Failure of the ENG/APU FIRE Panel or its Wiring to the GCU 1

TASK 24-20-00-810-866-A
Failure of the ENG/APU FIRE Panel or its Wiring to the GCU 1

1. Possible Causes

GCU-1 [1XU1]
ENG/APU FIRE PNL [1WD]
wiring

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 242202
AMM 24-22-34-000-001	Removal of the GCU-1(2)
AMM 24-22-34-400-001	Installation of the GCU-1(2)
AMM 24-41-00-740-002	Operational Check of the GAPCU via the CFDS
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 24-20-00-740-100-A ** ON A/C NOT FOR ALL

A. Test

do the BITE test of the GAPCU AMM 24-41-00-740-002.

NOTE: It is not necessary to do the trouble shooting for the CFDS message ENG1 FIRE PB SW (1WD)/ GCU1 (1XU1) if the flight or maintenance log books show that the flight crew or the maintenance personnel pushed the ENG 1 FIRE pushbutton switch on the ENG/APU FIRE panel after an engine-fire condition or to do a test of the engine fire loop.
To remove this CFDS message at the start of the subsequent flight, release and push the ELEC/GEN 1 pushbutton switch (2XU1) before the subsequent engine start sequence.
If the flight or maintenance crew did not push the ENG 1 FIRE pushbutton switch, the trip was accidental and you must do the trouble shooting procedure that follows:

(1) If the BITE test gives the message TEST FAILED:

do the trouble shooting given in Para 4.A.

(2) If the BITE test gives the message TEST PASSED:

do the trouble shooting given in Para 4.B.

4. Fault Isolation
Subtask 24-20-00-810-215-A ** ON A/C NOT FOR ALL

A. If the BITE test gives the message TEST FAILED:

push the line key adjacent to the TEST FAILED message.

(1) If the maintenance message GCU1 (1XU1) comes into view:

replace the GCU-1 [1XU1] AMM 24-22-34-000-001 and AMM 24-22-34-400-001.

Subtask 24-20-00-810-109-A ** ON A/C NOT FOR ALL

B. If the BITE test gives the message TEST PASSED:

do a check of the contact of the ENG/APU FIRE panel (1WD) for a correct operation between pin A/b and pin A/c ASM 242202.

(1) If the contact does not operate correctly:

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

(2) If the contact operates correctly:

do a check of the wiring for an open circuit or a short to ground between pin A/c of the ENG/APU FIRE panel and pin A/3J of the GCU 1 ASM 242202.

(a) If the wiring is not correct:

repair or replace as necessary.

(b) If the wiring is correct:

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

Subtask 24-20-00-740-101-A ** ON A/C NOT FOR ALL

C. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:26:16 UTC