What is crossfeed limited to with two engines operating?

Crossfeed capability is crucial for managing fuel during flight operations, particularly when there are two engines in use. When two engines are in operation, fuel crossfeed is limited to scenarios where the fuel load allows for safe and consistent operations. Specifically, when there is less than 600 lbs of fuel remaining in the supplying wing tank, crossfeed becomes critical to ensure that both engines receive the necessary fuel to maintain power and avoid an imbalance that would put the aircraft at risk.

This limitation is in place to prevent situations where one engine could potentially starve for fuel due to an insufficient supply from one of the tanks. By restricting crossfeed when the fuel level is low in the supplying tank, it enhances the safety and reliability of the engines, especially during critical phases of flight. Therefore, operating within this limitation helps maintain engine performance and overall aircraft safety during a flight, which is why this answer is correct.