# SDR UALA2009101203207

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: October 10, 2009
- Submitted: October 12, 2009
- Operation: Air carrier
- Aircraft: N549UA
- Make and model: Boeing 757222
- Aircraft serial: 25397
- Aircraft time: 67,704 hours, 19,554 cycles
- Engine: Pwa PW2037
- System (JASC): [2421 · AC Generator-Alternator](https://openairdocs.org/jasc/2421)
- Part: Relay
- Part number: B4301
- Part serial: CK57274CK57081
- Condition: Faulty
- Location: Electrical Sys
- Stage of operation: IN
- How discovered: O
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/UALA2009101203207

## Discrepancy

EICAS MSG R GEN DRIVE DISPLAYED.  GEN DRIVE LIGHT ILLUM.  GEN DRIVE DISCONNECTED.  NOTICED C/B 1 ON FACE OF R GCU WAS OPEN, LIKELY FROM IN FLT.  SWAPPED LT & RT ENG GCU'S & RAN RT ENG AGAIN.  C/B 1 POPPED AGAIN.  BPCU MSGS ARE 28V TO CONTROL SW, GCB-WIRING-GCU,  BTB-WIRING-GCU & POWER INTERRUPT.  NEED TO FIND WHY C/B 1 IS POPPING.  FIM SUGGESTS A PANEL SWITCH PROBLEM, RT GCB (C903), RT BTB (C904).  IDG SEEMS TO BE OK.  GCU'S STILL IN SWAPPED POS.  R & R RT IDG, NO HELP.  STILL NOT ABLE TO GENERATE A FIELD.  NOTED FIELD OFF LIGHT ILLUMINATED ON P61 PANEL.  REPLACED R GEN CONT BREAKER C903 & REPLACED RT BUSS TIE CONT BREAKER C904.  OPS CHECKS GOOD, NO FAULTS NOTED.

---
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, except the copies of manufacturers’ service documents, which belong to their rights holders.