What happened
Earlier on the day of the accident, the airplane was being operated on the ground when the main landing gear was inadvertently retracted. This caused the airplane to settle on its tail, though the propellers did not make contact with the ground. Following the incident, the engines were shut down and the occupants deplaned. The aircraft was subsequently raised, the gear was extended, and an inspection was performed, which included removing side and rear panels near the rudder and stabilator.
A ferry permit was issued to allow flight to another airport for repairs, under the specific restriction that the landing gear remain extended. During the flight, the pilot departed and, after takeoff, requested to return for a landing without providing a reason. The aircraft was observed turning crosswind and then downwind. It subsequently descended in a wings-level attitude below the level of the surrounding terrain, at which point black smoke was seen. The aircraft struck the side of a hill, leaving debris strewn across 267 feet.
The investigation
Investigators examined the engines and propellers, but found no evidence of mechanical malfunction. There was no evidence of a jam in the elevator or rudder flight controls. The aircraft featured an electric elevator trim, and the rudder trim was collocated with the manual elevator trim. At the time of the accident, the rudder trim was in the neutral position, while the elevator trim was found in the full nose down position. While the forward portion of the cockpit was crushed, no evidence of a pre-existing failure was identified.