What happened
The aircraft experienced a partial loss of engine power during flight, which necessitated an emergency procedure. The pilot was forced to execute a landing in an off-airport location, resulting in the airplane striking a ditch.
The investigation
A postflight examination of the aircraft was conducted to determine the mechanical cause of the power loss. Inspectors focused on the engine control systems, specifically the throttle mechanism.
The inspection revealed that the rod end on the throttle cable had completely separated from the cable itself. Further analysis of the detached components indicated that the initial installation of the rod end onto the throttle cable was inadequate. Specifically, the jam nut had not been tightened against the rod end, allowing it to detach under operational stress.
Findings
The separation of the throttle cable rod end directly caused the partial loss of engine power. The root cause was identified as improper maintenance or installation practices regarding the throttle cable assembly.