W DOC AIRBUS | TSM A320F

Feeder Short Circuits between the APU Generator and APU GLC

TASK 24-20-00-810-839-A
Feeder Short Circuits between the APU Generator and APU GLC

1. Possible Causes
  • wiring
  • GCU-APU [1XS]
  • GEN-APU [8XS]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
ASM 242301
AMM 24-23-34-000-001
Removal of the GCU-APU
AMM 24-23-34-400-001
Installation of the GCU-APU
AMM 24-23-51-000-001
Removal of the APU Generator
AMM 24-23-51-400-001
Installation of the APU Generator
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 24-20-00-700-082-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 24-20-00-810-078-B ** ON A/C NOT FOR ALL
A. If the fault symptom is identified by the CFDS message CHECK GEN APU FEEDER PIN T1 T2 T3 SHORT TO GROUND and the upper ECAM DU warning APU GEN FAULT:
  • disconnect the feeders from the APU generator terminals T/1, T/2, T/3 and N.
  • remove the wire connected on the GLC APU contactor pin A/D to the circuit breaker APU GEN EGIU2 (23XS).
  • do a check of the wiring for short to ground on the feeders between the APU generator terminals T/1, T/2, T/3 and the APU GLC terminals A/F, A/E, A/D ASM 242301.
   (1) If the wiring is not correct:
  • repair the above feeder.
   (2) If the wiring is correct:
   (3) If the fault continues:
Subtask 24-20-00-810-078-C ** ON A/C NOT FOR ALL
A. If the fault symptom is identified by the CFDS message CHECK GEN APU FEEDER PIN T1 T2 T3 SHORT TO GROUND and the upper ECAM DU warning APU GEN FAULT:
  • disconnect the feeders from the APU generator terminals T/1, T/2, T/3 and N.
  • remove the wire connected to the APU/EXP power contactor module (29XN) pin 9 to the circuit breaker APU GEN EGIU2 (23XS).
  • do a check of the wiring for short to ground on the feeders between the APU generator terminals T/1, T/2, T/3 and the APU/EXP power contactor module (29XN) pins 7, 8, 9 ASM 242301.
   (1) If the wiring is not correct:
  • repair the above feeder.
   (2) If the wiring is correct:
   (3) If the fault continues:
Subtask 24-20-00-700-083-A ** ON A/C NOT FOR ALL
B. Make sure that the aircraft electrical circuit 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
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