Failure of the APU GLC

TASK 24-20-00-810-845-A
Failure of the APU GLC

1. Possible Causes

GLC-APU [3XS]
GCU-APU [1XS]
wiring
RELAY-APU GLC AUX CTL [4XS]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 242302
AMM 24-23-34-000-001	Removal of the GCU-APU
AMM 24-23-34-400-001	Installation of the GCU-APU
AMM 24-23-55-000-001	Removal of the APU GLC
AMM 24-23-55-400-001	Installation of the APU GLC
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002	De-energize the Aircraft Electrical Circuits Supplied from the External Power

3. Fault Confirmation
Subtask 24-20-00-700-094-A ** ON A/C NOT FOR ALL

A. Test
Not applicable.

NOTE: As the APU GEN was set to OFF because of a true failure, the fault confirmation is not necessary.

4. Fault Isolation
Subtask 24-20-00-810-084-A ** ON A/C NOT FOR ALL

A. If the fault symptom is identified by the CFDS message GLC APU and the upper ECAM DU warning APU GEN FAULT:

replace the GLC-APU [3XS] AMM 24-23-55-000-001 and AMM 24-23-55-400-001.

(1) If the fault continues:

replace the GCU-APU [1XS] AMM 24-23-34-000-001 and AMM 24-23-34-400-001.

(2) If the fault continues:

do a check of the wiring for open circuit between the APU GLC pin B/3 and the APU GLC auxiliary control relay (4XS) pin B1 through the EPC (3XG), then between the APU GLC auxiliary control relay (4XS) pin B2 and the circuit breaker (5XU) through the 5XG, 9XU1, 9XU2, 11XU1, 11XU2 ASM 242302.

(a) If the wiring is not correct:

repair it.

(b) If the wiring is correct:

replace the RELAY-APU GLC AUX CTL [4XS] .

Subtask 24-20-00-700-095-A ** ON A/C NOT FOR ALL

B. Make sure that the aircraft electrical circuits operate correctly in APU configuration.
(1) Energize the aircraft electrical circuits from the APU AMM 24-41-00-861-002.
(2) De-energize the aircraft electrical circuits from the APU AMM 24-41-00-862-002.

[Rev.8 from Aug 2018] 2026.04.04 04:26:13 UTC