NTSB Identification: DEN04LA142.
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Accident occurred Tuesday, September 14, 2004 in Spanish Fork, UT
Probable Cause Approval Date: 02/24/2005
Aircraft: Robinson R22, registration: N777UH
Injuries: 1 Minor,1 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 helicopter was at 6,000 feet, flying at 70 knots, and exiting a canyon about 5 miles east of the airport. It was on a long final approach to runway 30. After performing pre-landing checks that included warning lights extinguished, rotor and engine tachometers and other pertinent instruments in the green arc, and carburetor heat outside the yellow arc, the instructor "pulled the carb[uretor heat] up a little, and then...pushed the trim in to prepare for landing." Shortly thereafter, the engine lost power. The collective control was lowered and the instructor took control of the helicopter. The LOW RPM light illuminated and the warning horn sounded. The instructor noticed the tachometer was "in the green" and manifold pressure (MAP) was in the red (25 inches) arc. He attempted an autorotation into an open field. He flared and the helicopter landed hard "with a slight nose right yaw." The helicopter bounced once, and then rolled over on its right side. The tail boom and tail rotor were severed. The engine was later functionally tested to full power. Nothing was found that would have been causal to the power loss. Temperature and dew point conditions were not conducive to carburetor icing.

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

the instructor's premature flare, resulting in a hard landing, and his failure to align the helicopter with the direction of travel, resulting in a rollover.Contributing factors were the low rotor RPM and inadequate airspeed. The reason for the loss of engine power was not determined.

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