What happened
The aircraft experienced a complete loss of engine power while in flight, necessitating an emergency forced landing. During the attempt to land on a nearby road, the pilot was unable to maintain sufficient control or altitude, resulting in the aircraft striking a tree and subsequently entering a ditch. The impact caused significant damage to the airframe, though the specific outcome regarding injuries is not detailed in the available records.
The investigation
Post-accident examination of the engine revealed that the throttle rod had become disconnected from the throttle control arm at the bolt hole. Investigation into the mechanical failure indicated that the hole in the control arm had worn through over time, allowing the rod to vibrate loose.
Maintenance records showed that the aircraft had undergone a 100-hour inspection only 22 hours prior to the accident. Analysis confirmed that the degree of wear observed on the surfaces could not have developed within that short 22-hour window. The throttle cable had previously been replaced at 850 hours of total time, and the aircraft had accumulated 1188 hours at the time of the incident. According to the C-206 service manual, engine controls and linkage are required to be inspected every 100 hours.
Findings
The mechanical failure was traced to fatigue wear on the throttle control arm bolt hole. The worn surfaces had taken significantly longer than the 22 hours since the last inspection to reach the point of failure. Despite the recent 100-hour inspection, the defect was not detected. After installing a new throttle arm and repairing the impact damage, the engine was successfully run, confirming that the power loss was isolated to this specific linkage failure.
Safety message
This incident highlights the importance of thorough inspections of engine controls and linkage during routine 100-hour checks. Wear on critical components like throttle arms can develop over long periods and may not be apparent in short intervals between major maintenance events.