What happens to the RPM when carburetor icing occurs initially?

When carburetor icing occurs, the initial effect on RPM is a decrease. This happens because ice formation in the carburetor restricts airflow and disrupts the fuel-air mixture entering the engine. The carburetor is designed to atomize fuel, and when ice accumulates, it can create a blockage or a disruption in the flow of the mixture. As a result, the engine may receive less power, leading to a reduction in RPM.

When the engine operates with a compromised mixture due to icing, it can result in a rough or uneven operation, which typically translates into lower engine performance. Pilots must recognize the symptoms of carburetor icing so they can take appropriate corrective actions, such as applying carburetor heat to melt the ice and restore normal operation.