Circuit Verification

TASK 26-22-00-040-005-A
Circuit Verification

WARNING: MAKE SURE THAT ALL THE CIRCUITS IN MAINTENANCE ARE ISOLATED BEFORE YOU SUPPLY ELECTRICAL POWER TO THE AIRCRAFT. UNWANTED ELECTRICAL POWER CAN BE DANGEROUS.

WARNING: THE CARTRIDGE IS AN EXPLOSIVE DEVICE. REMOVE IT BEFORE YOU DISASSEMBLE THE FIRE EXTINGUISHER BOTTLE. TO PREVENT INJURY TO THE PERSONNEL BECAUSE OF THE EXPLOSION OF THE CARTRIDGE IF IT HAS NOT BEEN FIRED:

INSTALL A SHUNT DEVICE.
THIS WILL SHUNT THE PINS TOGETHER ON THE CARTRIDGE BEFORE ITS REMOVAL.

DO NOT USE A FOIL SHUNT.

Task Summary

Access	Test	Specific Tools	Mhr	E/T	Nb Men
YES	YES	YES	0.3	0.7	2

1. Reason for the Job
MMEL 26-01-01-06A
APU AGENT PB SQUIB LIGHT
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	BOOMSET 600 OHMS
No specific	1	FLASHLIGHT
No specific	AR	HEADSET 600 OHMS
No specific	AR	MULTIMETER - STANDARD
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)
6971-0010	1	CAP SHUNT-FIRE BOTTLE
MS25043-10DA	1	CARTRIDGE CAP

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
APU FIRE-EXTINGUISHER BOTTLE

3. Job Set-up
Subtask 26-22-00-941-059-A

A. Put the WARNING NOTICE(S) in position on the overhead panel 25VU to tell persons not to operate the APU.

Subtask 26-22-00-865-071-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	APU/FIRE/EXTIG/SQUIB/B	2WF	L39
121VU	APU/FIRE/EXTIG/SQUIB/A	1WF	L38

Subtask 26-22-00-860-058-A

C. 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) 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 pushbutton switch is off.

Subtask 26-22-00-010-059-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Put the ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE in position below the access door 314AR.
(2) Open access door 314AR and safety it in the open position.
(Ref. AMM TASK 52-41-23-010-801).
(3) If necessary, use a FLASHLIGHT.
(4) In Zone 314, connect the BOOMSET 600 OHMS to the service interphone jack.
(5) Disconnect the electrical connector (2) from the cartridge (1).
(6) Put a MS25043-10DA CARTRIDGE CAP (3) on the cartridge (1).
(7) On the electrical connector (2), temporarily ground the pins A and B.

Subtask 26-22-00-010-059-B ** ON A/C NOT FOR ALL

D. Get Access
(1) Put the ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE in position below the access door 314AR.
(2) Open access door 314AR and safety it in the open position.
(Ref. AMM TASK 52-41-23-010-801).
(3) If necessary, use a FLASHLIGHT.
(4) In Zone 314, connect the BOOMSET 600 OHMS to the service interphone jack.
(5) Disconnect the electrical connector (2) from the cartridge (1).
(6) Put a 6971-0010 CAP SHUNT-FIRE BOTTLE (3) or CAP SHUNT-FIRE BOTTLE (CAPLUGS LLC CEC-10) (3) on the cartridge (1).
(7) On the electrical connector (2), temporarily ground the pins A and B.

Subtask 26-22-00-865-072-A

E. 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/FIRE/EXTIG/SQUIB/B	2WF	L39
121VU	APU/FIRE/EXTIG/SQUIB/A	1WF	L38

4. Procedure
Subtask 26-22-00-710-067-A

WARNING: MAKE SURE THAT YOU WILL NOT CAUSE UNWANTED CHANGES TO OTHER SYSTEMS BEFORE YOU PUSH THE APU FIRE PUSHBUTTON SWITCH. WHEN YOU PUSH THE APU FIRE PUSHBUTTON SWITCH, THESE VALVES CLOSE :

LP FUEL SHUTOFF VALVE (APU)
FUEL SOLENOID VALVE (APU)
BLEED AIR VALVE (APU)

A. Operational Test of the Firing Circuit and the Test Circuit

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 electrical connector (2): Remove the temporary ground connection from the pins A and B.
2.On the electrical connector (2): Connect a MULTIMETER - STANDARD between pin A and a ground.	On the multimeter 0 VDC is shown.
3.On the APU FIRE panel 20VU: Lift the guard then push and release the APU FIRE pushbutton switch. Push and hold the APU AGENT pushbutton switch.	On the multimeter 28 VDC is shown. NOTE: Ignore the APU AGENT SQUIB legend and other subsequent effects.
4.On the APU FIRE panel 20VU: Release APU AGENT pushbutton switch.	On the multimeter 0 VDC is shown.
5.On the electrical connector (2): Connect the MULTIMETER - STANDARD between pin B and a ground.	On the multimeter 0 VDC is shown.
6.On the APU FIRE panel 20VU: Push and hold the APU AGENT pushbutton switch.	On the multimeter 28 VDC is shown.
7.On the APU FIRE panel 20VU: Release APU AGENT pushbutton switch.	On the multimeter 0 VDC is shown.
8.On the APU FIRE panel 20VU: Push and latch the APU FIRE pushbutton switch. Put the guard of the APU pushbutton switch in the correct position.
NOTE: If the test is correct, the firing system will operate correctly. NOTE: If the test is not correct (no voltage), the firing system is defective and do the applicable trouble shooting procedure.

5. Close-up
Subtask 26-22-00-865-073-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	APU/FIRE/EXTIG/SQUIB/B	2WF	L39
121VU	APU/FIRE/EXTIG/SQUIB/A	1WF	L38

Subtask 26-22-00-410-060-A ** ON A/C NOT FOR ALL

B. Put the aircraft back to its initial configuration.
(1) Remove the MS25043-10DA CARTRIDGE CAP (3) from the cartridge (1).
(2) Make sure that all the electrical connections are clean and in the correct condition.
(3) Connect the electrical connector (2) to the cartridge (1).
(4) Disconnect the BOOMSET 600 OHMS from the service interphone jack.
(5) Disconnect the HEADSET 600 OHMS from the CAPT jack panel.
(6) Make sure that the work area is clean and clear of tools and other items.
(7) Close access door 314AR (Ref. AMM TASK 52-41-23-410-801).
(8) Remove the ground support and maintenance equipment, the special and standard tools and all other items.
(9) Remove the access platform(s).
(10) Remove the warning notice from the panel 25VU.
(11) Put the WARNING NOTICE(S) in the cockpit to tell the flight crew that the APU AGENT SQUIB light is deactivated.
(12) Make an entry in the aircraft technical logbook.

Subtask 26-22-00-410-060-B ** ON A/C NOT FOR ALL

B. Put the aircraft back to its initial configuration.
(1) Remove the 6971-0010 CAP SHUNT-FIRE BOTTLE (3) or CAP SHUNT-FIRE BOTTLE (CAPLUGS LLC CEC-10) (3) from the cartridge (1).
(2) Make sure that all the electrical connections are clean and in the correct condition.
(3) Connect the electrical connector (2) to the cartridge (1).
(4) Disconnect the BOOMSET 600 OHMS from the service interphone jack.
(5) Disconnect the HEADSET 600 OHMS from the CAPT jack panel.
(6) Make sure that the work area is clean and clear of tools and other items.
(7) Close the access door 314AR (Ref. AMM TASK 52-41-23-410-801).
(8) Remove the ground support and maintenance equipment, the special and standard tools and all other items.
(9) Remove the access platform(s).
(10) Remove the warning notice from the panel 25VU.
(11) Put the WARNING NOTICE(S) in the cockpit to tell the flight crew that the APU AGENT SQUIB light is deactivated.
(12) Make an entry in the aircraft technical logbook.

Subtask 26-22-00-865-074-A

C. 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/FIRE/EXTIG/SQUIB/B	2WF	L39
121VU	APU/FIRE/EXTIG/SQUIB/A	1WF	L38

[Rev.10 from 2021] 2026.03.31 23:45:24 UTC