ENGINE FLAMEOUT WHEN THRUST LEVERS REDUCED FOR DESCENT. ENGINE RESTARTED AT A LOWER ALT.

Narrative

AFTER RECEIVING REPORTS OF MODERATE TURBULENCE AND WAVE ACTIVITY AT FL410 THAT WAS NEAR OUR FLT TRACK AND A SUDDEN RISE OF OAT 526.49 DEG WE DECIDED TO DESCEND TO FL370. AN AUTO DESCENT WAS MADE TO FL370. AS THE ACFT STARTED A SLOW NOSE DOWN PITCH AND THE THROTTLES SLOWLY RETARDED I FELT AND HEARD A LOUD COMPRESSOR STALL (BACKFIRE). I NOTICED THAT THE #2 ENG EPR FLUCTUATING SLIGHTLY. I DISCONNECTED THE AUTOPILOT AND AUTOTHROTTLE AND AS THE POWER WAS INCREASED TO MAINTAIN .80 THE #2 ENG INDICATION REMAINED FIXED AND THE ACFT WAS IN A YAW. I CAN NOT RECALL THE EXACT EGT TEMP BUT IT WAS NOT IN THE YELLOW OR RED RANGE ON THE EICAS. I CALLED FOR THE ENG FAILURE CHECKLIST AND TO SELECT THE ENG OUT ALT ON THE FMC. THE CAPT SELECTED THE INFO FROM THE FMC AND REQUESTED DESCENT TO FL290 WHICH WE RECEIVED. DURING THE DESCENT THE ENG FAILURE CHECK LIST WAS COMPLETED. WE ELECTED TO RESTART THE #2 ENG BECAUSE WE FELT THERE WAS NO DAMAGE TO THE ENG AND THERE HAS BEEN PAST REPORTS OF THIS PROBLEM WITH OTHER WDB. ALSO THERE IS A PROCEDURE IN OUR HANDBOOK FOR AN ENG STEADY STATE STALL CONDITION 1) CLOSE THROTTLE; FUEL CONTACT SWITCH OFF; ENG FLT START. THE FIRST ATTEMPT TO START THE #2 ENG WAS UNSUCCESSFUL. NO ENG TEMP RISE AFTER 20 SEC. I CHECKED AGAIN OUR AIRSPEED AND THE START ENVELOPE DISPLAYED ON THE EICAS SCREENS AND WE WERE WELL ABOVE THE REQUIREMENTS. THE SECOND ATTEMPT WAS A CROSS BLEED START WAS SUCCESSFUL. ALL #2 ENG INDICATIONS WERE NORMAL. IE; EGT; F/F; VIG; ECT. THE CAPT DECIDED TO CLIMB BACK TO CRUISING ALT AND TO CONTINUE TO OUR DEST. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. COMPANY IS MODIFYING BLEED VALVE TO OPEN AT A DIFFERENT TIME. THEY ALSO HAVE CHANGED THE PROC FOR BEGINNING ASCENT. AUTOTHROTTLES ARE OFF AND CPR IS REDUCED TO 1.2 UNTIL THE ENG STABILIZES THE FLT IDLE IS SET. RPTR HAD NO PROB IN RESTARTING THE ENG ONCE THEY HAD STABILIZED AT THE LOWER ALT.