Narrative:

En route from madrid, spain, to dfw. While cruising at FL390 the airspeed began to decay and I observed that the left engine fuel flow had dropped off from 5.5 pounds/hour to 3.5 pounds/hour. All other left engine indications agreed with the decreased thrust on this engine (ie, north, egt and N2). There were no other indications such as an EICAS warning message to help determine the cause of my problem. To have advanced the left throttle would have over temperature'ed the engine. Due to the loss of power I felt I would not be able to maintain my assigned cruise altitude of 39000'. Therefore I declared an emergency with gander center on my assigned frequency at approximately XA30. I requested clearance to my en route alternate which was gander, newfoundland. I received a clearance to descend to FL350 and proceed direct to gander. Shortly thereafter I was cleared to FL290. I was 326 NM from gander at the time this first happened. En route to gander after approximately 10-15 mins, while trying to determine the cause of my problem using the QRH, I turned off the left eec. Then, according to QRH procedure I turned off the right eec. Engine power on the left engine returned to normal and with eec's off I was able to establish equal power on both engines. (There is no specific procedure in the QRH for the problem I had, west/O an EICAS eec warning message.) at this time I contacted airlines engine tech through ny commercial radio and dispatch. I advised them of my situation and the action I had taken. They concurred with my action, determining everything to be normal with the eec's off. I advised my dispatch that I would continue on toward my destination. At this time I cancelled the emergency I had declared and requested a clearance to chicago O'hare with gander center. They cleared me on course to climb to FL370. After leveling off at cruise altitude, I refigured my fuel and determined I could continue on to dfw. Then I requested clearance to dfw. This clearance was received from montreal center. I landed west/O further incident at dfw with just over 13000 pounds of fuel, about 5000 pounds more than required for reserve and alternate fuel. Callback conversation with reporter revealed the following: follow up with maintenance revealed that the eec had incurred a fault and was sensing a false overtemp which was the reason the eec reduced the power and until it was turned off would not allow engine power to be restored. Reason no EICAS message was because eec thought it was acting on valid input. After the descent and start of diversion flight still arrived in dfw only 8 mins over flight plan.

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Original NASA ASRS Text

Title: ACR WDB WITH EQUIPMENT MALFUNCTION UNABLE MAINTAIN ALT ACCOUNT LOW ENGINE POWER. EMERGENCY DECLARED.

Narrative: ENRTE FROM MADRID, SPAIN, TO DFW. WHILE CRUISING AT FL390 THE AIRSPD BEGAN TO DECAY AND I OBSERVED THAT THE LEFT ENG FUEL FLOW HAD DROPPED OFF FROM 5.5 LBS/HR TO 3.5 LBS/HR. ALL OTHER LEFT ENG INDICATIONS AGREED WITH THE DECREASED THRUST ON THIS ENG (IE, N, EGT AND N2). THERE WERE NO OTHER INDICATIONS SUCH AS AN EICAS WARNING MESSAGE TO HELP DETERMINE THE CAUSE OF MY PROB. TO HAVE ADVANCED THE LEFT THROTTLE WOULD HAVE OVER TEMP'ED THE ENG. DUE TO THE LOSS OF PWR I FELT I WOULD NOT BE ABLE TO MAINTAIN MY ASSIGNED CRUISE ALT OF 39000'. THEREFORE I DECLARED AN EMER WITH GANDER CENTER ON MY ASSIGNED FREQ AT APPROX XA30. I REQUESTED CLRNC TO MY ENRTE ALTERNATE WHICH WAS GANDER, NEWFOUNDLAND. I RECEIVED A CLRNC TO DSND TO FL350 AND PROCEED DIRECT TO GANDER. SHORTLY THEREAFTER I WAS CLRED TO FL290. I WAS 326 NM FROM GANDER AT THE TIME THIS FIRST HAPPENED. ENRTE TO GANDER AFTER APPROX 10-15 MINS, WHILE TRYING TO DETERMINE THE CAUSE OF MY PROB USING THE QRH, I TURNED OFF THE LEFT EEC. THEN, ACCORDING TO QRH PROC I TURNED OFF THE RIGHT EEC. ENG PWR ON THE LEFT ENG RETURNED TO NORMAL AND WITH EEC'S OFF I WAS ABLE TO ESTABLISH EQUAL PWR ON BOTH ENGS. (THERE IS NO SPECIFIC PROC IN THE QRH FOR THE PROB I HAD, W/O AN EICAS EEC WARNING MESSAGE.) AT THIS TIME I CONTACTED AIRLINES ENG TECH THROUGH NY COMMERCIAL RADIO AND DISPATCH. I ADVISED THEM OF MY SITUATION AND THE ACTION I HAD TAKEN. THEY CONCURRED WITH MY ACTION, DETERMINING EVERYTHING TO BE NORMAL WITH THE EEC'S OFF. I ADVISED MY DISPATCH THAT I WOULD CONTINUE ON TOWARD MY DEST. AT THIS TIME I CANCELLED THE EMER I HAD DECLARED AND REQUESTED A CLRNC TO CHICAGO O'HARE WITH GANDER CENTER. THEY CLRED ME ON COURSE TO CLB TO FL370. AFTER LEVELING OFF AT CRUISE ALT, I REFIGURED MY FUEL AND DETERMINED I COULD CONTINUE ON TO DFW. THEN I REQUESTED CLRNC TO DFW. THIS CLRNC WAS RECEIVED FROM MONTREAL CENTER. I LANDED W/O FURTHER INCIDENT AT DFW WITH JUST OVER 13000 LBS OF FUEL, ABOUT 5000 LBS MORE THAN REQUIRED FOR RESERVE AND ALTERNATE FUEL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: FOLLOW UP WITH MAINT REVEALED THAT THE EEC HAD INCURRED A FAULT AND WAS SENSING A FALSE OVERTEMP WHICH WAS THE REASON THE EEC REDUCED THE PWR AND UNTIL IT WAS TURNED OFF WOULD NOT ALLOW ENG PWR TO BE RESTORED. REASON NO EICAS MESSAGE WAS BECAUSE EEC THOUGHT IT WAS ACTING ON VALID INPUT. AFTER THE DSCNT AND START OF DIVERSION FLT STILL ARRIVED IN DFW ONLY 8 MINS OVER FLT PLAN.

Data retrieved from NASA's ASRS site as of August 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.