What happened
During the initial climb from runway 25, the aircraft type experienced a sudden loss of control. Eyewitnesses observed the plane banking sharply to the left shortly after departing the runway. While the aircraft appeared to briefly stabilize and begin a climb, it subsequently rolled into an inverted position and entered a steep dive. The aircraft then struck the airport terminal building, resulting in an explosion and severe fire. The impact and subsequent fire caused extensive damage to the airframe.
Investigations into the engines and propellers showed no mechanical discrepancies that would have prevented normal operation. Evidence from the propeller blades indicated that both engines were producing high power and the propellers were rotating at high energy at the moment of impact.
Findings
Evidence recovered from the wreckage included components of the autopilot system, specifically parts of the pitch and roll servo assemblies. Analysis of the roll servo mounting bracket and capstan suggested that these components had been recently reinstalled.
Records indicate that during an annual inspection performed the previous month, maintenance personnel had identified an undocumented autopilot system in the aircraft. During this inspection, mechanics had removed the roll servo and capstan because the aileron cable was rubbing against the capstan. Additionally, the pitch servo had been disabled and the autopilot control head removed. The aircraft was returned to the pilot with the annual inspection incomplete, and the removed autopilot components were provided to the pilot in a separate container. Evidence suggests that the pilot reinstalled the autopilot components the day before the accident. While it is possible that the improper installation or a malfunction of the autopilot system led to the loss of control, the extreme fragmentation of the wreckage prevented a definitive conclusion regarding the exact cause.