NTSB Identification: LAX00TA355.
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Accident occurred Friday, September 29, 2000 in Phoenix, AZ
Probable Cause Approval Date: 11/25/2003
Aircraft: Hughes TH-55A, registration: N331SD
Injuries: 2 Uninjured.

NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.

The single engine helicopter experienced a main rotor-tail boom strike at the termination of a practice autorotation. The flight instructor reported that he was demonstrating a 180-degree practice autorotation, and said that the entry, airspeed, rate of descent, deceleration, flare, and touchdown were normal. After touchdown he estimated that there was a ground slide of about 5 to 8 feet. As the aircraft stopped, he heard a loud sharp sound that was accompanied by sustained vibration and an uncommanded right yaw of about 30 degrees. After he and the student exited the helicopter, he noted that the main rotor blades had contacted the tail boom, damaging the tail rotor drive shaft, tail boom, as well as all the main rotor and tail rotor blades. The flight instructor stated that he did not perceive any action or inaction on his part that could be construed as detrimental to the safe outcome of the maneuver. According to the FAA inspector, who responded to the accident site and examined the helicopter, there were no signs of mechanical problems that would have contributed to the accident. The flight instructor had accumulated approximately 1,320 hours of helicopter flight time, of which approximately 800 hours were obtained in the same make and model as the accident helicopter.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

the flight instructor's misjudged flare during a simulated autorotation, which led to a hard landing.

Full narrative available

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