Incident Bell 47G-3B1 VH-SJI,
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ASN Wikibase Occurrence # 217409
 
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Date:Sunday 31 May 1987
Time:14:00
Type:Silhouette image of generic B47G model; specific model in this crash may look slightly different    
Bell 47G-3B1
Owner/operator:
Registration: VH-SJI
MSN: 6632
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Location:Mountain Valley Station, NT -   Australia
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Agricultural
Departure airport:Mountain Valley Station, NT
Destination airport:Mountain Valley Station, NT
Investigating agency: BASI
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot was approaching the rear of a herd of cattle when he attempted to climb the aircraft. As he raised the collective control the engine RPM started to decrease. There was no suitable landing site below the helicopter so the pilot was forced to manoeuvre the aircraft around several trees to get to a suitable landing area. As he flared the aircraft for a landing the tail rotor contacted the ground and the main rotor severed the trunks of a tree and two saplings. The helicopter yawed to the left and slid sideways collapsing the left landing skid. The throttle control shaft output assembly, within the throttle control cambox had become dislodged, depriving the pilot of throttle control. The resultant freeplay within the throttle control system allowed the throttle butterfly to return to the idle position. The bearings and sleeves within the cambox are secured at manufacture by roll staking, which is considered to be the superior method for securing these components. However, the manufacturers maintenance instructions makes no mention of the method of securing the bearings and sleeves in the cambox. These components in the subject aircraft had been overhauled and were retained by the use of adhesive, which subsequently failed.

Accident investigation:
cover
  
Investigating agency: BASI
Report number: 
Status: Investigation completed
Duration:
Download report: Final report

Sources:

https://www.atsb.gov.au/publications/investigation_reports/1987/aair/aair198700732/
https://www.atsb.gov.au/media/30169/aair198700732.pdf

History of this aircraft

Other occurrences involving this aircraft
19 March 1988 VH-SJI 0 Katherine Gorge, NT sub

Revision history:

Date/timeContributorUpdates
08-Nov-2018 09:43 Pineapple Added

Corrections or additions? ... Edit this accident description

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