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ASN Wikibase Occurrence # 40783
Last updated: 12 July 2020
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Date:06-JUL-1985
Time:11:09
Type:Silhouette image of generic H500 model; specific model in this crash may look slightly different
Hughes 369HS
Owner/operator:Rushmore Helicopters
Registration: N5410W
C/n / msn: 900255S
Fatalities:Fatalities: 4 / Occupants: 5
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Keystone, SD -   United States of America
Phase: En route
Nature:Unknown
Departure airport:
Destination airport:
Investigating agency: NTSB
Narrative:
MAIN ROTOR HUB WAS OVERHAULED BY A REPAIR STATION THAT WAS NOT AUTHROIZED BY HUGHES HELICOPTERS FOR HUB OVERHAULS. THE MAIN ROTOR HUB AND BLADES SEPARATED IN-FLT 279 HRS AFTER OVERHAUL. THE ACFT CRASHED IN A DENSILY WOODED AREA. POST ACCIDENT EXAM OF THE MAIN ROTOR SYSTEM REVEALED THE TORSION-TENSION STRAP PACK FAILED DUE TO FATIGUE CRACKING IN THE STAINLESS STEEL LAMINANTS. METALLURGICAL EXAM REVEALED EVIDENCE OF CORROSION PITTING IN THE LAMINANTS. THE CORROSION PITS WERE THE ORIGIN OF FATIGUE CRACKS. THE MAXIMUM ALLOWABLE NUMBER OF LAMINANT FAILURES IN ANY ONE STRAP IS 3. THE FAILED STRAP PACK CONTAINED 9 FATIGUE FAILED LAMINANTS. CAUSE:

Sources:

NTSB: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001214X37081


Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
21-Dec-2016 19:23 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]

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