On February 19, 2007, about 1055 mountain standard time, a Robinson R22 Beta, N453SH, touched down hard on open desert terrain about 10 nautical miles southwest of Tucson, Arizona. During touchdown, a main rotor blade impacted and bent the tail boom. Also, the horizontal stabilizer was bent. The helicopter was operated by Silver State Helicopters, Tucson. The rotorcraft was substantially damaged. Neither the certified flight instructor (CFI), who held a commercial pilot certificate, nor the rotorcraft-rated private pilot, who was receiving flight instruction, were injured. Visual meteorological conditions prevailed at the time, and no flight plan had been filed. The flight was performed under the provisions of 14 CFR Part 91, and it originated from Tucson about 1040. The CFI reported to the National Transportation Safety Board investigator that the mishap occurred during landing practice. The CFI was instructing his student to land under a simulated emergency condition where the objective was for the student to "land immediately" following an event such as blade delamination. The student was attempting to comply with his direction. During the emergency descent, the low rotor annunciator light illuminated, and the corresponding warning horn sounded. The CFI observed that the helicopter's main rotor blade rpm decreased, and he attempted to perform a recovery. According to the CFI, initially both he and his student were simultaneously attempting to take corrective action. However, the student "had too strong a grip on the throttle for me to overcome." The CFI was handling the controls as the rotorcraft approached and contacted the ground. The CFI stated that despite his efforts, the helicopter touched down hard. No mechanical malfunctions were experienced during the flight. In a subsequent statement, the CFI reported that during the final seconds of flight he believes a "gust of wind...caused the aircraft to sink."