Accident Bell 47G-3B-2 N4029G,
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ASN Wikibase Occurrence # 285815
 
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Date:Thursday 24 July 2008
Time:11:00 LT
Type:Silhouette image of generic B47G model; specific model in this crash may look slightly different    
Bell 47G-3B-2
Owner/operator:Townsend Aviation Inc.
Registration: N4029G
MSN: 6700
Year of manufacture:1968
Engine model:Lycoming TVO-435
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Lafetyette, Indiana -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Agricultural
Departure airport:Lafetyette, IN
Destination airport:Laffetyette, IN
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The helicopter began losing engine power during an aerial application run while maneuvering. The pilot attempted a landing in the field and the helicopter impacted terrain about 80 yards from an access road at the north edge of the field. The helicopter sustained substantial damage. The pilot was uninjured. Examination of the helicopter revealed that the carburetor heat control spring that keeps the carburetor closed was broken and its support rod had worn into the housing. The heat valve could only be opened about 1/3 and while corresponding cockpit control remained in the closed position. The fracture surface of the spring was consistent with fatigue. The spring had accumulated a total time in service of 832 hours. The pilot was a certificated aircraft mechanic who also performed maintenance on the helicopter. A National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report was not received from the pilot.

Probable Cause: The loss of engine power during an aerial application flight due to a fatigue fracture of the carburetor heat control valve spring and the inadequate maintenance inspection by the pilot/mechanic. An additional cause was the low altitude of the operation.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CHI08CA210
Status: Investigation completed
Duration: 2 months
Download report: Final report

Sources:

NTSB CHI08CA210

Location

Revision history:

Date/timeContributorUpdates
02-Oct-2022 15:28 ASN Update Bot Added

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