Air carrier MD88 flight crew experienced an AC electrical bus failure on departure, drifting off course until system failure could be overcome. Flight returned to land without further difficulty.

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Attributes
ACN	409730
Time
Date	199807
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dfw
State Reference	TX
Altitude	msl bound lower : 11500 msl bound upper : 22000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw tower : ewr
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	departure other departure sid : sid
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 6000 flight time type : 1700
ASRS Report	409730
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 315 flight time total : 2550 flight time type : 290
ASRS Report	410003
Events
Anomaly	aircraft equipment problem : less severe other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

During climb, lost left AC electrical bus bar, thus autoplt, autothrottles and course guidance disappeared. Took a while to find another way to monitor course. During this time, the SID course had changed and as a result, we were off course, probably a couple of mi. There was no loss of separation. It just took a while after losing FMS and map to figure out how to use CDI without course select window working. Supplemental information from acn 410003: ZFW queried us stating he showed us about 4 mi north of course. An apparent equipment problem with our aircraft FMS. Dead reckoning messages started to appear. Map displays were shifted noticeably to the left. FMS VOR and DME updating functions were not operating properly. Updated position over known point and all malfunctions returned to normal.

Original NASA ASRS Text

Title: ACR MD88 FLC EXPERIENCED AN AC ELECTRICAL BUS FAILURE ON DEP, DRIFTING OFF COURSE UNTIL SYS FAILURE COULD BE OVERCOME. FLT RETURNED TO LAND WITHOUT FURTHER DIFFICULTY.

Narrative: DURING CLB, LOST L AC ELECTRICAL BUS BAR, THUS AUTOPLT, AUTOTHROTTLES AND COURSE GUIDANCE DISAPPEARED. TOOK A WHILE TO FIND ANOTHER WAY TO MONITOR COURSE. DURING THIS TIME, THE SID COURSE HAD CHANGED AND AS A RESULT, WE WERE OFF COURSE, PROBABLY A COUPLE OF MI. THERE WAS NO LOSS OF SEPARATION. IT JUST TOOK A WHILE AFTER LOSING FMS AND MAP TO FIGURE OUT HOW TO USE CDI WITHOUT COURSE SELECT WINDOW WORKING. SUPPLEMENTAL INFO FROM ACN 410003: ZFW QUERIED US STATING HE SHOWED US ABOUT 4 MI N OF COURSE. AN APPARENT EQUIP PROB WITH OUR ACFT FMS. DEAD RECKONING MESSAGES STARTED TO APPEAR. MAP DISPLAYS WERE SHIFTED NOTICEABLY TO THE L. FMS VOR AND DME UPDATING FUNCTIONS WERE NOT OPERATING PROPERLY. UPDATED POS OVER KNOWN POINT AND ALL MALFUNCTIONS RETURNED TO NORMAL.

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.