Introduction
A dual student, who held a fixed wing pilot certificate issued by a foreign country and had no prior rotorcraft experience, was receiving flight instruction in a rotorcraft. The flight instructor was conducting pattern work with the student, who occupied the left seat. The instructor reported that he was guarding the controls while the student was flying.
Accident Sequence
On the third pattern, the student allowed the rotor RPM to decrease. The instructor cautioned the student to watch the RPM. The student then raised the collective without adding additional throttle. As the instructor reached for the throttle, the student quickly raised the collective without any other control input. The aircraft yawed to the right, and the rotor RPM decreased further. The student then applied a rearward cyclic input in an attempt to flare the aircraft.
Impact and Damage
The tail rotor struck the ground, destroying the tail rotor and shearing the tail rotor driveshaft. The aircraft touched down in a right turn, and the skids collapsed. During the accident sequence, the instructor reported that he was attempting to regain aircraft control while calling for the student to release the controls.