During a night operation and after numerous generator tips of #1 generator and associated electrical...

Attributes
ACN	639546
Time
Date	200412
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 39000
Environment
Flight Conditions	VMC
Light	Night Night
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 250 flight time total : 9000 flight time type : 3500
ASRS Report	639546
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : eicas and trip lights other flight crewa other flight crewb
Resolutory Action	flight crew : diverted to another airport flight crew : landed in emergency condition flight crew : declared emergency
Consequence	other other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Passing FL190, captain (PF) engaged 'C' autoplt. We noticed intermittent jerkiness in the autoplt. Captain disconnected 'C' autoplt and engaged 'left' autoplt. Same results, but then we noticed that concurrent with the jerks in the autoplt was a cycling from bright to dim of the ACARS screen. Engaged 'right' autoplt and jerks stopped, but ACARS still intermittently went dim. Had dispatch contact us with maintenance control and wrote up the problems and told them of our suspicion of a bus/electrical problem. About 100 mi sse of slc, left generator tripped with an left isolation light. Consulted flight manual and reset left generator. Left isolation remained illuminated. Started APU for backup for right a/C power. Re-engaged 'right' autoplt and continued at FL390. At 160 mi nne of ZZZ, left generator tripped again with autoplt disconnect and numerous EICAS messages. Captain was talking with maintenance control but lost communications. Had ATC relay intention to divert to ZZZ. Declared emergency and proceeded to ZZZ. Several unexpected electrical problems ensued en route to ZZZ. The EICAS had compacted, but intermittently went totally blank. Both altitude indicators turned black and white intermittently. Cabin and cockpit got warm. Selected packs to 'C.' informed flight attendants and passenger of deviation. On approach to ZZZ, flaps were slower to move than expected. Visual runway 25R uneventful landing.

Original NASA ASRS Text

Title: DURING A NIGHT OP AND AFTER NUMEROUS GENERATOR TIPS OF #1 GENERATOR AND ASSOCIATED ELECTRICAL DISTRIBUTION PROBS, A B757-200 FLT CREW DECIDES TO DIVERT TO ZZZ.

Narrative: PASSING FL190, CAPT (PF) ENGAGED 'C' AUTOPLT. WE NOTICED INTERMITTENT JERKINESS IN THE AUTOPLT. CAPT DISCONNECTED 'C' AUTOPLT AND ENGAGED 'L' AUTOPLT. SAME RESULTS, BUT THEN WE NOTICED THAT CONCURRENT WITH THE JERKS IN THE AUTOPLT WAS A CYCLING FROM BRIGHT TO DIM OF THE ACARS SCREEN. ENGAGED 'R' AUTOPLT AND JERKS STOPPED, BUT ACARS STILL INTERMITTENTLY WENT DIM. HAD DISPATCH CONTACT US WITH MAINT CTL AND WROTE UP THE PROBS AND TOLD THEM OF OUR SUSPICION OF A BUS/ELECTRICAL PROB. ABOUT 100 MI SSE OF SLC, L GENERATOR TRIPPED WITH AN L ISOLATION LIGHT. CONSULTED FLT MANUAL AND RESET L GENERATOR. L ISOLATION REMAINED ILLUMINATED. STARTED APU FOR BACKUP FOR R A/C PWR. RE-ENGAGED 'R' AUTOPLT AND CONTINUED AT FL390. AT 160 MI NNE OF ZZZ, L GENERATOR TRIPPED AGAIN WITH AUTOPLT DISCONNECT AND NUMEROUS EICAS MESSAGES. CAPT WAS TALKING WITH MAINT CTL BUT LOST COMS. HAD ATC RELAY INTENTION TO DIVERT TO ZZZ. DECLARED EMER AND PROCEEDED TO ZZZ. SEVERAL UNEXPECTED ELECTRICAL PROBS ENSUED ENRTE TO ZZZ. THE EICAS HAD COMPACTED, BUT INTERMITTENTLY WENT TOTALLY BLANK. BOTH ALT INDICATORS TURNED BLACK AND WHITE INTERMITTENTLY. CABIN AND COCKPIT GOT WARM. SELECTED PACKS TO 'C.' INFORMED FLT ATTENDANTS AND PAX OF DEV. ON APCH TO ZZZ, FLAPS WERE SLOWER TO MOVE THAN EXPECTED. VISUAL RWY 25R UNEVENTFUL LNDG.

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.

During a night operation and after numerous generator tips of #1 generator and associated electrical distribution problems, a B757-200 flight crew decides to divert to ZZZ.