Cirrus Vision SJ50
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Troubleshooting
Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Regained Aircraft Control; Flight Crew Diverted
Aircraft; Human Factors; Weather
It was raining in ZZZ when I departed; temperature around 13 degrees C. After takeoff I climbed through some rain clouds; light turbulence at best; and I noticed the temperature dropped down to 6 degrees C quick so I turned on the Engine IPS and monitored the wing/windshield for ice. I did not get any airframe icing at all. Above 10;000 and all the way to FL310 it was clear skies; no issues or signs of anything wrong during the climb. I verified that it pitched down and leveled off at the assigned altitude; performed checklist and checked fuel planning before I engaged in conversations with my passengers. Maybe 3-5 minutes into cruise flight I got an altitude alert and looked to see that I was 200 feet high; and initially I thought maybe Alt didn't capture on the autopilot so I selected VS and scrolled down and nothing happened. After a second of head scratching I clicked the autopilot off to hand fly it back to FL310 and the nose pitched aggressively up; when I tried to trim nose down that's when I discovered I couldn't hardly move the trim wheel at all; maybe a half inch either way and it stopped. I went flew back to FL310 and went through maybe 200 feet below before I finally figured out the control pressure and still fighting the trim wheel. ATC didn't say anything about my altitude deviation but without the autopilot I asked to descend out of RVSM airspace. I communicated with my passengers and assessed my location; and decided that instead of going to my original planned destination of ZZZ1 for fuel; I would go to the adjacent ZZZ2 just in case it wasn't icing on the controls like I suspected and ended up grounded the aircraft at in ZZZ2 so that my passengers could still catch airline flights to their homes; which they were able to.I think the rapid drop in temperature on an already wet soaked airplane froze the pitch trim tab hinges; or some part of the control input.I could have deviated around the weather possibly but it was light rain showers and again hardly any turbulence so I didn't think it was unsafe to fly through the rain cells. Maybe spend a little extra time monitoring the instruments after the level off as well.
Cirrus Vision SJ50 pilot reported that during cruise the aircraft trim system malfunctioned. Reporter stated when the autopilot was disengaged; the aircraft nose pitched up and the trim wheel was difficult to move. Pilot performed a successful diversion and stated that ice on control surfaces could have contributed to the event.