Aviation safety investigations & reports

Hiller UH-12E, VH-AGL, Cape Portland TAS, 9 October 1985

Investigation number:
Status: Completed
Investigation completed


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The pilot reported that while he was hovering the helicopter at about 25 feet agl, the engine suddenly lost power. He placed the helicopter in an autorotation but maintained the throttle setting that had been set while the aircraft was hovering. Just as the skids were about to contact the bushes, the engine momentarily regained power. The helicopter impacted the ground on its right hand side and fire broke out. Both the occupants escaped from the helicopter before it was destroyed by fire. An examination of the engine revealed that both valves in one cylinder had been striking the top of the piston, and the inlet valve was badly chipped. It was likely that when the inlet valve failed, a flashback occurred in the induction system, resulting in a complete loss of engine power. The engine regained power momentarily when the mixture build-up again reached a combustible level. Had the pilot closed the throttle when the engine initially failed, the sudden power surge should not have affected his ability to control the autorotation.

Download Final Report
[Download  PDF: 22KB]
General details
Date: 09 October 1985   Investigation status: Completed  
Time: 1405    
Location: Cape Portland    
State: Tasmania    
Release date: 17 April 1986   Occurrence category: Accident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Bell Helicopter Co  
Aircraft model 206  
Aircraft registration VH-AGL  
Type of operation Aerial Work  
Sector Helicopter  
Damage to aircraft Destroyed  
Departure point 9km South of Cape Portland TAS  
Departure time 1405  
Destination Rushy Lagoon Homestead TAS