Loss of the Reception of the ATH INST DISC Discretes by the FMGC 1

TASK 22-83-00-810-827-A
Loss of the Reception of the ATH INST DISC Discretes by the FMGC 1

1. Possible Causes

FMGC-1 [1CA1]
wiring of the ATH INST DISC NO discrete (from the FMGC 1 (1CA1) to the A/THR instinctive disconnect relays (5CA1 and 5CA2))
wiring of the ATH INST DISC NC (from the FMGC 1 (1CA1) to the A/THR 2 instinctive disconnect relay (5CE2))
wiring between the A/THR instinctive disconnect relays (5CA1 and 5CA2)
wiring of the GND FILTERED discrete (from the FMGC 1 (1CA1) to the A/THR 1 instinctive disconnect relay (5CA1))

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 223101
AMM 22-83-34-000-001	Removal of the FMGC
AMM 22-83-34-400-001	Installation of the FMGC
AMM 22-96-00-710-001	Operational Test of the AFS

3. Fault Confirmation
Subtask 22-83-00-710-090-A

A. Test
(1) On the FCU, make sure that the A/THR pushbutton switch is pushed.
(2) Do the operational tests of the AFS AMM 22-96-00-710-001 and read the result for the FMGC 1:
(a) With one A/THR instinctive disconnect pushbutton switch pushed (on the throttle control levers).
(b) With the two A/THR instinctive disconnect pushbutton switches released.

4. Fault Isolation
Subtask 22-83-00-810-082-A

A. If only the first test gives the maintenance message AFS: FMGC1/ATHR DISC CKT:

replace the FMGC-1 [1CA1] , AMM 22-83-34-000-001 and AMM 22-83-34-400-001.

(1) If the fault continues:

do a check and repair the wiring of the ATH INST DISC NO discrete (from the FMGC 1 (1CA1) to the A/THR instinctive disconnect relays (5CA1 and 5CA2)) ASM 223101.

Subtask 22-83-00-810-083-A

B. If only the second test gives the maintenance message AFS: FMGC1/ATHR DISC CKT:

replace the FMGC-1 [1CA1] , AMM 22-83-34-000-001 and AMM 22-83-34-400-001.

(1) If the fault continues:

do a check of the wiring of the ATH INST DISC NC (from the FMGC 1 (1CA1) to the A/THR 2 instinctive disconnect relay (5CE2)) ASM 223101.

(a) If there is no continuity:

repair the above wiring.

(b) If there is continuity:

do a check and repair the wiring between the A/THR instinctive disconnect relays (5CA1 and 5CA2) from 5CE1 pin A/5 to 5CE2 pin A/C ASM 223101 .

Subtask 22-83-00-810-084-A

C. If the two tests give the maintenance message AFS: FMGC1/ATHR DISC CKT:

replace the FMGC-1 [1CA1] , AMM 22-83-34-000-001 and AMM 22-83-34-400-001.

(1) If the fault continues:

do a check and repair the wiring of the GND FILTERED discrete (from the FMGC 1 (1CA1) to the A/THR 1 instinctive disconnect relay (5CA1)) ASM 223101.

Subtask 22-83-00-710-091-A

D. Do the tests given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:25:30 UTC