NTSB Identification: ERA10LA019
14 CFR Part 91: General Aviation
Accident occurred Thursday, October 15, 2009 in La Belle, FL
Probable Cause Approval Date: 05/05/2011
Aircraft: ROBINSON R44, registration: N3038W
Injuries: 1 Serious,3 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 pilot reported that he was conducting a flight at a low altitude and speed when he heard a light tapping sound followed by the low rotor rpm warning horn. He attempted to simultaneously initiate an autorotation and maintain forward speed to reach a clearing. The tail boom and tail rotor struck trees, and the pilot lost directional control of the helicopter. The helicopter touched down in the clearing, spun about 180 degrees to the right, and rolled onto its left side. A postaccident examination revealed that one of the rotor drive belts was separated and that each of the remaining three belts was frayed and partially displaced from at least one of its respective sheaves. According to a representative for the helicopter manufacturer, the fraying was typical of a drive belt that was displaced from the sheave while the engine was running. The fraying could be caused by the belt being too loose, by abrupt maneuvering of the helicopter, or by the helicopter striking the ground when the engine was running. The representative also stated that when a drive belt starts to fail, it tends to make a repetitive noise similar to that reported by the pilot, and that drive belt failure could result in low rotor rpm. The reason(s) for the drive belt failures could not be determined and maintenance records were not available during the investigation.

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

The loss of main rotor rpm due to the failure of one or more of the drive belts for undetermined reasons.

Full narrative available

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