Dry Motoring of the APU (131-9(A))

TASK 49-00-00-860-807-A
Dry Motoring of the APU (131-9(A))

WARNING: MAKE SURE THAT YOU HAVE THE CORRECT FIRE FIGHTING EQUIPMENT AVAILABLE.

WARNING: PUT THE SAFETY DEVICES AND THE WARNING NOTICES IN POSITION BEFORE YOU START A TASK ON OR NEAR:

THE FLIGHT CONTROLS
THE FLIGHT CONTROL SURFACES
THE LANDING GEAR AND THE RELATED DOORS
COMPONENTS THAT MOVE.

MOVEMENT OF COMPONENTS CAN KILL OR CAUSE INJURY TO PERSONS AND/OR CAN CAUSE DAMAGE TO THE EQUIPMENT.

WARNING: DO NOT TOUCH THE APU UNTIL IT IS SUFFICIENTLY COOL TO PREVENT BURNS WHEN YOU DO THE MAINTENANCE TASK(S).

WARNING: WHILE THE APU OPERATES, DO NOT GO INTO THESE AREAS:

THE AREA BEHIND THE APU EXHAUST DUCT: 25m (82ft.) REARWARD OF THE DUCT, MORE THAN 3m (10ft.) ABOVE THE GROUND, AND THE WIDTH OF THE HORIZONTAL STABILIZER
THE AREA AROUND THE APU AIR-INTAKE: 2m (7ft) AROUND THE INTAKE
THE AREA OF THE OIL-COOLER OUTLET.

THERE IS A RISK OF INJURY IF YOU GO INTO THESE AREAS.

FIN: 4005KM ** ON A/C NOT FOR ALL

1. Reason for the Job
The motoring is a procedure in which APU cranks due to the starter action and without combustion in the power section combustion chamber.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE
No specific	AR	CAP - BLANKING
No specific	1	CONTAINER 1 L (1/4 USGAL)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Referenced Information

REFERENCE	DESIGNATION
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 24-42-00-862-001-A	De-energize the Ground Service Network Supplied from the External Power
TASK 29-00-00-864-001-A	Put the Related Hydraulic System in the Depressurized Configuration before Maintenance Action
TASK 52-41-00-010-001-A	Open the APU Doors for Access
TASK 52-41-00-410-001-A	Close the APU Doors after Access

3. Job Set-up
Subtask 49-00-00-941-085-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) Make sure that the APU fire and overheat detection-system and the APU Fire-Extinguishing system are serviceable.
(2) Follow the Warning related to the Safety Precautions when the APU operates.

Subtask 49-00-00-860-176-A ** ON A/C NOT FOR ALL

B. Aircraft Maintenance Configuration
(1) Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).
(2) On the panel 25VU, make sure that the APU MASTER SW p/bsw is OFF.
(3) Put a WARNING NOTICE(S) in the cockpit to tell persons not to start the APU.
(4) Make sure that the hydraulic systems are depressurized
(Ref. AMM TASK 29-00-00-864-001).

Subtask 49-00-00-865-179-A ** ON A/C NOT FOR ALL

WARNING: BEFORE YOU OPEN THESE CIRCUIT BREAKERS (1QF, 2QF, 3QC), MAKE SURE THAT THE "APU MASTER" SWITCH IS SET TO THE "OFF" POSITION. IF YOU DO NOT DO THIS, THE APU FUEL ISOLATION-VALVE WILL STAY OPEN AND FUEL CAN FLOW OUT. THIS CAN CAUSE A DANGEROUS RISK OF FIRE.

C. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	APU/APU/CTL	2KD	L42
121VU	APU/ECB/SPLY	1KD	L41
121VU	APU/FUEL/LP VALVE/CTL	1QF	M40
121VU	APU/FUEL/LP VALVE/SPLY	2QF	M39
121VU	APU/FUEL/PUMP/CTL	3QC	M38

4. Procedure

WARNING: DISCONNECT THE LOW-TENSION ELECTRICAL SUPPLY 6 MINUTES BEFORE YOU START WORK ON THE IGNITION SYSTEM. THE HIGH CURRENT AND VOLTAGE WHICH ARE USED IN THE IGNITION SYSTEM CAN KILL YOU.

CAUTION: DO NOT PUT HYDROCARBON FUEL(S)/OIL(S) INTO THE ENGINE COMPRESSOR. THEY CAN BURN SUDDENLY AND DAMAGE THE APU.

Subtask 49-00-00-860-177-A ** ON A/C NOT FOR ALL

A. Dry Motoring of the APU
(1) Put the ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE below the access doors 315AL and 316AR.
(2) Open the APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-010-001).
(3) Set the LIGHT SW 11LJ to the ON position.
(4) Disconnect the electrical connector P19 from the FCU to isolate the APU from the fuel supply system.

WARNING: MAKE SURE THAT THE IGNITION UNIT IS DE-ENERGIZED AND GROUNDED BEFORE YOU DISCONNECT THE INPUT AND OUTPUT LEADS. DO NOT TOUCH THE CONTACTS OF THE OUTPUT TERMINAL. THE OUTPUT VOLTAGE FROM THE IGNITION UNIT IS HIGH AND DOES NOT DECREASE IMMEDIATELY AFTER DE-ENERGIZATION (THE UNIT IS OF THE CAPACITOR DISCHARGE TYPE). HIGH VOLTAGE CAN KILL YOU.

(5) Disconnect the electrical connector P10 from the ignition unit.
(6) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.
(7) Set the LIGHT SW 11LJ to the OFF position.
(8) Close the APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-410-001).
(9) Put a CONTAINER 1 L (1/4 USGAL) in position below APU drain mast.
(10) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(11) Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):
2KD, 1KD
(12) Dry motor the APU with the starter for 25 seconds at minimum of 8500 rpm:

WARNING: MAKE SURE THAT ELECTRICAL CONNECTOR P10 IS DISCONNECTED FROM THE IGNITION EXCITER. IF THE ELECTRICAL CONNECTOR IS NOT DISCONNECTED, THE APU CAN ACCIDENTLY START AND CAUSE INJURY TO PERSONS.

CAUTION: DO NOT START OR TRY TO START THE APU MORE THAN THREE TIMES, ONE AFTER THE OTHER. AFTER THE THIRD TIME, THERE MUST BE A MINIMUM OF ONE HOUR BEFORE YOU START OR TRY TO START THE APU AGAIN. THIS MAKES SURE THAT THE TEMPERATURE OF THE STARTER MOTOR DECREASES SUFFICIENTLY.

(a) On overhead panel 25VU push the APU MASTER SW p/bsw to the ON position.
(b) Push the APU START p/bsw for approx. 15 seconds to cycle engine.
(c) Stop the dry motor cycle by pushing the APU MASTER SW p/bsw to the OFF position.
(13) Make sure there are no unusual noises or vibration during motoring and rolldown to zero speed.
(14) Remove the CONTAINER 1 L (1/4 USGAL) from position below APU drain mast.
(15) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).
(16) Open, safety and tag this(these) circuit breaker(s):
2KD, 1KD
(17) Open the APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-010-001).
(18) Set the LIGHT SW 11LJ to the ON position.
(19) Remove the CAP-BLANKING from each electrical connector and receptacle.
(20) Make sure that all the electrical connections are clean and in the correct condition.
(21) Connect electrical connector P10 to the ignition unit.
(22) Connect electrical connector P19 to the fuel control unit.
(23) Set the LIGHT SW 11LJ to the OFF position.
(24) Close the APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-410-001).
(25) Remove the access platform(s).

5. Close-up
Subtask 49-00-00-865-180-A ** ON A/C NOT FOR ALL

A. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	APU/APU/CTL	2KD	L42
121VU	APU/ECB/SPLY	1KD	L41
121VU	APU/FUEL/LP VALVE/CTL	1QF	M40
121VU	APU/FUEL/LP VALVE/SPLY	2QF	M39
121VU	APU/FUEL/PUMP/CTL	3QC	M38

Subtask 49-00-00-860-178-A ** ON A/C NOT FOR ALL

B. Aircraft Maintenance Configuration
(1) Make sure that the work area is clean and clear of tools and other items.
(2) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-42-00-862-001)
(3) Remove the WARNING NOTICE(S).
(4) Put the aircraft back to its initial configuration.

[Rev.10 from 2021] 2026.04.01 12:42:47 UTC