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ASN Wikibase Occurrence # 36061
Last updated: 22 June 2021
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Type:Silhouette image of generic B06 model; specific model in this crash may look slightly different
Bell 206B JetRanger
Owner/operator:Royale Helicopter Service
Registration: N911RH
MSN: 1583
Fatalities:Fatalities: 4 / Occupants: 4
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:Sago, WV -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Departure airport:Spruce Fork, WV
Destination airport:Sawmill Run, WV (NONE)
Investigating agency: NTSB
A helicopter was transporting passengers to a remote site when it dropped in a flat attitude and impacted into trees. A witness said he watched as the helicopter approached and circled the local area. As the helicopter flew overhead for the second time, he waved his arms to attract the pilot's attention. As the helicopter continued past him again, he thought that they were taking aerial photographs of the site. He said that the helicopter appeared to be lower and slower on its second pass overhead. Examination of the engine revealed uncommanded engine shut downs. During bench testing, the power turbine governor failed to limit fuel flow, and during disassembly it was revealed that a machine self locking hex nut had backed off the muscles valve stem. Examination of the muscles valve components revealed that the threaded valve stem was below the minimum requirements for a UNJ thread, and the flank angle was too large. The turbine governor, with zero Time Since Overhaul, was installed on the engine in January 1997. The governor was last overhauled at the manufacturer's facility during May-June 1996. CAUSE: The improper overhaul of the turbine governor by the manufacturer, which resulted in the loss of power.



Revision history:

24-Oct-2008 10:30 ASN archive Added
21-Dec-2016 19:22 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]

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