07/01/24
Message Overview:
Message Description:
The APU Generator Control Unit (AGCU) has failed.
Possible Causes:
- Auxiliary Generator Control Unit (AGCU) (PCB9)
- Auxiliary Generator Power Module (AGPM) (PCB10)
- APU Generator (AGEN) (G3)
- Auxiliary DC Power Center (ADCPC) (A196)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin:
- AW300-24-0038 - Nuisance "ELECTRICAL FAULT" CAS Message Upon Engine or APU Shut Down.
- AW300-24-0115 - Introduction of Improved Generator P/N A3579-102
- AW300-24-0132 - Power Module (PMOD) P/N R3608-011 - Generator Failures at High Engine Speed
- AW300-24-0137 - Y06 Electrical System Upgrade
- AW300-24-0162 - Service Bulletin 100-24-20 - DC Power Center (DCPC) System - Inspection and Replacement of Internal Fuses in the L/H and R/H DC Power Center (DCPC)
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.
Quick Links:
| Standard Aircraft Configuration for Maintenance | AMM 12-00-00-867-803 |
| Electrical/Electronic Safety Precautions | AMM 24-00-00-910-801 |
| Removal of the Main Generator | AMM 24-31-05-000-801 |
| Installation of the Main Generator | AMM 24-31-05-400-801 |
| Operational Test of the Main Generator | AMM 24-31-05-710-801 |
| Removal of the Generator Control Unit (GCU) - Primary | AMM 24-31-13-000-801 |
| Installation of the Generator Control Unit (GCU) - primary | AMM 24-31-13-400-801 |
| Removal of the Generator Power Module | AMM 24-31-21-000-801 |
| Installation of the Generator Power Module | AMM 24-31-21-400-801 |
| Removal of the DC Power Center (DCPC) | AMM 24-61-01-000-801 |
| Installation of the DC Power Center (DCPC) | AMM 24-61-01-400-801 |
| Functional Test of the DC Power Center (DCPC) | AMM 24-61-01-720-801 |
| Standard Practices - Replace Wiring | SPM20-12-00-02-01 |
| Standard Practices - Wire Repair | SPM20-12-10-02-01 |
Troubleshooting Recommendations:
- Swap the Auxiliary Generator Control Unit (PCB9) with the Right or Left Generator Control Unit (PCB6 or PCB5). Is the fault message still present?
- If YES, continue with next step.
- If NO, replace the defective Generator Control Unit.
NOTE: Whilst the card is removed, inspect the card contacts and make sure they are clean and free from contamination.
- Swap the Auxiliary Generator Power Module (PCB10) with Right or Left Generator Power Module (PCB8 or PCB7). Is the fault message still present?
- If YES, continue with next step.
- If NO, replace the defective Generator Power Module.
- Perform a wiring check between the APU Generator (G3) and the AUX DC Power Center (DCPC) (A196) as follows:
From To Result G3P1-A A196P1-G G3P1-B A196P1-F G3P1-G A196P1-AA G3P1-D A196P1-K G3P1-F A196P1-h G3P1-E A196P1-H G3P1-L A196P1-JJ G3P1-M A196P1-z G3P1-H A196P1-D G3P1-J A196P1-d G3P1-K A196P1-E - If wiring defects are found, repair defective wiring as required and do close out.
- If no defects are found, continue with next step.
- Swap the Auxiliary Generator (G3) with the Right or Left Generator (G2 or G1). Is the fault message still present?
- If YES, continue with next step.
- If NO, replace the defective Generator.
- Replace AUX DCPC (A196).
- Do close out.