Narrative:

Cleared into block FL390-FL410, climbing through FL400 and just topping a thunderstorm, the left engine began a surge followed by about 2-3 mins of complete loss of power with dramatic compressor stalls. I instructed first officer to inform ATC of our problem and that we needed a lower altitude immediately. ATC cleared us to FL390. I attempted to slow the descent with the hope that I could get the engine back by FL390. The descent was arrested at FL387 but the airspeed began to decay as the engine slowly began to recover power. When the airspeed decayed to 220 KIAS at FL387, I re-established the descent. The engine stabilized to normal operation and we were able to maintain FL370. The above events occurred inside the thunderstorm with lightning, precipitation, and severe turbulence. This airplane had the left engine changed 3 days prior to our flight and then had an unscheduled landing because of surge. Adjustments were made and operation of the plane was uneventful until our experience. I was busy with the problem and I later became aware that my first officer may have not communicated the seriousness of our problem to ATC in a forceful manner.

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Original NASA ASRS Text

Title: FLC OF A B767 WERE FORCED TO DSND FROM ASSIGNED ALT AFTER L ENG STARTED SURGING AND HAVING COMPRESSOR STALLS DURING CLB TO A HIGHER CRUISE ALT.

Narrative: CLRED INTO BLOCK FL390-FL410, CLBING THROUGH FL400 AND JUST TOPPING A TSTM, THE L ENG BEGAN A SURGE FOLLOWED BY ABOUT 2-3 MINS OF COMPLETE LOSS OF PWR WITH DRAMATIC COMPRESSOR STALLS. I INSTRUCTED FO TO INFORM ATC OF OUR PROB AND THAT WE NEEDED A LOWER ALT IMMEDIATELY. ATC CLRED US TO FL390. I ATTEMPTED TO SLOW THE DSCNT WITH THE HOPE THAT I COULD GET THE ENG BACK BY FL390. THE DSCNT WAS ARRESTED AT FL387 BUT THE AIRSPD BEGAN TO DECAY AS THE ENG SLOWLY BEGAN TO RECOVER PWR. WHEN THE AIRSPD DECAYED TO 220 KIAS AT FL387, I RE-ESTABLISHED THE DSCNT. THE ENG STABILIZED TO NORMAL OP AND WE WERE ABLE TO MAINTAIN FL370. THE ABOVE EVENTS OCCURRED INSIDE THE TSTM WITH LIGHTNING, PRECIP, AND SEVERE TURB. THIS AIRPLANE HAD THE L ENG CHANGED 3 DAYS PRIOR TO OUR FLT AND THEN HAD AN UNSCHEDULED LNDG BECAUSE OF SURGE. ADJUSTMENTS WERE MADE AND OP OF THE PLANE WAS UNEVENTFUL UNTIL OUR EXPERIENCE. I WAS BUSY WITH THE PROB AND I LATER BECAME AWARE THAT MY FO MAY HAVE NOT COMMUNICATED THE SERIOUSNESS OF OUR PROB TO ATC IN A FORCEFUL MANNER.

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.