A CE560XL had an engine anomaly develop at FL400 and lost 300 ft while recovering power to return to...

Attributes
ACN	939208
Time
Date	201103
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Citation Excel (C560XL)
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Turbine Engine
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Check Pilot Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude

Narrative:

At FL400 we experienced a loud sudden bursting sound. Immediately after the loud pop the airplane's autopilot disengaged and the airplane nosed over. We both suspected that we were losing an engine or possibly both engines. Initially as the pilot flying powered up there was no response to an increase of throttle; but within a minute or less there was a response and it was sluggish at best. As more time passed the throttle response became significant. We were able to get back to our assigned altitude and maintain airspeed. We monitored both engine instruments to see if there were any symptoms that would have lead to this event. At this point we asked the center controller for a clearance to a nearby airport. Once in the destination airspace we did ask for priority handling. We landed without incident.

Original NASA ASRS Text

Title: A CE560XL had an engine anomaly develop at FL400 and lost 300 FT while recovering power to return to FL400. The crew diverted to a nearby airport where maintenance found no faults; but changed the torque motors which control bleed air that runs the EEC's.

Narrative: At FL400 we experienced a loud sudden bursting sound. Immediately after the loud pop the airplane's autopilot disengaged and the airplane nosed over. We both suspected that we were losing an engine or possibly both engines. Initially as the pilot flying powered up there was no response to an increase of throttle; but within a minute or less there was a response and it was sluggish at best. As more time passed the throttle response became significant. We were able to get back to our assigned altitude and maintain airspeed. We monitored both engine instruments to see if there were any symptoms that would have lead to this event. At this point we asked the Center Controller for a clearance to a nearby airport. Once in the destination airspace we did ask for priority handling. We landed without incident.

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.

A CE560XL had an engine anomaly develop at FL400 and lost 300 ft while recovering power to return to FL400. The crew diverted to a nearby airport where maintenance found no faults; but changed the torque motors which control bleed air that runs the eec's.