What happened
Shortly after liftoff, the pilot lost control of the tail rotor. This loss of control caused the helicopter to spin uncontrollably, resulting in the main rotor striking the ground. The aircraft came to rest on the terrain.
The investigation
An examination of the wreckage revealed that the engine mounting cage had suffered a fatigue failure. Specifically, the engine basket had failed, which allowed the tail rotor drive shaft to pull out of its coupling. Inspection of the failed basket showed it was cracked and corroded. The component had accumulated 800 flight hours prior to the accident.
Findings
The proximity of a fuel truck at the site limited the pilot's room for maneuvering during the emergency. However, the primary cause of the loss of control was mechanical failure.
Safety message
Regular inspection of engine mounting components is critical to detect corrosion and cracking before they lead to catastrophic failure.