FAA Ground School Practice Test

What could be a result of operating an aircraft with too much power and a lean mixture setting?

1. Enhanced engine efficiency

2. Normal operating temperatures

3. Potential engine overheating

4. Increased climb performance

The correct answer is: Potential engine overheating

Operating an aircraft with too much power while using a lean mixture setting can indeed lead to potential engine overheating. When the engine is running with a lean mixture, it means there is less fuel relative to air in the combustion process. While this can initially result in higher combustion temperatures, excessive power can exacerbate the situation. With the engine demanding more power, but receiving less fuel, it may not be adequately cooled. This imbalance can cause the engine to reach temperatures beyond its designed limits, risking overheating and potential failure. In contrast, the other scenarios—enhanced engine efficiency, normal operating temperatures, and increased climb performance—do not accurately reflect the risks associated with this situation. The lean mixture may improve efficiency under certain conditions but, combined with too much power, it is more likely to result in overheating rather than any of the other potential benefits.