On October 3, 2005, at 0745 mountain standard time, a Robinson Helicopter Company R22 Beta, N926SH, made a hard landing and rolled over during a practice autorotation near Tucson, Arizona. The certified flight instructor and the private pilot receiving instruction sustained minor injuries, and the helicopter was substantially damaged. The helicopter was registered to, and operated by, Silver State Helicopters out of their Tucson Flight Academy, as an instructional flight under the provisions of 14 CFR Part 91. The local area training flight originated from Tucson around 0700, and no flight plan had been filed. According to the instructor pilot, he directed the student to the training area where they were going to practice simulated engine failures and 180-degree autorotations. The student attempted a number of 180-degree autorotations, but did not meet the instructor's standards. The instructor demonstrated one and then gave the student the controls again following the recovery. The student performed another 180-degree autorotation, but let his rotor rpm drop slightly in the turn. The instructor requested that the student practice another. During the last demonstration, the airspeed dropped to about 55 knots; the low rotor rpm horn sounded, and the low rotor rpm light illuminated. The rotor rpm was around 95 percent on rollout. The instructor took the controls and announced this to his student, who in turn relinquished control of the helicopter. The instructor rolled on the throttle and initiated a go-around. However, because their vertical speed was high and rotor rpm was low, he was unable to recover adequate rotor rpm prior to making ground contact. The instructor attempted to cushion the landing with the remaining rotor rpm with up collective input and forward cyclic input. The helicopter impacted desert terrain in a level pitch attitude, but began to slide to one side. The right front skid hung up in the soft dirt, and the helicopter rolled over approximately three times before coming to rest on its left side. The student reported doing three successful 180-degree autorotations and was working on the fourth when upon rollout, the airspeed dropped to 60 knots and the rotor rpm decreased to 97 percent at 80 feet above ground level (agl). The instructor called for a go-around, but the rotor rpm did not respond and the instructor took over control of the helicopter. The instructor then pulled up on the collective and pushed forward on the cyclic in an attempt to land the helicopter in a level pitch attitude. The remaining statement was similar to that written by the instructor. The helicopter's main rotor system, tail boom, and fuselage were substantially damaged. Neither pilot reported any mechanical problems with the 218-hour helicopter prior to the accident. According to the chief pilot for the Tucson Flight Academy, Silver State Helicopters has a policy in place that dictates that instructors are only allowed to practice the autorotation entrance and glide so that they recover at least 500 feet agl when they are not at a controlled airport with emergency equipment. When asked why the instructor did not follow this procedure, the instructor indicated that there was too much traffic at the Tucson Airport and he needed to prepare his student for his upcoming check ride.