SA-227 AC Metro III
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Regained Aircraft Control
Aircraft
I was level at 10;000 with autopilot engaged; when I noticed an uncommanded pitch up and climb. The electric trim amber light was illuminated on autopilot annunciator panel. I disengaged the autopilot to return to level flight. It took considerable forward pressure to lower the nose. The pilot's trim switch made its normal trim in motion sound. The trim indicator showed pitch up to the upper green limit and it didn't move. I switched to the copilot's trim and used the yoke switch and the override switch with similar results. I continued to struggle to keep the nose level for several minutes. I started slowing and below about 180 knots; the trim started responding normally. I [advised ATC] and made an uneventful landing using the ILS. Only sometime later did I remember that I'd had a similar problem on a flight the previous evening. Again; the nose pitched up while on autopilot and I had to disengage the autopilot and use the trim switches to regain control. The earlier event only lasted a few seconds and was easily rectified at cruise altitude and airspeed.
SA-227 Metro pilot reported an uncommanded pitch up with the autopilot engaged.