NTSB Identification: SEA95LA078.
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Accident occurred Saturday, April 22, 1995 in WALLA WALLA, WA
Probable Cause Approval Date: 08/23/1995
Aircraft: BELL UH-1B, registration: N39SD
Injuries: 1 Serious.

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 STATED THAT DURING AN EXTERNAL LOAD OPERATION, JUST AFTER THE LOAD CLEARED THE GROUND THE HELICOPTER SHUTTERED AND MADE A LOUD SCRAPING NOISE FOLLOWED BY LOW ROTOR RPM. THE PILOT RELEASED THE LOAD AND MANEUVERED FOR AN EMERGENCY LANDING. DURING THE MANEUVER, THE HELICOPTER COLLIDED WITH TREES. DURING THE POST CRASH INSPECTION, IT WAS FOUND THAT THE FREEWHEELING ONE-WAY CLUTCH ASSEMBLY HAD FAILED IN FLIGHT. THE CLUTCH ASSEMBLY APPEARED TO BE WORN AND THE INNER CLUTCH RACE DISPLAYED SIGNS OF BRINELLING.

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

TOTAL FAILURE OF THE FREEWHEELING SPRAG UNIT. A FACTOR TO THE ACCIDENT WAS: SUITABLE TERRAIN WAS NOT AVAILABLE FOR LANDING.

Full narrative available

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