NTSB Identification: NYC08LA060
14 CFR Part 91: General Aviation
Accident occurred Wednesday, December 12, 2007 in Plant City, FL
Probable Cause Approval Date: 05/12/2009
Aircraft: ROBINSON HELICOPTER R22 BETA, registration: N7188J
Injuries: 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.
Shortly after departure, the pilot noted that more than "usual" forward cyclic and collective application was required to maintain the helicopter's desired airspeed, but that a scan of the instruments assured him that "All was okay." While cruising at 700 feet, and 70 knots, the pilot detected a strong odor of burning rubber, a loss of power, illumination of the clutch warning light, and yawing of the helicopter. The pilot entered autorotation, turned to a "dark, open area," and descended into trees. Examination of the helicopter at the scene revealed that the drive belts were twisted, torn, and off of their respective pulleys. Examination and testing revealed that the clutch actuator functioned as designed, but the alignment of the drive belt sheaves and pulleys could not be determined due to impact damage. In a follow-up interview, the pilot stated that during engine start, 10 to 15 seconds transpired between the times that he actuated the clutch switch, and the main rotor blades turned. According to the pilot's operating handbook starting engine checklist, the rotor blades should turn less than 5 seconds after engagement of the clutch switch. According to a note in the manufacturer's maintenance manual, V-Belt Installation, "A delay of more than 5 seconds between clutch switch engagement and rotor turning indicates excessive slack."
The National Transportation Safety Board determines the probable cause(s) of this accident to be: A loss of rotor drive due to excessive slack and breakage of the drive belts. Contributing to the accident was the pilot departing in the helicopter after the rotor engagement time during engine start exceeded the time outlined in the pilot's operating handbook. Full narrative available
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