FAA Powerplant Written Practice Test

Float-type carburetors equipped with economizers are set for what kind of mixture delivery?

1. Richest practical mixture delivery at cruising speeds

2. Leanest practical mixture delivery at cruising speeds

3. A balanced mixture for all speeds

4. Maximum fuel efficiency at take-off

The correct answer is: Leanest practical mixture delivery at cruising speeds

Float-type carburetors equipped with economizers are designed to provide a leaner mixture delivery at cruising speeds. This is important because, during cruising, an aircraft does not require the same power output as during take-off or climbing phases. By utilizing a leaner mixture, the engine operates more efficiently, leading to reduced fuel consumption and improved fuel economy. The economizer mechanism helps optimize the air-fuel ratio by enriching the mixture only during high power demands, such as acceleration or take-off, while maintaining a leaner mixture during stable cruising to minimize fuel flow. This approach supports overall engine efficiency and ensures that pilots can maximize performance while managing fuel costs effectively.