Incident Overview
A flight instructor reported that during a training flight, the student pilot was taxiing a helicopter north along a taxiway parallel to runway 12/30. The wind conditions included a near direct tailwind of 10 knots with gusts to 19 knots. While taxiing, the student began to lose tail rotor authority over the helicopter.
Sequence of Events
The instructor immediately took control of the helicopter and applied full left pedal. This action allowed them to regain tail rotor authority and directional control. Due to the strong winds from the south, the instructor opted to maintain control and continued taxiing to the displaced threshold of runway 12. Upon reaching the displaced threshold, the instructor initiated a 220-degree left turn to align the helicopter for a takeoff direction to the south, directly into the wind.
Halfway through the turn, the helicopter violently yawed to the left. The instructor applied full right pedal in an attempt to counteract the yaw but was unable to stop the left yawing moment.
Damage Assessment
The helicopter subsequently landed hard on its skids. The impact damaged the main rotor and severed the tail boom aft of the tail rotor blades hazard guard and before the tail rotor transmission.
Wind Conditions
The pilot reported no mechanical issues with the helicopter prior to the flight. According to the Pilot's Operating Handbook, the wind limitation for the helicopter is 25 knots, including any gust factor.