Removal of the Exhaust Muffler (131-9(A))

TASK 49-81-41-000-003-A
Removal of the Exhaust Muffler (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	1	ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)

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 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 52-41-18-000-001-A	Removal of the APU Exhaust Access-Fairing
Exhaust Muffler

3. Job Set-up
Subtask 49-81-41-860-055-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) 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 49-81-41-865-056-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 49-81-41-010-052-A ** ON A/C NOT FOR ALL

C. Get Access
(1) Put the ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE below the APU access doors 315AL and 316AR.
(2) Open the APU access doors 315AL 316AR (Ref. AMM TASK 52-41-00-010-001).
(3) Set the LIGHT SW 11LJ to the ON position.
(4) Remove the APU exhaust access-fairing 317AL (Ref. AMM TASK 52-41-18-000-001).

4. Procedure
Subtask 49-81-41-020-052-A ** ON A/C NOT FOR ALL

A. Removal of the Exhaust Muffler

Exhaust Muffler ** ON A/C NOT FOR ALL

(1) Loosen the nut (14) and disconnect the drain line (13).
(2) Removal of the Lockwire:

WARNING: USE PROTECTIVE GOGGLES AND GLOVES WHEN YOU REMOVE OR INSTALL LOCKWIRE. EACH TIME YOU CUT LOCKWIRE, REMOVE AND DISCARD IT IMMEDIATELY. LOOSE LOCKWIRE CAN CUT YOU OR MAKE YOU BLIND, AND/OR CAN CAUSE DAMAGE.

(a) Remove and discard the lockwire from the stud fasteners and remove the two halves of the insulation blanket.
(3) Remove the V-clamp (15) from the APU exhaust flange (16).
(4) Remove and discard the cotter pins (2) from the nuts (3) and (5).
(5) Remove the nut (5), the washer (6), the bolt (8) and the washer (9).
(6) Remove the nut (3), the washer (4), the bushing (11) and the bolt (12).
(7) Pull the exhaust muffler (7) from the guide rails (10).
(8) Make an inspection of the flexible seal (1) for damage or chafing. Replace the flexible seal (1) if necessary.
(9) Make an inspection of the thermal insulation segments for damage. Replace the insulation if necessary.

[Rev.10 from 2021] 2026.04.01 12:41:54 UTC