What happened
The flight continued despite adverse weather conditions that had previously forced the pilot to stop once en route to the destination. During the operation, directional control was lost when the tail rotor contacted the terrain. This impact separated both tail rotor blades from the aircraft and torsionally sheared the tail rotor drive shaft.
Following the mechanical failure, power was reduced and the pilot initiated an autorotation into a field. The tailboom was struck by the main rotor blade during the landing phase of the flight.
The investigation
The examination revealed that the tail rotor had contacted the ground, resulting in the separation of both blades and the shearing of the drive shaft. The aircraft sustained significant damage to the tailboom from contact with the main rotor system during the subsequent emergency landing.
Findings
The sequence of events indicates that adverse weather played a role in the operational decisions leading up to the incident. The critical mechanical failure was caused by the tail rotor striking terrain, which led to a loss of directional control. The pilot successfully executed an autorotation but could not prevent damage to the tailboom during the landing.
Safety message
Pilots should carefully evaluate weather conditions and be prepared to abort or divert flights when adverse weather threatens safe operation. Maintaining directional control in helicopters requires unimpeded tail rotor function, which can be compromised by ground contact.