# SDR 2000UALA00481

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: August 12, 2000
- Submitted: October 4, 2000
- Operation: Air carrier
- Aircraft: [N206UA](https://openairdocs.org/aircraft/N206UA), registered now
- Make and model: Boeing 777222
- Aircraft serial: 30212
- Aircraft time: 5,645 hours, 881 cycles
- Engine: Pwa PW4090
- System (JASC): [2420 · AC Generation System](https://openairdocs.org/jasc/2420)
- Part: Generator
- Condition: Failed
- Location: Backup
- Stage of operation: CR
- How discovered: O
- Nature of condition: J
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2000UALA00481

## Discrepancy

EN ROUTE SFO-FRA, CREW RECEIVED ADVISORY:  BACKUP ELECTRICAL SYSTEM FAILURE.  RETURNED TO SFO.  *S/D*  BOTH BACKUP GENERATORS FAILED.  ORIGINAL GRIPES INDICATED INTERNAL ELECTRICAL FAULTS TO THE BACKUP GENERATORS.  THEN, THE RIGHT BACKUP GENERATOR INDICATED A SHEARED SHAFT.  BOTH BACKUP GENERATORS WERE REPLACED.  THE MEL ACTION CONCERNING THE AD AGAINST A BACKUP GENERATOR SHEARED SHAFT WAS FOLLOWED.  THE FINDINGS FOR THE BACKUP GENERATORS ARE AS FOLLOWS: (UAL P/N MR24250-506 AND MR24250-379 OR MFG P/N 20VSCFGEN01).  379 MAIN ROTOR ANTI-DRIVE END BEARING SURFACE FAILED.  506 THE EXCITER ROTOR LEAD WIRES BROKE ON THE MAIN ROTOR.  COMPONENT TOTAL TIME AND CYCLE ARE NOT AVAILABLE FROM UNHI.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.