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ASN Wikibase Occurrence # 31087
Last updated: 31 May 2020
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Type:Silhouette image of generic UH1 model; specific model in this crash may look slightly different
Bell 204B
Owner/operator:South Coastal Helicopter/U.S. Forest Service
Registration: N4580Y
C/n / msn: 2066
Fatalities:Fatalities: 0 / Occupants: 1
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:near Calderwood, TN -   United States of America
Phase: Unknown
Departure airport:Copperhill ,TN
Destination airport:
Investigating agency: NTSB
The main drive failed at the transmission end resulting in loss of transmission drive. The pilot performed a autorotation landing in trees and the helicopter rolled inverted and descended through the trees coming to rest on a river bank. Metallurgical examination showed the main drive shaft teeth had separated at the transmission end due to wear from frictional overheating which is a result of loss of lubrication. The helicopter manufacturer instructions require that the main drive shaft be inspected by a mechanic for loss of lubrication and signs of overheating during a daily inspection before the first flight of each day. The operator did not have records to show that the daily inspection had been performed prior to the accident flight.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The inadequate maintenance inspection of the helicopter resulting in loss of lubrication from the main drive shaft going undetected until failure of the drive shaft.


Revision history:

27-Sep-2008 01:00 ASN archive Added
17-Jan-2009 11:21 harro Updated
25-Feb-2020 07:35 samfulton08 Updated [Narrative]

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