On March 29, 2002, at 1515 Pacific standard time, a Robinson R22 Beta, N7040C, collided with the ground and rolled over while practicing autorotations near North Las Vegas, Nevada. The helicopter was operated by Silver State Flight School under the provisions of 14 CFR Part 91 for the local area instructional flight that originated at the North Las Vegas airport at 1515 on the day of the accident. The helicopter sustained substantial damage. The commercial pilot/flight instructor sustained serious injuries and a dual primary student sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed. The instructor and the student completed written statements 4 days after the accident. The instructor reported that the flight from North Las Vegas to the practice area used by company helicopters was uneventful. After arrival in the practice area, the instructor orbited the landing area and determined the wind direction from flags the company had placed strategically around the desert terrain. Three practice traffic patterns to normal hover were conducted and the instructor next wanted to demonstrate an autorotation. The helicopter was climbed to about 800 feet agl and the instructor checked the wind conditions and the engine instruments one more time, then entered a standard autorotation into the wind. The instructor said he established an autorotational glide at 65 to 70 knots with the rotor speed in the green arc. About 40 feet agl he began a cyclic flare and noticed that the "ground rush was abnormal," and the ground was coming up more quickly than it should. He continued the flare to reduce the descent rate and airspeed; however, the helicopter did not respond. He stated that, "It felt like I was getting pushed to the ground from behind from a descending column of air." He then reapplied the engine power and pulled up on the collective. He noted that the low rotor rpm horn came on just before impact. The helicopter hit the ground, collapsing the left skid, then rolled over on the left side and slid to a stop. In his written report, the instructor said that there were no preimpact mechanical malfunctions or failures. In his statement, the 7-hour dual primary student said that this autorotation was no different than the three prior ones demonstrated by the instructor until the helicopter got to within 40 feet of the ground. He stated that the vertical speed seemed to increase even though the instructor was pulling aft cyclic and up collective. The low rotor warning horn came on either right at or just slightly before the ground impact. He reported that the engine was running after the accident and had to be shutoff. The flight instructor was interviewed in the hospital by detectives from the Las Vegas Metro Police Department in the late afternoon just after admission. The interview followed the medical administration of medication to control pain. He stated that one practice autorotation to a power recovery was successfully completed followed by a go-around for a left traffic pattern to do one more. At the termination point of the second autorotation, the "collective was pulled but not enough power was added," and the helicopter fell through the flare, hit hard, and rolled over. Responding officers from the Las Vegas Metro Police Department reported that the weather conditions at the site included clear skies with westerly winds at 10 knots or less. Wind reports from North Las Vegas airport indicated winds from 060 at 5 knots, gusting to 14 knots around the time of the accident.