Carb Icing Can Happen All Year Round
Carb icing can happen in any season from -10°C to +25°C and is most likely at 10–15°C with humidity above 40%; use carb heat below the green arc.
1 min readKapiti Aero Club safety team
Warmer weather can make it easy to overlook the risk of carburettor icing, but it can occur at any time of year. Carb icing develops when ice forms inside the carburettor, restricting airflow. This leads to an excessively rich mixture entering the cylinders, which can cause engine roughness and a reduction in power.
Icing is possible in a wide range of conditions – from as cold as -10°C to as warm as +25°C.
Typical signs: rough running and a noticeable drop in RPM. The correct response is to apply carburettor heat, which diverts warm air from around the exhaust system into the carburettor. As the ice melts, engine performance may briefly deteriorate as moisture passes through the engine.
Reducing the risk
- Use carb heat when operating outside the green arc (e.g. below 1900 RPM in a C152).
- Check carb heat during the run-up.
- Regularly check for icing during SCADIE checks.
Carb icing is most common between 10°C and 15°C when relative humidity exceeds 40 percent.