An L1011 at FL310 declared an emergency and diverted due to loss of all heading reference on left an...

Attributes
ACN	504886
Time
Date	200103
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 31000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zzz.artcc tower : bzn.tower
Operator	common carrier : air carrier
Make Model Name	L-1011-1 100/200/250
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute airway : r465.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 180 flight time total : 19000 flight time type : 2000
ASRS Report	504886
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical other anomaly other anomaly other other spatial deviation
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : diverted to another airport flight crew : declared emergency
Consequence	other other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

During climb en route ZZZ-xyz, with autoplt engaged, aircraft abruptly pitched over at about FL240. Disconnected a autoplt and resumed climb in hand flown manner. Engaged B autoplt and continued climb to FL310. Shortly after level off at fl 310, aircraft abruptly pitched over again. Disconnected autoplt and resumed hand flight, decided to return to ZZZ. At this point both flight directors froze in lined-up position (straight and level). Aircraft began to porpoise and deviation (+ 500 FPM maximum) from FL310 occurred. Heading at 070, no moon, only black outside. Received clearance to return to ZZZ and began left turn. All heading (both sides) information froze during turn at 360. Vertical speed control on mode select panel became inoperative. So advised of heading by reference to whisky compass. Dumped fuel while on way back to ZZZ. Performed all checklists. Shot visual approach to runway 8L ZZZ. All instrument either inoperative (except airspeed, and altimeter) or giving erroneous direction. Landed and taxied to gate without incident. Callback conversation with reporter revealed the following information: the reporter stated in climb at FL240 the aircraft pitched over with 'a' autoplt connected. The reporter said 'B' autoplt was engaged and climb continued normally to FL310 and level off where the aircraft pitched over again. The reporter said the 'B' autoplt was disconnected and the aircraft was hand flown. The reporter stated at this time all heading reference indications were lost, flight director bars froze and aircraft began to porpoise 500 ft up and down. The reporter said an emergency was declared and a turn was made using the standby compass. The reporter said maintenance found the captain's alternate source select panel had an internal electrical fire which rendered the heading reference data inoperative. The reporter stated at no time was smoke, flames or fumes detected, and no circuit breakers tripped.

Original NASA ASRS Text

Title: AN L1011 AT FL310 DECLARED AN EMER AND DIVERTED DUE TO LOSS OF ALL HEADING REFERENCE ON L AND R INSTRUMENTS CAUSED BY AN ELECTRICAL FIRE IN THE ALTERNATE SOURCE SELECT PANEL.

Narrative: DURING CLB ENRTE ZZZ-XYZ, WITH AUTOPLT ENGAGED, ACFT ABRUPTLY PITCHED OVER AT ABOUT FL240. DISCONNECTED A AUTOPLT AND RESUMED CLB IN HAND FLOWN MANNER. ENGAGED B AUTOPLT AND CONTINUED CLB TO FL310. SHORTLY AFTER LEVEL OFF AT FL 310, ACFT ABRUPTLY PITCHED OVER AGAIN. DISCONNECTED AUTOPLT AND RESUMED HAND FLT, DECIDED TO RETURN TO ZZZ. AT THIS POINT BOTH FLT DIRECTORS FROZE IN LINED-UP POS (STRAIGHT AND LEVEL). ACFT BEGAN TO PORPOISE AND DEVIATION (+ 500 FPM MAX) FROM FL310 OCCURRED. HEADING AT 070, NO MOON, ONLY BLACK OUTSIDE. RECEIVED CLRNC TO RETURN TO ZZZ AND BEGAN L TURN. ALL HEADING (BOTH SIDES) INFO FROZE DURING TURN AT 360. VERTICAL SPEED CTL ON MODE SELECT PANEL BECAME INOP. SO ADVISED OF HEADING BY REFERENCE TO WHISKY COMPASS. DUMPED FUEL WHILE ON WAY BACK TO ZZZ. PERFORMED ALL CHKLISTS. SHOT VISUAL APCH TO RWY 8L ZZZ. ALL INST EITHER INOP (EXCEPT AIRSPEED, AND ALTIMETER) OR GIVING ERRONEOUS DIRECTION. LANDED AND TAXIED TO GATE WITHOUT INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED IN CLB AT FL240 THE ACFT PITCHED OVER WITH 'A' AUTOPLT CONNECTED. THE RPTR SAID 'B' AUTOPLT WAS ENGAGED AND CLB CONTINUED NORMALLY TO FL310 AND LEVEL OFF WHERE THE ACFT PITCHED OVER AGAIN. THE RPTR SAID THE 'B' AUTOPLT WAS DISCONNECTED AND THE ACFT WAS HAND FLOWN. THE RPTR STATED AT THIS TIME ALL HEADING REFERENCE INDICATIONS WERE LOST, FLT DIRECTOR BARS FROZE AND ACFT BEGAN TO PORPOISE 500 FT UP AND DOWN. THE RPTR SAID AN EMER WAS DECLARED AND A TURN WAS MADE USING THE STANDBY COMPASS. THE RPTR SAID MAINT FOUND THE CAPTAIN'S ALTERNATE SOURCE SELECT PANEL HAD AN INTERNAL ELECTRICAL FIRE WHICH RENDERED THE HEADING REFERENCE DATA INOPERATIVE. THE RPTR STATED AT NO TIME WAS SMOKE, FLAMES OR FUMES DETECTED, AND NO CIRCUIT BREAKERS TRIPPED.

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.

An L1011 at FL310 declared an emergency and diverted due to loss of all heading reference on left and right instruments caused by an electrical fire in the alternate source select panel.