The SQUIB Legend of the ENG 1/AGENT 2 Pushbutton Switch does not Come on

TASK 26-21-00-810-802-A
The SQUIB Legend of the ENG 1/AGENT 2 Pushbutton Switch does not Come on

1. Possible Causes

lamp of the SQUIB legend of the ENG 1/AGENT 2 pushbutton switch
ENG 1/AGENT 2 pushbutton switch
ENG/APU FIRE PNL [1WD]
CARTRIDGE-ENG1 FIRE EXTING BOTTLE 2 [7WE1]
wiring from the engine 1 fire extinguishing bottle 2 cartridge (7WE1) to the ENG/APU FIRE panel (1WD)
wiring from the circuit breaker 1WE2 to the ENG/APU FIRE panel (1WD)
wiring from the circuit breaker 2WE2 to the ENG/APU FIRE panel (1WD)
wiring from the engine-1 fire-extinguisher-bottle 2 (7WE1) to the engine and APU FIRE panel (1WD)
wiring from the circuit breaker 1WE2 to the engine and APU FIRE panel (1WD)
wiring from the circuit breaker 2WE1 to the engine and APU FIRE panel (1WD)

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	MULTIMETER - STANDARD

B. Referenced Information

REFERENCE	DESIGNATION
ESPM 2045110
AMM 26-12-00-710-001	Operational Check of Loop/Squib
AMM 26-12-12-000-001	Removal of the ENG/APU Fire Panel
AMM 26-12-12-400-001	Installation of the ENG/APU Fire Panel
ASM 262101
AMM 26-21-41-000-001	Removal of the Engine Fire-Extinguisher Bottle
AMM 26-21-41-400-001	Installation of the Engine Fire-Extinguisher Bottle

3. Fault Confirmation
Subtask 26-21-00-865-051-A

A. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
122VU	LIGHTING/TST/BOARD/SPLY	30LP	X06

Subtask 26-21-00-710-052-A

B. Test
(1) Do the operational test of the engine fire and overheat detection (loop/squib) AMM 26-12-00-710-001.

4. Fault Isolation
Subtask 26-21-00-810-051-A ** ON A/C NOT FOR ALL

A. If the SQUIB legend of the ENG 1/AGENT 2 pushbutton switch does not come on during the fire test:

On the panel 25VU, set the ANN LT switch to TEST and do a check to see if the SQUIB legend of the ENG 1/AGENT 2 pushbutton switch comes on.

(1) If the SQUIB legend does not come on:
(a) Replace the lamp of the SQUIB legend of the ENG 1/AGENT 2 pushbutton switch.
1 If the fault continues:

Replace the ENG 1/AGENT 2 pushbutton switch.

(b) Or replace the ENG 1/AGENT 2 pushbutton switch that has LEDs ESPM 2045110.
(2) If the SQUIB legend comes on:

Replace the ENG/APU FIRE PNL [1WD] AMM 26-12-12-000-001 and AMM 26-12-12-400-001.

(a) If the fault continues:

Replace the CARTRIDGE-ENG1 FIRE EXTING BOTTLE 2 [7WE1] AMM 26-21-41-000-001 and AMM 26-21-41-400-001.

CAUTION: BEFORE YOU DO THIS TEST, MAKE SURE THAT THE SQUIB IS INSTALLED IN THE FIRE EXTINGUISHER BOTTLE. IF THE SQUIB IS REMOVED FROM THE BOTTLE, YOU MUST NOT DO THIS TEST BUT ONLY THE TESTS GIVEN IN THE CMM.

CAUTION: WHEN YOU DO THE TESTS OF A SQUIB, USE A MULTIMETER THAT KEEPS THE TEST CURRENT AT A MAXIMUM OF 0.040 A AT EACH POSITION OF THE SELECTOR SWITCH. TOO MUCH AMPERAGE WILL FIRE THE SQUIB AND CAUSE THE DISCHARGE OF THE RELATED FIRE EXTINGUISHER BOTTLE.

(b) If the fault continues:

Do a check of the wiring from the engine 1 fire extinguishing bottle 2 cartridge (7WE1) to the ENG/APU FIRE panel (1WD) ASM 262101.

NOTE: You can measure the resistance of the squib with a MULTIMETER - STANDARD or equivalent. Make sure that each internal squib bridgewire resistance is 1 +/- 0.1 ohm.

1 If there is no continuity:

Repair the above wiring.

2 If there is continuity:

Do a check of the wiring from the circuit breaker 1WE2 to the ENG/APU FIRE panel (1WD) pin B/F ASM 262101.

a If there is no continuity:

Repair the above wiring.

b If there is continuity:

Do a check and repair the wiring from the circuit breaker 2WE2 to the ENG/APU FIRE panel (1WD) pin B/H ASM 262101.

Subtask 26-21-00-810-051-B ** ON A/C NOT FOR ALL

A. If the SQUIB legend of the ENG 1/AGENT 2 pushbutton switch does not come on during the fire test:

On the overhead indicator and control panel 25VU, set the ANN LT switch to TEST to see if the SQUIB legend of the ENG 1/AGENT 2 pushbutton switch comes on.

(1) If the SQUIB legend does not come on:
(a) Replace the lamp of the SQUIB legend of the ENG 1/AGENT 2 pushbutton switch.
1 If the fault continues:

Replace the ENG 1/AGENT 2 pushbutton switch.

(b) Or replace the ENG 1/AGENT 2 pushbutton switch that has LEDs ESPM 2045110.
(2) If the SQUIB legend comes on:

Replace ENG/APU FIRE PNL [1WD] AMM 26-12-12-000-001 and AMM 26-12-12-400-001.

(a) If the fault continues:

Replace CARTRIDGE-ENG1 FIRE EXTING BOTTLE 2 [7WE1] AMM 26-21-41-000-001 and AMM 26-21-41-400-001.

(b) If the fault continues:

Do a check of the wiring from the engine-1 fire-extinguisher-bottle 2 (7WE1) to the engine and APU FIRE panel (1WD) ASM 262101.

NOTE: You can measure the resistance of the squib with a MULTIMETER - STANDARD or equivalent. Make sure that each internal squib bridgewire resistance is 1 plus or minus 0.1 ohm.

1 If there is no continuity:

Repair the wiring.

2 If there is continuity:

Do a check of the wiring from the circuit breaker 1WE2 to the engine and APU FIRE panel (1WD) pin B/F ASM 262101.

a If there is no continuity:

Repair the wiring.

b If there is continuity:

Do a check of the wiring from the circuit breaker 2WE1 to the engine and APU FIRE panel (1WD) pin B/H ASM 262101.

Subtask 26-21-00-710-053-A

B. Do the test given in Para. 3.

5. Close-up
Subtask 26-21-00-860-051-A

A. Put the aircraft back to its initial configuration.
(1) On the panel 25VU, set the ANN LT switch to BRT.

[Rev.8 from Aug 2018] 2026.04.04 04:27:23 UTC