Accident Overview
A flight instructor was providing instruction to a student in hovering flight operations. During the training, the instructor directed the student to perform a right pedal turn at a three-foot hover. As the student executed the maneuver, the helicopter began to behave unexpectedly.
Sequence of Events
According to the instructor, the student complied with the instruction to execute a right pedal turn. As the turn progressed, the helicopter’s tail came into the wind, causing the aircraft to weathervane. The turn rate accelerated rapidly and did not subside until the helicopter made contact with the ground. The impact resulted in substantial damage to the fuselage and both rotor systems.
Wind Conditions
The instructor reported that the wind velocity at the time of the accident was 11 knots, gusting to 16 knots. These wind conditions may have contributed to the loss of control, though no explicit causal link was provided in the report.
Technical Context
The instructor noted that no mechanical anomalies or malfunctions were present that would have prevented normal flight operations. The event is consistent with a phenomenon known as weathercock stability, which is defined as a region of loss of tail rotor effectiveness (LTE) in a 120-degree to 240-degree tailwind. This condition can cause the helicopter to weathervane, and if not corrected, may result in a loss of helicopter control about the horizontal axis. The Helicopter Flying Handbook (FAA 8083-21A) advises pilots to recognize the onset of LTE and react promptly to maintain control.