Removal of the Differential Pressure Switch and Indicator (APS 3200)

TASK 49-91-21-000-002-A
Removal of the Differential Pressure Switch and Indicator (APS 3200)

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	CAP - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
315AL, 316AR

C. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
2	PACKING	AIPC 49-91-04-50-060
3	PACKING	AIPC 49-91-04-50-070
2	PACKING	AIPC 49-91-84-20-080
3	PACKING	AIPC 49-91-84-20-090

D. 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 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
Differential Pressure Switch

3. Job Set-up
Subtask 49-91-21-860-051-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 the panel 25VU, make sure that the APU MASTER SW pushbutton switch is off.
(3) Put 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 49-91-21-865-055-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 49-91-21-010-052-A ** ON A/C NOT FOR ALL

C. Get Access
(1) Put the ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE in position 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 control switch 11LJ to the on position.

4. Procedure
Subtask 49-91-21-020-051-A ** ON A/C NOT FOR ALL

A. Removal of the Differential Pressure Switch and Indicator
(1) Disconnect the electrical connector P5 (1) from the differential pressure switch and indicator (5).
(2) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.
(3) Remove the screws (4) from the differential pressure switch and indicator (5).
(4) Remove the differential pressure indicator (5).
(5) Remove and discard the packing (2) AIPC 49-91-04-50-060 PACKING (2) or AIPC 49-91-84-20-080 PACKING (2).
(6) Remove and discard the packing (3) AIPC 49-91-04-50-070 PACKING (3) or AIPC 49-91-84-20-090 PACKING (3).

[Rev.10 from 2021] 2026.04.01 01:33:05 UTC