On November 22, 1997, at 0936 hours Pacific standard time, a Robinson R22 Beta, N45SG, rolled over during a practice autorotation at Daugherty Field, Long Beach, California. The aircraft was being operated by Watson Helicopters, Inc., as an instructional flight at the time of the accident. The helicopter sustained substantial damage; however, neither the flight instructor nor his private pilot rated student was injured. The flight originated from Whiteman Airport in Los Angeles, California, at 0830 on the morning of the accident. Visual meteorological conditions prevailed at the time and no flight plan was filed. The student reported that he was practicing autorotations to pad 1. On the previous maneuvers, he had been instructed to execute a "nice easy flare." During this maneuver, however, he was instructed to complete a "nice hefty flare." As a result of this direction from the flight instructor, he thought that they were going to execute a full touchdown autorotation but did not attempt to confirm his assumption. As he leveled the aircraft, the instructor reached for the controls that further strengthened the student's belief that they were now performing a full touchdown autorotation. He held the throttle at idle and pulled pitch to cushion the touchdown but the aircraft drifted left and fell through to the ground. The instructor reported that the student was in the process of completing his fourth straight-in autorotation to pad 1. This autorotation was to terminate with a power recovery in the same manner as the previous three maneuvers. During the flare, however, the student allowed the aircraft to descend lower than he had previously. At this point, the instructor orally reminded him of the importance of a more aggressive flare. The student accentuated his flare, also reducing his air and ground speed. As he leveled the aircraft, an excessive sink rate rapidly developed. The instructor attempted to reapply the throttle but his efforts were delayed by the student's tight grip on the controls. The aircraft was drifting left when the left skid contacted the ground. The aircraft bounced and then rolled onto its left side, coming to rest in the grass abeam of pad 1. Both occupants exited the aircraft without difficulty.