On October 17, 2002, at 1812 Pacific daylight time, a Schweizer 269C, N61416, landed hard and rolled over while practicing autorotations at Hayward Executive Airport, Hayward, California. The helicopter was operated by Sierra Academy of Aeronautics under the provisions of 14 CFR Part 91 for the local area instructional flight. The helicopter sustained substantial damage. The certified flight instructor (CFI) and student pilot were not injured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight originated at Oakland at 1730. The Federal Aviation Administration inspector reported that the helicopter started an autorotation during a turn beginning the maneuver approximately 500 feet above ground level (agl). The inspector further reported that as the helicopter hit the ground the tail was broken off. In a written statement by the CFI he stated that the purpose of the flight was to practice 180 degree autorotations. The student's primary instructor had requested the CFI to fly with the student for additional practice. Upon arrival at Hayward various maneuvers were practiced to get "warmed up." During the intial portion of the 180-degree autorotations the CFI demonstrated the maneuvers and slowly gave the student "more and more" control. The CFI further stated on the eventful autorotation the student initated the maneuver himself; however, as he initiated the turn he pulled "too much up on the collective." The CFI noticed the rpm go down but not at an alarming rate as "we were still well within the green." Through the turn the student put the nose of the aircraft down in order to maintain proper airspeed placing the helicopter in too much of a nose down attitude. The descent continued with low rpm and high airspeed out of trim. The CFI stated he then took control of the helicopter, initiated a flare, and lowered the collective slightly down in order to arrest the rate of descent; however, the helicopter impacted the ground tail low with "some downward force and momentous forward ground speed." The helicopter came to rest on its left side. In a written statement submitted by the student pilot he stated this flight was his second with the CFI, and the purpose of the flight was to improve the student's autorotations. The autorotation began with a normal short approach pattern toward the helipad and entry from 500 feet and 70 knots. The entry and turn were normal; however, upon establishing the helicopter on final approach to the helipad, a very high sink rate had developed. The student then attempted to roll on the throttle but the helicopter impacted the ground skids level, rolled up on its nose, and then rolled onto its left side. The student was trapped under the wreckage and the CFI lifted the wreckage to release him. The student stated the CFI was "with him" on the controls at all times.