What happened
The aircraft was engaged in a long-line heli-logging operation when it encountered a critical mechanical failure. At the time of the incident, the helicopter was hovering over a line of trees at an altitude of approximately 200 feet above ground level (AGL). The pilot was in the process of picking up a load of logs when the engine suddenly lost power.
Following the loss of power, the aircraft descended vertically without significant horizontal movement. It subsequently impacted the terrain and the surrounding trees, resulting in a crash.
The investigation
A thorough examination of the wreckage was conducted to determine the cause of the power failure. Disassembly and detailed inspection of the engine speed governor revealed the presence of foreign object debris inside the assembly. Specifically, particles of sealant material were found within the governor components, indicating that internal mechanical failure likely contributed to the loss of engine power.
Findings
The investigation determined that the primary factor in this accident was the failure of the engine speed governor due to sealant contamination. The presence of sealant particles inside the governor assembly compromised its ability to regulate engine speed, leading to an immediate loss of power while the aircraft was in a vulnerable hover phase.
Safety message
Regular inspection and maintenance of engine governors are critical to prevent foreign object contamination. Sealant materials used during assembly must be secured properly to avoid dislodging into sensitive mechanical components. Operators should ensure that maintenance procedures strictly control the use of sealants to prevent similar failures in aviation equipment.