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After becoming airborne the aircraft was climbed steeply in order to clear a 15 metre high powerline. As the aircraft cleared the powerline the passenger indicated that he wanted to proceed towards the left. The pilot turned the aircraft sharply and, as he did so, he noted a decrease in main rotor rpm. The pilot continued the left turn, until he was pointing towards a clear area, opened the throttle, lowered the collective control and dived towards the ground in an attempt to regain the lost rpm. The attempt was unsuccessful and the pilot elected to land. He raised the nose and increased collective pitch in an attempt to cushion the touchdown. The pilot's actions caused the main rotor blades to enter an overpitched condition and the aircraft touched down heavily. One skid collapsed and the main rotor struck the fuselage and the ground. No evidence was found that would indicate that the aircraft systems or components contributed to the accident. The steep climb out, to clear the powerline, required the pilot to use most of the excess power available. When the pilot entered a sharp left turn the additional aerodynamic load caused the main rotor rpm to reduce. There was no known reason why the pilot elected to turn abruptly under the particular circumstances. It is probable that the pilot, who had considerable experience on helicopters with low enertia rotor systems, expected the rpm to recover without difficulty. As a result he misjudged the height and performance change required and was forced to make a rushed decision to convert his attempt at rpm recovery to a landing.

Download Final Report
[ Download PDF: 23KB]
 
 
 
 
General details
Date: 15 March 1989 Investigation status: Completed 
Time: 1045 Investigation type: Occurrence Investigation 
Location:Kilarney Station Occurrence type:Collision with terrain 
State: Northern Territory Occurrence class: Operational 
Release date: 25 January 1990 Occurrence category: Accident 
Report status: Final Highest injury level: None 
 
Aircraft details
Aircraft manufacturer: Bell Helicopter Co 
Aircraft model: 47 
Aircraft registration: VH-WHF 
Serial number: 6763 
Type of operation: Aerial Work 
Sector: Helicopter 
Damage to aircraft: Destroyed 
Departure point:Kilarney Station NT
Departure time:N/A
Destination:Kilarney Station NT
 
 
 
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