The pilot elected to conduct a practice autorotation. His initial intention was to reapply power and to discontinue the exercise before reaching the ground, but during the descent he changed his mind and decided to continue to the ground. As the pilot flared the helicopter the tail skid contacted the ground and the main rotors struck the tail boom and tail rotor shaft. The pilot chose an unfamiliar sand bar on which to practice the autorotational landing. The associated glare from such a surface and the lack of visual cues for height assessment are considered to have led the pilot to misjudge his height for the flare.
