# SDR UPS98527427

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: August 13, 1998
- Submitted: March 26, 2000
- Operation: Air carrier
- Aircraft: [N439UP](https://openairdocs.org/aircraft/N439UP), registered now
- Make and model: Boeing 757-24APF
- Registry model: [Boeing 757-24APF](https://openairdocs.org/model/boeing-757-24apf) (OpenAirDocs)
- Aircraft serial: 25470
- System (JASC): [2424 · AC Regulator](https://openairdocs.org/jasc/2424)
- Part: Gcu
- Part number: 734284F
- Condition: Malfunctioned
- Location: Lt Generator
- Stage of operation: CL
- Nature of condition: H, J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/UPS98527427

## Discrepancy

AT VI INTERMITENT LEFT GEN OFF LIGHT ILLUM.  LEFT AC BUSS FAILED, RIGHT BUS DID NOT PICK UP LEFT BUS.  SHORLTY THERE AFTER THE R AC BUS FAILED.  MULTIPLE WARNINGS DISPLAYED.  RESET R GEN, R BUS POWER BACK ON.  FIRED APU L BUS POWERED.  SHORTLY AFTER L BUS POWER WAS INTERMITTENT.  RETURNED TO GDL AIRPORT.  PERFORMED BPCU BITE TEST AND SHOWED AUX CONTACTS/BPCU/GCU MES.  SWAPPED APU GCU TO LEFT GCU.  RUN ENGINES AND ATTEMPTED TO DUPLICATE PROBLEM.  SYSTEM OPS CK NORMAL.  DEFERRED APU PER MEL.

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