Check APU compartment and air intake duct for oil contamination

TASK 49-00-00-790-008-A
Check APU compartment and air intake duct for oil contamination

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: DO NOT START THE APU WHEN THE AIRCRAFT IS IN THE HANGAR. WHEN THE APU OPERATES, THERE ARE RISKS OF INJURY FROM HIGH TEMPERATURES AND DANGEROUS FUMES (THAT CAN FILL THE HANGAR). MAKE SURE THAT PERSONS STAY AWAY FROM THE EXHAUST DUCT. THE EXHAUST DUCT IS DANGEROUS.

WARNING: LOCK THE MECHANISM OF THE ACCESS DOOR 316AR WITH THE PIP PIN WHEN YOU OPEN THE ACCESS DOOR. THIS WILL PREVENT INJURY.

CAUTION: DO NOT START THE APU WITH ACCESS DOORS 315AL AND 316AR OPEN/REMOVED. THE APU FIRE EXTINGUISHER SYSTEM IS NOT SUFFICIENT TO EXTINGUISH A FIRE IF THE ACCESS DOORS 315AL AND 316AR ARE OPEN/REMOVED.

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.

ZONE: 315
ZONE: 316

1. Reason for the Job
Refer to the MPD TASK: 499100-B4
CHECK APU COMPARTMENT AND AIR INTAKE DUCT FOR OIL CONTAMINATION
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	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)
98L12003001000	AR	HARNESS,SAFETY

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
315	TAIL CONE APU AND ACCESSORY COMPARTMENT
316	TAIL CONE APU AND ACCESSORY COMPARTMENT
315AL, 316AR

C. 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 29-00-00-864-001-A	Put the Related Hydraulic System in the Depressurized Configuration before Maintenance Action
TASK 49-00-00-710-010-A	Operational Test of the APU
TASK 49-00-00-860-009-A	APU Shutdown by External Power (131-9(A))
TASK 49-00-00-860-009-A-01	APU Shutdown by Batteries (131-9(A))
TASK 49-11-11-000-004-A	Removal of the Power Plant (APU) (131-9(A))
TASK 49-11-11-400-004-A	Installation of the Power Plant (APU) (131-9(A))
TASK 49-91-48-000-801-A	Removal of the Oil Filler Cap
TASK 49-91-48-400-801-A	Installation of the Oil Filler Cap
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
TASK 49-11-11-000-004-A	Removal of the Power Plant (APU) (131-9(A)) (for corrective action)
TASK 49-11-11-400-004-A	Installation of the Power Plant (APU) (131-9(A)) (for corrective action)
TASK 49-13-00-200-003-A	General Visual Inspection of all APU Compartment Fire Walls and Seals (Compartment Doors, Fwd and Aft Walls, Side Fire Walls, Upper Fire Wall) (for corrective action)
TASK 49-16-00-100-005-A	Cleaning of the APU Air Intake (131-9(A)) (for corrective action)
TASK 49-16-45-000-003-A	Removal of the Air Intake Diffuser and Elbow (131-9(A)) (for corrective action)
TASK 49-16-45-400-003-A	Installation of the Air Intake Diffuser and Elbow (131-9(A)) (for corrective action)
TASK 49-17-41-000-003-A	Removal of the Drain Tank (131-9(A)) (for corrective action)
TASK 49-90-00-600-007-A	Check Oil Level and Replenish (131-9(A)) (for corrective action)
Witness drain for load compressor seal and APU drain lines (131-9(A))
APU Compartment firewall seal at frame 80

3. Job Set-up
Subtask 49-00-00-860-147-A ** ON A/C NOT FOR ALL

A. Aircraft Maintenance Configuration
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) On overhead panel 25VU, make sure that the APU MASTER SW pushbutton switch is released (the ON legend is off).
(3) Make sure that the hydraulic systems are depressurized
(Ref. AMM TASK 29-00-00-864-001).

4. Procedure
Subtask 49-00-00-790-057-A ** ON A/C NOT FOR ALL

A. Do a check of the APU for Oil/Fuel Leaks
(1) Start and operate the APU in the ECS mode (Ref. AMM TASK 49-00-00-710-010).
(2) During APU operation:

do a check for oil smell in the aircraft passenger compartment.
do a check for signs of smoke from the APU exhaust.

NOTE: Oil smell in the passenger compartment is an indication of internal and/or external oil leakage.

Smoke from the APU exhaust is an indication of internal oil leakage.

(3) Stop the APU (Ref. AMM TASK 49-00-00-860-009).
(4) On the APU section of overhead panel 25VU, put a WARNING NOTICE(S) to tell persons not to start the APU.

Subtask 49-00-00-865-145-A ** ON A/C NOT FOR ALL

B. 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

Subtask 49-00-00-010-082-A ** ON A/C NOT FOR ALL

C. Get Access

WARNING: BEFORE YOU START WORK, YOU MUST PUT ON A SAFETY HARNESS AND ATTACH IT TO THE ACCESS PLATFORM. WITHOUT A SAFETY HARNESS, YOU CAN FALL. THIS CAN KILL YOU OR CAUSE YOU INJURY.

(1) Put on and attach the HARNESS, SAFETY before you start work in the work area.
(2) Put an ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE in position below APU access doors 315AL and 316AR.
(3) Open APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-010-001).
(4) Set the light switch 11LJ to the ON position.

Subtask 49-00-00-210-076-A ** ON A/C NOT FOR ALL

D. APU Internal Oil Leakage
(1) Make sure that the APU oil level is correct (Ref. AMM TASK 49-90-00-600-007).

NOTE: If the oil system is too full it can cause APU internal oil-leakage which causes oil smell/fumes in the passenger compartment.

(2) To do a check for signs of oil leakage at the load-compressor carbon seal, you must examine the witness drain of the load compressor. This witness drain is at the centre of the drain mast.

Witness drain for load compressor seal and APU drain lines (131-9(A)) ** ON A/C NOT FOR ALL

Leakage is not permitted. If signs of oil leakage are found:
(a) Remove the APU (Ref. AMM TASK 49-11-11-000-004).
(b) Send the APU to the supplier to replace the load-compressor carbon seal with a new hydropad seal.
(c) Install the APU (Ref. AMM TASK 49-11-11-400-004).
(3) Do a check for signs of oil at the oil scavenge tube of the APU rear-bearing. Signs of oil are an indication of possible internal oil leakage, if signs of oil leakage are found:
(a) Replace the APU (Ref. AMM TASK 49-11-11-000-004) and (Ref. AMM TASK 49-11-11-400-004)

Subtask 49-00-00-210-077-A ** ON A/C NOT FOR ALL

E. Do a check for signs of Fluid Migration in the APU Air Intake Duct and APU Compartment.
(1) Do the steps that follow to find and/or prevent APU internal/external fluid leakage:

NOTE: APU internal/external fluid leakage can cause an oil smell/fumes in the cabin.

(a) Examine the APU air intake and air intake duct internally and externally for signs of fluid contamination by migration (engine oil, hydraulic oil, fuel, de-icing fluid). If signs of fluid contamination are found:

clean the air-intake duct and diffuser elbow (Ref. AMM TASK 49-16-00-100-005).
clean the air-intake flap internally and externally.
clean the APU access doors internally and externally.
clean the APU compartment walls and firewalls.

(b) Examine the APU inlet plenum for oil/fluid contamination. If signs of contamination are found:

clean the APU inlet plenum with a degreaser and/or steam cleaner.

Subtask 49-00-00-210-078-A ** ON A/C NOT FOR ALL

F. Do an inspection of the APU External Components/Interfaces for Oil Leakage
(1) Examine the gravity oil-filler cap for signs of oil leakage. If signs of oil leakage are found:
(a) Replace the oil-filler cap (Ref. AMM TASK 49-91-48-000-801) and (Ref. AMM TASK 49-91-48-400-801).

Subtask 49-00-00-210-080-A ** ON A/C NOT FOR ALL

G. Inspection of the APU Compartment; fire, duct and drain seals.
(1) Examine the APU Compartment firewall seal at frame 80 (Ref. AMM TASK 49-13-00-200-003). Signs of oil, are an indication of possible oil leakage.

If the APU Compartment firewall seal has signs of damage or is deformed, replace the seal.
APU Compartment firewall seal at frame 80 ** ON A/C NOT FOR ALL

(2) Examine the APU inlet seal at the diffuser to plenum interface. Do a check for signs of oil. Signs of oil, are an indication of possible internal oil leakage.

If the APU inlet seal has signs of damage or is deformed, replace the seal (Ref. AMM TASK 49-16-45-000-003).

NOTE: If the air-intake diffuser is not correctly aligned, this can let in unwanted fluids.

(3) Make sure that the air-intake diffuser is correctly aligned (Ref. AMM TASK 49-16-45-400-003).
(4) Examine the APU drain lines to make sure that they are correctly aligned with the APU drain-tank/spring-adapter assembly on the RH APU access door. If they are not correctly aligned:

adjust the APU drain-tank/spring-adapter assembly (Ref. AMM TASK 49-17-41-000-003).

5. Close-up
Subtask 49-00-00-410-084-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Set the light switch 11LJ to the OFF position.
(3) Close APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-410-001).
(4) Remove the access platform(s).
(5) Remove the 98L12003001000 HARNESS,SAFETY.

Subtask 49-00-00-865-146-A ** ON A/C NOT FOR ALL

B. 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

Subtask 49-00-00-860-148-A ** ON A/C NOT FOR ALL

C. Aircraft Maintenance Configuration
(1) Pressurize the aircraft hydraulic systems
(Ref. AMM TASK 29-00-00-864-001).
(2) Remove the WARNING NOTICE(S).
(3) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

[Rev.10 from 2021] 2026.04.01 01:26:02 UTC