NTSB Identification: DFW07LA197
14 CFR Part 91: General Aviation
Accident occurred Wednesday, September 12, 2007 in Fort Stockton, TX
Probable Cause Approval Date: 12/24/2008
Aircraft: ROBINSON HELICOPTER R22 BETA, registration: N993KC
Injuries: 1 Serious,1 Minor.

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 single-engine helicopter experienced a hard landing after a malfunction of the belt drive system for the main rotor. The pilot had just taken off from a trailer and had transitioned to low level cruise flight when he heard a loud bang. The pilot cross-checked his engine instruments and observed the engine RPM was excessively high and the rotor RPM was below 80 percent, accompanied by the low rotor RPM warning. The pilot then initiated an autorotation and landed hard with near zero forward speed. The aircraft bounced backwards after initial impact and came to rest in the upright position. The on-scene investigation noted that one of the v-belts to the main rotor drive system had separated which caused the other belt to slip off the upper spindle. The reason for the separation could not be determined.

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

The failure of the v-belt drive system to the main rotor for undetermined reasons. Contributing to the accident was insufficient altitude to perform a successful autorotation.

Full narrative available

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