Hard landing Accident Bell 47G N6356X,
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ASN Wikibase Occurrence # 289773
 
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Date:Saturday 31 August 2013
Time:08:50 LT
Type:Silhouette image of generic B47G model; specific model in this crash may look slightly different    
Bell 47G
Owner/operator:
Registration: N6356X
MSN: CCI-563
Year of manufacture:1963
Total airframe hrs:2851 hours
Engine model:Franklin 6V4 SERIES
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Sandy Hook, Kentucky -   United States of America
Phase: Approach
Nature:Ferry/positioning
Departure airport:Morehead, KY (M97)
Destination airport:Sandy Hook, KY
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot reported that as he approached a pre-planned landing zone, he reduced engine power for landing. The helicopter yawed to the right, then back to the left. The helicopter yawed again, and the pilot felt unusual vibrations, so he decided to perform an autorotation. The helicopter landed hard on a gravel road and sustained substantial damage. Examination of the wreckage revealed impact damage to the aft tail boom from main rotor contact. The aft-most section of the tail rotor drive shaft was missing and was not recovered. It is likely that, during the hard landing, a main rotor blade struck the tail boom and liberated the drive shaft section. Manipulation of the tail rotor shaft input at the tail rotor gearbox revealed a lack of continuity to the tail rotor hub and blades. The tail rotor did not rotate when the universal joint, located at the forward end of the extension housing tube, was turned. Subsequent examination showed that the tail rotor gearbox was operational; however, the tail rotor extension shaft was found disconnected from the input coupling to the tail rotor gearbox. Rotational scoring inside the extension shaft housing indicated excessive play in the shaft that was present before the accident, which would have resulted in the loss of tail rotor control.

Probable Cause: The in-flight disengagement of the tail rotor extension shaft from the tail rotor gearbox, resulting in a loss of tail rotor control.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ERA13LA390
Status: Investigation completed
Duration: 3 months
Download report: Final report

Sources:

NTSB ERA13LA390

Location

Revision history:

Date/timeContributorUpdates
05-Oct-2022 18:01 ASN Update Bot Added

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