Private Pilot Private Exam

During a run-up at a high-elevation airport, what initial action should a pilot take if engine roughness increases during the carburetor heat check?

1. Reduce power settings

2. Inspect the fuel tank

3. Check the results with a leaner mixture setting

4. Check for ice in the carburetor

The correct answer is: Check the results with a leaner mixture setting

The correct approach in this scenario is to check the results with a leaner mixture setting. When roughness occurs during a carburetor heat check, it often indicates that there may be an issue with the fuel-air mixture being too rich. By leaning the mixture, the pilot can enhance combustion, which could potentially reduce roughness in engine performance. This action adjusts the fuel-air ratio, leading to a better burn in the engine and can help identify if the roughness was indeed due to an overly rich mixture. Leaning the mixture can provide immediate feedback regarding how the engine responds, and if the roughness improves, it suggests that the initial condition was likely related to mixture settings rather than other factors. Other responses may address different aspects of engine operation but do not directly target the likely cause of the roughness during the carburetor heat check. In particular, reducing power settings might alleviate stress on the engine but does not address the potential issue of mixture richness. Inspecting the fuel tank is also not an immediate solution since it does not specifically respond to the symptoms observed during the run-up. Checking for ice in the carburetor is important but not likely the first action to take immediately after experiencing roughness during the heat check, as that condition is