Golden Eagle 421
Flight Crew Multiengine; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 86; Flight Crew Total 13368; Flight Crew Type 31
Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Loss Of Aircraft Control
Air Traffic Control Provided Assistance; Flight Crew Regained Aircraft Control; Flight Crew Overcame Equipment Problem; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Aircraft
A runaway AP (autopilot) caused the ailerons to bind in a right hand turn at 12;000 ft. just NE of ZZZ. Struggling to hand fly the airplane and keep on course I was unable to hold altitude. It varied between 12;350 [ft.] and 11;700 before I [received priority from ATC].The airplane was very difficult to control and I was in IMC. With great difficulty I was able to fly the RNAV [Runway] XX to ZZZ.I was able to land at ZZZ without incident
Pilot reported a runaway autopilot caused the ailerons to bind ; making the aircraft difficult to control for landing.