NTSB Identification: SEA94GA203.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Saturday, July 30, 1994 in DUCHESNE, UT
Probable Cause Approval Date: 09/24/1995
Aircraft: HUGHES OH-6A, registration: N12UT
Injuries: 1 Fatal.

: NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this public aircraft accident report.

WHILE RETURNING TO SALT LAKE CITY FROM THE SOUTHEAST, THE PILOT REPORTED SEEING THUNDERSTORMS IN THE AREA. AT ABOUT 1843 MDT, THE HELICOPTER CHANGED COURSE AND PROCEEDED OVER MOUNTAINOUS TERRAIN WITH A MODE C ALTITUDE READOUT OF 9600 TO 9800 FEET MSL. THE TERRAIN ELEVATION ALONG THE FLIGHT PATH CHANGED FROM 7700 TO ABOUT 10,000 FEET. SHORTLY AFTER PASSING OVER TERRAIN NEAR 10,000 FEET, THE PILOT RADIOED A MAYDAY AND DECLARED THAT THE ENGINE WAS LOSING POWER. THE HELICOPTER BEGAN A DESCENT, ROUGHLY FOLLOWING A CANYON DRAINAGE AREA. SUBSEQUENTLY, IT CRASHED AT AN ELEVATION OF APPROXIMATELY 8850 FEET AFTER IMPACTING TREES. THE LONGITUDINAL WRECKAGE DISTRIBUTION WAS MINIMAL, INDICATING SLOW FORWARD VELOCITY AT TREE IMPACT. AN EXAM OF THE ENGINE REVEALED EVIDENCE OF POWER PRODUCTION DURING IMPACT; NO PREIMPACT PART FAILURE/MALFUNCTION WAS FOUND. THE DENSITY ALTITUDE WAS ESTIMATED TO BE ABOUT 12,000 FEET, AND THE HELICOPTER'S GROSS WEIGHT AT THE TIME OF THE ACCIDENT WAS ESTIMATED TO BE 1977 POUNDS. PERFORMANCE EVALUATION SHOWED THAT WITH THESE CONDITIONS, THE HELICOPTER WOULD HAVE BEEN UNABLE TO MAINTAIN A HOVER OUT OF GROUND EFFECT. THE ROTOR BLADES SHOWED ROTATIONAL ENERGY IMPACT SIGNATURES.

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

THE PILOT'S IMPROPER IN-FLIGHT PLANNING/DECISION AND FAILURE TO MAINTAIN SUFFICIENT ALTITUDE/CLEARANCE FROM THE SURROUNDING TERRAIN. FACTORS RELATED TO THE ACCIDENT WERE: THUNDERSTORMS IN THE AREA (REQUIRING THE PILOT TO DEVIATE FROM THE DESIRED COURSE), HIGH MOUNTAINOUS TERRAIN, AND HIGH DENSITY ALTITUDE,

Full narrative available

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