W DOC AIRBUS | TSM A320F

Failure of the GAPCU Point-Of-Regulation Wiring or the Feeders to the APU GLC Contactor

TASK 24-23-00-810-827-A
Failure of the GAPCU Point-Of-Regulation Wiring or the Feeders to the APU GLC Contactor

1. Possible Causes
  • wiring
  • GAPCU [24XG]
  • feeders
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
ASM 242301
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
AMM 24-41-34-000-001
Removal of the Ground Power Control Unit (GPCU)
AMM 24-41-34-400-001
Installation of the Ground Power Control Unit (GPCU)
3. Fault Confirmation
Subtask 24-23-00-869-066-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 24-23-00-810-080-A ** ON A/C NOT FOR ALL
A. If the fault symptom is identified by the CFDS message WRG: GEN APU POR/ GAPCU (24XG)/WRG: FEEDER and the upper ECAM-DU warning APU GEN FAULT:
  • do a check of the Point-Of-Regulation (POR) sense wiring ASM 242301 for a short to ground, a short circuit or an open circuit between:
    . pin 9 of the APU/EXT power contactor module (29XN) and pin A/15G of the GAPCU
    . pin 8 of the APU/EXT power contactor module and pin A/15H of the GAPCU
    . pin 7 of the APU/EXT power contactor module and pin A/14G of the GAPCU
    . POR neutral connection and pin A/14H of the GAPCU.
   (1) If the wiring is not correct:
  • repair or replace as necessary.
   (2) If the wiring is correct:
   (3) If the fault continues:
  • do a check and repair the feeders ASM 242301 for an open circuit or a high resistance condition between:
    . terminal T1 of the APU generator and pin 7 of the APU/EXT power contactor module (29XN)
    . terminal T2 of the APU generator and pin 8 of the APU/EXT power contactor module
    . terminal T3 of the APU generator and pin 9 of the APU/EXT power contactor module
    . terminal N of the APU generator and airframe.
Subtask 24-23-00-860-068-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) Let the APU generator operate for five minutes.
   (3) De-energize the aircraft electrical circuits from the APU AMM 24-41-00-862-002.
[Rev.8 from Aug 2018] 2026.04.04 04:26:42 UTC
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