Message Name:

FAULT

Message Code:

B3-007087

Associated CAS:

L GEN FAIL
(Caution)

ELECTRICAL FAULT
(Caution)

The Left Generator Control Unit (LGCU) has failed.

• Left Generator Control Unit (LGCU) (PCB5)
• Left Generator Power Module (LGPM) (PCB7)
• Left Generator (LGEN) (G1)
• Left DC Power Center (LDCPC) (A35)
• Associated Wiring

Advisory Wire/Service Bulletin:

• AW300-24-0013 - Loss of Normal Electrical Power
• AW300-24-0038 - Nuisance "ELECTRICAL FAULT" CAS Message Upon Engine or APU Shut Down.

Forum Articles/Infoservice/Newsletter: None

NOTES:

• If all or any combination of the following MDC faults are posted at the same time, troubleshoot the MDC Fault B3-006657 first.  
  B3-007087 - FAULT [L GEN GCU]
  B3-006292 - FAULT [APU GEN GCU]
  B3-006657 - DPMS2/RPROT/WIRING FAULT [DIFF PROT SNSR
• If the MDC is reporting multiple GEN GCU fault messages simultaneously, accompanied by a Proximity Sensing Electronics Unit (PSEU) failure, most likely B3-007551 - PSEU SYSTEM FAILURE or B3-007550 - PSEU OFF/NO OUTPUT, the ATA 32 fault(s) must be addressed first.
• For troubleshooting purposes you may refer to the Generators Windings Values table.

1. Swap the Left Generator Control Unit (PCB5) with the Right Generator Control Unit (PCB6). Is the fault message still present?

   1. If YES, continue with next step.
   2. If NO, replace the defective Generator Control Unit.

2. Swap the Left Generator Power Module (PCB7) with the Right Generator Power Module (PCB8). Is the fault message still present?

   1. If YES, continue with next step.
   2. If NO, replace the defective Generator Power Module.

3. Do wiring check of the following wires:

   From	To	Results
   L GEN conn. G1P1 - pin A	L DCPC conn. A35P1 - pin F
   L GEN conn. G1P1 - pin B	L DCPC conn. A35P1 - pin G
   L GEN conn. G1P1 - pin G	L DCPC conn. A35P1 - pin AA
   L GEN conn. G1P1 - pin D	L DCPC conn. A35P1 - pin H
   L GEN conn. G1P1 - pin F	L DCPC conn. A35P1 - pin h
   L GEN conn. G1P1 - pin E	L DCPC conn. A35P1 - pin J
   L GEN conn. G1P1 - pin L	L DCPC conn. A35P1 - pin JJ
   L GEN conn. G1P1 - pin M	L DCPC conn. A35P1 - pin z
   L GEN conn. G1P1 - pin H	L DCPC conn. A35P1 - pin D
   L GEN conn. G1P1 - pin J	L DCPC conn. A35P1 - pin d
   L GEN conn. G1P1 - pin K	L DCPC conn. A35P1 - pin E

   1. If wiring check is satisfying, continue with next step.
   2. If wiring check is not satisfying, repair the defective wire.

4. Swap the Left Generator (G1) with the Right Generator (G2). Is the fault message still present?

   1. If YES, continue with next step.
   2. If NO, replace the defective Generator.

5. Replace Left DC Power Center (A35).
6. Do close out.