What happened
The aircraft was operating during cruise flight when it experienced an unexpected engine failure. The pilot initiated an emergency landing procedure, directing the aircraft toward an open field for a forced landing. Upon touchdown and during the subsequent landing roll, the aircraft continued forward until it collided with small trees located at the far end of the field.
The investigation
Following the accident, investigators conducted a post-crash examination of the aircraft's engine to determine the mechanical cause of the failure. The inspection revealed that the bolt securing the crankshaft drive gear in place was loose. This looseness allowed the drive gear to rotate excessively, which ultimately resulted in the shearing and breaking of the dowel pin that holds the assembly together.
Findings
The investigation determined that the primary factor contributing to the accident was the mechanical failure of the engine's crankshaft drive gear retention system. The loose bolt permitted the drive gear to move out of alignment, leading to the catastrophic breakage of the dowel pin and the subsequent loss of engine power during cruise flight.