NTSB Identification: SEA94LA171.
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Accident occurred Thursday, July 07, 1994 in PORTLAND, OR
Probable Cause Approval Date: 12/02/1994
Aircraft: ROBINSON R-22M, registration: N42WC
Injuries: 2 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 PILOT ATTEMPTED AN AUTOROTATION AFTER LOSS OF TAIL ROTOR EFFECTIVENESS. THE TAIL BOOM AND ROTOR STRUCK THE SURFACE WHEN THE FLOAT EQUIPPED HELICOPTER LANDED IN THE RIVER. INVESTIGATION REVEALED THAT THE TAIL ROTOR GEARBOX OUTPUT SHAFT PINION RETAINING KEY HAD NOT BEEN INSTALLED DURING ASSEMBLY. THE TAIL ROTOR HUB AND BLADE ASSEMBLY WERE FREE TO TURN ON THE SHAFT AT THE TIME OF INVESTIGATION.

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

TAIL ROTOR GEARBOX FAILURE DUE TO INADEQUATE ASSEMBLY AND INSPECTION PROCEDURES BY THE MANUFACTURER.

Full narrative available

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