NTSB Identification: LAX00LA156.
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Nonscheduled 14 CFR
Accident occurred Sunday, April 16, 2000 in GRAND CANYON, AZ
Probable Cause Approval Date: 07/17/2001
Aircraft: Bell 407, registration: N175PA
Injuries: 6 Uninjured.

NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

About 5 minutes after takeoff, while in cruise flight, the pilot felt a few short 'clunks' and then heard grinding noise and felt violent shaking. The pilot elected to perform a precautionary, autorotative, off-airport landing. During the landing flare, the tail rotor and tail stinger contacted the ground. The tail rotor blades were damaged, the stinger broken, and the tail rotor gearbox was fractured. The vibration that the pilot felt was traced to a failed bearing at the oil cooler fan forward hanger. The bearing was sent to the helicopter manufacturer for examination; however, a fracture mode could not be identified due to damage to the fracture surfaces. An airworthiness directive applied to the bearing and was complied with 11 flight hours prior to the accident.

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

The failure and subsequent disintegration of the oil cooler fan forward hanger bearing.

Full narrative available

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