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ASN Wikibase Occurrence # 44775
 
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Date:21-JUL-2004
Time:15:40
Type:Silhouette image of generic EXEC model; specific model in this crash may look slightly different
RotorWay Exec 162F
Owner/operator:Private
Registration: N103RW
MSN: 6235
Fatalities:Fatalities: 1 / Occupants: 1
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Cameron Park, CA -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Test
Departure airport:Cameron Park, CA (O61)
Destination airport:
Investigating agency: NTSB
Narrative:
Witnesses said the helicopter was in cruise flight when it pitched up, rolled left to an inverted attitude while portions of the airframe separated, then it descended straight down to ground impact. Wreckage examination found evidence that the main rotor blades (MRB) diverged from their plane of rotation, and mast bumping occurred. Thereafter, the blades impacted the tail boom, which separated from the helicopter. The helicopter became uncontrollable, rolled inverted, and descended into a residence. Portions of both the helicopter and residence were consumed in the post impact fire. The pilot-builder held a repairman certificate for his experimental category helicopter. The pilot had replaced RotorWay's main rotor blades with blades manufactured by another company. During assembly of the helicopter, each MRB was attached to its respective blade yoke with a single retention nut/bolt assembly. The subsequent wreckage examination revealed that the nut that secured one of the MRBs to its retention bolt was missing. The retention bolt was examined, and its threads were not stripped; the bolt was intact. During the MRB installation, the nut had likely been inadequately torqued, and thereafter, it had worked off the bolt during flight. With the bolt loose, the MRB was free to diverge from its normal rotation plane, thus rendering the helicopter uncontrollable.
Probable Cause: The owner-builder's improper main rotor blade (MRB) maintenance/installation by under torquing the blade retaining nut.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20040727X01081&key=1

Location


Revision history:

Date/timeContributorUpdates
28-Oct-2008 00:45 ASN archive Added
21-Dec-2016 19:24 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
07-Dec-2017 18:15 ASN Update Bot Updated [Operator, Destination airport, Source, Narrative]

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