Narrative:

It appears our situation isn't the first of it's kind in a flat panel 767. Approximately 3 hours into our flight we were at fl 340; operating with LNAV/VNAV and autothrottles on. I had just scanned the flight instruments. I looked over as the captain plotted the 2 degree/10 minute mark. Approximately 2 minutes later we realized our airspeed had decayed because we got an initial buffet. I disconnected the autothrottles and pushed them forward. I also disconnected the autopilot and began descending slightly to gain airspeed. The pitch limit indicator (pli) was in view; but well above the command bars. We never had a stick shaker. I don't recall the altitude loss; but know it wasn't more than a few hundred feet because it didn't take much to climb back to fl 340. After recovering the airspeed; we reengaged the autothrottles and autopilot. The commanded airspeed was .82 mach and 285 knots. The speed increased to 292 knots. We disconnected the autothrottles and flew the rest of the trip without autothrottles. What I believe is significant to note is that we had no EICAS message; mc; mw or aural warnings. The throttles had not physically moved. We just lost airspeed for no apparent reason. We were dispatched with an inoperative eec under MEL 73-01. After reviewing the MEL; we chose to use the autothrottles. Departing; we were cleared to 6000 feet. As we were leveling off; the throttles attempted to retard to idle. I turned them off and pushed the power forward to maintain 250 knots. We reengaged the autothrottles. This happened again as we were climbing though 9000 feet. I continued the climb to cruise with manual throttles. We reengaged them and everything seemed stable for 3 hours.

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Original NASA ASRS Text

Title: A B767-300's EEC malfunctioned at cruise altitude causing a precipitous airspeed loss with no warning; annunciations or throttle movements.

Narrative: It appears our situation isn't the first of it's kind in a flat panel 767. Approximately 3 hours into our flight we were at FL 340; operating with LNAV/VNAV and autothrottles on. I had just scanned the flight instruments. I looked over as the Captain plotted the 2 degree/10 minute mark. Approximately 2 minutes later we realized our airspeed had decayed because we got an initial buffet. I disconnected the autothrottles and pushed them forward. I also disconnected the autopilot and began descending slightly to gain airspeed. The Pitch Limit Indicator (PLI) was in view; but well above the command bars. We never had a stick shaker. I don't recall the altitude loss; but know it wasn't more than a few hundred feet because it didn't take much to climb back to FL 340. After recovering the airspeed; we reengaged the autothrottles and autopilot. The commanded airspeed was .82 Mach and 285 knots. The speed increased to 292 knots. We disconnected the autothrottles and flew the rest of the trip without autothrottles. What I believe is significant to note is that we had no EICAS message; MC; MW or aural warnings. The throttles had not physically moved. We just lost airspeed for no apparent reason. We were dispatched with an inoperative EEC under MEL 73-01. After reviewing the MEL; we chose to use the autothrottles. Departing; we were cleared to 6000 feet. As we were leveling off; the throttles attempted to retard to idle. I turned them off and pushed the power forward to maintain 250 knots. We reengaged the autothrottles. This happened again as we were climbing though 9000 feet. I continued the climb to cruise with manual throttles. We reengaged them and everything seemed stable for 3 hours.

Data retrieved from NASA's ASRS site as of April 2012 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.