On May 30, 2002, at 0930 eastern daylight time, a Bell 206 helicopter, N820H, owned and operated by the Ohio Department of Transportation, was substantially damaged during a practice touchdown autorotation at the Ohio State University Airport (OSU), Columbus, Ohio. The certificated flight instructor, and airline transport pilot were not injured. Visual meteorological conditions prevailed for the local flight. A flight plan was not filed, and the instructional flight was conducted under 14 CFR Part 91. According to the pilot receiving instruction, he and a Bell Helicopter employed flight instructor were scheduled for a training flight on the day of the accident. They met about 0745, had a general conversation, and then went to the helicopter about 0815 to start the preflight. The two pilots completed the preflight, and then boarded the helicopter. The instructor occupied the left seat, and the pilot occupied the right. Once onboard, the instructor briefed the pilot on the training goals for the flight, and how the maneuvers would be conducted. The pilot then started the engine, initiated a hover, and taxied the helicopter to the intersection of taxiway "G" and "F" for a north-northwest departure. Once airborne, the pilot climbed the helicopter to 2,000 feet agl, and completed three autorotations. All three autorotations terminated at altitude with a power recovery, and during the maneuvers, rotor RPM remained within normal operating limits. Satisfied with the autorotational characteristics of the helicopter, they returned to the airport to continue the training. The pilot first performed a normal approach and progressed to autorotations. The pilot had completed approximately eight hovering autorotations, and six touchdown autorotations prior to the accident. The accident autorotation started with the pilot executing a normal approach. During the approach, and while the helicopter was descending through 300 feet agl, the instructor rolled the throttle to idle. The pilot lowered the collective and entered an autorotation. At first, he did not think he was going to make his intended touchdown point, and wanted to increase airspeed, but the instructor told him to slow the helicopter to 50 knots. The pilot applied aft cyclic, and airspeed decreased to about 40 knots. The pilot was now sure he would not make his intended touchdown point by maintaining 50 knots, so he lowered the nose. As airspeed increased, the pilot realized he was going to overshoot, so he initiated a left, and then a right turn to lose altitude. The pilot initiated a flare, applied initial collective, and then used additional collective to cushion the landing. Rotor RPM decayed during the landing sequence, and the helicopter touched down hard on the aft part of the skids. The pilot then instinctively applied aft cyclic, which the instructor was unable to prevent. The helicopter came to rest upright, and the pilots exited under their own power. Examination of the helicopter revealed substantial damage to the tailboom, and main transmission mounts.