At the conclusion of a survey flight, the pilot elected to conduct a practice autorotative landing. The wind at the time was varying by about 30 degrees, and was gusting between 15 and 30 knots. The exercise proceeded normally until the helicopter had reached a height of about 10 feet above the ground. At this point the aircraft encountered heavy sink, and the pilot was unable to level the skids before the aircraft contacted the ground in a tail-low attitude. The tail boom was broken and both tail rotor blades were damaged. Although the pilot had extensive helicopter experience, his exposure to the lightweight types such as that involved in this accident was limited. It was likely on this occasion that he did not detect that the rotor rpm had decayed at a critical stage of the approach.