What happened
During a flight training session, an instructor demonstrated a practice autorotation to touchdown before transferring control to the student for an autorotation to landing. The instructor noted that the student's initial entry into the maneuver was abrupt, causing the rotor RPM to fluctuate from high to low; however, the RPM had stabilized to a proper level prior to the landing flare.
During the flare, the student applied an initial pitch that was slightly too high but considered satisfactory. As the helicopter approached the ground, additional collective was applied to manage the descent. This application proved insufficient to check the sink rate, causing the heels of the skids to make contact with the ground. The impact caused the aircraft to rock forward onto the toe of the skid and then settle back down on the full skid. During this movement, the pilot heard a metallic sound. A subsequent external inspection revealed that the tail boom was bent downward at the juncture where it attaches to the fuselage. There were no injuries resulting from the incident.