Bottle Pressure Switch Check

TASK 26-22-00-040-007-A
Bottle Pressure Switch Check

Task Summary

Access	Test	Specific Tools	Mhr	E/T	Nb Men
YES	YES	NO	0.3	0.5	2

1. Reason for the Job
MMEL 26-22-02A
APU FIRE EXTINGUISHER OVERPRESSURE INDICATION (RED DISC)
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	ALLEN KEY 3/32 IN
No specific	AR	BOOMSET 600 OHMS
No specific	1	FLASHLIGHT
No specific	AR	HEADSET 600 OHMS
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
314AR

C. 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-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 52-41-23-010-801-A	Opening of Access Door 314AR
TASK 52-41-23-410-801-A	Closing of Access Door 314AR
CHECK OF THE PRESSURE SWITCH CIRCUIT

3. Job Set-up
Subtask 26-22-00-860-062-A

A. Aircraft Maintenance Configuration
(1) Make sure that the aircraft electrical circuits are energized
(Ref. AMM TASK 24-41-00-861-002) or (Ref. AMM TASK 24-41-00-861-002).
(2) In the Cockpit on the CAPT jack panel, connect the HEADSET 600 OHMS to the related connector.
(3) On the overhead panel 50VU, make sure that the ON legend on the SVCE INT OVRD p/bsw is OFF.

Subtask 26-22-00-865-081-A

B. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	APU/APU/CTL	2KD	L42
121VU	APU/ECB/SPLY	1KD	L41

Subtask 26-22-00-010-062-A

C. Get Access

WARNING: BEFORE YOU START WORK, YOU MUST PUT ON A SAFETY HARNESS AND ATTACH IT TO THE ACCESS PLATFORM. WITHOUT A SAFETY HARNESS, YOU CAN FALL. THIS CAN KILL YOU OR CAUSE YOU INJURY.

(1) Put on and attach a safety harness before you start work in the work area
(2) Put the ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE in position below the access door 314AR.
(3) Open access door 314AR and safety it in the open position.
(Ref. AMM TASK 52-41-23-010-801).
(4) If necessary, use a FLASHLIGHT.
(5) In Zone 314, connect the BOOMSET 600 OHMS to the service interphone jack.

4. Procedure
Subtask 26-22-00-710-070-A

A. Do a check at the Pressure Switch of the APU Fire Extinguisher Bottle

NOTE: For this test procedure we recommend that a minimum of two persons are in constant contact with each other through the service interphone system. One person must monitor the cockpit APU FIRE panel 20VU, the other person must be at Zone 314.

ACTION	RESULT
1.On the pressure switch (3): Put the ALLEN KEY 3/32 IN (1) into the pressure switch hexagon test-socket (2). Slowly turn the Allen key (1) clockwise or counterclockwise approx. 10 degrees.	On the APU FIRE panel 20VU: The DISCH legend in the AGENT p/bsw comes on.
NOTE: The pressure effect puts the Allen key (1) back to its initial position. 2.On the pressure switch (3): Release the Allen key (1).	On the APU FIRE panel 20VU: The DISCH legend in the AGENT p/bsw goes off.
3.On the pressure switch (3): Remove the Allen key (1) from the test-socket (2).

5. Close-up
Subtask 26-22-00-410-063-A

A. Close Access
(1) Disconnect the BOOMSET 600 OHMS from the service interphone jack.
(2) Disconnect the HEADSET 600 OHMS from the CAPT jack panel.
(3) Make sure that the work area is clean and clear of tools and other items.
(4) Close access door 314AR (Ref. AMM TASK 52-41-23-410-801).

(5) Remove the access platform(s).
(6) Make an entry in the aircraft technical logbook.

Subtask 26-22-00-865-082-A

B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	APU/APU/CTL	2KD	L42
121VU	APU/ECB/SPLY	1KD	L41

[Rev.10 from 2021] 2026.03.31 23:45:25 UTC