NTSB Identification: SEA86LA143.
The docket is stored on NTSB microfiche number 32051.
Accident occurred Thursday, June 12, 1986 in ZILLAH, WA
Aircraft: BELL 47G-2, registration: N11VH
Injuries: 1 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.

EN ROUTE TO THE LOCAL SPRAY AREA A TOTAL LOSS OF POWER OCCURRED ALONG WITH A LOSS OF OIL PRESSURE. THE ACFT WAS APRX 200 FT AGL OVER A PEAR ORCHARD. THE PLT WAS ATTEMPTING TO AUTOROTATE ONTO A NEARBY ROAD BUT THE LEFT SKID CAUGHT THE ROOF TOP OF A METAL SHED. THE HELICOPTER CRASHED THROUGH THE ROOF OF THE SHED AND ROLLED OVER ONTO ITS SIDE. INVESTIGATION REVEALED THAT THE NUMBER THREE CYLINDER ROD BOLT HAD FAILED. METALLURGICAL EXAM REVEALED THAT THE NUMBER 3 CYLINDER CONNECTING ROD CAP HAD FAILED AS A RESULT OF OVERSTRESS FORCES DUE TO EXCESSIVE HEATING OF THE ROD AND CAP. FAILURE OF THE NUMBER 3 CYLINDER CONNECTING ROD BOLT WAS DUE TO FATIGUE CRACKING. THE MOST LIKELY CAUSE OF THE OVERHEATING WAS DUE TO A DETERIORATED BEARING.

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

ENGINE ASSEMBLY,CONNECTING ROD..OVERTEMPERATURE

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

ENGINE ASSEMBLY,CONNECTING ROD..FAILURE,TOTAL

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

ENGINE ASSEMBLY,BEARING..WORN



Contributing Factors

OBJECT..BUILDING(NONRESIDENTIAL)

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