Aviation safety investigations & reports

Aerospatiale SA365C-2, VH-HCF, 5 km W Prospect NSW, 14 October 1990

Investigation number:
199002013
Status: Completed
Investigation completed

Summary

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The helicopter was hovering at a height of 35 ft as part of a training exercise to provide a doctor and a paramedic with experience in winching procedures. The doctor, who was in the sling suspended on the winch cable, was raised to within 5 ft of the helicopter when there was an uncommanded firing of the explosive cable cutter. The doctor fell 30 ft and sustained serious injuries. Investigation revealed the uncommanded firing had resulted from a short circuit in the winch electrical system caused by a blown power resistor in the winch motor circuit. This allowed a substantial current flow in the cable cutter, sufficient to fire the squib. The current flow was not contained within the body of the hoist because of poor bonding between the winch motor and its mounting. The resistor failed due to inadequate heat dissipation at high current flow. The Civil Aviation Authority (CAA) subsequently issued a mandatory requirement to remove pyrotechnic cable cutting devices from helicopter hoists when used to raise or lower personnel. Additionally, both the CAA and the manufacturer have issued mandatory requirements to rectify the bonding problem pending a technical solution to preclude power resistor overheating.

Download Final Report
[Download  PDF: 24KB]
 
 
 
General details
Date: 14 October 1990   Investigation status: Completed  
Time: 1030    
Location   (show map): 5 km W Prospect    
State: New South Wales   Occurrence type: Miscellaneous - Other  
Release date: 23 September 1991   Occurrence category: Accident  
Report status: Final   Highest injury level: Serious  

Aircraft details

Aircraft details
Aircraft manufacturer Aerospatiale Industries  
Aircraft model SA365  
Aircraft registration VH-HCF  
Serial number 5068  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Nil  
Departure point Westmead Hospital NSW  
Departure time 950  
Destination Westmead Hospital NSW  
Last update 16 November 2015