On April 23, 2001, at 1600 hours Pacific daylight time, a Robinson R22 Beta, N806EH, rolled over while completing an autorotative landing in Fortuna, California. The helicopter sustained substantial damage; however, neither the certificated flight instructor nor his student were injured. Executive Helicopters, Inc., was operating the helicopter as an instructional flight under 14 CFR Part 91 when the accident occurred. The flight originated from the Sacramento Executive Airport about 1530. Visual meteorological conditions prevailed at the time and no flight plan had been filed. The helicopter departed for a local instructional flight at Franklin Field in Fortuna. According to the instructor, they were in the process of practicing a series of over autorotations. The first three were conducted jointly. On the fourth hover autorotation the student abruptly lowered the collective as the instructor reduced the throttle and the helicopter touched down hard. The helicopter then rolled onto its side. The instructor stated that the student pushed the collective so quickly he had insufficient time to react. The pilot reported 580 hours of total flight time and 300 hours as an instructor. All flight time and instruction had been in the make and model. Winds at Sacramento were reported as from 320 degrees at 4 knots with 10 miles of visibility. In the operator's aircraft accident report, form 6120.1/2, he reported the total time on the airframe as 9,675 hours and it had been 93 hours since its last inspection. He also reported the helicopter damage. Both the main and tail rotor were damaged from the impact, and damage to the airframe, drive train, and tail boom was also evident.