02/25/21
Message Overview:
Message Description:
The Auxiliary Power Unit Sensor (DPMS 5) has detected a current imbalance between the 2 feeders.
A failure with the Auxiliary Power Unit Sensor (DPMS5) or the Auxiliary Power-Center Primary-Logic has been reported by the Aux DCPC.
Possible Causes:
- Auxiliary Power Unit Sensor (DPMS5)
- Auxiliary Power-Center Primary-Logic (ALOG) (PCB11)
- Auxiliary Power Unit Power Feeders
- Auxiliary Power Center (Aux DCPC) (A196)
Troubleshooting Tips:
Advisory Wire/Service Bulletin:
- AW300-24-0024 - Electrical System - Troubleshooting Tips
- AW300-24-0034 - "ELECTRICAL FAULT" CAS Message When External Power is Connected
- AW300-24-0222 - Aft Fuselage - APU Generator Power Feeder Cable Fouling Condition (20501 - 20635)
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the APU Generator | AMM 24-31-09-000-801 |
| Installation of the APU Generator | AMM 24-31-09-400-801 |
| Operational Test of the APU Generator | AMM 24-31-09-710-801 |
| Removal of the Auxiliary DC Power Center (Aux DCPC) | AMM 24-64-01-000-801 |
| Installation of the Auxiliary DC Power Center (Aux DCPC) | AMM 24-64-01-400-801 |
| Operational Test of the Auxiliary DC Power Center (Aux DCPC) | AMM 24-64-01-710-801 |
| Removal of the Auxiliary Power Center Primary-Logic | AMM 24-64-13-000-801 |
| Installation of the Auxiliary Power Center Primary-Logic | AMM 24-64-13-400-801 |
| Removal of the Auxiliary Power Unit Sensor | AMM 24-64-17-000-801 |
| Installation of the Auxiliary Power Unit Sensor | AMM 24-64-17-400-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
| Electrical Connectors - Maintenance Practice - ALL | SPM 20-20-00-02 |
Troubleshooting Recommendations:
- Disconnect the Auxiliary Power Unit Sensor DPMS5 connector. Do visual inspection of the connector and associated wiring for any loose pins and/or damaged wire.
- If inspection is satisfying, continue with next step.
- If inspection is not satisfying, go to step 5.
- Swap the Auxiliary Power Unit Sensor DPMS5 with Auxiliary Power Unit Sensor DPMS7. Is the fault message still present?
- If YES, continue with next step.
- If NO, replace the defective Auxiliary Power Unit Sensor.
- Do visual inspection and a wiring check (with a high precision milli-ohm meter) of the feeder cables between the APU Generator G3 Stud and the Aux DCPC T31 and T32 Studs.
- If inspection and wiring check are satisfying, go to next step.
- If inspection and wiring check are not satisfying, repair defective wiring.
NOTE: Due to the high precision of the generator sensor (100 mA), to confirm the integrity of a power feeder, it is suggested to connect an extra feeder cable to bypass the suspected one.
- Replace the Auxiliary Power-Center Primary-Logic. Is the fault message still present?
- If YES, continue with next step.
- If NO, go to step.
- Replace the Aux DCPC (A196).
- Do close out.