On September 5, 2004, at 0820 Pacific daylight time, a Robinson R22 Beta, N994RW, made a hard landing and rolled over at the North Las Vegas Airport, North Las Vegas, Nevada. The helicopter was substantially damaged. The commercial pilot held a certified flight instructor (CFI) certificate, and he sustained minor injuries. The pilot who was receiving dual flight instruction (student pilot) held a private pilot certificate, with a rotorcraft-helicopter rating, and he was seriously injured. Visual meteorological conditions prevailed at the time of the instructional flight, and no flight plan had been filed. Silver State Helicopter was operating the flight under the provisions of 14 CFR Part 91, and it commenced from the airport at 0803. According to the Federal Aviation Administration's (FAA) Western-Pacific Quality Assurance staff (AWP-505), immediately prior to the accident the pilot had performed a series of left-hand closed traffic patterns to runway 12L. The accident occurred during the 7th approach to the runway. An on-duty air traffic controller observed the helicopter perform what he described as a very steep approach to the runway. The helicopter's descent rate did not appear to significantly decrease, whereupon it impacted the ground and rolled over. The FAA reported that radio transmissions from the helicopter's crew sounded normal, and no tones were heard in the background. According to responding airport operation and management officials, the helicopter's initial point of impact (IPI) was in a dirt infield area approximately 20 feet east of the left side of runway 12L, and about 400 feet south of intersecting runway 07. They observed an estimated 90-foot-long debris field between the IPI and the main wreckage, which came to rest on runway 12L. The CFI reported to the National Transportation Safety Board investigator that during the flying lesson he was training his student in autorotations, and his student was working toward obtaining a commercial pilot certificate. The student had performed a series of six or seven 180-degree autorotations to the runway. The CFI stated that both he and his student were on the controls at the time of the accident. The CFI provided the Safety Board investigator with a written statement, dated September 8, 2004, in which he described the accident flight. In pertinent part, the CFI indicated that the mishap occurred on the 4th practice 180-degree autorotation. After the student improperly initiated the autorotation, the CFI told his student that he had the controls. The student let go of the controls, and the CFI commenced the 180-degree turn toward the runway. The CFI intended to complete the maneuver by performing a power recovery and a go-around. The CFI reported the following sequence of events then occurred: "As I rolled out of the turn and attempted the power recovery, I realized through the turn I had accumulated a huge descent rate that did not seem to stabilize after leveling out at approximately 15 ft AGL. We were still descending very fast. I pulled aft cyclic as quick as I could and attempted to roll the throttle on and raise the collective, but before I could initiate a flare, we hit the ground. After that we slid for approximately 200 to 300 ft, and rolled."