Oil Smoke at the APU Exhaust (131-9(A))

TASK 49-00-81-810-889-A
Oil Smoke at the APU Exhaust (131-9(A))

1. Possible Causes

gearbox vent tube
air/oil separator adapter
APU [4005KM]
flexible seals on the air intake system

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	LIGHT SOURCE - ULTRA-VIOLET

B. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 49-00-81-810-874-A	Fumes in the Cabin/Oil Smoke at the APU Exhaust (131-9(A))
AMM 12-33-21-618-001	Pre-conditioning through the LP Ground Connection
AMM 21-00-00-100-001	Cleaning of Special Components in the Environmental Control System (ECS)
AMM 21-00-00-615-001	Decontamination of the Environmental Control System (ECS) when the Temperature is below 24 deg.C (APU)
AMM 21-00-00-615-002	Decontamination of the Environmental Control System (ECS) when the Temperature is above 24 deg.C (APU)
AMM 49-00-00-100-003	Cleaning of the APU Compartment with installed APU
AMM 49-00-00-710-010	Operational Test of the APU
AMM 49-00-00-860-008	APU Start by External Power
AMM 49-00-00-860-009	APU Shutdown by External Power (131-9(A))
AMM 49-11-11-000-004	Removal of the Power Plant (APU) (131-9(A))
AMM 49-11-11-400-004	Installation of the Power Plant (APU) (131-9(A))
AMM 49-16-00-100-005	Cleaning of the APU Air Intake (131-9(A))
AMM 49-16-00-200-002	Detailed Inspection of APU Air Intake, Diffuser Elbow, Seals and Felt Metal (131-9(A))
AMM 49-20-00-100-004	APU Compressor Cleaning (131-9 (A))
AMM 49-26-54-000-003	Removal of the Air/Oil Separator Adapter
AMM 49-26-54-400-001	Installation of the Air/Oil Separator Adapter
AMM 49-26-55-000-801	Removal of the Gearbox Vent Tube
AMM 49-26-55-100-801	Cleaning of the Gearbox Vent Tube
AMM 49-26-55-400-801	Installation of the Gearbox Vent Tube

3. Fault Confirmation
Subtask 49-00-81-710-228-A ** ON A/C NOT FOR ALL

A. Do the operational test of the APU AMM 49-00-00-710-010 and do a check on the APU exhaust for oil smoke.

4. Fault Isolation
Subtask 49-00-81-810-154-A ** ON A/C NOT FOR ALL

A. Make sure visually that no oil smoke comes from the APU exhaust:
(1) If there is no oil smoke at the exhaust during the operation of the APU:

Do the cleaning and testing as given in the Para. 4.B.

(2) If there is oil smoke at the exhaust during the operation of the APU:
(a) Remove and clean the gearbox vent tube AMM 49-26-55-000-801 AMM 49-26-55-100-801.
(b) Replace the air/oil separator adapter AMM 49-26-54-000-003 and AMM 49-26-54-400-001.
(c) Install the gearbox vent tube AMM 49-26-55-400-801 and do the cleaning and testing as given in the Para. 4.B.
(3) If the fault continues:

Replace the APU [4005KM] AMM 49-11-11-000-004 and AMM 49-11-11-400-004.

Subtask 49-00-81-710-229-A ** ON A/C NOT FOR ALL

B. Cleaning and Testing

NOTE: If an external leak was identified on the APU:

do the repair,
clean the area,
start and operate the APU with no bleed air supply and no APU generator load AMM 49-00-00-860-008,
let the APU operate 15 minutes for thermal stabilization,
make sure visually that no oil smoke comes from the APU exhaust,
do the APU shutdown AMM 49-00-00-860-009,
immediately after the APU has stopped, examine the area carefully and make sure that there is no leak,
if there is a leak (the repair was not succesful), do the repair and/or replace as necessary.
if there is no leak (the repair was successful), continue as given subsequent.

If no external leak was identified on the APU, do the procedure as given subsequent.

(1) If dirty, clean the APU compartment AMM 49-00-00-100-003.
(2) If dirty, clean the air intake diverter, the air inlet duct and the air intake diffuser and elbow AMM 49-16-00-100-005.
(3) Do a check and make sure that the flexible seals on the air intake system are in correct condition AMM 49-16-00-200-002 and clean.
(4) Do the cleaning of the APU compressors AMM 49-20-00-100-004.
(5) Clean the APU bleed air duct, the pneumatic ducts of the aircraft and the environmental control system AMM 21-00-00-615-001 or AMM 21-00-00-615-002 and AMM 21-00-00-100-001.
(6) Do the pre-conditioning with the APU AMM 12-33-21-618-001 and make sure that you do not smell fumes in the cabin and/or there is no oil smoke at the APU exhaust.

if you smell smoke in the cabin, do the applicable trouble shooting procedure (Ref. TSM TASK 49-00-81-810-874).

(7) Do a leak check and make sure that there is no fuel leak and/or no oil leak on the APU and/or the APU generator.

NOTE: Do the leak check with a LIGHT SOURCE - ULTRA-VIOLET.

[Rev.8 from Aug 2018] 2026.04.04 04:34:38 UTC