The airplane was in cruise flight at 12,500 feet when the pilot disengaged the autopilot to maneuver over mountains. Shortly, the airplane began banking uncontrollably; the pilot steadied the airplane with rudder. The flight controls were difficult to manipulate, a difficulty that grew in intensity as airspeed was reduced. The pilot declared an emergency, began a descent and proceeded to the nearest airport. After he was unable to locate the airport, the pilot elected to perform a wheels-up landing on a snow-covered field during which the airplane sustained substantial damage. Subsequent examination revealed no anomalies that could explain the stiff controls.
