NTSB Identification: DEN87LA199.
The docket is stored on NTSB microfiche number 34813.
Accident occurred Wednesday, July 29, 1987 in DUBOIS, WY
Probable Cause Approval Date: 10/07/1988
Aircraft: BELL 204B, registration: N4580Y
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 COMMERCIAL PLT WAS PERFORMING EXTERNAL SLING LOADS IN SUPPORT OF SEISMIC OPERATIONS. THE PLT REPORTED THAT THE ENGINE FAILED DURING A LOAD RELEASE AND THE PLT EXECUTED AN AUTOROTATION. THIS RESULTED IN A HARD LANDING IN HEAVY TIMBER ON SLOPING TERRAIN. THE HELICOPTER ROLLED OVER ON THE RIGHT SIDE. A POST ACCIDENT ENGINE INSPECTION REVEALED NO PREIMPACT MECHANICAL MALFUNCTIONS /FAILURES.

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

REASON FOR OCCURRENCE UNDETERMINED

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

TERRAIN CONDITION..NONE SUITABLE

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