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Know the risk of carburettor icing before flying

Bell helicopter VH-KHJ

On 23 July 2013, a Bell 47G2A helicopter flying on a local photography flight from Lake Manchester, Queensland sustained a total power loss. The pilot conducted an auto-rotation which resulted in a heavy landing, causing substantial damage to the helicopter.

The pilot had taken off from Lake Manchester with the carburettor heat on, as was required for the climb. The pilot also adjusted the carburettor heat as required according to the gauge. At the time of the accident the temperature was 13.5 ˚C and the dew point was 9.1 ˚C. According to the carburettor icing probability chart, these conditions were conducive to carburettor icing.   

When the insurance assessor arrived following the accident, the helicopter was started and performed without fault. No fuel contamination was found and the helicopter was found to have been well maintained and in excellent condition. The insurance assessor considered that the weather conditions may have caused icing of the carburettor. The pilot reported that he would have expected the engine to run roughly if icing was present.

All pilots of aircraft fitted with a carburettor are advised to check weather forecast conditions and know the risk of carburettor icing before each flight. The carburettor icing probability chart  is available from the CASA website. The report contains details of other helpful publications on carburettor icing.

Read the ATSB investigation report AO-2013-119.

 
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Last update 11 November 2013