W DOC AIRBUS | TSM A320F

Failure of the EPC Control Circuit

TASK 24-41-00-810-818-A
Failure of the EPC Control Circuit

1. Possible Causes
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 24-22-55-000-001
Removal of the Contactors
AMM 24-22-55-400-002
Installation of the Contactors
ASM 242302
AMM 24-23-55-000-001
Removal of the APU GLC
AMM 24-23-55-400-001
Installation of the APU GLC
AMM 24-41-00-740-002
Operational Check of the GAPCU via the CFDS
ASM 244101
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)
AMM 24-41-55-000-001
Removal of the External Power Contactor (EPC)
AMM 24-41-55-400-001
Installation of the External Power Contactor (EPC)
3. Fault Confirmation
Subtask 24-41-00-740-056-A ** ON A/C NOT FOR ALL
A. Test
   (1) Do the BITE test of the GAPCU AMM 24-41-00-740-002.
     (a) If the BITE test gives the message TEST FAILED:
  • do the trouble shooting given in Para 4.A.
     (b) If the BITE test gives the message TEST PASSED:
  • do the trouble shooting given in Para 4.B.
4. Fault Isolation
Subtask 24-41-00-810-083-A ** ON A/C NOT FOR ALL
A. If the BITE test gives the message TEST FAILED:
  • push the line key adjacent to the TEST FAILED message.
   (1) If the maintenance message GAPCU (24XG) comes into view:
Subtask 24-41-00-810-062-A ** ON A/C NOT FOR ALL
B. If the BITE test gives the message TEST PASSED:
  • do a check of the EPC (3XG) coil for correct electrical continuity between pin B/3 and pin B/5 ASM 244101.
   (1) If the coil electrical continuity is not correct:
   (2) If the coil electrical continuity is correct:
  • do a check of the auxiliary contacts of the contactors and relay of the EPC control circuit ASM 244101 for correct operation between:
    . pins B/22 and B/24 of the APU GLC (3XS) (normally closed)
    . pins A/C1 and A/C2 of the EPC auxiliary control relay (5XG) (normally open)
    . pins A/D1 and A/D2 of the EPC auxiliary control relay (5XG) (normally open)
    . pins B/10 and B/12 of the GLC 2 (9XU2) (normally closed)
    . pins B/6 and B/8 of the BTC 2 (11XU2) (normally closed)
    . pins B/10 and B/12 of the GLC 1 (9XU1) (normally closed)
    . pins B/6 and B/8 of the BTC 1 (11XU1) (normally closed).
     (a) If the auxiliary contacts are not correct:
     (b) If the auxiliary contacts are correct:
  • do a check of the wiring of the EPC control circuit ASM 244101 for an open circuit or a short to ground between:
    . pin B/5 of the EPC (3XG) and ground
    . pin B/3 of the EPC and pin B/22 of the APU GLC (3XS)
    . pin B/24 of the APU GLC and pin A/C1 of the EPC AUX CTL relay (5XG)
    . pin A/C2 of the EPC auxiliary control relay and pin B/10 of the GLC 2
    . pin A/C2 of the EPC auxiliary control relay and pin B/8 of the BTC 2
    . pin B/12 of the GLC 2, pin B/6 of the BTC 2, pin B/12 of the GLC 1 and pin B/6 of the BTC 1
    . pin B/10 of the GLC 1 and pin A/D2 of the EPC auxiliary control relay
    . pin B/8 of the BTC 1 and pin A/D2 of the EPC auxiliary control relay
    . pin A/D1 of the EPC auxiliary control relay and pin 2 of the ELEC/EXT/PWR/CTL circuit breaker (11XG).
       1 If the wiring is not correct:
  • repair or replace the wiring as necessary.
       2 If the wiring is correct:
  • do a check of the wiring of the APU GLC status-circuit ASM 242302 for an open circuit or a short to ground between:
    . pin A/A1 of the APU AVAIL relay (6KD) and pin B/28 of the EPC (3XG)
    . pin B/26 of the EPC and pin B/20 of the APU GLC contactor (3XS)
    . pin B/18 of the APU GLC contactor and pin A/6A of the GAPCU.
  • do a check of the auxiliary contacts ASM 242302 for correct operation between:
    . pin B/18 and pin B/20 of the APU GLC (3XS) (normally closed)
    . pin B/26 and pin B/28 of the EPC (3XG) (normally closed).
         a If the wiring or the auxiliary contacts are not correct:
         b If the wiring or the auxiliary contacts are correct:
Subtask 24-41-00-740-057-A ** ON A/C NOT FOR ALL
C. Do the test given in Para. 3.
[Rev.8 from Aug 2018] 2026.04.04 04:26:54 UTC
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