Piper Pitch Trim Service Manual

Tension ................................. Pendulous Sensor Unequal Elevator or Stabilator Cable Tension .‘ ...............................’ . Servicing Aids Typical Stabilator Holding Fixture PA-23-250, PA—24 and PA-3O Trim servo Cable Routing ......' . PA—23-250, PA—24 and PA—3O Pendulous Trim Sensor ......... PA—23-250, PA—24 and PA—3O Positioning and Alignment of Plate Type Trim Sensor ........................ PA-28 Trim Servo Cable Routing PA—28 and PA-32 Trim Servo Cable Routing .............. Plate Sensor with Amplifier Pendulous Sensor with Amplifier Electric Trim Stop Sensor Assembly Installation (PA-28481, PA-32R—300, PA—32RT-300 and PA-32RT-300T) - P. E. T. Trim Servo Clutch Adjustment ................. Switch Adjustment Cams ......................... PA—23-250, PA-24 and PA-30 P. E. T. -1 Manual Electric Trim Control Wheel Switch PA-23-250, PA—24 and PA—30 P. E. T. -1 Manual, P. E. T. -1 Automatic and P. E.T. -2 Automatic Electric Trim Control Wheel Switch PA-28 and PA-32 Manual Electric Trim Control Wheel Switch Electric Trim Stop Sensor Assembly 5-2 Test Equipment ’ 5-2 P. E. T. Series Pitch Trim Servo Motor Windings ............ 6-2 P. .-1 Manual Electric Trim Schematic ............... 6—2 P. .-1 Automatic Electric Trim Schematic . . . . .' ........ 6-3 P. P. .-2 Automatic Electric Trim Schematic ............. 6-4 .T.—1 Manual Electric Trim Schematic (Electric Trim Stip Sensor PA—28-181, PA-32R-300, PA-32RT-300 and PA-32RT-3OOT) ............................ P. E. T. -1 Manual Electric Trim Schematic ............... Plate Sensor Equal Elevator or Stabilator Cable Tension ....... Plate Sensor Unequal Elevator or Stabilator Cable Tension ...... Pendulous Sensor Equal Elevator or Stabilator Cable Tension . . . . Revised: 12/20/77 PIPER PITCH TRIM SERVICE MANUAL Figure 9-10. 9-11. 9-lla. 9-12. 9—13. 9-14. lO-l. 10-2. 10-3. 10-4. 10-5. 10-6. 10-7. 10—8. 10-9. 10-10. 10-11. lO—12. 10-13. 10-14. 10-15. 10—16. 11-1. 11-2. 12—1. 12—2. LIST OF ILLUSTRATIONS (cont.) Pendulous Sensor Unequal Elevator or Stabilator Cable Tension . Servicing Aids ............................... Typical Stabilator Holding Fixture ................... PA—23-250, PA-24, PA-30 and PA-39 Trim Servo Cable Routing PA-23-250, PA-24, PA-30, PA-31P, PA—34-200 and PA-39 Trim Sensor .......................... PA—3l Trim Servo Cable Routing .................... PA-3l and PA-31-350 Trim Servo Cable Routing ........... PA—3l and PA—31-350 Pendulous Trim Sensor ............. PA-31P Trim Servo Cable Routing .................... PA—31P Trim Servo Amplifier Replacement .............. PA-32 Trim Servo Cable Routing .................... Trim Servo Amplifier Replacement (lD345) .............. PA—23-250, PA-24, PA—30, PA—31, PA-31-350 PA—31P and PA—39 Trim Warning System ..................... Plate Sensor Without Amplifier ................ . . . . . Pendulous Sensor Without Amplifier .................. PA-34—200 Trim Servo Cable Routing .................. III Series Trim Servo Clutch Adjustment ................ Clutch and Clutch Solenoid Coil Adjusting Details .......... Switch Adjustment Cams ......................... PA-23-250, PA—24 and PA—30 AltiMatic II ............... PA-23-250 AltiMatic III .......................... PA—237250 AltiMatic III B ........................ PA—23-250, PA-24 and PA-3O AltiMatic III ............... PA-24 and PA-30 AltiMatic III ...................... PA—24, PA-3O and PA-39 AltiMatic IIIB ................ PA-32 AltiMatic III ............................. PA—31 AltiMatic IIIand AltiMatic IIIB (With Trim Relay) ...... PA—3l and PA-31P AltiMatic III B (Without Trim Delay) ....... PA—24—260 and PA—39 AltiMatic IIIB-l . . . . ............. PA—31 and PA—31P AltiMatic III B-l ................... PA—31-350 AltiMatic IIIB-l ...........- ............ PA-34-200 AltiMatic III B-l ....................... Test Equipment ........' .............‘ ......... Trim Servo Test Plug, Piper P/N 757 299 ................ III Series Automatic Pitch Trim Servo Motor ............. III Series Automatic Electric Trim Schematic AltiMatic II AutoPilot ................................ Page 8—6 9-1 9-2 9—9 9-9 9-10 9-10 9-17 9-17 9-19 9—19 9-20 9-26a 9—26b 9-26b 9-28 10-3 10-4 10—7 10—7 10-8 10-8 10-9 10-9 10-10 10-10 10—11 10-11 10-11a 10—1 1a 10-11b 10-11b 11-2 11-2 12-1 12-3 Revised: 2/28/73 PIPER PITCH TRIM SERVICE MANUAL LIST OF ILLUSTRATIONS (cont.) Figure ' Page 12-3. Ill Series Automatic Electric Trim Schematic (Without Trim Relay) AltiMatic III and III B AutoPilots . .7 ........... 12-4 12—4. _, III Series Automatic Electric Trim Schematic (With Trim Relay), PA—3l Serial Nos. 31-1 to 31-424 ............. 12-5 12-5. Ill Series Automatic Electric Trim Schematic AltiMatic III and III B AutoPilots ......................... 12-6 12-6. Ill Series Automatic Electric Trim Schematic AltiMatic IIIB-l AutoPilots ................. p .............. 12—7 12-7. III Series Automatic Electric Trim Schematic AltiMatic IIIB-l AutoPilots, PA-34—200 ........................ 12-8 12-8. Ill Series Automatic Electric Trim Schematic AltiMatic IIIB-l AutoPilots, PA-31-350 ........................ 12-9 15-1. Servicing Aids ............................... 15—2 15-2. PA-23-250, PA-24-260, PA-30 and PA—39 Trim Servo Cable Routing 15-3 15-3. PA-34-200 and PA-34-2OOT Trim Servo Cable Routing ........ ' 15-5 16-1. M. E. T. - 3 Trim Servo Clutch Adjustment ............... 16-2 16-2. Clutch Adjustment Detail ......................... 16-3 16-3. PA-23-250 M. E. T. - 3, Control Wheel Switch ............-. 16-4 16-4. PA-24-260, PA—30, PA—39 M. E. T. - 3, Control Wheel Switch . . . . 16-5 16-5. PA—34-200 and PA-34-200T M. E. T. - 3, Control Wheel Switch . . . 16-5 18-1. M. E. T. - 3 Series Pitch Trim Servo Motor ............... 18-1 18-2. M. E. T. - 3 Manual Electric Trim Schematic, PA-23-250, PA—24—260, PA-3O and PA-39 .................... 18-2 18-3. M. E. T. - 3 Manual Electric Trim Schematic, PA-34-200 and PA-34—200T . . _ ............................ 18-2 ‘20—1. Plate Sensor (Dual Contact) Equal Stabilator Cable Tension ..... 20—3 20—2. Plate Sensor (Dual Contact) Unequal Stabilator Cable Tension . . . 20—3 21—1. Servicing Aids .....' .......................... 21-1 _ 21-2. Typical Stabilator Holding Fixture . ................... 21-2 21-3. PA-23-250 Trim Servo Cable Routing .................. 21-5 21-4. PA-23-250 Dual Contact Type Trim Sensor .............. 21—6 21-5. Dual Contact Type Trim Sensor ..................... 21—8 22-1. III Series Trim Servo Clutch Adjustment ................ 22-2 22-2. Clutch Adjustment Detail ......................... 22-3 22—3. - PA-23-250 AltiMatic III B-l ....................... 22-4 23-1. Test Equipment .............................. 23-2 24—1. Ill Series Automatic Pitch Trim Servo Motor ............. 24—1 24-2. Ill Series Automatic Electric Trim Schematic (Dual Contact Type Trim Sensor) AltiMatic IIIB-l AutoPilots, PA-23-250 ...... 24—3 Revised: 6/3/75 PIPER PITCH TRIM SERVICE MANUAL LIST OF TABLES Table 11-1. Simplified Block Diagram P. E. T. Series Electric Pitch Trim Systems ....................... II—II. Identifying Features P. E. T. Series Electric Pitch Trim Systems .......................... III-I. Trim Servo Cable Tension .................. III-II. Trim Sensor Cable Tension .................. VIII-I. Simplified Block Diagram III Series Automatic Electric Pitch Trim System .................... VIII-II. Identifying Features III Series Automatic Electric Pitch Trim System ....................... IX—I. Trim Servo Cable Tension .................. IX—II. Trim Sensor Cable Tension .................. X-I. III Series Trim Servo Clutch Tension ............ XIV-I. Simplified Block Diagram M. E. T. Series Electric Pitch Trim System ...... XIV-II. Identifying Features M. E. T. Series Electric Pitch Trim System ...... XV-I. Trim Servo Cable Tension .................. XVI-I. M. E. T. Series Trim Servo Clutch Tension ......... XVII-I. Servo Continuity Test ..................... XXI-I. Trim Servo Cable Tension .................. XXI-II. Trim Sensor Cable Tension .................. XXII-I. III Series Trim Servo Clutch Tension ............ xii ...... 2-6 ...... 2—7 ...... 3-2 1 ...... 8—4 ...... 9—27 ...... 14-2 ...... 17—2 Issued: 8/25/72 PART I P.E.T. [PIPER ELECTRIC TRIM] ' SYSTEMS Issued: 8/25/72 Na} PIPER PITCH TRIM SERVICE MANUAL Paragraph 1-1. 1-2. Issued: 8/25/72 SECTION I INTRODUCTION AND DESCRIPTION Page Introduction . Description . |—1|—1 T . -,T 14 . 1 r/ r. H‘K‘ifly/ PIPER PITCH TRIM SERVICE MANUAL SECTION I INTRODUCTION A ND DESCRIPTION 1-1. INTRODUCTION. This part of the service manual is divided into six sec- tions. SectionI contains a description of the P. E. T.-1 and P. E. T. -2 Elec— tric Trim Systems . P. E. T. is the abbreviation for Piper Electric Trim which is designed and manufactured at Piper Aircraft Corporation, Vero Beach, Florida. Section II, Theory of Operation, explains the modes of operation. SectionIII, Removal and Installation, provides the information necessary for removal and installation of all trim components . Section IV, Adjustment Procedures and Op- erational Checks, provides the information necessary to check the operationof the system and perform minor adjustments. Section V, Test Equipment, pro- vides the equipment requiredto center the trim sensor. Section VI, Schematics, provides the schematics of the trim systems for troubleshooting purposes . l—2. DESCRIPTION. There are two types of Electric Pitch Trim Systems used to trim the pitch axis of the airplane electrically, manual and automatic. The P. E. T. systems discussed inSectionI are: P. E. T.-l Manual, P. E. T.-l Automatic and P. E. T.-2 Automatic Pitch Trim Systems. The operation of these systems will be explained in Section II. When servicing the Piper Electric Pitch Trim Systems, the serviceman must determine which system is installed in the airplane being serviced to determine the service procedures to be used. The following description of each system will assist the servicemanin determin— ing which system is installed in a particular airplane. a. P. E. T.-1 MANUAL ELECTRIC PITCH TRIM SYSTEM. The P. E. T.-1 Manual Trim System is available for use anytime an AltiMatic AutoPilot is not installed. b. P. E. T.—l AUTOMATIC ELECTRIC PITCH TRIM SYSTEM. (Push button system .) The P. E. T.-l Automatic Trim System is the only Piper Electric Trim System which employs a push button on the control wheel. This Pitch Trim Sys- tem has a manual mode and an automatic mode of operation and incorporates the use of a pitch servo selector switch to determine which mode of trim operation 1s m use. INTRODUCTION AND DESCRIPTION l—l Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL c. P. E. T.-2 AUTOMATIC ELECTRIC PITCH TRIM SYSTEM. The P. E.T. -2 Automatic Trim System has a manual mode and an automatic mode of opera- tion and incorporates the use of a pitch servo selector switchto determine which mode of trim operation is in use. The P. E. T.-2 Trim servo has the addition of a relay to incorporate the use of a toggle switch in place of the pushbutton switch. NOTE A simplified block diagram in Table 11-1 and an iden- tifying features diagram in Table 11-11 is presented in Section II of this manual. These diagrams illustrate the basic components and features of the P. E. T.-l Manual, P. E. T.-1 Automatic and the P. E. T.-2 Automatic Electric Pitch Trim Systems. I—.2 INTRODUCTION AND DESCRIPTION Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL SECTION II THEORY OF OPERATION Paragraph Description . P. E. T. -1 Manual Electric Trim system P. E. T. —1 Automatic Electric Trim System P. E. T.-,2 Automatic Electric Trim System 2— 2- 2- 2- Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL SECTION II THEORY OF OPERATION 2—1 . DESCRIPTION. P. E. T. is an abbreviation for Piper Electric Trim which is designed and manufacturedat Piper Aircraft Corporation, Vero Beach, Florida. The types of'P. E. T. Electric Pitch Trim Systems installed in Piper airplanes are: P. E. T.-l Manual, P. E. T.—1 Automatic and P. E. T.—2 Automatic. The operation of each system is explained inthe following paragraphs. All Automat— ic Electric Pitch Trim Systems have a manual mode and an automatic mode of operation. The manual mode of all Automatic Electric Pitch Systems is opera- tional only when the pitch axis of the AutoPilot is disengaged and the automatic mode of all Automatic Electric Pitch Trim Systems is operational when the pitch axis of the AutoPilot is engaged. Engaging the pitch axis of the AutoPilot, switches the pitch trim system from the manual mode to the automatic mode while disen- gaging the pitch portion of the AutoPilot switches the pitch trim system from the automatic mode to the manual mode. The micro switch that controls the mode of trim operation is located on the Pitch AutoPilot Servo as shown in illustration form, (Refer to Figure 2—1 and 2-2) . Simplified block diagrams of the P. E. T. pitch trim systems are shown in Table 11—1. A differential cable tension sensing mechanism known as a Trim Sensor is incorporated in the various Automatic Electric Pitch Trim Systems installed in Piper airplanes. There are two types of trim sensors installed in Piper air— planes, plate type and pendulous type. The trim sensor consists of a set of ad— justable electrical contacts which, when actuated by unequal elevator or Stabila— tor cable tension, completes an electrical circuit in the trim amplifier, The trim amplifier converts the trim sensor signals into electrical power sufficient to drive the DC trim servo motor in the proper direction to correct an out of trim condition. The centering adjustment of the trim sensor contacts is of prime importance since the operation of the P. E. T. -1 Automatic Electric Pitch Trim System and the automatic mode of the P. E, T. -2 Automatic Electric Pitch Trim System is dependent on the centering adjustment of the trim sensor. The reac— tion of the sensor contacts to both equal and unequal elevator or Stabilator con— trol cable tension is shown in illustration form, see Figure 2—3 thru 2-6. A de— tailed procedure on trim sensor centering is contained in Section III, paragraph 3—22, Stabilator or elevator control cable tension is very important for the cor- rect operation of the trim sensor. Low cable tension can cause insensitive trim THEORY OF OPERATION 2-l Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL sensor action and high cable tension can cause oversensitive trim sensor action. A substantial decrease in temperature can cause a decrease in cable tension, while a substantial increase in temperature can cause an increase in cable ten— sion. This is caused by the unequal coefficient of expansion between the alumi- num in the airplane structure and the steel control cables. It is recommended that temperature be consideredwhen adjusting or checking controlcable tension, to insure that the control cable tension will remain within the tolerance specifi— cation published in the appropriate Airframe Service Manual. The high portion of the control cable tension specification should be used when checking or setting the control cable tension during extremely high temperatures. The low portion of the control cable tension specification should be usedwhen checking or setting the control cable tension during extremely low temperatures. This procedure will insure that the control cable tension will remain within the control cable tension specification for temperature variations. 2-2. P. E. T. —l MANUAL ELECTRIC TRIM SYSTEM. The P. E. T. -1 Manual Electric Pitch Trim System is available for use anytime an AltiMatic AutoPilot is not installed, as shown in Table 11—1. Trim is accomplished by the pilot ac- tuating the trim switch on the control wheel which is a three position switch, spring loaded to the center or OFF position. When the trim switch is moved to the forward position, it completes a circuit to the servo motor, supplying voltage to the proper field winding to assure rotation of the motor in the correct direc - tion. At the same time, the trim switch supplies electrical power to the clutch solenoid which engages the servo motor- to the capstan through the clutch in the trim servo. Since the trim system cables are wrapped around the capstan, any rotation of the trim servo motor results in a change of position of the airplane's trim system, thus deflecting the Stabilator or elevator trim tab in the conven— tional manner. When the human pilot releases the switch, it returns to the OFF position and electrical power is then disconnected from the trim servo motor and the clutch solenoid which completely disengages the electric pitch trim servo motor from the airplane's trim system cables. If the switch is moved to the rear position, the same events occur except the voltage is applied to the oppo- site field winding, insuring the opposite direction of rotation. 2—3. P. E. T.-l AUTOMATIC ELECTRIC TRIM SYSTEM. This system has a manual mode and an automatic mode of operation and is the only Piper Electric Pitch Trim System which employs a push button on the control wheel. The P. E. T.—l Automatic Electric Pitch Trim System incorporates the use of a pitch servo selector switch to determine which mode of trim operation is in use. In the AltiMatic IIAutoPilot, the servo selector switch is located on the Auto— 2—2 THEORY OF OPERATION Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL Pilot pitch servo as shown in Figure 2-1 and 2-2 . This system has a trim sensor with an amplifier attached, which operates the trim servo motor . The trim sen- sor and amplifier are operational when the push button is depressed in the man- ual mode and when the pitch axis of the AutoPilot is engaged . The difference be— tween the automatic mode and the manual mode, is that in the manual mode, the pilot must depress the push button switch to allow the trim sensor and amplifier to correct an out of trim condition. a. P. E. T.-1 AUTOMATIC ELECTRIC TRIM SYSTEM—MANUAL MODE. This mode applies to the trim system when the pitch axis of the AutoPilot is dis- engaged. Pitch trim can be accomplished electrically by the use of the push but— ton on the pilot's control wheel. When the push button is depressed, the clutch solenoid is engaged and electrical power is applied to the trim amplifier. If at this time the "Trim Sensor" detects a differential in stabilator or elevator cable tension causedby an out of trim condition, the trim sensor mechanically actuates a set of electrical contacts. These contacts complete an electrical circuit in the trim amplifier which converts the trim sensor signals into electrical power suf- ficient to drive the DC trim servo motor . Due to the fact that the airplane's trim system cables are wrapped around the capstan, any rotation of the trim servo motor results in a change of position of the airplane's trim system, retrimming the control surface trim tab in the conventional manner. Repositioning of the control surface trim tab is reflected back to the trim sensor through the stabila- tor or elevator control cables. The trim sensor, sensing that the stabilator or elevator control cable tension is equal, signals the trim amplifier to shut off power to the trim servo motor. After establishing any pitch attitude, the pilot can depress the push button and the electric trim will relieve the control pres- sure. b. P. E. T.-l AUTOMATIC ELECTRIC TRIM SYSTEM—AUTOMATIC MODE. When the pitch axis of the AutoPilot is engaged, the push button on the pilot's control wheel is inoperative and electrical power is applied to the trim amplifier pitch trim servo clutch solenoid by the servo selector switch. When the trim sensor detects a differential in stabilator or elevator cable tension caused by an out of trim condition, the trim sensor actuatesa set of electrical contacts. These contacts complete an electrical circuit in the trim amplifier which converts the trim sensor signals into electrical power sufficient to drive the DC trim servo motor. NOTE The clutch solenoid will maintain engagement of the servo motor and capstan gears continuously while the pitch axis of the AutoPilot is engaged. THEORY OF OPERATION ' 2-3 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL Due to the fact that the airplane's trim system cables are wrapped around the capstan, any rotation of the trim servo motor results in a change of position of the airplane's trim system retrimming the control surface trim tab in the conventional manner. Repositioning of the control surface trim tab is reflected back to the trim sensor through the stabilator or elevator control cables. The trim sensor, sensing that the stabilator or elevator control cable tension is e— qual, signals the trim amplifier to shut off power to the trim servo motor. This trim condition remains constant until some new load appears on the stabilator or elevator through normal flight conditions, at which time the automatic trim operation is repeated. 2-4. P.E.T.—2 AUTOMATIC ELECTRIC TRIM SYSTEM. This pitch trim system has a manual mode and an automatic mode of operation. The P.E.T.—2 Automatic Pitch Trim System incorporates the use of a pitch servo selector switch to determine which mode of trim operation is in use. In the AltiMatic IIAutoPilot, the servo selector switch is located on the AutoPilot pitch servo as shOWn in Figures 2-1and 2—2. In the manual mode, pitch trim is accomplished by the pilot actuating the trim switch on the control wheel which is a three position switch, spring-loaded to the center or OFF position. In the automatic mode, the trim switch is inoperative and electric power is supplied to the trim amplifier by the servo selector switch on the AutoPilot Pitch servo. The trim amplifier and trim sensor utilized in the automatic mode only. Both modes are explained _in the following paragraphs. , a. P.E.T. —2 AUTOMATIC ELECTRIC TRIM SYSTEM — MANUAL MODE. This mode applies to the Trim Systems when the pitch axis of the AutoPilot is disengaged. Pitch trim must be accomplished by the human pilot, either by the use of the manual trim crank, wheel or electrically by the use of the trim switch on the pilot's control wheel which is a three position switch, spring-loaded to the center or OFF position. When the trim switch is moved to the forward position, it completes a circuit to the servo motor, supplying voltage to the proper field winding to assure rotation of the motor in the correct direction. At the same time, the switch supplies electrical power to the clutch solenoid, which engages the motor to the capstan through the clutch on the trim servo. Since the trim system cables are wrapped around the capstan, any rotation of the trim servo motor results in a change of position of the airplane's trim system, thus deflect- ing the stabilator or elevator trim tab in the conventional manner. When the hu- man pilot releases the switch, it returns to the OFF position and power is then disconnected from the trim servo motor and the clutch solenoid which completely disengages the Electric PitchTrim Servo Motor from the airplane's trim system cables. If the switch is moved to the rear position, the same events occur ex— THEORY OF OPERATION Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL cept voltage is applied to the opposite field winding, insuring the opposite direc— tion of rotation. b. P.E.T.—2 AUTOMATIC ELECTRIC TRIM SYSTEM—AUTOMATIC MODE . When the pitch axis of the AutoPilot is engaged, the switch on the pilot's control wheel is inoperative and electrical power is applied to the trim amplifier and pitch trim servo clutch solenoid by the servo selector switch. When the trim sensor detects a differential in stabilator or elevator cable tension caused by an out of trim condition, the trim sensor mechanically actuates a set of electrical contacts. These contacts complete an electrical circuit in the trim amplifier which converts the trim sensor signals into electrical power sufficient to drive the DC trim servo motor. NOTE The clutch solenoid will maintain engagement of the servo motor and capstan gears continuously while the pitch axis of the AutoPilot is engaged. Due to the fact that the airplane's trim system cables are wrapped around the capstan, any rotation of the trim servo motor results in a change of position of the airplane's trim system, retrimming the control surface trim tab in the conventional manner. Repositioning of the control surface trim tab is reflected back to the trim sensor through the stabilator or elevator control cables . The trim sensor, sensing that the stabilator or elevator controlcable tension is equal, signals the trim amplifier to shut off power to the trim servo motor. The trim- med condition remains constant until some new load appears on the stabilator or elevator through normal flight conditions, at which time the automatic trim op- eration is repeated . THEORY OF OPERATION 2—5 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL TABLE II-I. SIMPLIFIED BLOCK DIAGRAM P.E.T. SERIES ELECTRIC PITCH TRIM SYSTEMS MANUAL ' AUTOMATIC P.E.T.—I P-E-T-—l PITCH SERVO A, o PITCH SELECTOR SWITCH __o_ TRIM 0 SERVO A+ 5,1} o-fi TOGGLE SWITCH PUSH BUTTON TRIM SENSOR AND AMPLIFIER PITCH TRIM SERVO PITCHSERVO SELECTOR SWITCH _A_+ o TRIM SENSOR _A_+ o 0 AND AMPLIFIER TOGGLE SWITCH PITCH TRIM SERVO /’ 2-6 THEORY OF OPERATION Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL TABLE II-II. IDENTIFYING FEATURES P.E.T. SERIES ELECTRIC PITCH TRIM SYSTEMS MANUAL AUTOMATIC P.E.T. - l VERO BEACH DESIGN TOGGLE SWITCH ON CONTROL WHEEL NO RELAY IN TRIM SERVO NO TRIM SENSOR CENTER TAPPED MOTOR LARGE DISK ON CAPSTAN NOT USED WITH ALTIMATIC AUTOPILOT P.E.T. - l VERO BEACH DESIGN PUSH BUTTON SWITCH ON CONTROL WHEEL TRIM SENSOR AMPLIFIER ON TRIM SENSOR NO RELAY IN TRIM SERVO CENTER TAPPED MOTOR LARGE DISK ON CAPSTAN TRIM SENSOR AND AMPLIFIER USED 100% OF THE TIME WHETHER USED IN MANUAL MODE OR AUTOMATIC MODE P.E.T. - 2 VERO BEACH DESIGN TOGGLE SWITCH ON CONTROL WHEEL TRIM SENSOR AMPLIFIER ON TRIM SENSOR RELAY IN TRIM SERVO CENTER TAPPED MOTOR LARGE DISK ON CAPSTAN TRIM SENSOR AND AMPLIFIER USED IN AUTOMATIC MODE ONLY THEORY OF OPERATION Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL NOTE: INSTALLED ON LATE PRODUCTION 5ERV05,SERVOS EXCHANGED THROUGH THE PIPER EXCHANGE PROGRAM AND SERVOS THAT HAVE HAD SWITCH KIT 756 569 INSTALLED IN THE FIELD. SELECTOR SWITCH SE LECTOR ' SWITCH may“ 2-8 Figure 2-2. Servo Selector Switch Rack and Pinion Pitch Servo THEORY OF OPERATION . Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL I II I: {I AMPLIFIER I /, I1:Q\ // \ . I ”(PM (E a \\"'_,/f, VDT—flO II ‘I III \\ 9) I \ (L ”4:2, A O a l/ \‘.l I > I ©]2 \ II: _ 5?"r L @ ‘ ECCENTRIC NUT \ I':\ //\ if \\ ‘i I II ‘I ‘QH IIS;¢/’ Figure 2-3. ECCENTRIC NUT Figure 2—4. Plate Sensor Un-Equal Elevator or Stabilator Cable Tension THEORY OF OPERATION 2—9 Issued: 8/25/72 ' PIPER PITCH TRIM SERVICE MANUAL 5 AMPLIFIER \- ADJUSTING SCREWS . Figure 2-5. Pendulous Sensor Equal Elevator or Stabilator Cable Tension AMPLIFIER ADJUSTING SCR EWS Figure 2—6. Pendulous Sensor Un—Equal Elevator or Stabilator Cable Tension 2—10 THEORY OF OPERATION Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL Paragraph 3—8. 3-9. 3-10. 3—11. 3-12. 3-13. 3-14. 3-15. 3-16. 3—17. 3-I8. 3-19. 3—20. 3-21. Issued: 8/25/72 SECTION III REMOVAL AND INSTALLATION Introduction. Removal of Trim Servo - .PA-23-250 Installation of Trim Servo - PA-23-250 Removal of Pendulous Trim Sensor and Amplifier PA-23-250 . . . . . Installation of Pendulous Trim Sensor and Amplifier - PA-23-250 . . . Removal of Plate Type Trim Sensor and Amplifier PA-23-250 - - - - - Installation of Plate Type Trim Sensor and Amplifier — PA-23-250 - - Removal of Trim Amplifier— Plate Type Trim Sensor - PA—23-250- - - - Installation of Trim Amplifier— Plate TypeTrim Sensor - PA-23-250 - -Removal of Trim Servo - PA-24 andPA-30- Installation of Trim Servo - PA-24 and PA-30 - Removal of Pendulous Trim Sensor and Amplifier PA-24 and PA-30- - - - - Installation Of Pendulous Trim Sensor and Amplifier - PA-24 and PA— 30 - - Removal of Plate Type Trim Sensor and Amplifier PA—24andPA--30- . . .. Installation of Plate Type Trim Sensor and Amplifier - PA-24 and PA-30 - - - Removal of Trim Amplifier— Plate Type Trim Sensor - PA-24 and PA-30 . Installation of Trim Amplifier— Plate Type Trim Sensor - PA-24 and PA-30 Removal of Trim Servo - PA-28 - Installation of Trim Servo - PA-28 - Removal _of Trim Servo - PA-32 - Installation of Trim Servo - PA-32 - PIPER PITCH TRIM SERVICE MANUAL 3-22. ']1im Sensor Centering Procedures and Trim Amplifier Delay Circuit Check in P. E._'_I‘. 11 and P.E.T. -2 Systems ................... 3-15 3-23. Removal of Electric Trim Stop Sensor Assembly PA-28—181, PA-32R-300, PA-32RT-300 and PA-32RT-300T 3-24. Installation of ElectricTrim Stop Sensor Assembly PA-28-181, PA-32R-300, PA-32RT-300 and PA-32RT-3OOT Revised: 12/20/77 PIPER PITCH TRIM SERVICE MANUAL NOTE: USED ONLY AS SERVEE AID USED ONLY AS SERVICE AID Methods of Blocking Trim Cables SCHEMATIC\ SPDT TOGGLE SWITCH Substitute Servo Selector Switch Figure 3—1. Servicing Aids REMOVAL AND INSTALLATION 3—1 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL WELD _STEEL TUBE TELESCOPES TO BOTTOM OF STAND //_8x 1 2 BOLT 1/4 X 2 / 3/4 x 2’ x 8’ FOAM RUBBER CEMENTED To ' 1/8” x 2" x 8” COLD ROLLED STEEL 1/4 x 28 HEX NUT (WELD TO STAND) A 3/4 X 24” STEEL TUBE WELD WINGS TO BOLT / BRACE APPROXIMATELY 12" (SPACED 120°) 3/4" STEEL PLATE. 18” D Figure 3-2. Typical Stabilator Holding Fixture 3—2 _ REMOVAL AND INSTALLATION Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL SECTION III REMOVAL A ND INSTALLATION 3-1. INTRODUCTION. The informationin this section describes the procedures for removal and installation of the components of the P. E. T. Electric Pitch Trim Systems used in Piper airplanes. Included with the installation procedures are the necessary set-up and adjustment instructions. When any component of the trim system is installed, a complete functional check of the entire trim sys- tem must be made to confirm correct system operation. When using this sec- tion, refer to the type of component to be removed and installed. Refer to Para- graph 3-22 for Trim Sensor Centering Procedures and the Trim Amplifier Delay Circuit Check. To maintain cable routing of the trim cable during removal and installation of trim servos, it is recommended that the service aids shown in Figure 3-1 be utilized. Service aids as shown can be fabricated locally from shop material. The substitute Servo Selector Switch shown in Figure 3-1 can be fabricated from shop material. If in doubt about the operation of the Servo Se- lector Switch, the locally‘fabricated Servo Selector Switch may be substituted by connecting it to the trim cable CD-40 plug which is connected to the AutoPilot pitch servo . 3-2. REMOVAL OF TRIM SERVO. (PA-23-250.) The trim servo is located in the top aft baggage compartment. a. Access to the servo is through the aft baggage compartment door. b. Remove the box type trim panel forward of the baggage compartment dome light by removing six attaching screws . c . Remove the baggage area rear panel to gain access to the cable turnbuckles to release the tension on the cables . d. Disconnect all electrical connections from the servo assembly. e . Remove four mounting bolts securing the servo assembly to the mounting brackets. f . Unwrap trim cable from capstan and idler pulley and remove servo assem- bly from the airplane. REMOVAL AND INSTALLATION 3-3 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL 3-3. INSTALLATION OF TRIM SERVO. (PA-23—250.) (Refer to Figure 3-3.) a. Position trim servo on the mounting brackets and secure with mounting bolts . b. Route the trim cable from the forward part of the airplane around the top capstan groove, to the idler pulley and around the bottom capstan groove to the aft section of the airplane, completing a figure eight. c . Tighten the trim cable to obtain appropriate tension as listedin Table III-I. d. Connect all electrical connections to trim servo assembly and check servo operation. e. Install baggage area rear panel and secure with attaching screws . f .' Install box type trim panel forward of baggage compartment dome light and secure with attaching screws . 3-4. REMOVALOF PENDULOUS TRIM SENSOR AND AMPLIFIER .(PA-23-250 . ) The trim sensor is located on a mounting bracket under the main spar of the airplane . NOTE If the trim amplifier on the pendulous trim sensor fails, a plate type trim sensor and trim amplifier will be provided as a replacement. a . Remove the bottom fuselage panel aft of the nose gear doors by removing screws securing panel. b. The cables on trim sensor can be removed by applying pressure to both cables and moving the cables out of trim sensor pulley grooves . If desired the stabilator control cable may be loosened to facilitate removing from the trim sensor. c. Disconnect the CD-41 electrical connection. d. Remove the screws securing the trim sensor to the mounting bracket. e. Remove the trim sensor from the airplane. 3-5. INSTALLATION OF PENDULOUS TRIM SENSOR AND AMPLIFIER. (PA- 23-250.) (Refer to Figure 3-4 .) a. With sensor pulleys facing down, position the trim sensor on the mounting bracket, align the trim sensor so the pulleys are parallel and centered over the stabilator control cables and install the appropriate mounting screws . b. Place the stabilator control cables in the top groove of the appropriate trim sensor pulleys . 3-4 REMOVAL AND INSTALLATION Issued: 8/25/72 PIPER PITCH TRlM SERVICE MANUAL 0. Check stabilator controlcables for proper tension as listed inTable III-II. NOTE The stabilator control cables are routed over the trim sensor pulleys . The pulleys on the trim sensor must have horizontal movement from their normal position when the trim sensor is correctly aligned with the sta- _ bilator control cables . d. Refer to Paragraph 3-22 for trim sensor centering instructions. e. Connect the CD-41 electrical connection and perform the ground opera- tional check of the pitch trim system as outlined in Section IV, Paragraph 4-6. f . Install bottom fuselage panel previously removed and secure with the ap- propriate screws . 3-6. REMOVAL OF PLATE TYPE TRIM SENSOR AND AMPLIFIER. (PA-23- 250.) The trim sensor is located on a mounting bracket under the main spar of the airplane . I NOTE If the trim amplifier onthe plate type trim sensor fails, the amplifier can be replaced without removing the trim sensor or affecting the trim sensor centering ad- justment. a. Remove the bottom fuselage panel aft of the nose gear doors by removing screws securing panel. b. The cables on trim sensor can be removed by applying pressure to both cables and moVing the cables out of the trim sensor pulley grooves. If desired the stabilator control cable may be loosened to facilitate removing from the trim sensor. c. Disconnect the CD-41 electrical connection. d. Loosen nut under trim sensor plate at rear mounting screw and remove rear mounting screw, washer, and nut from the trim sensor. e. Remove the screws securing the trim sensor to mounting bracket. f. Remove the trim sensor from the airplane. REMOVAL AND INSTALLATION 3-5 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL .3-7. INSTALLATION OF PLATE TYPE TRIM SENSOR AND AMPLIFIER. (PA— 23-250.) (Refer to Figure 3—5.) a. With the trim sensor pulleys facing down, route the stabilator control ca— bles through the trim sensor pulleys. The trim sensor will center itself on the stabilator control cables. b. Position the trim sensor on the forward mounting bracket and secure with appropriate screws. 0. Install screw, washer and nut in rear mounting hole. (1. Adjust mounting screw and nut as required to align the trim sensor par- allel with the stabilator control cables. e. Check stabilator control cables for proper tension as listed in Table III—II. NOTE The outboard pulleys on the trim sensor must have freedom of rotation and vertical movement from their normal position when the trim sensor is properly aligned with the stabilator control cables. f. Refer to Paragraph 3—22 for trim sensor centering instructions. g. Connect the CD-4l electrical connection and perform the ground opera- tional check of the pitch trim system as outlined in Section IV, Paragraph 4-6. h. Install bottom fuselage panel previously removed and secure with the appropriate screws. 3-8. REMOVAL OF TRIM AMPLIFIER—PLATE TYPE TRIM SENSOR. (PA-23- 250.) The trim amplifier is located on the trim sensor mounting plate under the main spar of the airplane. a. Remove the bottom fuselage panel aft of the nose gear doors by removing screws securing panel. b. Disconnect the CD-4l and CD-52 electrical connections. c. Disconnect the end of the braided lead going from the trim sensor linkage bar to a terminal on the side of the amplifier by removing the retaining nut on the amplifier terminal. (1. Remove the mounting screws from either end of the amplifier and remove the amplifier from the trim sensor mounting plate. 3—9. INSTALLATION OF TRIM AMPLIFIER—PLATE TYPE TRIM SENSOR. (PA-23—250.) (Refer to Figure 3-5.) 3-6 REMOVAL AND INSTALLATION . Issued: 8/25 72 flirty I. PIPER PITCH TRIM SERVICE MANUAL IDLER PULLEY T— AFT FWD // AMPLIFIER ADJUSTING SCREWS Figure 3—3. PA-23-250, PA—24 and PA-30 Trim Servo Cable Routing Figure 3—4. PA—23-250, PA—24 and PA-30 Pendulous Trim Sensor REMOVAL AND INSTALLATION Issued: 8/25/72 3—7 PIPER PITCH TRIM SERVICE MANUAL | |\ L, ‘I‘ \1\\ rl", “ T, II I: a I I I: II,- II‘ I l’.\|‘ nfi'IIIflT TRIM SENSOR MJST BE CENTERED ON CABLES AND MJST BE FORE AND AFT PARALLEL TO CABLES TOP VIEW TRIM SENSOR WST BE LATERALLY PARALLEL TO CABLES TRIM SENSOR MJST BE LONGITUDINALLY PARALLEL TO CABLES Figure 3-5. PA—23-250, PA-24 and PA-30 Positioning and Alignment of Plate Type Trim Sensor IDLER SPRING IDLER PULLEY FWD II NOT ON EAR LY PRODUCTION CHEROKEE AIR PLANES PIVOT POINT AFT P.E.T. SERVO WITH SPRING ON IDLER PULLEY 3-8 Figure 3-6. PA—28 Trim Servo Cable Routing REMOVAL AND INSTALLATION Issued: 8/25/72 “swam” ' PIPER PITCH TRIM SERVICE MANUAL a a. Position the trim amplifier on the trim sensor mounting plate and secure with appropriate screws . b. Connect the braided lead to the amplifier terminal and secure with re- taining nut. c. Connect the CD-4l and CD—52 electrical connections and perform the ground operational check of the pitch trim system as outlined in SeCtion IV, Para— graph 4-6. . d. Install bottom fuselage panel previously removed and secure with appro— priate screws. ‘ 3-10. REMOVAL OF TRIM SERVO. (PA-2,4 and PA-30.) The trim servo is lo- cated aft of the baggage compartment on the upper fuselage. NOTE When servicing six-place airplanes, the 5th and 6th seats must be removedbefore proceeding with the fol- lowing instructions. a. Access to the servo is through the baggage compartment door. b. Remove attaching screws from left rear window trimstrip and remove trimstrip . c. Remove attaching screws from the hat shelf panel and remove panel by pushing right side of panel aft to force left side of panel forward to free panel from right rear window trimstrip . (1. Remove attaching screws from rear baggage area panels and remove pan- els to gain access to turnbuckle to release cable tension. e. Disconnect electrical connections. f . Remove four mounting bolts from trim servo assembly mounting bracket. g. Unwrap trim cable from the capstan and idler pulley and remove servo assembly from the airplane . 3-11 . INSTALLATION OF TRIM SERVO. (PA—24 and PA-30.) (Refer to Figure 3-3 .) a. Position trim servo on mounting bracket and secure with mounting bolts. b. Route the trim cable from the forward part of the airplane around the top capstan groove, to the idler pulley and around the bottom capstan groove to the aft section of the airplane, completing a figure eight. c. Tighten the trim cable to obtain appropriate tension as listed in Table III-I. REMOVAL AND INSTALLATION 3-9 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL (1. Connect all electrical connections to trim servo assembly and check ser— vo operation. e. Install rear baggage area panels and secure with attaching screws. f . Install hat shelf panel and left rear window trimstrip and secure with at- taching screws . 3-12 . REMOVAL OF PENDULOUS TRIM SENSOR AND AMPLIFIER . (PA-24 and PA -30 .) NOTE When servicing standard airplanes, the sensor is be- neaththe forward access footwell panel of the left rear seat. On the six-place airplanes the sensor is beneath the forward access footwell panel of the center left seat. In either case, appropriate seat must be re- moved to gain access to sensor . NOTE If the trim amplifier on the pendulous trim sensor fails, a plate type trim sensor and trim amplifier will be provided as a replacement. a. Remove carpet from footwell. b. Remove forward access panel of footwell by removing attaching screws. c. The cables on trim sensor can be removed by applying pressure to both cables and moving the cables out of trim sensor pulley grooves. If desired the stabilator control cable may be loosened to facilitate removing from the trim sensor. (1. Disconnect the CD-41 electrical connection. e. Remove the screws securing the trim sensor to the mounting bracket. f . Remove the trim sensor from the airplane. 3-13. INSTALLATION OF PENDULOUS TRIM SENSOR AND AMPLIFIER. (PA- 24 and PA—30.) (Refer to Figure 3-4.) a. With sensor pulleys facing down, position the trim sensor on the mounting bracket. Align the trim sensor so the pulleys are parallel and centered over the stabilator control cables and install the appropriate mounting screws. 3-10 REMOVAL AND INSTALLATION Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL b. Place the stabilator control cables inthe top groove of the appropriate trim sensor pulleys. c . Check stabilator control cables for proper tension as listedin Table III-II. NOTE The stabilator control cables are routed over the trim sensor pulleys. The pulleys on the trim sensor must have horizontal movement from their normal position .whenthe trim sensor is correctly aligned with the sta- bilator control cables . (1. Refer to Paragraph 3-22 for trim sensor centering instructions . e. Connect the CD-4l electrical connection and perform the ground opera- tional check of the pitch trim system as outlined in Section IV, Paragraph 4-6. I. Install forward footwell access panel and secure with attaching screws. g. Install footwell carpet and appropriate seat previously removed. 3-14. REMOVAL OF PLATE TYPE TRIM SENSOR ANDAMPLIFIER .(PA-24 and PA-30 .) ' NOTE When servicing standard airplanes, the sensor is be- neath the forward access footwell panel of the leftrear seat. On the six-place airplanes the sensor is be- neath the forward access footwell panel of the center left seat. In either case, appropriate seat must be removed to gain access to sensor. NOTE If the trim amplifier on the plate type trim Sensor fails, the amplifier can be replaced without removing the trim sensor or affecting the trim sensor centering adjustment. a. Remove carpet from footwell. b. Remove forward access panel of footwell by removing attaching screws. c. The cables on trim sensor can be removed by applying pressure to both cables and moving the cables out of the trim sensor pulley grooves. If desired REMOVAL AND INSTALLATION 3-11 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL the stabilator control cable may be loosened to facilitate removing from the trim flsensor. (1. Disconnect the CD—4l electrical connection. e. Loosen nut under trim sensor plate at rear mounting screw and remove rear mounting screw, washer and nut from the trim sensor. f. Remove the screws securing the trim sensor to mounting bracket. g. Remove the trim sensor from the airplane. 3--15. INSTALLATION OF PLATE TYPE TRIM SENSOR AND AMPLIFIER. (PA— 24 and PA~30.) (Refer to Figure 3—-.5 ) a. With the trim sensor pulleys facing down, route the stabilatOr control ca- bles through the trim sensor pulleys. The trim sensor will center itself on the stabilator control cables. b. Position the trim sensor on the forward mounting bracket and secure with appr0priate screws. c. Install screw, washer and nut in rear mounting hole. (1. Adjust mounting screw and nut as required to align the trim sensor par- allel with the stabilator control cables. e. Check stabilator control cables for proper tension as listed in Table III—II. NOTE The outboard pulleys on the trim sensor must have freedom of rotation andvertical movement from their normal position when the trim sensor is prOperly aligned with the stabilator control cables. f. Refer to Paragraph 3—22 for trim sensor centering instructions. g. Connect the CD—4l electrical connection and perform the ground opera- tional check of the pitch trim system as outlined in Section IV, Paragraph 4-6. h. Install forward footwell access panel and secure with attaching screws. i. InStall footwell carpet and appropriate seat previously removed. 3-16. REMOVAL OF TRIM AMPLIFIER—PLATE TYPE TRIM SENSOR. (PA— 24 and PA—30.) The trim amplifier is located on the trim sensor mounting plate. 3 —12 REMOVAL AND INSTALLATION Issued: 8/25/72 II c , p" . . L. W PIPER PITCH TRIM SERVICE MANUAL NOTE When servicing standard airplanes, the sensor is be- neath the forward access footwell panel of the left rear seat. On the six-place airplanes the sensor is be- neath the forward access footwell panel of the center left seat. In either case, appropriate seat must be removed to gain access to the sensor. Remove carpet from footwell . Remove forward access panel of footwell by removing attaching screws. Disconnect the CD-41 and CD-52 electrical connections. Disconnect the end of the braided lead going from the trim sensor linkage barto a terminal on the side of the amplifier by removing the retaining nut on the amplifier terminal. e. Remove the mounting screws from either end of the amplifier and remove the amplifier from the trim sensor mounting plate. Q-OO‘ID 3-17. INSTALLATION OF TRIM AMPLIFIER—PLATE TYPE TRIM SENSOR. (PA-24 and PA-30.) (Refer to Figure 3-5.) a . Position the trim amplifier on the trim sensor mounting plate and secure with appropriate screws. b. Connect the braided lead to the amplifier terminaland secure with retain- ing nut. c . Connect the CD-41and CD-52 electrical connections and perform the ground operational check of the pitch trim system as outlined in Section IV, Paragraph 4-6. d. Install forward footwell access panel and secure with attaching screws. e. Install footwell carpet and appropriate seat previously removed. 3-18. REMOVAL OF TRIM SERVO. (PA-28.) The trim servo is located aft of the baggage compartment. NOTE On PA-28 airplanes the servo is mounted on brackets on either the upper or lower fuselage. Access to the trim servo is through the baggage compartment. REMOVAL AND INSTALLATION 3-13 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL a. Remove securing screws in rear baggage compartment panel and remove panel. b. Disconnect electrical connections from the servo. c. Remove four mounting bolts securing the servo assembly to the mounting brackets. d. Unwrap trim cable from capstan and idler pulleys and remove assembly from the airplane. 3-19. INSTALLATION OF TRIM SERVO. (PA-28.) (Refer to Figure 3-6 or 3-7.) a. Position trim servo on mounting brackets and secure with mounting bolts. b. If an idler spring is installed on the servo, temporarily disconnect the spring from cotter pin at end of servo. c. . On PA—28-150, PA-28-160 and PA-28-180 airplanes with Serial Nos. 28~2172 to 28-4377 inclusive; PA—28-235 airplanes with Serial Nos. 28-10606 to” 28-10719 inclusive; and PA-28-140 airplanes with Serial Nos. 28-20002 and up, (refer to Figure 3—6), route the trim cable from the forward section of the airplane around the top capstan groove, around the aft side of the idler pulley located in the center of the servo, around the bottom capstan groove toward the aft section of the airplane until cable forms a figure eight. Proceed to step “e”. ' d. On PA-28—151, Serial Nos. 28-7415001 and up; PA-28-l61, Serial Nos. 28-7716001 and up; PA-28—180, Serial Nos. 28-4378 and up; PA-28-181, Serial Nos. 28-7690001 and up; PA-28R—l80, Serial Nos. 28R—30005 and up; PA-28R-200, Serial Nos. 28R-35001 and up; PAf28R-201, Serial Nos. 28R-7737001 and up; PA-28R-201T, Serial Nos. 28R-7703001 and up; PA-28-235, Serial Nos. 28—10720 and up, (refer to Figure 3-7), route the trim cable from the forward section of the airplane around the aft idler pulley; then around the top capstan groove and around the aft side of the idler pulley located approximately in the center of the servo. Form a figure eight by continuing the cable around the bottom capstan groove; then around the forward idler pulley and route trim cable toward the aft section of airplane. e. Tighten the trim cable to obtain appropriate tension as listed in Table III-I. f. Reconnect idler spring to cotter pin at end of servo. g. Connect electrical connections to trim servo assembly and check servo operation. h. Install rear baggage compartment panel and secure with attaching screws. 3-20. REMOVAL OF TRIM SERVO. (PA-32.) The trim servo is located aft of the baggage compartment. Access to the servo is through the aft baggage compartment. a. Remove securing screws in rear baggage compartment panel and remove panel. 3-14 REMOVAL AND INSTALLATION Revised: 2/25/77 PIPER PITCH TRIM SERVICE MANUAL b. Disconnect electrical connections from the servo. c. Remove four mounting bolts securing the servo assembly to the mounting brackets. , d. Unwrap trim cable from capstan and idler pulleys and remove assembly from the airplane. 3-21. INSTALLATION OF TRIM SERVO. (PA-32.) (Refer to Figure 3—7.) a. Position trim servo on mounting brackets and secure with mounting bolts. b. If an idler spring is installed on the servo, temporarily disconnect the spring from the cotter pin at end of servo. c. Route the trim cable from the forward section of the airplane aroUnd the aft idler pulley, then around the top capstan groove and around the aft side of the idler pulley located approximately in the center of the servo. Form a figure eight by continuing the cable around the bottom capstan groove, then around the forward idler pulley and route trim cable toward the aft section of the airplane. d. Tighten the trim cable to obtain appropriate tension as listed inTable III-I. e. Reconnect idler spring to cotter pin at end of servo. f. Connect electrical connections to trim servo assembly and check servo operation. g. Install rear baggage compartment panel and secure with attaching screws. 3—22. TRIM SENSOR CENTERING PROCEDURES AND TRIM AMPLIFIER DE— LAY CIRCUIT CHECK IN P.E.T. —1 AND P.E.T. —2 SYSTEMS. The two types of trim sensors used in Piper airplanes with the P.E.T. —l and P.E.T. -2 Auto- _matic Pitch Trim Systems are shown in illustration form in this section of the manual, (Refer to Figure 3-8 and 3-9). When making trim sensor centering adjustments, it is very important to ascertain the type of sensor being adjusted and to follow the detailed instructions for that particular type sensor to avoid damage to the test equipment and the sensor. The procedure used to check for proper functioning of the trim amplifier delay circuit is incorporated in the trim sensor centering procedure instructions. This is done so both tests can be accomplished with the initial hook up of test equipment. a. The following listed test equipment should be used to adjust trim sensor centering. 1. Output Meter (66B83-l). 2. Output Meter Cable (30Al77). b. Support the stabilator in approximate level flight position before proceed— ing with trim sensor contact centering procedure, regardless of type of sensor being serviced. REMOVAL AND INSTALLATION 3-15 Issued: 8/25/72' PIPER PITCH TRIM SERVICE MANUAL NOTE The stabilator should be firmly supported at its trail— ing edge. Place support on stabilator, not on trim tab. Do not attempt to hold the stabilator in position as it is impossible to hand hold the stabilator steady enough to accomplish the correct adjustment. A typical sta- bilator holding fixture is shown in Figure 3—2. Such a fixture should be used in conjunction with a jack placed under the tail skid. c. Centering procedure for plate type trim sensor with amplifier. (Refer to Figure 3-8.) 1. Turn OFF airplane master switch. 2. Connect either end of Cable 30Al77 to the Output Meter. (The 30Al77 Cable is the one with a single wire lead terminating with an alligator clip.) 3. Connect the other end of the Cable to the CD—41 plug coming from the top of the amplifier. CAUTION When testing a trim sensor on the bench, the sensor must be grounded to prevent damage to the transis— tors. In the airplane, it is grounded through the in— stallation of the sensor to the airframe. 4. Connect alligator clip of Cable 30Al77 to 12-volt POSITIVE source. 5. Make sure the sensor pulleys are parallel to the stabilator cables and stabilator is blocked to approximately level flight. 6. Turn on 12—volt source. 7. For Centering Check if Output Meter indicates zero output, the con- tacts are centered, proceed to Step D. If not, proceed with the following steps. (a) Loosen both screws of the contact support bar. (Refer to Figure 3-8.) (b) Rotate eccentric nut on the contact support bar to obtain zero out— put on the meter. (c) Tighten screws on the contact support bar. 3-16 REMOVAL AND INSTALLATION Issued: 8/25/72 PEER PITCH TRIM SERVICE MANUAL (d) For Trim Amplifier Delay Circuit Check, apply forward pressure on the control column and observe the Output Meter needle move— ment. The needle should show immediate movement during the initial part of its travel, and then the rate of needle movement should taper off until the needle comes to rest in the area of the green dot. (Approximately .25 on the scale.) When forward pressure on the control column is released, the needle should either return to zero or remain deflected in the same direction but should not reverse direction. (e) Apply aft pressure on the control column and observe the Output Meter needle movement in the opposite direction. The-needle should show immediate movement during the initial part of its travel, and then the rate of needle movement should taper off until the needle comes to rest in the area of the green dot. (Approxi— mately .25 on the scale.) When aft pressure on the control column is released, the needle should either return to zero or remain deflected in the same direction but should not reverse direction. NOTE If the Output Meter reverses direction of deflection when the forward or aft pressure on the control wheel is released; the trim sensor centering must be re— accomplished . (f) Turn off lZ—volt source and disconnect Output Meter and associ— ated cables . (g) Connect CD-41 electrical connection. d. Centering procedure for pendulous type trim sensor with amplifier. (Refer to Figure 3—9.) 1. Turn OFF airplane master switch. 2. Connect either end of Cable 30Al77 to the Output Meter. (The 30Al77 Cable is the one with a single wire lead terminating with an alligator clip.) 3. Connect the other end of the Cable to the CD-4l plug coming from the top of the amplifier. CAUTION When testing a trim sensor on the bench, the sensor must be grounded to prevent damage to the transis— tors. In the airplane, it is grounded through the in- stallation of the sensor to the airframe. REMOVAL AND INSTALLATION 3-17 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL 3-18 4. 5. 6. 7. Connect alligator clip Cable 30Al77 to 12—volt POSITIVE source. Stabilator to be blocked to approximately level flight. Turn on 12—volt source. For Centering Check if Output Meter indicates zero output, the con— tacts are centered, proceed to Step F. If not, proceed with the following steps. (a) (b) (C) (d) (e) (f) (g) Remove amplifier cover. It is not necessary to completely re- move screws securing cover, as cover is slotted. Carefully loosen the two adjusting screws to permit the contact adjustment bracket to move with some friction. (Refer to Figure 3-9.) Grasp both stabilator cables, pull evenly upward, then release cables and allow them to snap back to position. NOTE When the cables snap back to position, the cables vi— brate the pendulum assembly which centers the ad- justable contacts. When the Output Meter is centered, carefully tighten the adjusting screws. Tighten each adjusting screw a slight amOunt then pro— ceed to the other screw. Repeat this sequence until both screws are tight. - The Output Meter should read zero output. If zero output is not obtained, repeat steps b through d. For Trim Amplifier Delay Circuit Check, apply forward pressure on the control column and observe the Output Meter needle move— ment. The needle should show immediate movement during the initial part of its travel, and then the rate of needle movement should taper off until the needle comes to rest in area of the green dot. (Approximately .25 on the scale.) When forward pressure on the control column is released, the needle should either returnto zero or remain deflected in the same direction but should not re- reverse direction. Apply aft pressure on the control column and observe the Output Meter needle movement in the opposite direction. The needle should show immediate movement during the initial part of its travel, and then the rate of needle movement should taper off until the needle comes to rest in the area of the green dot. (Approxi- mately .25 on the scale.) When aft pressure on the control column is released, the needle should either return to zero or remain deflected in the same direction but should not reverse direction. REMOVAL AND INSTALLATION Issued: 8/25/72 , I ‘ . I“. 4 \¢__y/ PEER PITCH TRIM SERVICE MANUAL NOTE If the Output Meter reverses direction of deflection when the forward or aft pressure on the control wheel is released, the trim sensor centering must be reac— I complished. (h) Turn off 12-voltsource and disconnect Output Meter and associated cables. (i) Connect CD-41 electrical connector. (j ) Install amplifier cover and secure. FWD 1 IDLER SPRING IDLER PULLEY II m// I /I\ O /I \\1/ 9”:<\ / ° Np I 0 ,\ //‘\ j / \| \ \I O l/ M NOT ON EARLY PRODUCTION CHEROKEE PIVOT POINT AIRPLANES LI AFT P.E.T. SERVO WITH SPRING ON IDLER PULLEY Figure 3—7. PA-28 and PA—32 Trim Servo Cable Routing REMOVAL AND INSTALLATION 3-19 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL AMPLIFIER ECCENTRIC NUT / l LOCK SCREWS L. .L’ Figure 3-8. Plate Sensor with Amplifier AMPLIFIER ADJUSTING SCREWS Figure 3-9. Pendulous Sensor with Amplifier 3—20 REMOVAL AND INSTALLATION Issued: 8/25/72 _—— PEER PITCH TRIM SERVICE MANUAL TABLE III-I. TRIM SERVO CABLE TENSION AIRPLANE CABLE CABLE TENSION PA-23-250 Stabilator Trim 10 lbs. i207, (2 lbs.) PA—24 Stabilator Trim 12 lbs. i20% (2 .4 lbs.) PA-28 Stabilator Trim 10 lbs. 1- 1 1b. PA-30 I Stabilator Trim 12 lbs. i 20% (2 .4 lbs .) | PA-32 Stabilator Trim 10 lbs. 11lb. TABLE III-II. TRIM SENSOR CABLE TENSION AIRPLANE CABLE CABLE TENSION PA-23-250 Stabilator 35 lbs. 110% (3.5 lbs.) PA-24 Stabilator 18 lbs.i20% (3.6 lbs.) PA-30 Stabilator 18 lbs. i’ 207, (3.6 lbs.) REMOVAL AND INSTALLATION 3-21 Revised: 2/25/77 PIPER PITCH TRIM SERVICE MANUAL 3-23. REMOVAL OF ELECTRIC TRIM STOP SENSOR ASSEMBLY. (PA-28-181, PA—32R—300, PA—32RT -300 and PA-32RT-300T only.) The electric trim stop sensor assembly is located behind the left instrument panel. a. Access to the unit is from beneath the left instrument panel. b. Disconnect the electrical connections from the electric trim stop sensor assembly. "Identify wires to facilitate reinstallation. 0. Disconnect the static lines from the airspeed indicator and the static line T fitting. Identify hoses to facilitate reinstallatiOn. To prevent contamination, place protective covers over the ends of the hoses, the airspeed indicator and the static line T fitting ports. (1. Remove the screws securing the electric trim stop sensor assembly to the instrument panel and remove sensor assembly frOm the airplane. 3-24. INSTALLATION OF ELECTRIC TRIM STOP SENSOR ASSEMBLY. (PA-28-181, PA—32R—300, PA-32RT—300 andPA-32RT-3OOT.) (Refer to Figure 3-10.) a. Position the electric trim stop sensor assembly in its proper mounting location behind the left instrument panel and secure with appropriate screws. b. Remove any caps which were placed over the hoses, the airspeed indicator and the static line T fitting ports. . 0. Connect hoses to the proper ports of the airspeed indicator and the static line T fitting. (1. Connect the electrical connections to the electric trim stop sensor assembly. e. Check operation of electric trim stop sensor assembly. (Refer to Section IV.) ELECTRIC TRIM STOP SENSOR ASS'Y ADIUSTMENT SCREW DISCONNECT SENSOR ASS'Y AT THESE POINTS Figure 3-10. Electric Trim Stop Sensor Assembly Installation 3-22 REMOVAL AND INSTALLATION Revised: 12/20/77 PEER PITCH TRIM SERVICE MANUAL SECTION IV ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS Paragraph . Page 4—1. Description .................................. 4-1 4-2. Control Wheel Harness Connections .................... 4-1 4-3. - P. E. T. Servo Clutch Clearance Adjustment Procedure for Proper Clutch Torque' ................. 4-1 4-4. Clutch Solenoid Coil Adjustment Procedure ............... 4-2 4-5. Adjustment of Servo Selector Switch and Pitch AutoPilot Servo Motor Switch ..................... 4-3 4-6. Ground Checks for the P. E. T. Electric Pitch Trim Systems .................................. 4-4 4-7. Flight Checks of the P. E. T. Electric Pitch Trim Systems ................_ ..... , . . .;.,....... 4-10 4-8. Ground Check for Piper Electric Trim Stop Sensor Assembly (PA-28-181, PA—32R—300, PA—32RT-300 and PA-32RT-300T ........................... 4el3 Revised: 12/20/77 iv -i I" PEER PITCH TRIM SERVICE MANUAL SECTION IV ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS 4-1. DESCRIPTION. This section provides the information necessary to prop— erly adjust and perform operational checks of the P. E. T. Electric Pitch Trim Systems used in Piper airplanes. The first part of this section is comprised of servo adjustments and wiring connections for the control wheel trim switch. The second part consists of operational checks of the P. E. T. Electric Pitch Trim Systems . Complete trim sensor contact centering procedures are described in Sec— tion III, Removal and Installation. Information pertaining to trim sensor adjust- ments can be obtained by referring to the particular type of sensor installation. The Trim Sensor Delay Circuit Check is also included in the Trim Sensor Center- ing adjustment instructions . 4-2. CONTROL WHEEL HARNESS CONNECTIONS. The pitch trim switch is mounted in the control wheel and is electrically connected to the components of the trim system through a coiled harness assembly. The connections for each installation is shown in illustration form in this section. When replacing a de— fective switch, refer to Figures 4-3 thru 4-5 for the proper wiring connections to be made on the airplane being serviced. 4—3. P.E.T. SERVO CLUTCH CLEARANCE ADJUSTMENT PROCEDURE FOR PROPER CLUTCH TORQUE. (Refer to Figure 4-1.) a . Check for .002" to .003" clearance with the trim servo disengaged. b. Ifclutch clearance is out of tolerance, remove cotter pin and rotate castle nut one (1) castellation in the desired direction and recheck clutch clearance. NOTE Clockwise rotation of nut decreases clutch clearance. Counterclockwise rotation of nut increases clutch clearance. ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS 4—1 Revised. 12/20/77 PEER PITCH TRIM SERVICE MANUAL _ \ ,. I c. ‘If clutch clearance cannot be obtained when the castle nut is turned one (1) castellation from its original position, remove nut, washers, shims and cap- stan from shaft. Remove capstan carefully to avoid losing shims and washers. Interchange shims from the top and bottom of the capstan to obtain proper clutch clearance. NOTE Adding shims inside the capstan (BOTTOM) increases the clutch clearance. Removing shims from inside the capstan (BOTTOM) decreases the clutch clear- ance. Any shims removed from inside the capstan (BOTTOM) should be installed on top of the capstan for future use, if necessary. (1. Reinstall capstan, shims, washers and nut. e. Tighten the capstan nut until the capstan just makes contactwith the clutch clearance spring. Do not tighten the nut as this will compress the clutch clear- ance spring and lock the clutch disks together. p g f . Install cotter pin. _ P“ T 4-4. CLUTCH SOLENOID COIL ADJUSTMENT PROCEDURE. (Refer to Figure 4-1.) NOTE Use 14 VDC external power supply to insure sufficient solenoid current to develop maximum torque on clutch. Low battery voltage will cause low torque on the clutch even when the clutch is properly adjusted. a. Loosen four screws securing solenoid coil to the frame. b. Engage trim servo electrically to bottom the Solenoid coil and mark the frame where the edge of coil is located while the trim servo is engaged electri- cally. ' c. Move the solenoid coil away from mark 1/16” to 1/8” and tighten the four coil mounting screws . Adjust the solenoid coil within the 1/16" to 1/8" dimen- sion to obtain maximum clutch torque. 4-2 ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS Issued: 8/25/72 PEER PITCH TRIM SERVICE MANUAL NOTE Check that the coil is not cocked in the frame thereby causing friction between the solenoid slug and coil. Friction may cause clutch engage and/or disengage malfunctions. d. Engage servo electrically to check for maximum clutch torque by holding - trim crank or wheel while electric trim is operating. 4-5. ADJUSTMENT OF SERVO SELECTOR SWITCH AND PITCH AUTOPILOT SERVO MOTOR SWITCH. (Refer to Figure 4-2.) This adjustment procedure is for AltiMatic II Installations containing the Rack and Pinion type servo. The cams used for adjustment of the switches are double stacked on the same retaining screw. The top cam adjustment is for the servo selector switch and the bottom cam adjustment is for the pitch servo motor switch. The following detailed ad— justing procedures will explain the adjusting details for both switches. The switches are actuated by the AltiMatic IIpitch engage knob. The cams must be adjusted so the top switch (servo selector switch) actuates when the AltiMatic II pitch engage knob is rotated through the 11:00 o'clock position and the bottom switch (AutoPilot servo motor switch) actuates when the AltiMatic IIpitch engage knob is rotated through the 1:00 o'clock position. In addition, the bottom switch must actuate before the AutoPilot servo motor gears begin to mesh and both“ switches must deactuate before the AltiMatic IIpitch engage knob is rotated to its OFF position. NOTE The adjustment of these switches mustbe accomplished in the airplane. The switch adjustment procedure can be accomplished in the PA—23 airplanes without re— moving the AltiMatic IIPitch Servo. In the PA-_24 and PA-30 airplanes the AltiMatic 11 Pitch Servo must be removed to adjust these switches. Do not disconnect the servo engage flex cable. Refer to the I and II Series AutoPilot Service Manual Piper P/N 753 798 for AltiMatic II Pitch Servo Removal and Installation in— structions. No provision is provided to adjust the switches on the chain type pitch AutoPilot servo. ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS 4—3 Issued: 8/25/72 PEER PITCH TRIM SERVICE MANUAL a. SWITCH ADJUSTMENT PROCEDURE. (Refer to Figure 4—2 .) l. Loosen cam screw slightly. NOTE If the cam screw is loosened excessively, cam adjust- ment will be more difficult. Use extreme caution when adjusting the cams to prevent damage to the follow—up condenser plates and switch springs . 2. Position the bottom cam so the bottom switch actuates when the Alti- Matic II pitch engage knob is at the 1:00 o'clock position. 3. Hold the bottom cam in position and tighten the cam screw. 4. Rotate the AltiMatic II pitch engage knob through the 1:00 o'clock posi- tion and ascertain that the bottom switch actuates . If the switch fails to actuate at the 1:00 o'clock position repeat steps 1thru 3 until the bottom switch is ac- tuated when the pitch AutoPilot knob is rotated through the 1:00 o'clock position. 5. Hold the bottom cam in position and loosen cam screw slightly. 6. Position the top cam until the top switch actuates when the AltiMatic II pitch engage knob is at the 11:00 o'clock position. 7 . Hold both cams in position and tighten the cam screw . 8. Ascertain that the top switch actuates when the AltiMatic IIpitch engage knob is rotated to the 11:00 o'clock position and the bottom switch actuates when the AltiMatic II pitch engage knob is rotated to the 1:00 o'clock position. The bottom switch should actuate before the pitch servo gears start to engage and both switches should deactuate before the pitch engage knob is returned to its OFF position. 4-6. GROUND CHECKS FOR THE P. E.T. ELECTRIC PITCH TRIM SYSTEMS. This section contains the information necessary to ground check the opera- tion of P. E T. Electric Pitch Trim Systems used in Piper airplanes. When using this section, be sure to utilize the tests that are appropriate to the type of system being serviced. The following checks are accomplished with the airplane master switch ON and the trim circuit breaker pushed IN. Schematics for the electrical circuits of the P. E T Electric Pitch Trim Systems are located in Section VI of this manual. 4-4 ADJUSTMENT PROCEDURES AND OPERATIONALCHECKS Issued: 8/25/72 PIPER PITCH TRIM SERVICEMANUAL CLUTCH DISK .ooz’io .OOS’CLEARANC E CLUTCH DISENGAGED _ \ _ Q _‘s 0 . L B. II/cn CLUTCH COIL 24 V FOR USE IN 12 V SYSTEM SCREWS 4 PLACES F RAME TENSION SPRING NUT CLUTCH w SHIMS CLUTCH CLEARANCE SPRING PIVOT POINT‘/ Figure 4-2. ' ADJUSTMENT PROCEDURES AND OPERATIONAL. CHECKS Issued: 8/25/72 Switch Adjustment Cams 4—5 PEER PITCH TRIM SERVICE MANUAL AAAAAAAAAAAAAAAAAAAAAAAAA EEEEEEEEEEEEEEEEEEEEEEE AAAAAAAAA WHITE [CD-43) C N O N 0 BLACK (CD-35] BLACK (CD-36] GREEN ICO-Ml GREEN (CD-44] . WHITE ICU-43] I Figure 4—3. PA—23-250, PA-24 and PA—30 P. E. T. -1 Manual Electric Trim Control Wheel Switch \\ /\\\ / I r s.I .- ;\ / Figure 4—4. PA-23-250, PA-24 and PA—30 P. E. T. -1 Manual, P. E.T. -1 Automatic and P. E. T. -2 Automatic Electric Trim Control Wheel Switch /J //§\\'\- 4—6 ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS Revised: 6/3/75 PIPER PITCH TRIM SERVICE MANUAL KEY WAY BLACK WHITE Figure 4-5. Manual Electric Trim Control Wheel Switch PA-28-l40, Serial Nos. 28-20002 to 28-7’525059 incl; PA-28—150, 160, and 180, Serial Nos. 28-1 to 28-4377 incl; PA-28-235, Serial Nos. 28-10003 to 28-11039 incl; PA-32—260, Serial Nos. 32-1 to 32-11 10 incl; and PA-32-300, Serial Nos. 3240000 to 3240565 incl. BLACK O \7 SHIELD Figure 4-5 (cont.) Manual Electric Trim Control Wheel Switch PA-28-151. Serial Nos. 28-7415001 to 28—7515212 incl; PA-28—180, Serial Nos. 28-4378 to 28-7505079 incl; PA—28R—180. Serial Nos. 28—30005 and up: PA—28R-200. Serial Nos. 28-30482, 28—3500] to 28—7535077 incl: PA-28-235. Serial Nos. 28-11040 to 28-7510027 incl; PA—32-260, Serial Nos. 32—1111 to 32-7500008 incl; and PA—32-300, Serial Nos. 32—40566'to 32-7540058 incl. - ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS 4-6a Added: 6/3/75 PEER PITCH TRIM SERVICE MANUAL O \, . WHITE \—, BLACK Figure 4-5 (cont.) Manual Electric Trim Control Wheel Switch PA—28-151, Serial Nos. 28—7515213 and up;‘PA-28—l6l, Serial Nos. 28-7716001 and up; PA-28-l80, Serial Nos. 28-7505080 and up; PA-28-l8l, Serial Nos. 28-7690001 and up; PA-28R—200, Serial Nos. 28R—7535078 and up; ‘PA-28R—201, Serial Nos. 28R—7737001 and up; PA-28R-201T, Serial Nos. 28R-7703001 and up; PA-28-235, Serial Nos. 28-7510028 and up; PA-32-260, Serial Nos. 32-7500009 and up; PA-32-300, Serial Nos. 32-7540059 and up; PA—32R-300, Serial Nos. 32-7680001 and up;PA—32RT-300, Serial Nos. 32RT-7885001 and up; and the PA-32RT-300T, Serial Nos. 32RT-7887001 and up; KEY WAY Figure 4-5 (cont.) Manual Electric Trim Control Wheel Switch PA-28-l40, Serial Nos. 28-752509-6 and up ADJUSTMENT PROCEDURES”AND OPERATIONAL CHECKS Revised: 12/20/77 PIPER PITCH TRIM SERVICE MANUAL NOTE In the event the trim servo does not drive the pitch trim system, it must be determinedif the malfunction is mechanical or electrical. If mechanical malfunc- tion, refer to Clutch Adjustment Procedure, Paragraph 4—3. If electrical, refer to Section VI and utilize the appropriate schematic to troubleshoot the trim system. a. p P. E. T.—1 MANUAL ELECTRIC TRIM SYSTEM. 1. Place the pitch trim at approximately neutral position- 2. Push the TRIM SWITCH to the NOSE DOWN position. The trim servo should drive the pitch trim NOSE DOWN. 3. Pushthe TRIM SWITCH to the NOSE UP position. The trim servo should drive the pitch trim NOSE UP. ‘ 4. While holding the trim switch in the NOSE DOWN or NOSE UP position, hold the trim crank or trim wheel to check that the trim servo clutch has ade— quate torque. If the clutch torque is low, refer to Paragraph 4—3 of this section for the trim servo clutch adjustment procedure. b. P. E T. ~1 AUTOMATIC ELECTRIC TRIM SYSTEM—MANUAL MODE. 1. Place the pitch trim at approximately neutral position. 2. Rotate the AltiMatic II pitch engage knob to the OFF position. 3. With the PUSHBUTTON TRIM SWITCH released, apply FORWARD and AFT pressure on control wheel. "The trim servo should not drive the pitch trim . 4. Depress the PUSHBUTTON TRIM SWITCH and apply FORWARD pres- sure on the control wheel. The trim servo should drive the pitch trim toward the NOSE DOWN position. i 5. Release the FORWARD pressure on the control wheel. The trim servo may either STOP or continue driving the pitch trim toward the NOSE DOWN posi- tion. 6. Depress the PUSHBUTTON TRIM SWITCH and apply AFT pressure on the control wheel. The trim servo should drive the pitch trim toward the NOSE UP position. ' , 7. Release the AFT pressure on the control wheel. The trim servo may either STOP or continue driving the pitch trim toward the NOSE UP position. ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS 4-7 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL NOTE If the trim servo reverses direction when the forward or aft pressure on the control wheel is released, the centering of the trim sensor contacts should be checked . Refer to Section III, Paragraph 3-22, for the trim sen- sor centering instructions . c. P.E.T.-1AUTOMATIC ELECTRIC TRIM SYSTEM—AUTOMATIC MODE. 1. Partially engage the AltiMatic II pitch axis by rotating the pitch engage knob to approximately 12 o'clock position. NOTE When the AltiMatic II pitch engage knob is at approxi- mately 12 o'clock position, the pitchtrim crank should be difficult to rotate which will confirm that the servo selector switch has switched the electric trim from the manual mode to the automatic mode. The clutch solenoid will be energized whenever the electric trim is in the automatic mode. 2 . Rotate the trim handle to check that the trim servo clutch has adequate torque. If the clutch torque is low, refer to Paragraph 4-3 of this section for trim servo clutch adjustment procedure. 3 . Apply FORWARD pressure on the control wheel . The trim servo should drive the pitch trim NOSE DOWN. 7 4. Release the FORWARD-pressure on the control wheel. The trim servo may either STOP or continue driving the pitch trim NOSE DOWN. 5. Apply AFT pressure on the control wheel. The trim servo should drive the pitch trim NOSE UP. 6. Release the AFT pressure on the control wheel. The trim servo may either STOP or continue driving the pitch trim NOSE UP. NOTE - -» If the trim servo reverses direction when the forward or aft pressure on the control wheel is released, the centering of the trim sensor contacts should be checked, Refer to Section III, Paragraph 3—22, for the trim sen~ sor centering instructions . 4—8 ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL _ 7 . Return the AltiMatic II pitch engage knob to the OFF position. (1. P. E. T. -2 AUTOMATIC ELECTRIC TRIM SYSTEM—MANUAL MODE. 1. Place the pitch trim at approximately neutral position. 2. Place the AltiMatic II pitch engage knob to the OFF position. » 3. Push the TRIM SWITCH to the NOSE DOWN position. The trim servo should drive the pitch trim NOSE DOWN. ' 4 . Push the TRIM SWITCH to the NOSE UP position . The trim servo should drive the pitch trim NOSE UP. _ 5. With the TRIM SWITCH in the neutral or OFF position, apply forward and aft pressure on the control wheel. The trim servo should not drive the pitch trim . e. P.E.T.-2AUTOMATIC ELECTRIC TRIM SYSTEM—AUTOMATIC MODE. 1 . Partially engage the AltiMatic II pitch axis by rotating the pitch engage knob to approximately 12 o 'CIock position. NOTE When the AltiMatic IIpitch engage knob is at approxi— mately 12o'clock position, the pitch trim crank should be difficult to rotate which will confirm that the servo selector switch has switched the electric trim from the manual mode to the automatic mode. The clutch solenoid will be energized whenever the electric trim is in the automatic mode. 2. Rotate the trim crank to check that the servo clutch has adequate torque. If the clutch torque is low, refer to Paragraph 4—3 of this section for the trim servo clutch adjustment procedure. 3. Apply FORWARD and AFT movement to the TRIM SWITCH. The trim switch should be inoperative. 4 . Apply FORWARD pressure on the control wheel . The trim servo should drive the pitch trim NOSE DOWN ._ I 5. Release the FORWARD pressure on the control wheel. The trim servo may either STOP or continue driving the pitch trim NOSE DOWN. 6. Apply AFT pressure on the control wheel. The trim servo should drive the pitch trim NOSE UP. 7 . Release the AFT pressure on the control wheel. The trim servo may either STOP or continue driving the pitch trim NOSE UP. ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS 4-9 Issued: 8/25/72 PIPER PITCH TRllVI SERVICE MANUAL NOTE If the trim servo reverses direction when the forward or aft pressure on the control wheel is released, the centering of the trim Sensor contacts should be checked. Refer to Section III, Paragraph 3-22, for the trim sen— sor centering instructions . 8 . Return the AltiMatic II pitch engage knob to the OFF position. . 4-7. FLIGHT CHECKS OF THE P. E. T. ELECTRIC PITCH TRIM SYSTEMS. This section contains the information necessary to flight check the opera- tion of the P. E. T. Electric Pitch Trim Systems used in Piper airplanes . When using this section, be sure to utilize the tests which are appropriate to the type of system, being checked . NOTE In the event the trim servo does not drive the pitch trim system, it must be determinedif the malfunction is mechanical or electrical. If mechanical malfunc- tion, refer to Clutch Adjustment Procedure, Paragraph 4-3. If electrical, refer to Section VI and utilize the appropriate schematic to troubleshoot the trim system. a. P. E. T.-1 MANUAL ELECTRIC TRIM SYSTEM. 1 . Move the TRIM SWITCH on the pilot's control wheel to the forward or NOSE DOWN position. 2. The airplane should trim NOSE DOWN. . 3. Release the TRIM SWITCH, it will return to the center or OFF posi— tion. 4. The electrical power used to drive the trim servo motor will be dis— connected and the airplane will be trimmed NOSE DOWN until it is retrimmed to a new pitch attitude. 5 . Move the TRIM SWITCH on the pilot's control wheel to the'aft or NOSE UP position. ’ 6. The airplane should trim NOSE UP. 7. Release the TRIM SWITCH, it will return to the center or OFF posi- tion. ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL 8. The electrical pOWer used to drive the trim servo motor will be dis- connected, and the airplane will be trimmed NOSE.UP until it is retrimmed to a new pitch attitude. b. P.E.T. —1 AUTOMATIC ELECTRIC TRIM SYSTEM—MANUAL MODE. 1. Disengage the pitch axis of the AutoPilot. , 2. Depress the PUSHBUTTON TRIM SWITCH on the pilot's control wheel. The airplane should trim in the correct direction until all pressure is relieved at the control wheel. 3. Release the PUSHBUTTON TRIM SWITCH. The airplane should fly at the trimmed pitch attitude. 4. With the PUSHBUTTON TRIM SWITCH depressed, pull AFT on the control wheel. The airplane should trim for a climb. 5. With the PUSHBUTTON TRIM SWITCH depressed, push FORWARD on the control wheel. The airplane should trim for a descent. . 6. After establishing any pitch attitude, depress the PUSHBUTTON TRIM SWITCH. The electric trim should retrim to the airplane attitude. c. P.E.T.-1 AUTOMATIC ELECTRIC TRIM SYSTEM—AUTOMATIC» MODE. 1. Engage the pitch axis of the AutoPilot. 2. Anytime the AutoPilot changes the pitch attitude of the airplane or anytime a power change is made, the Automatic pitch trim will automatically retrim the airplane. ' 3. When the AltiMatic II pitch axis is disengaged, the airplane should be trimmed to the attitude at the time of AutoPilot disengagement. If an out of trim condition exists always in the same direction at the time of AutoPilot disengage- ment, the trim sensor centering should be checked, refer to Section III, Para- graph 3-22. If when disengaging the AutoPilot sometimes the airplane is in trim, sometimes it is trimmed NOSE UP or sometimes it is trimmed NOSE DOWN, check operation of the automatic mode of the electric pitch system. NOTE When engaging the AutoPilot, observe the trim crank. If the trim crank turns in either direction in excess of 1/3 of a complete turn, check the trim sensor centering in Section III, Paragraph 3-22. d. P.E.T.-2 AUTOMATIC ELECTRIC TRIM SYSTEM—MANUAL MODE. 1. Disengage the pitch axis of the AutoPilot. 2. Move the TRIM SWITCH on the pilot's control wheel to the forward or NOSE DOWN position. 3. The airplane should trim NOSE DOWN. 4. Release the TRIM SWITCH. It will return to the center or OFF position. ADJUSTMENT-PROCEDURES AND OPERATIONAL CHECKS 4—11 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL 5. The electrical power- used to drive the trim servo motor will be dis— connected and the airplane will continue to be trimmed NOSE DOWN until it is retrimmed to a new pitch attitude. 6. Move the TRIM SWITCH on the pilot's control wheel to the aft or NOSE UP position. 7. The airplane should trim NOSE UP. 8. Release the TRIM SWITCH, it will return to the center or OFF position. 9. The electrical power used to drive the trim servo motor will be dis- connected and the airplane will continue to be trimmed NOSE UP until it is re— trimmed to a new pitch attitude. e. P. E.T. —2 AUTOMATIC ELECTRIC TRIM SYSTEM—AUTOMATIC MODE. 1. Engage the pitch axis of the AutoPilot. ’ 2. Anytime the AutoPilot changes the pitch attitude of the airplane or any- time a power change is made the automatic pitch trim will automatically retrim the airplane. I 3. When the AltiMatic IIpitch axis is disengaged the airplane should be trimmed to the attitude at the time of AutoPilot disengagement. If an out of trim condition exists always in the same direction at the time of AutoPilot disengage— ment, the trim sensor centering should be checked, refer to Section III, Para- graph 3—22. If when disengaging the AutoPilot sometimes the airplane is in trim, sometimes it is trimmed NOSE UP or sometimes it is trimmed NOSE DOWN, check operation of the automatic mode of the electric pitch system. NOTE When engaging the AutoPilot, observe the trim crank. If the trim crank turns in either direction in excess of 1/3 of a complete turn, check the trim sensor centering in Section III, Paragraph 3—22 . 4—12 ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS - Issued: 8/25/72 x...) PIPER PITCH TRIM SERVICE MANUAL 4-8. GROUND CHECK AND ADJUSTMENT PROCEDURE FOR THE PIPER ELECTRIC TRIM STOP SENSOR ASSEMBLY. (PA-181, PA-32R—300, PA-32RT-300 and PA-32RT-3OOT.) This section consists of the information required to check and adjust the Piper Electric Trim Stop Sensor Assembly. This unit is incorporated in the PA-28—18l, PA-32R—300, PA-32RT-300 and PA-32RT-300T, when the P.E.T.-l is installed. The unit is located behind the left instrument panel. Refer to Section II, Removal and Installation to , gain access to the unit. _ a. TEST PROCEDURE FOR ELECTRIC TRIM STOP SENSOR ASSEMBLY. 1. Connect a suitable airspeed pressure simulator to the pitot head of the aircraft. Verify that there are no leaks present in the aircraft pitot system or the simulator. 2. Check the trim circuit breaker and place switch in the ON position.. 3. Apply pressure with simulator to increase the aircrafts airspeed. When the airspeed increases to 166 i 5 M.P.H. on the PA-28-l8l or 195 r 5 M.P.H. on the PA-32R—300, PA—32RT—300 and the PA-32RT-3OOT, actuate the trim switch in either direction. Trim should not operate. If trim operates proceed to step 5, if not, proceed to next step. 4. While holding the trim switch in the engaged position, reduce the simulator pressure to decrease the airspeed. Trim should operate when the airspeed is reduced below the specified settings as outlined in step 3. If trim fails to operate proceed to step 7. 5. While holding the trim switch in the engaged position, turn the adjustment screw (refer to Figure 4—8), as required, to obtain correct operation of electric trim stop sensor assembly. NOTE CLOCKWISE rotation of the adjustment screw will decrease the trim cut-off speed. COUNTERCLOCKWISE rotation of the adjustment screw will increase the trim cut-off speed. 6. If the serviceman is unable to adjust the unit in accordance with the specifications outlined in this procedure the unit should be replaced. Should a new unit be installed, reaccomplish this adjustment procedure. 7. Place the panel mounted pitch master switch in the OFF position and remove simulator. ‘ 8. This completes the adjustment procedure for the electric trim stop sensor assembly. ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS Revised: 12/20/77 PIPER PITCH TRIM SERVICE MANUAL ELECTRIC mm STOP sruson ASS'Y ADJUSTMENT SCREW DTSEDNNECT SENSOR ASS'Y /AT THESE POINTS J» E“ Figure 46. Electric Trim Stop Sensor Assembly ADJUSTMENT PROCEDURES AND OPERATIONAL CHECKS Added: 7/12/76 PIPER PITCH TRIM SERVICE MANUAL section V TEST EQUIPMENT Paragraph ‘ Page 5-1. Introduction - #66B83-1 Output Meter. . . . . . 5-1 Issued: 8/25/72 . ' _ ' ’ v—i “My"; PIPER PITCH TRIM SERVICE MANUAL SECTION V TEST EQUIPMENT 5—1. INTRODUCTION—#66B83—l OUTPUT METER. (Refer to Figure 5-1.) The Output Meter consists of a center reading meter, a dummy load re— sistor and an Alden receptacle to be used in conjunction with the Output Cable 30Al77. a. This meter is used for the following purposes: 1. Adjusting the "center" of the contact points on the P. E.T. Trim Sensor. 2. Checking the trim sensor and amplifier circuitry for equal output. 3. Checking the delay circuit of the trim amplifier. - NOTE During prolonged use of the Output Meter, it will be— come hot due to the dummy load resistors dissipating the output of the trim amplifier which generates heat. TEST EQUIPMENT ' , 5—1 Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL OUTPUT METER CAB LE Piper H/N 753 928 (30Al77) OUTPUT METER Piper P/N 753 79I (668834) 5-2 Figure 5 —1.. Test Equipment TEST EQUIPMENT ' Issued: 8/2—5/72 N , \‘~n‘_‘/“/ PIPER PITCH TRIM SERVICE MANUAL SECTION VI SCHEMATICS Paragraph 1 . - - A Page 6-1, “Introduction. . . . . . . . . . _. . . . . . 6-1 Issued: 8/25/72 , vi—i PIPER PITCH TRIM SERVICE MANUAL SECTION VI SCHEMATICS 6-1. INTRODUCTION. This section of the manual consists of schematic dia— grams of the electrical circuitry of the P.E.T. Electric Trim Systems installed in Piper airplanes. When using this section ascertain the type of trim system being serviced and refer to the appropriate schematic. The schematic diagrams should be used as an aid in troubleshooting the electrical portion of the trim sys- tem . SCHEMATICS _ 6-1 Issued: 8/25/72 PIPER PITCH TRllVI SERVICE MANUAL CW (ROT) CCW (ROT) Figure 6-1. P.E.T. Series Pitch Trim Servo Motor Windings 55343 PITCH TRIM SERVO rig. r-"fi————————a I A +—t~. O—I—- I SOLENOID CICW.(R0T.)} _.. __I I _ l ITOGGLE SWITCH OR SLIDE SWITCH I u 600V I 5 ' l FILTER \ 4 z CONTROL WHEEL CID-38 w m J 1 ISWITCH _ —>>E_L_I_c%e - - . 3 < II— — — — flWHITE CID/44 ® I ‘Iw./Y.I' I f-T—J.‘ I | cw.(ROT.I' ' - '\ I I I ' I l IBLACK IWJBLU : 2 6T I I Tc'ceroQ '| RED CD43 : "r—I \g .osu 200V | _ _ _ 7 l FILTER CW.(ROT.) I © I P 2 REQ. I @fiCD-se I. r _| NTTS-ERVO CAPSTAN ROTATION LEGEND ."CLOCKWISE'TORZ CONNECTOR TYPE: WIRE CODE: PIX-23 SERIES "UP TRIM" @ DELCO xx-xx AUTOPILOT.(N0'S APPLY TO Pan-24 SERIES .. .. TEST EQUIPTMENT AND PA-30 0” TR'M KNIFE PROCEDURES.) ' 2.MOTOR"ROTATION"AS VIEWED © WRISTLOCK AT COMMUTATOR END. Figure 6—2. P.E.T. -1 Manual Electric Trim Schematic 6—2 ' SCHEMATICS Issued: 8/2‘5/72 Mgr/V \‘~¢:.-.>/' PIPER PITCH TRIM SERVICE MANUAL 0 5A C/B ELECTRIC TRIM SWITCH ELECTRIC TRIM STOP SENSOR ASS'Y r. _ _ _ —1 I I I I CONTROL WHEEL] I _—O—T_—l SWITCH 1 I WHITE I LO—I— I______l . EACK EEC—E—SOLENOID 5 E Figure 6-5. P.E.T.-1 Manual Electric Trim Schematic (Electric Trim Stop Sensor PA-28—181, PA-32R—300, PA-32RT—300, and PA-32RT-3OOT.) 0 5A C/B ELECTRIC TRIM SWITCH fl/O I 5CONTROL WHEEL | SWITCH - WHITE SOLENOID J_ Figure 6-6. P.E.T.-1 Manual Electric Trim Schematic SCHEMATICS Revised: 12/20/77 Issued: 8/2 PART II_ ALTIMATIC III,II|B AND IIIB-I ELECTRI.C..,TRIM SYSTEMS 5/72 l l I PIPER PITCH TRIM SERVICE MANUAL SECTION VII INTRODUCTION AND DESCRIPTION Paragraph ' Page 7-1. : [Introduction . 7-2 . Description . \l\l Issued: 8/25/72 - . ' . _ vii —i~ all} PIPER PITCH TRIM SERVICE MANUAL SECTION VII INTRODUCTION AND DESCRIPTION 7—1 . INTRODUCTION. This part of the service manual is divided into six sec- tions. Section VII contains a description of the III Series Automatic Electric Pitch Trim System. Section VIII, Theory of Operation, explains the modes of operation . Section IX, Removal and Installation, provides the information nec- essary for removal and installation of all trim components. Section X, Adjust- ment Procedures and Operational Checks, provides the information necessary to check the Operation of the system and perform minor adjustments. Section XI, Test Equipment, describes the test equipment required to center the trim sen- sor contacts. Section XII, Schematics, provides the schematics of the trim sys— tems for troubleshooting purposes . 7-2. DESCRIPTION. The 111 Series Automatic Electric Pitch Trim System is a system which trims the pitch axis of the airplane electrically. The operation of this system will be explained in Section VIII. It utilizes solenoid engage and in- corporates the use Of a permanent magnet type motor. This system uses a double pole, double throw switch on the control wheel. NOTE A simplified block diagram inTable VIII-I and an iden- tifying features diagram in Table VIII-II is presented in Section VIII of this manual. These diagrams illus- trate the basic components and features of the III Se- ries Automatic Electric Pitch Trim System . INTRODUCTION AND DESCRIPTION Issued: 8/25/72 I A . Paragraph OOCDOO I OJNI—I Issued: 8/25/72 PIPER PITCH TRIM SERVICE MANUAL SECTION VIII THEORY OF OPERATION Description . . Trim Sensor Considerations Pitch Trim Warning System - III Series AutOmatic Electric Pitch Trim System. Page viii —i PIPER PITCH TRIM SERVICE MANUAL SECTION VIII THEORY OF OPERATION 8—1. DESCRIPTION. The III Series Automatic Electric Pitch Trim System has both a manual mode and an automatic mode of operation. The manual mode is Operational only when the pitch axis of the AutoPilot is disengaged and the auto— matic mode is Operational when the pitch axis of the AutoPilot is engaged. The switch that controls the _mode of Operation is located on the Pitch AutoPilot Servo on the AltiMatic II AutoPilot and is located in the AltiMatic III Series Console PITCH engage sWitches. A simplified block diagram of the III Series Automatic Electric Pitch Trim System is shown in Table VIII-I. ' A differential cable tension sensing mechanism known as a Trim Sensor is incorporated i