B737 first officer experiences a compressor stall at FL410 while flying in IMC and light turbulence ...

Narrative:

We were on our last leg of our day and I was the flying pilot. We started to paint a little weather up ahead on our route but at 41;000 feet; we were pretty much on top of most of weather and the radar was depicting very little returns. Being at night in a moonless environment; it was hard to tell or avoid all the weather. We started to encounter moderate turbulence and entered IMC. The outside temp was -61 C and; per the aom limitations; didn't require any engine ice protection. With the bumps though; the captain elected to turn the ignition switches to cont. We were IMC conditions and light to occasional moderate for two to three minutes when we felt the shudder and vibration and heard two muffled bangs. I noticed the number two N1 indication started to spool from cruise thrust of 90 to about 76% to 75%. I immediately announced I think we had an engine failure and the captain took control of the thrust levers. All other indications stayed normal and never deviated from their normal cruise indications. The captain vocalized it probably was a compressor stall and prepared for the checklist memory items. After about 10 to 15 seconds; the N1 spooled back up to normal cruise thrust and all secondary indications remained normal. We continued to monitor the indications closely and continued the flight. We landed uneventfully and all engine indications remained normal through the remainder of the flight.

Original NASA ASRS Text

Title: B737 First Officer experiences a compressor stall at FL410 while flying in IMC and light turbulence at -61 degrees C. The engine anti-ice was off but continuous ignition was selected. The engine recovered by itself and the flight continued to its destination.

Narrative: We were on our last leg of our day and I was the flying pilot. We started to paint a little weather up ahead on our route but at 41;000 feet; we were pretty much on top of most of weather and the radar was depicting very little returns. Being at night in a moonless environment; it was hard to tell or avoid all the weather. We started to encounter moderate turbulence and entered IMC. The outside temp was -61 C and; per the AOM limitations; didn't require any engine ice protection. With the bumps though; the Captain elected to turn the ignition switches to CONT. We were IMC conditions and light to occasional moderate for two to three minutes when we felt the shudder and vibration and heard two muffled bangs. I noticed the number two N1 indication started to spool from cruise thrust of 90 to about 76% to 75%. I immediately announced I think we had an engine failure and the Captain took control of the thrust levers. All other indications stayed normal and never deviated from their normal cruise indications. The Captain vocalized it probably was a compressor stall and prepared for the checklist memory items. After about 10 to 15 seconds; the N1 spooled back up to normal cruise thrust and all secondary indications remained normal. We continued to monitor the indications closely and continued the flight. We landed uneventfully and all engine indications remained normal through the remainder of the flight.

Data retrieved from NASA's ASRS site 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	1206378
Time
Date	201409
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Component
Aircraft Component	Turbine Engine
Person 1
Function	First Officer Pilot Flying
Experience	Flight Crew Last 90 Days 256 Flight Crew Type 500
Events
Anomaly	Aircraft Equipment Problem Less Severe Inflight Event / Encounter Weather / Turbulence

B737 first officer experiences a compressor stall at FL410 while flying in IMC and light turbulence at -61 degrees C. The engine anti-ice was off but continuous ignition was selected. The engine recovered by itself and the flight continued to its destination.