Check of Engine Firing Circuit Continuity

TASK 26-21-00-720-001-A
Check of Engine Firing Circuit Continuity

CAUTION: TO RESET THE ENG 1(2) APU FIRE PUSHBUTTON SWITCH:

PUSH THE PUSHBUTTON SWITCH FULLY IN (LATCHED POSITION).

THEN CLOSE THE GUARD. DO NOT TRY TO CLOSE THE GUARD AND PUSH THE PUSHBUTTON SWITCH AT THE SAME TIME.

ZONE: 415
ZONE: 425
FIN: 6WE1
FIN: 6WE2
FIN: 8WE1
FIN: 8WE2

1. Reason for the Job
Refer to the MPD TASK: 262100-03
CHECK FIRING CIRCUIT CONTINUITY
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	VOLTMETER - DC
No specific	AR	WARNING NOTICE(S)
263193	2	SHUNT PLUG-FIRE EXTINGUISHER CARTRIDGE
53100141-1	1	PLUG, SHUNT
OR	OR
M83723-60-18AN	1	CAP, PROTECTIVE

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
415	LOWER PYLON
425	LOWER PYLON
FOR [6WE1] (BOTTLE 1-FIRE EXTING, ENG 1)
FOR [8WE1] (BOTTLE 2-FIRE EXTING, ENG 1)
415BL
415BR
415CR
FOR [6WE2] (BOTTLE 1-FIRE EXTING, ENG 2)
FOR [8WE2] (BOTTLE 2-FIRE EXTING, ENG 2)
425BL
425CR
425BR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 20-15-00-910-001-A	Handling Precautions for Electrostatic Discharge Sensitive Devices
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 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 26-12-00-710-001-A	Operational Check of Loop/Squib
TASK 29-10-00-710-001-A	Operational Check of Hydraulic Fire Shut Off Valves and Associated Indicating System
TASK 54-51-21-000-802-A	Removal of the Pylon Lateral Access-Doors
TASK 54-51-21-400-802-A	Installation of the Pylon Lateral Access-Doors
Engine Fire-Extinguisher Bottle ** ON A/C NOT FOR ALL
Engine Fire-Extinguisher Bottle ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 26-21-00-861-050-A

A. Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002).

Subtask 26-21-00-941-050-A

B. Safety Precautions
(1) On the ENG panel 115VU:
(a) Make sure that the ENG/MODE/CRANK/NORM/IGN/START selector switch is in the NORM position.
(b) Put a WARNING NOTICE(S) in position to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than 5 minutes before you do this procedure.
(3) On the maintenance panel 50VU:
(a) Make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) in position to tell persons not to energize the FADEC 1(2).

Subtask 26-21-00-865-080-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE1	Q44
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE2	Q42
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/A	1WE1	Q43
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/A	1WE2	Q41
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE1	Q44
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE2	Q42
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE1	Q43
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/A	1WE1	Q42
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE2	Q41
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/A	1WE2	Q40

Subtask 26-21-00-010-050-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position.
(2) Remove the access doors:
(a) FOR [6WE1] (BOTTLE 1-FIRE EXTING, ENG 1), [8WE1] (BOTTLE 2-FIRE EXTING, ENG 1)
415BL 415BR
(b) FOR [6WE2] (BOTTLE 1-FIRE EXTING, ENG 2), [8WE2] (BOTTLE 2-FIRE EXTING, ENG 2)
425BL 425BR.

Subtask 26-21-00-010-050-B ** ON A/C NOT FOR ALL

D. Get Access
(1) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position.
(2) Remove the access doors (Ref. AMM TASK 54-51-21-000-802):
(a) FOR [6WE1] (BOTTLE 1-FIRE EXTING, ENG 1), [8WE1] (BOTTLE 2-FIRE EXTING, ENG 1)
415BL 415CR
(b) FOR [6WE2] (BOTTLE 1-FIRE EXTING, ENG 2), [8WE2] (BOTTLE 2-FIRE EXTING, ENG 2)
425BL 425CR.

Subtask 26-21-00-020-053-B ** ON A/C NOT FOR ALL

E. Aircraft Maintenance Configuration

WARNING: DO NOT TOUCH THE CARTRIDGE BEFORE YOU DO THE PROCEDURE APPLICABLE TO DEVICES THAT ARE SENSITIVE TO ELECTROSTATIC DISCHARGE. ELECTROSTATIC DISCHARGE CAN CAUSE THE FIRE EXTINGUISHER BOTTLE TO RELEASE ITS CONTENTS SUDDENLY AND CAUSE INJURY TO PERSONS.

(1) Before you touch the cartridge, do the procedure for devices that are sensitive to electrostatic discharge (Ref. AMM TASK 20-15-00-910-001).
(2) In the engine pylon, on the engine fire extinguisher bottle, disconnect the electrical connectors from the cartridges:

for the engine 1: 5WE1-A (bottle 1) and 7WE1-A (bottle 2)
for the engine 2: 5WE2-A (bottle 1) and 7WE2-A (bottle 2).

(3) Put 53100141-1 PLUG, SHUNTM83723-60-18AN CAP, PROTECTIVE on the cartridges.

Subtask 26-21-00-020-053-C ** ON A/C NOT FOR ALL

E. Aircraft Maintenance Configuration

for the engine 1: 5WE1-A (bottle 1) and 7WE1-A (bottle 2)
for the engine 2: 5WE2-A (bottle 1) and 7WE2-A (bottle 2).

(3) Put 263193 SHUNT PLUG-FIRE EXTINGUISHER CARTRIDGE on the cartridges.

Subtask 26-21-00-020-057-A

F. On the ENG/APU FIRE panel 1WD, open the guard of the ENG 1(2) FIRE pushbutton switch.

Subtask 26-21-00-865-066-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE1	Q44
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE2	Q42
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/A	1WE1	Q43
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/A	1WE2	Q41
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE1	Q44
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE2	Q42
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE1	Q43
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/A	1WE1	Q42
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE2	Q41
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/A	1WE2	Q40

4. Procedure
Subtask 26-21-00-720-050-A

A. Do this test

ACTION	RESULT
1.In the engine pylon, on the engine fire-extinguisher bottle 1:
A.Connect a VOLTMETER - DC to the electrical connector 5WE1-A (5WE2-A) between: the pin 1 and the aircraft grounding point the pin 2 and the aircraft grounding point.	In the engine pylon: the voltmeter must read 0VDC.
2.On the ENG/APU FIRE panel 1WD:
A.Push then release the ENG 1(2) FIRE pushbutton switch.	You can hear the single chime.
	On the ENG/APU FIRE panel 1WD: on the AGENT 1 and AGENT 2 pushbutton switches, the SQUIB legend comes on.
	On the glareshield panels 130VU and 131VU: the MASTER CAUT lights come on.
B.Push and hold the AGENT 1 pushbutton switch.	In the engine pylon, make sure that the voltmeter reads between 25.5VDC and 30.3VDC: between pin 1 and the ground, and between pin 2 and the ground.
C.Release the AGENT 1 pushbutton switch.	In the engine pylon, make sure that the voltmeter reads 0VDC: between pin 1 and the grounding point, and between pin 2 and the grounding point.
3.In the engine pylon, on the engine fire-extinguisher bottle 1: Disconnect the voltmeter.
4.In the engine pylon, on the engine fire-extinguisher bottle 2:
A.Connect the voltmeter to the electrical connector 7WE1-A (7WE2-A) between: the pin 1 and the aircraft grounding point the pin 2 and the aircraft grounding point.	In the engine pylon: the voltmeter must read 0VDC.
5.On the ENG/APU FIRE panel 1WD:
A.Push and hold the AGENT 2 pushbutton switch.	In the engine pylon, make sure that the voltmeter reads between 25.5VDC and 30.3VDC: between pin 1 and the grounding point, and between pin 2 and the grounding point.
B.Release the AGENT 2 pushbutton switch.	In the engine pylon, make sure that the voltmeter reads 0VDC: between pin 1 and the grounding point, and between pin 2 and the grounding point.
C.Push the ENG 1(2) FIRE pushbutton switch.	On the ENG/APU FIRE panel 1WD : on the AGENT 1 and AGENT 2 pushbutton switches, the SQUIB legend goes off.
	On the glareshield panels 130VU and 131VU : the MASTER CAUT light goes off.

5. Close-up
Subtask 26-21-00-865-096-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE1	Q44
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE2	Q42
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/A	1WE1	Q43
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/A	1WE2	Q41
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE1	Q44
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE2	Q42
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE1	Q43
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/A	1WE1	Q42
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE2	Q41
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/A	1WE2	Q40

Subtask 26-21-00-420-052-A

B. Put the aircraft back to the serviceable condition.
(1) Disconnect the voltmeter.
(2) Remove the shunt plugs from the cartridges.
(3) In the engine pylon, on the engine fire extinguisher bottle, connect the electrical connectors:

for the engine 1: 5WE1-A (bottle 1) and 7WE1-A (bottle 2)
for the engine 2: 5WE2-A (bottle 1) and 7WE2-A (bottle 2).

(4) On the ENG/APU FIRE panel 1WD, close the guard of the ENG 1(2) FIRE pushbutton switch.

Subtask 26-21-00-865-097-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 NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE1	Q44
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE2	Q42
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/A	1WE1	Q43
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/A	1WE2	Q41
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE1	Q44
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE2	Q42
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/B	2WE1	Q43
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/A	1WE1	Q42
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL1/SQUIB/B	2WE2	Q41
121VU	ENGINE/ENG1 AND 2 FIRE EXTIG/BTL2/SQUIB/A	1WE2	Q40

Subtask 26-21-00-710-051-A

D. Operational Test
(1) Do an operational test of the engine fire and overheat detection (Loop/Squib) (Ref. AMM TASK 26-12-00-710-001).
(2) Do an operational test of the hydraulic fire shut-off valves (Ref. AMM TASK 29-10-00-710-001).

Subtask 26-21-00-410-050-A ** ON A/C NOT FOR ALL

E. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the access doors:
(a) FOR [6WE1] (BOTTLE 1-FIRE EXTING, ENG 1), [8WE1] (BOTTLE 2-FIRE EXTING, ENG 1)
415BL 415BR
(b) FOR [6WE2] (BOTTLE 1-FIRE EXTING, ENG 2), [8WE2] (BOTTLE 2-FIRE EXTING, ENG 2)
425BL 425BR
(3) Remove the WARNING NOTICE(S).
(4) Remove the access platform(s).

Subtask 26-21-00-410-050-B ** ON A/C NOT FOR ALL

E. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the access doors (Ref. AMM TASK 54-51-21-400-802):
(a) FOR [6WE1] (BOTTLE 1-FIRE EXTING, ENG 1), [8WE1] (BOTTLE 2-FIRE EXTING, ENG 1)
415BL 415CR
(b) FOR [6WE2] (BOTTLE 1-FIRE EXTING, ENG 2), [8WE2] (BOTTLE 2-FIRE EXTING, ENG 2)
425BL 425CR
(3) Remove the WARNING NOTICE(S).
(4) Remove the access platform(s).

Subtask 26-21-00-862-050-A

F. De-energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-862-002)

[Rev.10 from 2021] 2026.03.31 23:44:34 UTC