On August 12, 1997, at 1000 hours Pacific daylight time, a Bell 47G2, N9021R, landed hard on runway 4 at the Mojave, California, airport. The local area instructional flight was operated by National Test Pilot School of Mojave. Visual meteorological conditions prevailed at the time, including calm winds, and no flight plan was filed. The helicopter sustained substantial damage. The flight instructor and dual student onboard were not injured. The flight originated at Mojave about 0930 on the day of the accident. In his written report, the flight instructor reported that the dual student had a fixed wing pilot certificate issued by a foreign country, but no prior rotorcraft flight experience. The instructor reported that during their pattern work, he was "guarding the flight controls while the left seat pilot was flying." He further reported that on the third pattern the student allowed the rpm to decrease and the instructor cautioned him to "watch the RPM." The student then raised the collective control slightly without adding additional throttle. As the instructor reached for the throttle, the student quickly raised the collective without any other action. The aircraft yawed to the right, and the rotor rpm decreased even further. The student then applied a rearward cyclic input in an attempt to flare the aircraft. The tail rotor then 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. The instructor reported that during the accident sequence he was "attempting to regain aircraft control while calling for [the student] to release the controls."