Flight Crew Air Transport Pilot (ATP)
Confusion; Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Loss Of Aircraft Control
Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed As Precaution; Flight Crew Regained Aircraft Control; General Maintenance Action
Aircraft
Cruising at FL410; the aircraft began a shallow decent followed by a cyan auto pilot A/B fail. This was followed by a sharper decent and at approx. 40;600 feet we advised ATC we unable to maintain altitude. After completing memory items QRC and QRH we were able to regain control of the aircraft and level at FL390. We diverted to ZZZ and the remainder of the flight was uneventful.
The reporter states that horizontal stabilizer trim actuators were replaced initially by maintenance; followed by stabilizer control electronics.
[Narrative contained no additional information].
A CE680 at FL410 begins a shallow descent which then causes the auto pilot to disengage. The descent steepens and the crew is initially unable to arrest the descent. Control is regained at FL390 after completing memory items and QRH procedures. Secondary trim is selected and the diversion is flown without further difficulty.