Carburetor icing

Carburetor (or carburettor) icing is an icing condition which can affect any carburetor under certain atmospheric conditions. Carb icing occurs when there is humid air, and the temperature drop in the venturi causes the water vapour to freeze. The ice will form on the surfaces of the carburetor throat, further restricting it. This may increase the venturi effect initially, but eventually restricts airflow, perhaps even causing a complete blockage of the carburetor. Icing may also cause jamming of the mechanical parts of the carburetor, such as the throttle butterfly valve.

While it applies to all carburetors, it is of particular concern in association with piston-powered aircraft, particularly small single-engined light aircraft. Aircraft powered by carbureted engines are equipped with carburetor heat systems to overcome the icing problem. In cars, carb icing can occasionally be a nuisance. The inlet manifold and parts of the carburetor often have warm water from the cooling system or exhaust circulating through them to combat this problem. Motorcycles can also suffer from carb icing, although some engine designs are more prone to it than others. Air-cooled engines may be more prone to icing.

For information about when there is a chance of carburetor icing, consult a graph (compiled by the UK Civil Aviation Authority) that can be downloaded here: Carburetor icing chart.

See also

This article about aviation terminology is a stub. You can help Wikipedia by expanding it.