# SDR ASAA2019120961531

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 6, 2019
- Submitted: December 10, 2019
- Operation: Air carrier
- Aircraft: [N440AS](https://openairdocs.org/aircraft/N440AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 41705
- Aircraft time: 24,269 hours, 7,859 cycles
- System (JASC): [2421 · AC Generator-Alternator](https://openairdocs.org/jasc/2421)
- Part: Unknown
- Condition: Unknown
- Location: Apu Generator
- Stage of operation: NR
- How discovered: O
- Nature of condition: N
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2019120961531

## Discrepancy

AFTER APU START, APU ELEC SHOWS NO VOLTS OR FREQ. BLUE APU AVAIL LIGHT IS ON. GROUNDED - YES. COULD NOT DUPLICATE. SWAPPED APU GCU AND #1 ENGINE GCU. BOTH SYSTEMS OP'ED NORMAL. RETURNED GCU'C TO ORIGINAL POSITIONS. BOTH #1 ENGINE GENERATOR AND APU GENERATOR OP NORMAL REF B737-900 AMM 24-21-00.

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