On May 16, 1998, at 1048 hours Pacific daylight time, a Robinson R22B, N2332G, impacted the terrain and rolled over at the Reid-Hillview Airport in San Jose, California. The aircraft sustained substantial damage and the certified flight instructor and dual student were not injured. Visual meteorological conditions prevailed and no flight plan was filed. The local instructional flight originated at 1010. The certified flight instructor reported that he and the commercial rated pilot were working on traffic patterns and had made several practice landings to a 10-degree slope. At the time of the accident, the student was on the controls. She reported that as she set the helicopter down, "it didn't feel right," and she attempted to abort the landing by pulling in full collective and applying aft cyclic. The helicopter became airborne and the main rotor rpm decreased to the point where the low rotor rpm horn and light were activated. The flight instructor reported that he lowered the collective, rolled on the throttle, and neutralized the pedals. The instructor reported that the rotor rpm was recovered to approximately 92 percent. He then applied aft cyclic and lifted the collective to cushion the landing. The helicopter landed hard on the forward portion of the left skid. The skid tip impacted the berm and the helicopter rolled onto its left side. The pilot reported no prior mechanical malfunctions with the aircraft.