W DOC AIRBUS | TSM A320F

FCU 2 Inoperative

TASK 22-81-00-810-803-A
FCU 2 Inoperative

1. Possible Causes
  • FCU [2CA]
  • wiring of the FMGC 2 A bus from the FCU (2CA) to the first terminal block
  • wiring of the FCU OWN A bus from the FMGC 2 (1CA2) to the first terminal block
  • wiring of the FCU OWN B bus from the FMGC 2 (1CA2) to the first terminal block
  • wirings of the FCU 1 A F/B and FCU 1 B F/B buses from the FCU (2CA) to the first terminal block
  • wiring of the 28VDC signal from the circuit breaker (9CA2) to the FCU (2CA)
  • wiring of the ground signal at the FCU (2CA)
  • C/B-AUTO FLT/FCU/2 [9CA2]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
TSM TASK 24-00-00-810-818-A
Computer Reset
AMM 22-81-12-000-001
Removal of the FCU
AMM 22-81-12-400-001
Installation of the FCU
ASM 228401
ASM 228603
AMM 22-91-00-710-001
Ground Scanning of the AFS
3. Fault Confirmation
Subtask 22-81-00-865-052-A
A. Make sure that this(these) circuit breaker(s) is(are) closed:
PANELDESIGNATIONFINLOCATION
** ON A/C ALL
121VUAUTO FLT/FCU/29CA2M21
Subtask 22-81-00-710-053-A
B. Test
   (1) Do the Ground Scanning of the AFS AMM 22-91-00-710-001.
     (a) If the circuit breaker (9CA2) is open, refer to Para. 4.B. of this trouble shooting procedure.
4. Fault Isolation
Subtask 22-81-00-810-053-A
A. If the circuit breaker (9CA2) is closed and if the test gives the maintenance message AFS: FCU:
NOTE: The 7 minute reset is necessary to do a full test sequence of the FCU.
   (1) If the fault continues:
  • do a check for 28VDC at the FCU (2CA) pin B/Z.
     (a) if there is 28VDC:
       1 If the fault continues:
  • do a check of the:
    . wiring of the FMGC 2 A bus from the FCU (2CA) to the first terminal block
    . wiring of the FCU OWN A bus from the FMGC 2 (1CA2) to the first terminal block
    . wiring of the FCU OWN B bus from the FMGC 2 (1CA2) to the first terminal block
  • ASM 228603.
       2 If there is no continuity:
  • repair the above wirings.
       3 If there is continuity:
  • do a check and repair the wirings of the FCU 1 A F/B and FCU 1 B F/B buses from the FCU (2CA) to the first terminal block ASM 228603.
     (b) If there is no 28VDC:
  • do a check of the wiring of the 28VDC signal from the circuit breaker (9CA2) to the FCU (2CA) and the wiring of the ground signal at the FCU (2CA), pin B/A ASM 228401.
       1 If there is no continuity:
  • repair the above wirings.
       2 If there is continuity:
  • replace the C/B-AUTO FLT/FCU/2 [9CA2] .
Subtask 22-81-00-810-054-A
B. If the circuit breaker (9CA2) is open:
  • close this circuit breaker.
   (1) If the circuit breaker trips:
     (a) If the fault continues:
  • do a check for a short to ground from the circuit breaker (9CA2) to the FCU (2CA) ASM 228401.
       1 If there is a short to ground:
  • repair the above wiring.
       2 If there is no short to ground:
  • replace the C/B-AUTO FLT/FCU/2 [9CA2] .
Subtask 22-81-00-710-054-A
C. Do the test given in Para. 3.
[Rev.8 from Aug 2018] 2026.04.04 04:25:25 UTC
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