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ASN Wikibase Occurrence # 80383
Last updated: 11 March 2020
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Type:MD Helicopters MD 500E (369E)
Owner/operator:Winco Inc.
Registration: N765WH
C/n / msn: 0600E
Fatalities:Fatalities: 1 / Occupants: 4
Aircraft damage: Substantial
Location:Lead Mine Mountain area -   United States of America
Phase: En route
Departure airport:Thomas, WV
Destination airport:Thomas, WV
Investigating agency: NTSB
The pilot transitioned the helicopter to pick up three linemen who were working from the peak of a 100-foot-tall transmission tower. Before the linemen boarded the helicopter (two were in the helicopter and one was on the skid), they secured their equipment to the external load grappling hook suspended 50 feet below the helicopter. The pilot positioned the helicopter adjacent to the tower structure between the two sets of electrical conductors, with the grappling hook and the linemen's equipment suspended below. As the pilot attempted to maneuver the helicopter clear of the tower, it paused, and then began to shake before the helicopter contacted wires on the opposite end of the tower and impacted the ground under power. Both of the linemen who were seated in the helicopter before it impacted the ground incurred minor injuries; the lineman standing on the helicopter's skid was fatally injured. The pilot did not attempt to release the external load at any point during the accident sequence, and postaccident testing of the system revealed no anomalies. Postaccident examination of the airframe and engine revealed no evidence of any preimpact mechanical malfunctions or failures of the helicopter. Examination of the power transmission tower and external-load sling revealed evidence consistent with entanglement of the external load with the tower's structure. Immediate compliance with the operator's recommended procedure of jettisoning the external load in the event of an emergency (actual or perceived) would have provided an opportunity for the pilot to have prevented the accident.
Probable Cause: The pilot's failure to clear the helicopter and its external load from surrounding structures and his failure to execute a timely release of the external load, which resulted in an inadvertent entanglement and collision with wires and terrain. Contributing to the lineman's fatal injury was his position outside of the helicopter during the accident.



Revision history:

01-Nov-2010 11:22 gerard57 Added
02-Nov-2010 01:01 bizjets101 Updated [Aircraft type, Registration, Cn, Operator, Source]
21-Dec-2016 19:25 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
26-Nov-2017 18:35 ASN Update Bot Updated [Operator, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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