NTSB Identification: DEN04CA143.
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Accident occurred Thursday, September 16, 2004 in Spanish Fork, UT
Probable Cause Approval Date: 03/30/2005
Aircraft: Robinson R22 Beta 2, registration: N7533E
Injuries: 1 Minor,1 Uninjured.
NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.
The flight instructor was preparing the commercial pilot for his upcoming flight instructor practical test. He asked the pilot to demonstrate a simulated engine failure with autorotation to landing. The pilot rolled off the power and entered an autorotation. Airspeed was between 65 and 70 knots, and rpm was maintained between 98 and 100 percent. The rate of descent was 2,000 feet per minute (fpm) in the 180-degree turn, but decreased to 1,800 fpm when they lined up with the runway. Rpm was at 97 percent and started to drop. The warning horn and light activated at 100 feet agl. Rpm was at 94 percent. The instructor took control of the helicopter and applied full power and "a small cyclic flare, and lowered the collective slightly to recover rpm." The helicopter began to shake with a low frequency vibration. Rpm was between 92 and 94 percent. Approximately 50 feet agl, the instructor applied "a strong cyclic flare" to reduce the rate of descent. The vibrations continued and the helicopter continued to settle. Just before ground contact, the instructor noted the rpm needles were "married at 92 percent (sic)." The helicopter contacted the runway tail first, then the rear portion of the skids hit. The helicopter bounced and began to spin. The helicopter came to rest right side up and the engine continued to run.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the pilot's failure to maintain adequate rotor rpm during a practice autorotation, and the flight instructor's improper flare. A contributing factor was the instructor's inadequate supervision of the pilot. Full narrative available
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