N43791

The instructor pilot was demonstrating an “extended glide” autorotation to a paved landing “lane” when the accident occurred. The autorotation was initiated at an altitude of approximately 740 feet above ground level (agl). Upon reaching an altitude of 75 feet agl, the pilot determined he was going to land short of the paved surface so he applied power; however, lift was suddenly lost. He then noticed a raised concrete lip between the grass and the landing lane so he applied aft cyclic hoping the front of the skids would not catch on the raised pavement. The helicopter touched down in the soft terrain, slid over the rise in the pavement, and became airborne. The helicopter then touched down on the pavement at which time the tail boom was severed. The helicopter slid about 75 feet and turned to the right about 40 degrees prior to coming to rest. Winds at the time of the accident were from 180 degrees at 9 knots gusting to 18 knots. The autorotation was being performed to the south