Aviation safety investigations & reports

Bell 47 G5, VH-LEF, 20 km SE Old Delamere NT, 11 July 1986

Investigation number:
Status: Completed
Investigation completed


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During mustering activities the aircraft was operating between 50 and 80 feet above the ground, when the engine suddenly stopped. The wind at the time was a quartering tailwind, and during the attempted autorotation the aircraft struck the ground in a tail-low attitude. The tail boom was severed, the aircraft bounced, spun to the right and came to rest with the landing skids collapsed. An inspection of the engine revealed that the magneto idler shaft had sheared due to overload caused by foreign objects fouling the magneto drives. The foreign objects were identified as crankshaft flange bolts which had been incorrectly torqued at overhaul.

Download Final Report
[Download  PDF: 22KB]
General details
Date: 11 July 1986   Investigation status: Completed  
Time: 1000    
Location: 20 km SE Old Delamere    
State: Northern Territory    
Release date: 15 June 1987   Occurrence category: Accident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Bell Helicopter Co  
Aircraft model 47  
Aircraft registration VH-LEF  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Substantial  
Departure point Old Delamere NT  
Departure time 1000  
Destination Old Delamere NT