Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 15; Flight Crew Total 12200; Flight Crew Type 1000
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew FLC complied w / Automation / Advisory; Flight Crew Regained Aircraft Control; Flight Crew Returned To Clearance
Aircraft; Weather
Flight originated in ZZZ with ZZZ1 as destination; original planned cruise was FL230.Upon reaching cruise level we were in IMC and light to moderate turbulence; a request was made for higher cruise level.After leveling off at FL270 we were on top of the layer and smoother air; a few minutes later we had an indication that #3 fuel computer had failed and proceeded to follow POH procedures to attempt a reset; that required bringing the affected engine to idle before cycling the fuel computer control switch. While we were in the process to reset the computer there was an advisory message on the FMS regarding an out of trim condition; before attempting to re-trim the aircraft I disengaged the auto pilot to ascertain the condition; while re-trimming we started to encounter that the tops of the clouds below were in fact rising to our current cruising fl and encountered a sudden but brief increase in turbulence from nil to moderate so the aircraft was pushed upwards about 500 feet before I could correct it without a violent maneuver as we had passengers; ATC requested a confirmation of our current flight level and we advised that we were returning to FL270.The flight proceeded to ZZZ1 without further complication or comment from Controller.As the turbulence encounter occurred while the autopilot was disengaged and the sudden change in flying conditions (from smooth to moderate turbulence) Except for the use of more aggressive maneuvering the altitude excursion was in my opinion almost unavoidable.
Falcon 900 pilot reported that a fuel computer failed followed by an out of trim advisory message. They disengaged the autopilot to respond to the problems and encountered turbulence that caused an altitude excursion.