Flight and Maneuver
The pilot reported that during arrival, the downwind leg was entered without any issues. However, when attempting to turn onto a left base leg, the aileron control became locked. The pilot stated that he could turn neither left nor right using the ailerons, and the aircraft would bank to the right when left rudder was applied, and vice versa.
Emergency Declaration and Landing
The pilot declared an emergency and continued westerly for approximately 6 miles. After reducing power, he landed in a wheat field. During the landing roll, the nose gear struck a ditch, causing it to collapse, and the aircraft nosed over.
Post-Incident Examination
An examination of the flight controls failed to disclose any preimpact failure or malfunction. A check of the autopilot revealed that the control servo (part number 1C-465-1-732) was covered with an oily, sticky substance and would not slip until cable tension was well above the specified 42 pounds. No other preimpact malfunctions or failures of the aircraft were found.
Pilot Experience
The pilot, described as relatively inexperienced, did not recall having engaged the autopilot.