Full Report:

LAX05CA263 On August 8, 2005, at 1115 Pacific daylight time, a Hughes 369D, N58431, collided with the ground during a practice autorotation at the North Las Vegas Airport, Las Vegas, Nevada. Las Vegas Metropolitan Police Department, also the registered owner of the helicopter, was operating it under the provisions of 14 CFR Part 91. The instructor pilot and commercial pilot undergoing recurrency training were not injured; the helicopter sustained substantial damage. The helicopter departed from North Las Vegas at 1030 that morning for the local area instructional flight. Visual meteorological conditions prevailed and no flight plan had been filed. The instructor pilot reported that he was conducting a 120-day recurrent training for the commercial pilot. While performing their fifth full-down autorotation with both pilots on the controls, the stinger impacted the ground, followed by the tail rotor. Just prior to the ground contact in the flare, the instructor pilot advised the commercial pilot to push forward; however, the tail rotor impacted the ground. The tail rotor was substantially damaged and had to be replaced. The instructor pilot did not report any mechanical problems with the helicopter prior to the accident. According to the Rotorcraft Flying Handbook (FAA-H-8083-21), "Care must be taken in the execution of the flare so that the cyclic control is not moved rearward so abruptly as to cause the helicopter to climb, nor should it be moved so slowly as to not arrest the descent, which may allow the helicopter to settle so rapidly that the tail rotor strikes the ground."