|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||airport : zzz.airport|
|Altitude||agl single value : 0|
|Operator||common carrier : air carrier|
|Make Model Name||MD-83|
|Operating Under FAR Part||Part 121|
|Flight Phase||climbout : takeoff|
climbout : initial
ground : takeoff roll
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Affiliation||company : air carrier|
|Function||flight crew : first officer|
|Anomaly||aircraft equipment problem : critical|
|Independent Detector||aircraft equipment other aircraft equipment : left and right gen 'off' lights|
other flight crewa
other flight crewb
|Problem Areas||Chart Or Publication|
Just after rotation both buses started to alternate on and off line. Lost both captain and first officer EFIS and primary airspeed and altimeters and vsi. All cockpit and cabin lighting was intermittent. Left and right generator off lights were flickering. Started APU and declared an emergency for a 148300 pound overweight landing. Approach and landing on runway 14R uneventful. Callback conversation with reporter revealed the following information: the reporter stated both left and right buses alternated off and on in a fairly high frequency with the left and right generator 'off' lights flickering. Lost left and right EFIS; all air data instruments; and all cabin and cockpit lighting flickering. It appears the generators were attempting to parallel. This event went on for 30 seconds to 1 minute. The reporter followed up on the cause of the malfunction and found the maintenance fix was replacement of both constant speed drives due to output frequencies out of limits. The reporter had never experienced an event of this nature and believed it was fortunate to happen in day VFR. One fact noticed was that the standby instruments operated as advertised. Callback conversation with reporter acn 670698 revealed the following information: reporter stated that right after rotation; the lights started flashing on and off and the AC power relays behind the captain's seat were clacking and banging. Lost EFIS; vsi; altimeters; and airspeed indications. Declared an emergency; started the auxiliary power unit; and landed overweight. Believed the left generator was replaced. Reporter also stated that there is no procedure for this type of event in the QRH.
Original NASA ASRS Text
Title: AN MD83; JUST AFTER ROTATION; DECLARED AN EMER DUE TO BOTH BUSES ALTERNATING L TO R. LOST #1 AND #2 EFIS; PRIMARY INSTRUMENTS; AND ALTIMETERS. CREW LANDED OVERWT. FLT CREW NOTED THAT THE FLT MANUAL CONTAINED NO PROCEDURE TO ADDRESS THIS SITUATION.
Narrative: JUST AFTER ROTATION BOTH BUSES STARTED TO ALTERNATE ON AND OFF LINE. LOST BOTH CAPT AND FO EFIS AND PRIMARY AIRSPEED AND ALTIMETERS AND VSI. ALL COCKPIT AND CABIN LIGHTING WAS INTERMITTENT. L AND R GENERATOR OFF LIGHTS WERE FLICKERING. STARTED APU AND DECLARED AN EMER FOR A 148300 LB OVERWT LNDG. APCH AND LNDG ON RWY 14R UNEVENTFUL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED BOTH L AND R BUSES ALTERNATED OFF AND ON IN A FAIRLY HIGH FREQUENCY WITH THE L AND R GENERATOR 'OFF' LIGHTS FLICKERING. LOST L AND R EFIS; ALL AIR DATA INSTRUMENTS; AND ALL CABIN AND COCKPIT LIGHTING FLICKERING. IT APPEARS THE GENERATORS WERE ATTEMPTING TO PARALLEL. THIS EVENT WENT ON FOR 30 SECONDS TO 1 MINUTE. THE RPTR FOLLOWED UP ON THE CAUSE OF THE MALFUNCTION AND FOUND THE MAINT FIX WAS REPLACEMENT OF BOTH CONSTANT SPD DRIVES DUE TO OUTPUT FREQUENCIES OUT OF LIMITS. THE RPTR HAD NEVER EXPERIENCED AN EVENT OF THIS NATURE AND BELIEVED IT WAS FORTUNATE TO HAPPEN IN DAY VFR. ONE FACT NOTICED WAS THAT THE STANDBY INSTRUMENTS OPERATED AS ADVERTISED. CALLBACK CONVERSATION WITH RPTR ACN 670698 REVEALED THE FOLLOWING INFO: RPTR STATED THAT RIGHT AFTER ROTATION; THE LIGHTS STARTED FLASHING ON AND OFF AND THE AC POWER RELAYS BEHIND THE CAPT'S SEAT WERE CLACKING AND BANGING. LOST EFIS; VSI; ALTIMETERS; AND AIRSPD INDICATIONS. DECLARED AN EMER; STARTED THE AUXILIARY POWER UNIT; AND LANDED OVERWT. BELIEVED THE L GENERATOR WAS REPLACED. RPTR ALSO STATED THAT THERE IS NO PROC FOR THIS TYPE OF EVENT IN THE QRH.
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.