An MD80 in cruise at FL340 declared an emergency and diverted due to a malfunctioning AC bus tie rel...

Attributes
ACN	661004
Time
Date	200506
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 34000
Aircraft 1
Controlling Facilities	artcc : zzz1.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	661004
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : diverted to another airport flight crew : overcame equipment problem flight crew : declared emergency
Consequence	other other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

During cruise flight at FL340 in VMC conditions; we experienced a total malfunction of all electrical flight instruments and several other related navigational and control systems. The autoplt and autothrottles kicked off accompanied with a total failure of all EFIS displays and total loss of communication and navigational radios. Several (8-10) overhead amber caution lights illuminated. I immediately selected the emergency power selector to the 'on' position; which restored the captain's flight instruments and #1 communication radio to normal. At that time we experienced continuous verbal warning indications including; 'too low terrain;' 'altitude; altitude;' etc. Several flight deck and cabin lights and chime bells were rapidly activating. The loud sound of an electrical relay rapidly clicking behind the captain's seat was heard in the flight deck and by the forward flight attendant. The flight attendants also reported that the cabin overhead lights were flashing as well as the emergency exit lights illuminated. We declared an emergency and requested to divert to ZZZ for landing. During troubleshooting; the 'left generator off' light was noted as illuminated. When selecting the left generator to 'off' during the reset procedure; all systems restored to normal. The generator was left in the 'off' position; the APU was started and a normal landing followed. Callback conversation with reporter revealed the following information: the reporter stated this airplane had the AC tie relay replaced several days prior to this incident and this was the primary cause of the electrical power malfunction. With the AC tie relay opening and closing it was attempting to parallel the left and right generators. The quick reference handbook has no procedure for this type of event. No bus failure warnings were visible but a dimly lighted generator 'off' light on the annunciation panel alerted to switching the left generator off. This restored everything to normal. Auxiliary power unit was started and then powered the left bus normally.

Original NASA ASRS Text

Title: AN MD80 IN CRUISE AT FL340 DECLARED AN EMER AND DIVERTED DUE TO A MALFUNCTIONING AC BUS TIE RELAY. FLT CREW LOST NUMEROUS ACFT SYSTEMS BUT THEIR ACFT FLT MANUAL DID NOT ADEQUATELY ADDRESS THE ABNORMAL SITUATION.

Narrative: DURING CRUISE FLT AT FL340 IN VMC CONDITIONS; WE EXPERIENCED A TOTAL MALFUNCTION OF ALL ELECTRICAL FLT INSTRUMENTS AND SEVERAL OTHER RELATED NAVIGATIONAL AND CTL SYSTEMS. THE AUTOPLT AND AUTOTHROTTLES KICKED OFF ACCOMPANIED WITH A TOTAL FAILURE OF ALL EFIS DISPLAYS AND TOTAL LOSS OF COMMUNICATION AND NAVIGATIONAL RADIOS. SEVERAL (8-10) OVERHEAD AMBER CAUTION LIGHTS ILLUMINATED. I IMMEDIATELY SELECTED THE EMER POWER SELECTOR TO THE 'ON' POSITION; WHICH RESTORED THE CAPT'S FLT INSTRUMENTS AND #1 COMMUNICATION RADIO TO NORMAL. AT THAT TIME WE EXPERIENCED CONTINUOUS VERBAL WARNING INDICATIONS INCLUDING; 'TOO LOW TERRAIN;' 'ALTITUDE; ALTITUDE;' ETC. SEVERAL FLT DECK AND CABIN LIGHTS AND CHIME BELLS WERE RAPIDLY ACTIVATING. THE LOUD SOUND OF AN ELECTRICAL RELAY RAPIDLY CLICKING BEHIND THE CAPT'S SEAT WAS HEARD IN THE FLT DECK AND BY THE FORWARD FLT ATTENDANT. THE FLT ATTENDANTS ALSO RPTED THAT THE CABIN OVERHEAD LIGHTS WERE FLASHING AS WELL AS THE EMER EXIT LIGHTS ILLUMINATED. WE DECLARED AN EMER AND REQUESTED TO DIVERT TO ZZZ FOR LNDG. DURING TROUBLESHOOTING; THE 'LEFT GENERATOR OFF' LIGHT WAS NOTED AS ILLUMINATED. WHEN SELECTING THE L GENERATOR TO 'OFF' DURING THE RESET PROC; ALL SYSTEMS RESTORED TO NORMAL. THE GENERATOR WAS LEFT IN THE 'OFF' POSITION; THE APU WAS STARTED AND A NORMAL LNDG FOLLOWED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THIS AIRPLANE HAD THE AC TIE RELAY REPLACED SEVERAL DAYS PRIOR TO THIS INCIDENT AND THIS WAS THE PRIMARY CAUSE OF THE ELECTRICAL POWER MALFUNCTION. WITH THE AC TIE RELAY OPENING AND CLOSING IT WAS ATTEMPTING TO PARALLEL THE LEFT AND RIGHT GENERATORS. THE QUICK REFERENCE HANDBOOK HAS NO PROC FOR THIS TYPE OF EVENT. NO BUS FAILURE WARNINGS WERE VISIBLE BUT A DIMLY LIGHTED GENERATOR 'OFF' LIGHT ON THE ANNUNCIATION PANEL ALERTED TO SWITCHING THE L GENERATOR OFF. THIS RESTORED EVERYTHING TO NORMAL. AUXILIARY POWER UNIT WAS STARTED AND THEN POWERED THE LEFT BUS NORMALLY.

Data retrieved from NASA's ASRS site as of January 2009 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.

An MD80 in cruise at FL340 declared an emergency and diverted due to a malfunctioning AC bus tie relay. Flight crew lost numerous aircraft systems but their aircraft flight manual did not adequately address the abnormal situation.