Incident Overview
A practice autorotation to touchdown resulted in a hard landing that bent the tail boom of the helicopter at the fuselage attachment juncture. The flight was a training session with an instructor and a student.
Sequence of Events
The instructor first demonstrated a practice autorotation to touchdown, then turned control of the helicopter over to the student to perform the next autorotation to landing. According to the instructor, the student's entry into the autorotation was abrupt, leading first to high rotor rpm and subsequently to low rotor rpm. However, before initiating the landing flare, the rotor rpm had returned to proper values.
During the flare, the student's initial pitch application was slightly too high but considered satisfactory. As the aircraft approached the landing point, additional collective pitch was applied, but the input was insufficient to check the sink rate. The heels of the skids made ground contact, causing the helicopter to rock forward onto the toe of the skids and then back down onto the full skids.
Findings
After the landing, the pilot heard a metallic sound. An external inspection revealed that the tail boom was bent downward at its attachment point to the fuselage.
No injuries or other damage were reported.