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ASN Wikibase Occurrence # 202105
Last updated: 15 October 2021
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Type:Silhouette image of generic C180 model; specific model in this crash may look slightly different
Cessna 180J Skywagon 6
Registration: N420SB
MSN: 18052313
Fatalities:Fatalities: 0 / Occupants: 2
Other fatalities:0
Aircraft damage: Substantial
Location:Iliamna, AK -   United States of America
Phase: Landing
Departure airport:
Destination airport:Palmer, AK (PAQ)
Investigating agency: NTSB
The pilot was landing the wheel/ski equipped airplane on a frozen lake to wait for improving weather. During the landing roll, the pilot heard a 'whump' and the airplane settled onto the left wing. Inspection revealed the main landing gear attaching bolt had fractured in overload across a threaded area. The installed NAS-147R bolt was not the one specified for installation, and had a shorter smooth shank section (1.3 inches) than the specified AN bolt (1.43 inches). When an undamaged NAS-147R bolt is installed in the landing gear, a threaded area remains within the bolt hole. The bolt had been installed three weeks prior to the accident during the last annual inspection.
Probable Cause: The improper installation of the main landing gear attaching bolt by maintenance personnel, which resulted in total failure of the bolt and collapse of the landing gear.



Revision history:

26-Nov-2017 12:37 ASN Update Bot Added

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