Event Details
At the end of a flight, while approaching the airport, the pilot disconnected the autopilot. The downwind, base, and final legs of the traffic pattern were normal until short final, when the airplane suddenly nosed up and banked right. The pilot attempted to correct the situation, but the right main landing gear contacted the runway. The pilot initiated a go-around and landed at an alternate airport without further incident.
Pilot Report
The pilot reported that the autopilot appeared to have re-engaged itself.
Investigation Findings
Testing of the autopilot system did not reveal any mechanical failures or malfunctions that would indicate a self-engagement. However, it was found that the location of the autopilot in the airplane was two inches lower than the Supplemental Type Certificate (STC) recommended, and that the autopilot engage button is in close proximity to the flap handle and engine controls.