NTSB Identification: DEN99LA058.
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Accident occurred Thursday, March 25, 1999 in ENGLEWOOD, CO
Probable Cause Approval Date: 05/08/2001
Aircraft: Robinson R22 BETA, registration: N8354Z
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The flight instructor and his student were practicing autorotations. The entry was made at 700 feet above the ground (agl), and the turn was completed at approximately 200 agl. As the helicopter rolled out of the turn, the collective was lowered 'but not enough,' and the rpm continued to decay. At the end of the flare, approximately 20-25 feet agl, a high sink rate began to build. The instructor took control and rolled the throttle to recover the rpm but did not have sufficient altitude or rpm. The helicopter impacted the ground hard in a level attitude. Upon impact, the skids buckled outward and the main rotor blades flexed downward, severing the tail boom.

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

The flight instructor allowed the rotor rpm to decay during an autorotation which resulted in a hard landing.

Full narrative available

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