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ASN Wikibase Occurrence # 21717
Last updated: 18 January 2020
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Date:29-JUN-2008
Time:22:30
Type:Silhouette image of generic UH1 model; specific model in this crash may look slightly different
Bell UH-1B Iroquois
Owner/operator:Pollux Avaition LTD
Registration: N64RA
C/n / msn: 3112
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Substantial
Location:Iliamna Airport, Iliamna, AK -   United States of America
Phase: Landing
Nature:Ferry/positioning
Departure airport:Platinum, AK
Destination airport:Iliamna, AK (ILI)
Narrative:
The commercial pilot said that as the helicopter approached the destination airport during a Part 91 repositioning flight, he elected to make a practice autorotation to the runway. As he lowered the collective to enter the autorotation, the helicopter began to vibrate violently. He continued the autorotation to runway, and stated that during the landing flare the helicopter's tail boom contacted the runway, the helicopter rocked forward, and the landing gear skids struck the ground. The hard landing resulted in substantial damage to the fuselage, tail boom assembly, and main rotor transmission supports. A maintenance technician that did a postaccident inspection of the helicopter discovered loose and worn bearings on the helicopter's stabilizer bar, swashplate, flight control tube assemblies, and the right and left hydraulic servos. In a written report the maintenance technician reported that the mechanical discrepancies he discovered during his inspection were, in part: "noted as being the root cause of the vertical vibration..."
Probable Cause: The failure of company maintenance personnel to ensure the helicopter was properly maintained, resulting in a severe in-flight vibration due to collective bounce. Contributing to the accident was loose and worn bearings on the helicopter's stabilizer bar, swashplate, flight control tube assemblies, and the right and left hydraulic servos.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20080709X01001&key=1


Revision history:

Date/timeContributorUpdates
12-Jul-2008 10:13 Fusko Added
21-Dec-2016 19:14 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
21-Dec-2016 19:16 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
21-Dec-2016 19:20 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
03-Dec-2017 11:21 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]
09-Mar-2019 14:28 RobertMB Updated [Cn, Other fatalities]

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