On May 21, 1998, at 1924 hours Pacific daylight time, a Robinson R22B, N2312N, rolled over at the San Luis Obispo, California, airport while practicing hovering autorotations. The aircraft sustained substantial damage, and the certified flight instructor and dual student were not injured. Visual meteorological conditions prevailed for the local instructional flight and no flight plan was filed. The certified flight instructor (CFI) reported that he and the student were practicing maneuvers on a nonactive runway. He reported that he asked the student to demonstrate an autorotation from a hover from approximately 2 to 3 feet agl. The CFI stated that he stayed on the controls with the student throughout the maneuver. As they initiated the maneuver by closing the throttle, the helicopter moved backward with some sideward movement to the left. As the helicopter touched the ground, the rear left skid became imbedded in the runway surface and the aircraft rolled over onto its left side. The aircraft came to rest approximately 180 degrees from its original heading. Both pilots exited the aircraft with no injuries. The winds at the time were reported to be from a direction of 310 degrees at a velocity of 18 knots gusting to 22 knots. The CFI reported that they conducted all their maneuvers headed into the wind.