The ref- to reference specifications, as required under erence specifications used to determine any this part. The final SAR value for each ref- SAR value as described in section A38.2 of erence mass is the simple arithmetic average this appendix.

of all valid test points at the appropriate A38.6.3 Test Data. The following measured gross mass, or derived from a validated per- test data, including any corrections for in- formance model. No data acquired from a strumentation characteristics, must be pro- valid test point may be omitted unless ap- vided for each of the test measurement proved by the FAA. points used to calculate the SAR values for

Federal Aviation Administration, DOT § 39.7

each of the reference masses defined in 39.11 What actions do airworthiness direc- § 38.13(b): tives require?

A38.6.3.1 Airspeed, ground speed and true 39.13 Are airworthiness directives part of airspeed; the Code of Federal Regulations?

A38.6.3.2 Fuel flow; 39.15 Does an airworthiness directive apply A38.6.3.3 Pressure altitude; if the product has been changed?

A38.6.3.4 Static air temperature; 39.17 What must I do if a change in a prod- A38.6.3.5 Airplane gross mass and CG for uct affects my ability to accomplish the each test point; actions required in an airworthiness di- A38.6.3.6 Levels of electrical and mechan- rective?

ical power extraction and bleed flow; 39.19 May I address the unsafe condition in A38.6.3.7 Engine performance; a way other than that set out in the air- A38.6.3.7.1 For jet airplanes, engine power worthiness directive?

setting; or 39.21 Where can I get information about A38.6.3.7.2 For propeller-driven airplanes, FAA-approved alternative methods of shaft horsepower or engine torque, and pro- compliance?

peller rotational speed; A38.6.3.8 Fuel lower heating value; 39.23 May I fly my aircraft to a repair facil- A38.6.3.9 When volumetric fuel flow meters ity to do the work required by an air- are used, fuel specific gravity and kinematic worthiness directive?

viscosity (see section A38.4.2.1.5. of this ap- 39.25 How do I get a special flight permit?

pendix); 39.27 What do I do if the airworthiness di- A38.6.3.10 The cumulative error (RSS) of rective conflicts with the service docu- the overall measurement system (see section ment on which it is based?

A38.5.1.7 of this appendix); AUTHORITY : 49 U.S.C. 106(g), 40113, 44701.

A38.6.3.11 Heading, track and latitude; A38.6.3.12 Stability criteria (see section S OURCE : Docket No. FAA–2000–8460, 67 FR A38.4.2.2.2 of this appendix); and 48003, July 22, 2002, unless otherwise noted.

A38.6.3.13 Description of the instruments and devices used to acquire the data needed § 39.1 Purpose of this regulation.

for the determination of SAR, and the indi- vidual accuracies of the equipment relevant The regulations in this part provide a to their effect on SAR (see sections A38.5.1.6 legal framework for FAA’s system of and A38.5.1.7 of this appendix).

Airworthiness Directives.

A38.6.4 Calculations and Corrections of SAR Test Data to Reference Specifications.

§ 39.3 Definition of airworthiness di- The measured SAR test data, all corrections rectives.

of the measured data to the reference speci- fications, and the SAR values calculated FAA’s airworthiness directives are from the corrected data must be provided for legally enforceable rules that apply to each of the test measurement points.

the following products: aircraft, air- A38.6.5 Calculated Values. The following craft engines, propellers, and appli- values must be provided for each airplane ances.

used to establish fuel efficiency certification in accordance with this part: A38.6.5.1 SAR (km/kg) for each reference § 39.5 When does FAA issue airworthi- airplane mass and the associated 90 percent ness directives?

confidence interval; FAA issues an airworthiness direc- A38.6.5.2 Average of the 1/SAR values; tive addressing a product when we find A38.6.5.3 RGF; and that: A38.6.5.4 Fuel efficiency metric value.

(a) An unsafe condition exists in the product; and

PART 39—AIRWORTHINESS

(b) The condition is likely to exist or

DIRECTIVES

develop in other products of the same type design.

Sec.

39.1 Purpose of this regulation.

§ 39.7 What is the legal effect of failing 39.3 Definition of airworthiness directives.

to comply with an airworthiness di- 39.5 When does FAA issue airworthiness di- rective?

rectives?

39.7 What is the legal effect of failing to Anyone who operates a product that comply with an airworthiness directive?

does not meet the requirements of an 39.9 What if I operate an aircraft or use a applicable airworthiness directive is in product that does not meet the require- ments of an airworthiness directive? violation of this section.