# SDR UALA2009051101332

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 10, 2009
- Submitted: May 14, 2009
- Operation: Air carrier
- Aircraft: [N783UA](https://openairdocs.org/aircraft/N783UA), registered now
- Make and model: Boeing 777222
- Aircraft serial: 26950
- Aircraft time: 54,151 hours, 7,919 cycles
- Engine: Pwa PW40903
- System (JASC): [4990 · APU Oil System](https://openairdocs.org/jasc/4990)
- Part: Switch
- Part number: 41320332
- Condition: Faulty
- Location: Apu
- Stage of operation: NR
- How discovered: O
- Nature of condition: O
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/UALA2009051101332

## Discrepancy

APU APUC DETECTED FAULT THAT WOULD CAUSE AUTOMATIC SHUTDOWN OF APU IN UNATTENDED MODE OPERATION, OR COMPLETE LOSS OF APUC BUS ACTIVITY (BOTH L AND R 629) FOR 3 SECONDS AFTER THE APU MASTER CONTROL SWITCH HAS BEEN IN THE ON POSITION FOR TEN SECONDS.  STATUS CREW COMMENTS: MOMENTARY APU LIMIT EICAS MSG DURING NORMAL SHUTDOWN. MSG-4910270 INACTV PO MODE. -MAT MSG 49-12970.   REPLACED LOW OIL PRESSURE SWITCH. RAN APU, NO LEAKS NOTED. NO MSG PRESENT. REMOVED AND REINSTALLED GEN BYPASS SWITCH. NO LEAKS NOTED. SECURED SWITCH. NO LEAKS NOTED.

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