An MD11 in cruise at FL350 diverted due to strong odor of overheated electrical equipment caused by ...

Narrative:

In cruise we smelled a strong odor of something burning like electrical or equipment. We diverted off track, descended to FL270, and preceded direct to shannon (einn), ireland airport. The relief pilot did the 'smoke/fumes of electrical, air conditioning, or unknown source' checklist and was able to isolate problem and odor decreased. I was flying and with doing the checklist I lost my instruments (which is supposed to happen with the abnormal checklist) and the captain then flew to shannon. We had a normal landing at shannon. Maintenance found a water pressure pump that seized and overheated. Callback conversation with reporter revealed the following information: the reporter stated the cause of the electrical smell was the flexible rubber water compressor drive belt and the overheated electrical motor which was operating continuously. The reporter said the water tank air compressor only operates on the ground and only with no other source of pneumatic air, APU, engine or ground air cart. The reporter said the malfunction was suspected in the failed tank pressure switch or a leak in the flexible hose sensing pressure in the tank allowing the motor to run continuously. The smell was caused mainly by the rubber drive belt that was chewed up stalled the motor which overheated and tripped the circuit breaker in the cabin. The reporter said the loss of the first officer's instruments was caused by the checklist procedure to isolate the electrical busses and the water pressure compressor was on the #3 bus which also feeds the first officer's instruments.in cruise we smelled a strong odor of something burning like electrical or equipment. We diverted off track, descended to FL270, and proceeded direct to shannon (einn), ireland airport. The relief pilot did the 'smoke/fumes of electrical, air conditioning, or unknown source' checklist and was able to isolate problem and odor decreased. I was flying and with doing the checklist I lost my instruments (which is supposed to happen with the abnormal checklist) and the captain then flew to shannon. We had a normal landing at shannon. Maintenance found a water pressure pump that seized and overheated. Callback conversation with reporter revealed the following information: the reporter stated the cause of the electrical smell was the flexible rubber water compressor drive belt and the overheated electrical motor which was operating continuously. The reporter said the water tank air compressor only operates on the ground and only with no other source of pneumatic air, APU, engine or ground air cart. The reporter said the malfunction was suspected in the failed tank pressure switch or a leak in the flexible hose sensing pressure in the tank allowing the motor to run continuously. The smell was caused mainly by the rubber drive belt that was chewed up stalled the motor which overheated and tripped the circuit breaker in the cabin. The reporter said the loss of the first officer's instruments was caused by the checklist procedure to isolate the electrical busses and the water pressure compressor was on the #3 bus which also feeds the first officer's instruments.

Original NASA ASRS Text

Title: AN MD11 IN CRUISE AT FL350 DIVERTED DUE TO STRONG ODOR OF OVERHEATED ELECTRICAL EQUIP CAUSED BY THE MALFUNCTION OF THE WATER PRESSURE COMPRESSOR MOTOR.

Narrative: IN CRUISE WE SMELLED A STRONG ODOR OF SOMETHING BURNING LIKE ELECTRICAL OR EQUIP. WE DIVERTED OFF TRACK, DSNDED TO FL270, AND PRECEDED DIRECT TO SHANNON (EINN), IRELAND ARPT. THE RELIEF PLT DID THE 'SMOKE/FUMES OF ELECTRICAL, AIR CONDITIONING, OR UNKNOWN SOURCE' CHKLIST AND WAS ABLE TO ISOLATE PROB AND ODOR DECREASED. I WAS FLYING AND WITH DOING THE CHKLIST I LOST MY INSTS (WHICH IS SUPPOSED TO HAPPEN WITH THE ABNORMAL CHKLIST) AND THE CAPT THEN FLEW TO SHANNON. WE HAD A NORMAL LNDG AT SHANNON. MAINT FOUND A WATER PRESSURE PUMP THAT SEIZED AND OVERHEATED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CAUSE OF THE ELECTRICAL SMELL WAS THE FLEXIBLE RUBBER WATER COMPRESSOR DRIVE BELT AND THE OVERHEATED ELECTRICAL MOTOR WHICH WAS OPERATING CONTINUOUSLY. THE RPTR SAID THE WATER TANK AIR COMPRESSOR ONLY OPERATES ON THE GND AND ONLY WITH NO OTHER SOURCE OF PNEUMATIC AIR, APU, ENG OR GND AIR CART. THE RPTR SAID THE MALFUNCTION WAS SUSPECTED IN THE FAILED TANK PRESSURE SWITCH OR A LEAK IN THE FLEXIBLE HOSE SENSING PRESSURE IN THE TANK ALLOWING THE MOTOR TO RUN CONTINUOUSLY. THE SMELL WAS CAUSED MAINLY BY THE RUBBER DRIVE BELT THAT WAS CHEWED UP STALLED THE MOTOR WHICH OVERHEATED AND TRIPPED THE CIRCUIT BREAKER IN THE CABIN. THE RPTR SAID THE LOSS OF THE FO'S INSTS WAS CAUSED BY THE CHKLIST PROC TO ISOLATE THE ELECTRICAL BUSSES AND THE WATER PRESSURE COMPRESSOR WAS ON THE #3 BUS WHICH ALSO FEEDS THE FO'S INSTS.IN CRUISE WE SMELLED A STRONG ODOR OF SOMETHING BURNING LIKE ELECTRICAL OR EQUIP. WE DIVERTED OFF TRACK, DSNDED TO FL270, AND PROCEEDED DIRECT TO SHANNON (EINN), IRELAND ARPT. THE RELIEF PLT DID THE 'SMOKE/FUMES OF ELECTRICAL, AIR CONDITIONING, OR UNKNOWN SOURCE' CHKLIST AND WAS ABLE TO ISOLATE PROB AND ODOR DECREASED. I WAS FLYING AND WITH DOING THE CHKLIST I LOST MY INSTS (WHICH IS SUPPOSED TO HAPPEN WITH THE ABNORMAL CHKLIST) AND THE CAPT THEN FLEW TO SHANNON. WE HAD A NORMAL LNDG AT SHANNON. MAINT FOUND A WATER PRESSURE PUMP THAT SEIZED AND OVERHEATED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CAUSE OF THE ELECTRICAL SMELL WAS THE FLEXIBLE RUBBER WATER COMPRESSOR DRIVE BELT AND THE OVERHEATED ELECTRICAL MOTOR WHICH WAS OPERATING CONTINUOUSLY. THE RPTR SAID THE WATER TANK AIR COMPRESSOR ONLY OPERATES ON THE GND AND ONLY WITH NO OTHER SOURCE OF PNEUMATIC AIR, APU, ENG OR GND AIR CART. THE RPTR SAID THE MALFUNCTION WAS SUSPECTED IN THE FAILED TANK PRESSURE SWITCH OR A LEAK IN THE FLEXIBLE HOSE SENSING PRESSURE IN THE TANK ALLOWING THE MOTOR TO RUN CONTINUOUSLY. THE SMELL WAS CAUSED MAINLY BY THE RUBBER DRIVE BELT THAT WAS CHEWED UP STALLED THE MOTOR WHICH OVERHEATED AND TRIPPED THE CIRCUIT BREAKER IN THE CABIN. THE RPTR SAID THE LOSS OF THE FO'S INSTS WAS CAUSED BY THE CHKLIST PROC TO ISOLATE THE ELECTRICAL BUSSES AND THE WATER PRESSURE COMPRESSOR WAS ON THE #3 BUS WHICH ALSO FEEDS THE FO'S INSTS.

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.

Attributes
ACN	416360
Time
Date	199810
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : eggx
State Reference	FO
Altitude	msl bound lower : 35000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : eggx
Operator	common carrier : air carrier
Make Model Name	DC-10 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute : other oceanic
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 160 flight time total : 11000 flight time type : 1400
ASRS Report	416360
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 230 flight time total : 25300 flight time type : 630
ASRS Report	416468
Events
Anomaly	aircraft equipment problem : less severe other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

An MD11 in cruise at FL350 diverted due to strong odor of overheated electrical equipment caused by the malfunction of the water pressure compressor motor.