What is the correct procedure for leaning the mixture for best economy cruise?

The procedure for leaning the mixture for best economy cruise involves adjusting the mixture until the Exhaust Gas Temperature (EGT) begins to rise and then enriching to a specific temperature below the peak. Leaning the mixture correctly optimizes fuel efficiency by ensuring the engine operates at a stoichiometric mixture, which is essential for the best combustion and fuel economy.

Leaning until the EGT increases indicates that the combustion process is becoming more efficient as you reduce the amount of fuel relative to air. When the EGT reaches its peak, it signifies that the mixture has become too lean, which can lead to engine roughness and potential detonation. Enriching the mixture slightly after reaching peak EGT—specifically by 50˚F—ensures a safe and efficient operating temperature, providing a balance between sufficient fuel flow and optimal performance. This method helps in achieving the best economy without risking engine damage or performance issues.

This approach distinguishes itself from others in the list by providing a precise and safe technique to maximize fuel efficiency while minimizing the risk of engine problems.