A B737-300 in cruise at FL350 declared an emergency and diverted due to loss of left main AC and left AC transfer bus. All instruments and units pwred from these busses were inoperative.

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Attributes
ACN	518686
Time
Date	200107
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : las.airport
State Reference	NV
Altitude	msl single value : 35000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 11700 flight time type : 6163
ASRS Report	518686
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : bus off warning other flight crewa other flight crewb
Resolutory Action	flight crew : declared emergency flight crew : diverted to another airport
Consequence	other other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

At FL350 lost general bus #1, transfer bus #1,amber autopilot, automatic transfer of pressurization. Controller to standby mode, dc bus #1 and captain's instruments and FMC. Used manual mode for pressure control. Unable to power #1 general bus with APU. Declared an emergency, advised the flight attendant's and passenger of the situation. Flew an orbit over cdc VOR airport and coordinated with maintenance and dispatch as to a diversion station and possible in-flight resolution of problem. We were unable to power the left general bus with APU and discovered the #1 transfer relay popped. Completed the single engine general checklist and diverted to las. After landing, debriefed flight attendant's, called system duty flight manager.

Original NASA ASRS Text

Title: A B737-300 IN CRUISE AT FL350 DECLARED AN EMER AND DIVERTED DUE TO LOSS OF L MAIN AC AND L AC TRANSFER BUS. ALL INSTS AND UNITS PWRED FROM THESE BUSSES WERE INOPERATIVE.

Narrative: AT FL350 LOST GENERAL BUS #1, TRANSFER BUS #1,AMBER AUTOPILOT, AUTO TRANSFER OF PRESSURIZATION. CTLR TO STANDBY MODE, DC BUS #1 AND CAPT'S INSTS AND FMC. USED MANUAL MODE FOR PRESSURE CTL. UNABLE TO PWR #1 GENERAL BUS WITH APU. DECLARED AN EMER, ADVISED THE FA'S AND PAX OF THE SIT. FLEW AN ORBIT OVER CDC VOR ARPT AND COORDINATED WITH MAINT AND DISPATCH AS TO A DIVERSION STATION AND POSSIBLE INFLT RESOLUTION OF PROB. WE WERE UNABLE TO PWR THE L GENERAL BUS WITH APU AND DISCOVERED THE #1 TRANSFER RELAY POPPED. COMPLETED THE SINGLE ENG GENERAL CHECKLIST AND DIVERTED TO LAS. AFTER LNDG, DEBRIEFED FA'S, CALLED SYS DUTY FLT MGR.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.