Loss of the FLT/GND Discrete from the Engine 1 FDU

TASK 26-12-00-810-821-A
Loss of the FLT/GND Discrete from the Engine 1 FDU

1. Possible Causes

FDU-ENG1 [2WD1]
LGCIU-1 [5GA1]
wiring of the FLT/GND discrete from the engine 1 FDU (2WD1) to the LGCIU 1 (5GA1)
LGCIU-2 [5GA2]
wiring of the FLT/GND discrete from the engine 1 FDU (2WD1) to the LGCIU 2 (5GA2)
wiring of the FLT/GND discrete from the engine 1 FDU (2WD1) to LGCIU 1 (5GA1)
wiring of the FLT/GND discrete from the engine 1 FDU (2WD1) to LGCIU 2 (5GA2)

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 26-12-00-710-002	Operational Test of the Engine Fire and Overheat Detection with the Centralized Fault Display System (CFDS)
ASM 261201
AMM 26-12-34-000-001	Removal of the Engine Fire-Detection Unit (FDU)
AMM 26-12-34-400-001	Installation of the Engine Fire-Detection Unit (FDU)
AMM 32-31-71-000-001	Removal of the LGCIU
AMM 32-31-71-400-001	Installation of the LGCIU

3. Fault Confirmation
Subtask 26-12-00-710-088-A

A. Test
(1) Do the operational test of the engine fire and overheat detection from the Multipurpose Control and Display Unit (MCDU) AMM 26-12-00-710-002.

4. Fault Isolation
Subtask 26-12-00-810-070-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message CHECK FDU ENG 1 LGCIU INTFC:

replace the FDU-ENG1 [2WD1] AMM 26-12-34-000-001 and AMM 26-12-34-400-001.

(1) If the fault continues:

replace the LGCIU-1 [5GA1] AMM 32-31-71-000-001 and AMM 32-31-71-400-001.

(2) If the fault continues:

do a check of the wiring of the FLT/GND discrete from the engine 1 FDU (2WD1) to the LGCIU 1 (5GA1) ASM 261201.

(a) If there is no continuity:

repair the above wiring.

(b) If there is continuity:

replace the LGCIU-2 [5GA2] AMM 32-31-71-000-001 and AMM 32-31-71-400-001.

1 If the fault continues:

do a check and repair the wiring of the FLT/GND discrete from the engine 1 FDU (2WD1) to the LGCIU 2 (5GA2) ASM 261201.

Subtask 26-12-00-810-070-B ** ON A/C NOT FOR ALL

A. If the message WAITING FOR SYSTEM RESPONSE is shown for more than 15 seconds and the Class 3 directory gives the message CHECK FDU ENG 1 LGCIU INTFC:

Replace the FDU-ENG1 [2WD1] AMM 26-12-34-000-001 and AMM 26-12-34-400-001.

(1) If the fault continues:

Replace LGCIU-1 [5GA1] AMM 32-31-71-000-001 and AMM 32-31-71-400-001.

(2) If the fault continues:

Do a check of the wiring of the FLT/GND discrete from the engine 1 FDU (2WD1) to LGCIU 1 (5GA1) ASM 261201.

(a) If there is no continuity:

Repair the wiring.

(b) If there is continuity:

Replace LGCIU-2 [5GA2] AMM 32-31-71-000-001 and AMM 32-31-71-400-001.

1 If the fault continues:

Do a check and repair the wiring of the FLT/GND discrete from the engine 1 FDU (2WD1) to LGCIU 2 (5GA2) ASM 261201.

Subtask 26-12-00-710-089-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:27:09 UTC