NTSB Identification: LAX94LA132.
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Accident occurred Wednesday, February 23, 1994 in ETNA, CA
Probable Cause Approval Date: 11/14/1994
Aircraft: BELL TH-1L, registration: N204AP
Injuries: 2 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 42-DEGREE GEAR BOX FAILED SHORTLY AFTER DEPARTING ON A HELICOPTER LOGGING OPERATION. THE PILOT JETTISONED THE LOAD, BUT WAS UNABLE TO STOP THE HELICOPTER'S ROTATION AND IT CRASHED. METALLURGICAL EXAMINATION OF THE GEAR BOX REVEALED A FATIGUE BANDING PATTERN NEAR THE TOOTH ROOT OF THE INPUT GEAR.

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

THE FAITUGE OF THE GEAR TOOTH WHICH CAUSED THE FAILURE OF THE 42-DEGREE GEAR BOX.

Full narrative available

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