NTSB Identification: FTW01LA214.
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Nonscheduled 14 CFR
Accident occurred Wednesday, September 26, 2001 in W Cameron 168, GM
Probable Cause Approval Date: 07/01/2002
Aircraft: Bell 206L-1, registration: N1067D
Injuries: 3 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 helicopter was on approach to an offshore platform, turning from base to final at 300 feet, when the pilot heard the low rotor rpm audio warning, and then noticed that the low rotor rpm warning light was illuminated. He initiated an autorotation and observed that the rotor rpm needle had dropped to zero. The pilot stated that as the helicopter was descending, he noticed feedback in the flight controls and decided that a precautionary landing was necessary. Subsequently, the pilot landed the helicopter in the water and shut down the engine. During the main rotor coast down, the tail rotor contacted a five foot wave, resulting in separation of the tail rotor drive shaft. The internal splines of the shaft and sleeve assembly of the rotor tachometer generator (part number 206-076-373-001) were found to be worn and not engaging. The failure of the rotor tachometer generator splines resulted in a loss of hydraulic pressure to the helicopter flight controls, since the hydraulic pump is driven by the rotor tachometer generator.

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

the failure of the rotor tachometer generator, which resulted in a precautionary landing in the Gulf of Mexico. A contributing factor to the accident was the rough water condition.

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