What happened
Following takeoff, the pilot notified air traffic control of a loss of engine power. The pilot initially intended to divert to a nearby airfield and received appropriate headings. After reporting that the power loss had stabilized, the pilot attempted to return to the departure airport. However, the pilot soon reported a second instance of power loss and decided to divert to a different airport located approximately three miles away.
While performing a 360-degree turn to establish a left base approach at 4,500 feet, the engine lost all power. The pilot was unable to reach the runway, and the aircraft type impacted a field near the airport. The impact caused the wings to separate from the fuselage, and a small fire occurred after the crash. There were 0 fatalities and 0 injuries reported in the provided text.
Findings
Investigations into the engine and propeller assembly revealed that the beta control cable had been mis-rigged during maintenance performed on the day of the accident. While recent maintenance had addressed binding in the propeller reversing cable, the post-accident examination showed the beta valve plunger was extended beyond the chamfer face of the propeller governor. This specific position was capable of cutting off oil flow from the governor oil pump to the constant speed unit.
It was determined that the forward beta control cable clevis adjustment nut had been rotated fully aft. Additionally, the swaging ball end on the forward end of the cable was not properly secured, allowing it to rotate within the assembly. It is believed that engine vibrations and spring forces caused this unsecured component to move, lengthening the cable assembly. This movement allowed the beta valve to stroke forward and interrupt the oil flow necessary to maintain propeller control, causing the blades to move to the feathered position and resulting in a loss of thrust.