Loss of the FIRE TEST (LOOP B) Discrete Input from the Engine 1 FDU

TASK 26-12-00-810-828-A
Loss of the FIRE TEST (LOOP B) Discrete Input from the Engine 1 FDU

1. Possible Causes

ENG/APU FIRE PNL [1WD]
wiring of the 28VDC signal from the circuit breaker (8WD1) to the ENG/APU FIRE panel (1WD)
wiring of the FIRE TEST (LOOP B) discrete from the engine 1 FDU (2WD1) to the ENG/APU FIRE panel (1WD)

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 26-12-00-710-001	Operational Check of Loop/Squib
ASM 261202
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

3. Fault Confirmation
Subtask 26-12-00-710-102-A

A. 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 26-12-00-810-081-A

A. If the ENG 1 FIRE indication does not come into view on the upper ECAM DU:

do a check to see if the DISCH legend of the ENG 1/AGENT 2 pushbutton switch on the ENG/APU FIRE panel (1WD) comes on during the fire test.

(1) If the DISCH legend does not come on:

(a) If the fault continues:

do a check and repair the wiring of the 28VDC signal from the circuit breaker (8WD1) to the ENG/APU FIRE panel (1WD), pin B/M ASM 261202.

(2) If the DISCH legend comes on:

(a) If the fault continues:

do a check and repair the wiring of the FIRE TEST (LOOP B) discrete from the engine 1 FDU (2WD1) to the ENG/APU FIRE panel (1WD) ASM 261202.

Subtask 26-12-00-710-103-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:27:10 UTC