# SDR ASAA2022111240784

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: November 12, 2022
- Submitted: November 16, 2022
- Operation: Air carrier
- Aircraft: [N949AK](https://openairdocs.org/aircraft/N949AK), registered now
- Make and model: Boeing 737-9
- Registry model: [Boeing 737-9](https://openairdocs.org/model/boeing-737-9) (OpenAirDocs)
- Aircraft serial: 43356
- Aircraft time: 129 hours, 41 cycles
- System (JASC): [4900 · Airborne Auxiliary Power Unit (APU) System](https://openairdocs.org/jasc/4900)
- Part: Apu
- Condition: Faulted
- Stage of operation: TX
- How discovered: O
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2022111240784

## Discrepancy

APU FAULT ON START. GROUNDED - YES. OBSERVING APU MDS DATA PAGE, APU ECU DOES NOT INITIALIZE WHEN EITHER APU SWITCH POSITIONED TO ON, OR WHEN MDS MAINT CTL APU SELECTED TO TEST. CYCLED APU ECU C/B, THEN NORMAL OPERATION RESTORED. ACCOMPLISHED APU OPERATIONAL TEST PER B737-9 AMM 49-11-00 WITH NO DEFECTS OBSERVED. NO MDS STATUS OR FAILURE MESSAGES PRESENT AT ANY TIME. ETOPS GROUND VERIFICATION SUCCESSFUL.

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