What happened
The pilot was operating a helicopter in a rural environment with the objective of managing livestock. Specifically, the aircraft was being used to herd cattle down a steep incline characterized by a gradient between 20 and 25 degrees. During this maneuver, the tail rotor made contact with a rock on the ground.
This impact caused an immediate loss of directional control over the aircraft. In response to the situation, the helicopter began to rotate uncontrollably. The pilot attempted to mitigate the descent by rolling off the throttle and executing a hard landing, described as planting the helicopter onto the ground. During this final contact with the surface, the main rotor system severed the tail boom from the fuselage.
The investigation
The physical evidence indicated that the primary mechanical failure originated from the interaction between the tail rotor and terrain obstacles. The force of the tail rotor striking the rock compromised the structural integrity of the rear section of the aircraft. Subsequent to this initial impact, the main rotor assembly interacted with the weakened tail boom structure during the landing phase, resulting in the complete separation of the tail boom.
Findings
The accident was primarily caused by the pilot's attempt to operate a helicopter in terrain that presented significant hazards for low-level maneuvering. The steep slope and presence of ground obstacles contributed directly to the loss of control. The specific sequence of events highlights the risks associated with using rotary-wing aircraft for agricultural tasks in rugged topography without adequate clearance from terrain features.