W DOC AIRBUS | TSM A320F

Failure of the APU Generator Channel

TASK 24-20-00-810-941-A
Failure of the APU Generator Channel

1. Possible Causes
  • feeders
2. Job Set-up Information
 A. Fixtures, Tools, Test and Support Equipment
REFERENCE
QTY
DESIGNATION
No specific
AR
SAFETY CLIP - CIRCUIT BREAKER
 B. Referenced Information
REFERENCE
DESIGNATION
TSM TASK 24-20-00-810-862-A
Failure of the Generator 1 Channel
TSM TASK 24-20-00-810-863-A
Failure of the Generator 2 Channel
ASM 242202
ASM 242203
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
ASM 244101
3. Fault Confirmation
Subtask 24-20-00-869-100-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 24-20-00-810-178-D ** ON A/C NOT FOR ALL
A. If the fault symptom is identified by the upper ECAM-DU warning APU GEN FAULT and one of these two CMS messages:
DELTA CURRENT GEN APU CHANNEL or
OVERCURRENT GEN APU CHANNEL
NOTE: This CFDS messages can come into view with other CFDS messages related to a delta current or an overcurrent condition of one of the generator channels 1 or 2.
  • Do the trouble shooting procedure related to the delta current or the overcurrent condition messages.
NOTE: When you do the trouble shooting for the CFDS message DELTA CURRENT GEN APU CHANNEL or OVERCURRENT GEN APU CHANNEL, you can remove one after the other the GCU 1 and the GCU 2 from their position in the forward avionics rack 90VU to isolate the main AC buses 1XP and 2XP.
   (1) If the fault continues:
  • Do a check of the feeders ASM 242301 for a short circuit or a short to ground between:
    . Feeder A pin L1 of the APU generator AC current transformer (42XS) and pin 7 of the APU/EXT power contactor module (29XN)
    . Feeder B pin L2 of the APU generator AC current transformer and pin 8 of the APU/EXT power contactor module
    . Feeder C pin L3 of the APU generator AC current transformer and pin 9 of the APU/EXT power contactor module.
     (a) If the feeders are not correct:
  • Repair or replace the feeders as necessary.
     (b) If the feeders are correct:
  • Do a check and repair the feeders between the APU/EXT power contactor module (29XN), the generator 1 contactor module (30XN1) and the generator 2 contactor module (30XN2) ASM 242202, ASM 242203 and ASM 244101.
Subtask 24-20-00-865-054-A ** ON A/C NOT FOR ALL
B. Open, safety and tag this(these) circuit breaker(s):
PANELDESIGNATIONFINLOCATION
** ON A/C NOT FOR ALL
122VUELEC/GCU/22XU2T27
Subtask 24-20-00-810-179-A ** ON A/C NOT FOR ALL
C. If the feeders are correct:
  • loosen and lower the nuts that attach the GCU 2 and pull it from the forward electronics rack 90VU to disconnect the electrical connectors
  • energize the aircraft electrical circuits from the APU AMM 24-41-00-861-002
  • after five minutes, see if there is a trip.
   (1) If there is a trip:
   (2) If there is no trip:
  • push the GCU 2 on its rack to connect the electrical connectors and engage the nuts on the lugs and tighten. Then on the rear circuit breaker panel 122VU, remove the safety clip and tag and close the circuit breaker 2XU2
  • after five minutes, see if there is a trip.
     (a) If there is a trip:
Subtask 24-20-00-860-172-A ** ON A/C NOT FOR ALL
D. Make sure that the aircraft electrical circuits operate correctly in APU configuration.
   (1) Make sure that the GCU 1 and the GCU 2 are correctly installed on their forward electronics rack 90VU.
   (2) On the rear circuit breaker panel 122VU, make sure that the circuit breakers 2XU1 and 2XU2 are closed (if the circuit breakers are not closed, remove the safety clips and tags and close them).
   (3) Energize the aircraft electrical circuits from the APU AMM 24-41-00-861-002.
   (4) Let the APU generator operate for five minutes to make sure that it operates correctly.
   (5) De-energize the aircraft electrical circuits from the APU AMM 24-41-00-862-002.
[Rev.8 from Aug 2018] 2026.04.04 04:26:25 UTC
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