Loss of the INOP LOOP A Discrete from the Engine 1 FDU

TASK 26-12-00-810-831-A
Loss of the INOP LOOP A Discrete from the Engine 1 FDU

1. Possible Causes

FDU-ENG1 [2WD1]
wiring of the INOP LOOP A discrete from the engine 1 FDU (2WD1) to the first terminal block

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)

3. Fault Confirmation
Subtask 26-12-00-710-108-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 26-12-00-810-084-A

A. If the test gives the maintenance message CHECK FDU ENG 1 LOOP A WARN CKT:

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

(1) If the fault continues:

do a check and repair the wiring of the INOP LOOP A discrete from the engine 1 FDU (2WD1) to the first terminal block ASM 261201.

Subtask 26-12-00-710-109-A

B. Do the test given in Para. 3.

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