NTSB Identification: NYC02LA099.
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Accident occurred Saturday, June 08, 2002 in Sterling, MA
Probable Cause Approval Date: 07/23/2003
Aircraft: Boucher Revolution Mini 500, registration: N54VP
Injuries: 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 pilot hover-taxied the helicopter from its tiedown spot to a grassy area for takeoff. Upon reaching the grassy area, he initiated a takeoff, and the helicopter accelerated through effective translational lift and began to climb. About 30 feet and 25 mph, the rotor system drive belt broke. The helicopter yawed to the left, and the pilot immediately lowered the collective and applied right rudder to correct the yaw. The helicopter impacted the ground "straight ahead but tail down." The main rotor deflected downward, and a rotor blade stuck the tail boom. The helicopter's right skid collapsed, and the helicopter rolled over on its right side and caught on fire. A section of drive belt, about 46 inches in length, had "broomstraw" separations at both ends. On the toothed side of the belt, there were about 15 areas along one edge that were worn down or missing. Another section of belt, about 40 inches in length, also had broomstaw separations at both ends, although one end had considerably less. The belt was missing material its entire length, with the missing material varying between 1/2 to 3/4 the width of the belt.

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

A misalignment of the rotor system drive belt, which resulted in belt chaffing, its subsequent separation, and a resultant loss of power to the rotor system. Also causal was the relatively low altitude and airspeed at which the separation occurred, which inhibited the pilot's inability to maintain a level attitude during the autorotation.

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