Private Pilot Private Exam

What is likely the first indication of carburetor ice in an aircraft with a fixed-pitch propeller and float-type carburetor?

1. Increase in fuel consumption

2. Loss of RPM

3. Irregular engine sounds

4. Surge in altitude

The correct answer is: Loss of RPM

The first indication of carburetor ice, particularly in an aircraft equipped with a fixed-pitch propeller and a float-type carburetor, is usually a loss of RPM. When carburetor ice forms, it restricts the flow of air and fuel into the engine, leading to a reduction in power output. As a result, pilots may notice this reduction in engine performance reflected as a drop in RPM during flight. Carburetor ice develops in conditions of high humidity and low temperatures, which can cause the fuel-air mixture to cool significantly as it passes through the carburetor. The formation of ice can start obstructing the carburetor's throat, leading to ineffective mixing of air and fuel and triggering this loss of power. Therefore, monitoring RPM becomes crucial for early detection, as this initial drop can serve as a prompt for the pilot to take corrective action, such as applying full throttle to attempt to clear the ice. The other choices, while they may occur in various contexts involving engine performance issues, do not serve as the primary or most immediate indicators of carburetor icing. For instance, an increase in fuel consumption or irregular engine sounds may present later stages of engine efficiency issues, while a surge in altitude would be more indicative