Loss of the ACS1 Signal of the ELAC1 COM Side

TASK 27-90-00-810-811-A
Loss of the ACS1 Signal of the ELAC1 COM Side

1. Possible Causes

ELAC-1 [2CE1]
SEC-1 [1CE1]
wiring of the ACS1 SPLY signal from the ELAC1 COM side to the MON side
wiring of the ACS1 SPLY COM signal from the ELAC1 MON side to the first terminal block

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 27-90-00-810-801-A	Failure of an Alternating Current Supply (ACS)
ASM 279307
AMM 27-93-34-000-001	Removal of the ELAC
AMM 27-93-34-400-001	Installation of the ELAC
AMM 27-94-34-000-001	Removal of the SEC
AMM 27-94-34-400-001	Installation of the SEC
AMM 27-96-00-740-001	BITE Test of the EFCS (Ground Scanning)

3. Fault Confirmation
Subtask 27-90-00-740-069-A

A. Test
(1) Do the BITE test of the EFCS (ground scanning) AMM 27-96-00-740-001.

4. Fault Isolation
Subtask 27-90-00-810-060-A

A. If the ground scanning gives at least two maintenance messages of the list below:
ELAC1 COM OR WIRING FROM THS ACTR XDCR2 9CE
ELAC1 OR WIRING FROM L B ELEV POS XDCR 34CE3
ELAC1 OR WIRING FROM R B ELEV POS XDCR 34CE4
(1) Remove the ELAC1 AMM 27-93-34-000-001 and the SEC1 AMM 27-94-34-000-001.
(2) At the ELAC1 receptacle, do a check of the resistance between the pin AD/6B and the pin AD/6C ASM 279307:
(a) If the resistance is less than 10 Ohms:
1 Do this procedure (Ref. TSM TASK 27-90-00-810-801).
2 Replace the ELAC-1 [2CE1] AMM 27-93-34-000-001 and AMM 27-93-34-400-001.
3 Replace the SEC-1 [1CE1] AMM 27-94-34-000-001 and AMM 27-94-34-400-001.
(b) If the resistance is more than 10 Ohms:

do a check of the wiring of the ACS1 SPLY signal from the ELAC1 COM side to the MON side ASM 279307:
. pins AA/13A and AA/13B to pins AA/8K and AA/8G of the ELAC1 COM side
. pins AA/8H and AA/8J of the ELAC1 COM side to pins AD/6A and AD/6D of the ELAC1 MON side.

1 If the wiring is not correct:

repair it
install the ELAC1 AMM 27-93-34-400-001 and the SEC1 AMM 27-94-34-400-001.

a If the fault continues:

replace the ELAC-1 [2CE1] AMM 27-93-34-000-001 and AMM 27-93-34-400-001.

2 If the wiring is correct:
a Replace the ELAC-1 [2CE1] AMM 27-93-34-000-001 and AMM 27-93-34-400-001.
b Install the SEC1 AMM 27-94-34-400-001.
c If the fault continues:

do a check and repair the wiring of the ACS1 SPLY COM signal from the ELAC1 MON side to the first terminal block , pins AD/6B and AD/6C ASM 279307.
if the wiring is correct, do the failure of an alternating current supply (ACS) procedure (Ref. TSM TASK 27-90-00-810-801).

Subtask 27-90-00-740-070-A

B. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:27:52 UTC