L/G - Gear Indicator Lights Flickering

TASK 32-31-00-810-895-A
L/G - Gear Indicator Lights Flickering

1. Possible Causes

RELAY-GND SERVICE BUS CHG OVER [53GA]
LGCIU-1 [5GA1]
LGCIU-2 [5GA2]
BOARD-ANN LT TEST & INTFC [9LP]
wiring and connectors
PROX SNSR-R L/G DNLK, SYS 1 [14GA]
PROX SNSR-L L/G DNLK, SYS 1 [15GA]
PROX SNSR-NLG DNLK, SYS 1 [18GA]
landing-gear indicator light

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 32-31-00-810-822-A	RLG Downlock Proximity Sensor Fault
TSM TASK 32-31-00-810-823-A	LLG Downlock Proximity Sensor Fault
TSM TASK 32-31-00-810-824-A	NLG Downlock Proximity Sensor Fault
TSM TASK 32-31-00-810-896-A	L/G Downlock Proximity Sensor TGT POS Fault (sensors 14GA thru 19GA)
ESPM 204650
ASM 323103
ASM 323105
AMM 32-31-71-000-001	Removal of the LGCIU
AMM 32-31-71-400-001	Installation of the LGCIU
ASM 326101
AMM 33-14-33-000-001	Removal of the Annunciator-Light Test and Interface-Board
AMM 33-14-33-400-001	Installation of the Annunciator-Light Test and Interface-Board
AMM 49-00-00-860-003	APU Start by External Power
AMM 49-00-00-860-004	APU Shutdown by External Power
AMM 49-00-00-860-005	APU Start by External Power
AMM 49-00-00-860-006	APU Shutdown by External Power
AMM 49-00-00-860-008	APU Start by External Power
AMM 49-00-00-860-009	APU Shutdown by External Power (131-9(A))

3. Fault Confirmation
Subtask 32-31-00-700-056-A

A. Test
(1) If all the landing-gear indicator lights flicker, do step (1) of the Para. Fault Isolation.
(2) If only one of the landing-gear indicator light flickers, do step (2) of the Para. Fault Isolation.

4. Fault Isolation
Subtask 32-31-00-810-157-A

A. Procedure
(1) If all the landing-gear landing lights flicker, do the steps that follow:
(a) Start the APU:

(b) Do a check for 28VDC at the RELAY-GND SERVICE BUS CHG OVER [53GA] pin A2 ASM 323105:

If there is 28VDC, do step (1)(c)
If there is no 28VDC, do step (1)(d).

(c) Interchange the LGCIU-1 [5GA1] and LGCIU-2 [5GA2] AMM 32-31-71-000-001 and AMM 32-31-71-400-001:
1 Do a check of the landing-gear indicator lights:

If the fault continues, go to step (1)(d)
If the lights do not flicker, replace LGCIU-2 [5GA2] AMM 32-31-71-000-001 and AMM 32-31-71-400-001.

(d) If the fault continues:
1 Replace:

The BOARD-ANN LT TEST & INTFC [9LP] AMM 33-14-33-000-001 and AMM 33-14-33-400-001
The RELAY-GND SERVICE BUS CHG OVER [53GA] ESPM 204650 and ASM 323105.

2 Do a check of the landing-gear indicator lights.
(e) If the fault continues:
1 Do a check and repair the aircraft wiring and connectors from:

The LGCIU-1 [5GA1] to the BOARD-ANN LT TEST & INTFC [9LP]
The BOARD-ANN LT TEST & INTFC [9LP] to the landing-gear indicator lights
ASM 326101.

2 Do a check of the landing-gear indicator lights.
(f) Stop the APU:

(2) If only one landing-gear indicator light flickers, do the steps that follow:
(a) Start the APU:

(b) If there is a target position fault for a downlock proximity sensor:
1 Do the downlock proximity sensor TGT POS fault (Ref. TSM TASK 32-31-00-810-896).
2 Do a check of the applicable landing-gear indicator light.
(c) If there is a downlock proximity sensor fault:
1 Do the applicable troubleshooting procedure:

For a PROX SNSR-R L/G DNLK, SYS 1 [14GA] fault (Ref. TSM TASK 32-31-00-810-822)
For a PROX SNSR-L L/G DNLK, SYS 1 [15GA] fault (Ref. TSM TASK 32-31-00-810-823)
For a PROX SNSR-NLG DNLK, SYS 1 [18GA] fault (Ref. TSM TASK 32-31-00-810-824).

2 Do a check of the applicable landing-gear indicator light.
(d) Interchange the LGCIU-1 [5GA1] and LGCIU-2 [5GA2] AMM 32-31-71-000-001 and AMM 32-31-71-400-001:
1 Do a check of the applicable landing-gear indicator light.
2 If the fault continues, go to step (2)(e).
3 If the landing-gear indicator light does not flicker, replace the LGCIU-2 [5GA2] AMM 32-31-71-000-001 and AMM 32-31-71-400-001.
(e) If the fault continues:
1 Do a check and repair the applicable wiring and connectors from:

The LGCIU-1 [5GA1] to the applicable proximity sensor
The LGCIU-1 [5GA1] to the BOARD-ANN LT TEST & INTFC [9LP]
The BOARD-ANN LT TEST & INTFC [9LP] to the applicable landing-gear indicator light
The RELAY-GND SERVICE BUS CHG OVER [53GA] to the BOARD-ANN LT TEST & INTFC [9LP]
ASM 326101, ASM 323103 and ASM 323105.

2 Do a check of the applicable landing-gear indicator light.
(f) If the fault continues:
1 Replace the applicable landing-gear indicator light .
(g) If the fault continues:
1 Replace:

The BOARD-ANN LT TEST & INTFC [9LP] AMM 33-14-33-000-001 and AMM 33-14-33-400-001
The RELAY-GND SERVICE BUS CHG OVER [53GA] ESPM 204650 and ASM 323105.

2 Do a check of the landing-gear indicator light.
(h) Stop the APU:

[Rev.8 from Aug 2018] 2026.04.04 04:31:27 UTC