Aviation safety investigations & reports

Aerospatiale AS 355F-1, VH-NWA, Bankstown NSW, 28 July 1986

Investigation number:
Status: Completed
Investigation completed


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During the downwind leg of the circuit, the pilot heard a sharp cracking noise, which was accompanied by a vibration in the airframe. He also noted that the transmission oil pressure warning light had illuminated. A precautionary landing was carried out, and an initial inspection revealed that a transmission cowling had become detached in flight. The cowling had struck the main rotor disc, and a piece of debris had then hit a tail rotor blade. The design of the latches of the cowling is such that they can appear to be locked when they are actually in an unsecured position. It was possible that the pilot had not fully secured the cowling during his pre-flight inspection. However, the locks were not recovered and the precise reason for the cowling opening in flight could not be established. A detailed examination failed to reveal any reason for the illumination of the oil pressure warning light. It was likely that the warning was spurious, probably being generated by moisture around the pressure sensing switch wiring.

Download Final Report
[Download  PDF: 22KB]
General details
Date: 28 July 1986   Investigation status: Completed  
Time: 750    
Location: Bankstown    
State: New South Wales   Occurrence type: Airframe - Other  
Release date: 01 September 1986   Occurrence category: Accident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Aerospatiale Industries  
Aircraft model AS355  
Aircraft registration VH-NWA  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Substantial  
Departure point North Ryde NSW  
Departure time 0750  
Destination Bankstown NSW  
Last update 16 November 2015