Inspection / Check of the Thermocouples (131-9(A))

TASK 49-72-15-200-002-A
Inspection / Check of the Thermocouples (131-9(A))

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

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
315AL, 316AR

C. Referenced Information

REFERENCE	DESIGNATION
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 49-72-15-000-002-A	Removal of the Thermocouples (131-9(A))
TASK 49-72-15-400-003-A	Installation of the Thermocouples (131-9(A))
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 49-72-15-860-061-A ** ON A/C NOT FOR ALL

A. 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) Make sure that there is a warning notice 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 49-72-15-865-061-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 49-72-15-010-054-A ** ON A/C NOT FOR ALL

C. Get Access
(1) Make sure that the access platform is in position below the APU compartment.
(2) Make sure that the APU access doors 315AL 316AR are open (Ref. AMM TASK 52-41-00-010-001).
(3) Set the LIGHT SW 11LJ to the ON position.

4. Procedure
Subtask 49-72-15-210-051-A ** ON A/C NOT FOR ALL

A. Inspection/Check of the Thermocouple
(1) Do a visual check of the thermocouple and make sure that:

there are no dents or cracks,
the thermocouple is not bent,
the threads on the electrical connectors are not damaged or worn,
there are no holes in the thermocouple.

NOTE: Replace the thermocouple if damage is found (Ref. AMM TASK 49-72-15-000-002), (Ref. AMM TASK 49-72-15-400-003).

(2) Do an electrical resistance check of the thermocouple and make sure that:

the resistance across the terminals is not more than 1.0 Ohm,
the resistance between the terminals and the case of the thermocouple is not less than 10 K Ohms.

NOTE: Replace the thermocouple if the results of the electrical checks are not correct (Ref. AMM TASK 49-72-15-000-002), (Ref. AMM TASK 49-72-15-400-003).

5. Close-up
Subtask 49-72-15-410-054-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 SW 11LJ to the OFF position.
(3) Close the APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-410-001).
(4) Remove the access platform(s).

Subtask 49-72-15-865-062-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 49-72-15-860-064-A ** ON A/C NOT FOR ALL

C. Aircraft Maintenance Configuration
(1) Put the related hydraulic system in the pressurized configuration (Ref. AMM TASK 29-00-00-864-001).
(2) De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).
(3) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 01:32:11 UTC