Aviation safety investigations & reports

Bell 47 KH4, VH-KSU, 165 km South West of Kununurra WA, 29 September 1988

Investigation number:
Status: Completed
Investigation completed


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The pilot was departing a confined pad amongst some small trees. He made a vertical take-off to about 20 feet and then commenced forward movement. The aircraft then began to descend and the pilot increased the collective pitch. The blades entered an overpitched condition and during the subsequent attempted landing the main rotor struck a tree. The pilot had flown in and out of the DEPARTURE pad a number of times, on the day of the accident, without encountering any difficulty. Immediately prior to the accident he had refuelled the aircraft to what he believed was approximately half tanks. Subsequent investigation indicated that the tanks were three quarters full. Temperature at the time of the accident was about five degrees above that for the pilot's earlier flights. The pilot was aware that a power check should be carried out at each lift off but he did not check the excess power available on this occasion. When the aircraft moved from the hover into forward flight there was insufficient power available to maintain rotor rpm when the pilot increased the collective pitch angle to stop the descent. It is possible that the terrain and wind conditions may have caused some mechanical turbulence which could have added to the amount of power required to transfer from the hover to forward flight.

Download Final Report
[Download  PDF: 23KB]
General details
Date: 29 September 1988   Investigation status: Completed  
Time: 1030    
Location: 165 km South West of Kununurra    
State: Western Australia    
Release date: 24 April 1989   Occurrence category: Accident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Kawasaki Heavy Industries  
Aircraft model 47  
Aircraft registration VH-KSU  
Serial number 2082  
Type of operation Aerial Work  
Damage to aircraft Substantial  
Departure point 165 km SW of Kununurra WA  
Departure time N/A  
Destination Kununurra WA