W DOC AIRBUS | TSM A320F

Loss of the 28VDC Supply of the BSCU SYS 2

TASK 32-42-00-810-829-A
Loss of the 28VDC Supply of the BSCU SYS 2

1. Possible Causes
  • BSCU [10GG]
  • wiring from the BSCU (10GG) pin AB/15A to the ground terminal
  • SW-A/SKID & NW STRG (5GG)
  • wiring from the BSCU (10GG) to the switch (5GG)
  • wiring from the switch (5GG) pin 1C to the circuit breaker (4GG)
  • C/B-HYDRAULIC/BRAKING AND STEERING/SYS2/SPLY [4GG]
  • ABCU [95GG]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
SPM 205221
SPM 205222
ASM 324201
SPM 324201
AMM 32-42-21-000-001
Removal of the Normal-Brake Pressure Transducer
AMM 32-42-21-400-001
Installation of the Normal-Brake Pressure Transducer
AMM 32-42-34-000-001
Removal of the Braking/Steering Control Unit (BSCU)
AMM 32-42-34-400-001
Installation of the Braking/Steering Control Unit (BSCU)
AMM 32-43-34-000-001
Removal of the Alternate Braking Control Unit (ABCU)
AMM 32-43-34-400-001
Installation of the Alternate Braking Control Unit (ABCU)
AMM 32-46-00-740-001
BITE Test of the BSCU
3. Fault Confirmation
Subtask 32-42-00-740-076-A
A. Test
   (1) Not applicable
4. Fault Isolation
Subtask 32-42-00-865-051-A
A. Make sure that this(these) circuit breaker(s) is(are) closed:
PANELDESIGNATIONFINLOCATION
** ON A/C ALL
121VUHYDRAULIC/BRAKING AND STEERING/SYS2/SPLY4GGM36
Subtask 32-42-00-810-215-A
B. Test
   (1) Do the BITE test of the BSCU with the BSCU channel that is the source of the fault message AMM 32-46-00-740-001.
   (2) Do a check of the status of the circuit breaker (4GG).
Subtask 32-42-00-810-081-A
C. If the circuit breaker (4GG) is closed:
  • Do a check for 28VDC at pin AB/14A of the BSCU (10GG) ASM 324201.
   (1) If there is 28VDC:
   (2) If there is no 28VDC:
  • Do a check for a ground signal at pin AB/15A of the BSCU (10GG) ASM 324201.
     (a) If there is no ground signal:
  • Repair the wiring from the BSCU (10GG) pin AB/15A to the ground terminal ASM 324201.
     (b) If there is a ground signal:
  • Replace the SW-A/SKID & NW STRG (5GG) ASM 324201.
       1 If the fault continues:
  • Do a check and repair the wiring from the BSCU (10GG) to the switch (5GG), pin AB/14A to pin 2C ASM 324201.
  • Do a check and repair the wiring from the switch (5GG) pin 1C to the circuit breaker (4GG) ASM 324201.
       2 If the fault continues:
  • Replace the C/B-HYDRAULIC/BRAKING AND STEERING/SYS2/SPLY [4GG] ASM 324201.
       3 If the fault continues:
Subtask 32-42-00-810-082-A
D. If the circuit breaker is open:
   (1) Remove the BSCU (10GG) AMM 32-42-34-000-001.
   (2) Disconnect the connector A of these units:
   (3) Disconnect the connector A of this unit:
  • RELAY-WHEEL 1 SPEED (24GG).
   (4) Disconnect the connector A of this unit:
  • SW-A/SKID & NW STRG (5GG).
   (5) Do a check for a short circuit of the wiring between the BSCU and PRESS XDCR-NORM BRK WHEEL and RELAY-WHEEL 1 SPEED and SW-A/SKID & NW STRG SPM 205221, SPM 205222, SPM 324201.
     (a) If there is a short circuit:
       1 Repair the wiring.
       2 Connect the connector A of these units:
       3 Connect the connector A of this unit:
  • RELAY-WHEEL 1 SPEED (24GG).
       4 Connect the connector A of this unit:
  • SW-A/SKID & NW STRG (5GG).
       5 Install the BSCU (10GG) AMM 32-42-34-400-001.
     (b) If there is no short circuit:
  • Close the circuit breaker (4GG).
   (6) If the circuit breaker (4GG) stays closed:
     (a) Connect the units one after the other, and if the circuit breaker (4GG) trips again, replace the related unit:
   (7) If the fault continues:
  • Replace the C/B-HYDRAULIC/BRAKING AND STEERING/SYS2/SPLY [4GG] ASM 324201.
Subtask 32-42-00-740-077-A
E. After the subsequent flight, make sure that the fault does not continue.
[Rev.8 from Aug 2018] 2026.04.04 04:31:32 UTC
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