On May 23, 2005, at 1210 mountain daylight time, a Robinson R22 Beta, N553SH, operated by Silver State Helicopters and flown by a student pilot under the supervision of a commercial certificated flight instructor, was substantially damaged during an uncontrolled descent and impact with terrain near Provo, Utah. Visual meteorological conditions prevailed at the time of the accident. The local instructional flight was being conducted under the provisions of 14 CFR Part 91 without a flight plan. The student pilot was not injured, but the flight instructor sustained minor injuries. The flight originated at Provo, Utah. The flight instructor said that they were practicing hovering and the student had control of the cyclic. The helicopter began to oscillate and drift to the right. The student put in more right cyclic control, and then released the controls when the LOW ROTOR RPM warning sounded. The instructor "pulled collective and hard left cyclic" in an attempt to regain control of the aircraft but was unsuccessful, and the helicopter impacted terrain and rolled over. FAA investigators said the tail boom was severed, the main rotor was bent and separated from the engine, the rotor mast torsionally buckled, the windscreen was shattered, and the skin was wrinkled. The winds at the Provo airport, located 15 miles northeast of the accident site, at the time of the accident were 290 degrees at 6 knots and the instructor noted light turbulence.