APU AUTO SHUT DOWN - OVERTEMPERATURE, Fuel Control Unit Fault (APS 3200)

TASK 49-00-00-810-894-A
APU AUTO SHUT DOWN - OVERTEMPERATURE, Fuel Control Unit Fault (APS 3200)

1. Possible Causes

damage and/or unwanted material in the air intake system and/or on the engine air-intake screen
damage and/or unwanted material in the exhaust system and/or on the 2nd stage turbine trailing edges
FUEL CONTROL UNIT (8022KM)
PILOT NOZZLES
APU [4005KM]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 49-00-81-810-900-A	APU SLOW START, Start System (APS 3200)
AMM 49-00-00-710-008	Operational Test of the APU
AMM 49-11-11-000-003	Removal of the Power Plant (APU) (APS 3200)
AMM 49-11-11-400-003	Installation of the Power Plant (APU) (APS 3200)
AMM 49-16-00-210-002	Detailed Inspection of APU Air Intake, Diffuser Elbow, Seals and Felt Metal (APS 3200)
AMM 49-20-00-290-001	APU Power Plant Borescope Inspection (APS 3200)
AMM 49-31-41-000-002	Removal of the Pilot Fuel Nozzles and Manifold (APS 3200)
AMM 49-31-41-400-002	Installation of the Pilot Fuel Nozzles and Manifold (APS 3200)
AMM 49-32-11-000-002	Removal of the Fuel Control Unit (APS 3200)
AMM 49-32-11-400-002	Installation of the Fuel Control Unit (APS 3200)
AMM 49-32-51-000-001	Removal of the Combustion Chamber Drain Valve (APS 3200)
AMM 49-32-51-400-001	Installation of the Combustion Chamber Drain Valve (APS 3200)
AMM 49-73-00-00-

3. Fault Confirmation
Subtask 49-00-00-710-236-A ** ON A/C NOT FOR ALL

A. Check/Test
(1) If this Overtemperature Autoshutdown was preceded by a No Flame, check the combustor drain valve for being stucked open and replace as necessary AMM 49-32-51-000-001 and AMM 49-32-51-400-001. Otherwise, continue with the troubleshooting.
(2) Before you start the APU for the operational test:

do a visual inspection and make sure that you do not find damage and/or unwanted material in the air intake system and/or on the engine air-intake screen AMM 49-16-00-210-002.
do a visual inspection and make sure that you do not find damage and/or unwanted material in the exhaust system and/or on the 2nd stage turbine trailing edges AMM 49-20-00-290-001.
turn manually the drive shaft of the cooling fan assembly and make sure that:
. you can turn the manual drive shaft of the cooling fan freely,
. the APU rotors, bearings and gears do not rub,
. the APU rotors, bearings and gears do not make unsual noise.

(a) If you find that the drag of the APU rotors, bearings and gears is too much, they do rub or they make unsual noise, replace the AUXILIARY POWER UNIT (4005KM) AMM 49-11-11-000-003 and AMM 49-11-11-400-003.
(3) Do the operational test of the APU AMM 49-00-00-710-008.

4. Fault Isolation
Subtask 49-00-00-810-145-B ** ON A/C NOT FOR ALL

A. If the APU Last Leg Report gives the maintenance message:

FUEL CTL UNIT (8022KM):
Fault Code Number: 098 or 175

NOTE: The APU SHUTDOWNS report gives the maintenance message:
OVERTEMPERATURE - FUEL CTL UNIT (8022KM)
APU Auto Shut Down Fault Code Number: 098 or 175

replace the FUEL CONTROL UNIT (8022KM) AMM 49-32-11-000-002 and AMM 49-32-11-400-002.

(1) If the fault continues:
Interrogate CFDS for APU fault message. Use prompts (>) to go to the fault conditions screen AMM 49-73-00-00-.

Print Fault Condition Screen and review APU speed (NA).
(a) If speed (NA) is less than 15%:

Do the TSM procedure (Ref. TSM TASK 49-00-81-810-900).

(b) If speed (NA) is more than or equal to 15%:

replace the PILOT NOZZLES AMM 49-31-41-000-002 and AMM 49-31-41-400-002.

(2) If the fault continues:

replace the APU [4005KM] AMM 49-11-11-000-003 and AMM 49-11-11-400-003.

Subtask 49-00-00-710-237-A ** ON A/C NOT FOR ALL

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:34:24 UTC