What happened
During a cargo flight, the pilot experienced a loss of engine oil in the left engine of the twin-engine cargo airplane. In response to the failure, the pilot shut down the left engine and feathered the propeller. Air Traffic Control provided vectors toward a VOR to assist with the emergency situation. Because the aircraft was at an altitude and distance that placed it outside of radar coverage, the pilot was required to execute a complete instrument approach procedure.
While the aircraft maintained its assigned enroute altitude until passing the VOR outbound, radar data indicated a continuous descent throughout the procedure turn and the inbound leg of the approach. The final radar contact occurred while the aircraft was 300 feet below the required inbound approach altitude and positioned outside the final approach fix. The aircraft subsequently struck trees and terrain roughly 2.25 miles from the airport, which is located 5.5 miles from the VOR. The pilot, who was the only person on board, was killed in the accident.
Findings
Post-accident investigations at the scene confirmed that the left engine's propeller had been feathered. Examination of the engine revealed that the number nine cylinder mounting studs on the engine case were either broken off at the surface or crushed downward. Additionally, investigators noted that the landing gear had been extended at the time of the impact.