Failure of the Internal Circuit Breaker of the APU GCU

TASK 24-20-00-810-838-A
Failure of the Internal Circuit Breaker of the APU GCU

1. Possible Causes

wiring
GCU-APU [1XS]

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 24-41-00-861-002	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 24-20-00-700-080-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 24-20-00-810-077-A ** ON A/C NOT FOR ALL

A. If the fault symptom is identified by the CFDS message CHECK GLC APU GCU APU PIN B2D WIRING and the upper ECAM DU warning APU GEN FAULT:

reset the circuit breaker on the front of the APU GCU.

(1) If the circuit breaker trips:

Do a check of the wiring for short to ground successively between:
. the APU GCU pin B/2D and APU GLC pin B/3,
. the APU GCU pin B/2D and APU GCU pins A/5B, A/12D, A/13D, A/6A, A/6C,
. the APU GCU pin B/2D and EGIU 2 pin B/6D,
. the APU GCU pin A/12C and APU GLC AUX pin X/1,
. the APU availability relay (6KD) pin A/1 and APU GCU pin A/13C and EGIU 2 pin B/7C ASM 242302.

(a) If the wiring is not correct:

repair it.

(b) If the wiring is correct:

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

Subtask 24-20-00-700-081-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