Under AUTO mode with center tank transfer switches ON, when do the center tank transfer valves close after the center tank is empty?

Under AUTO mode with center tank transfer switches ON, when do the center tank transfer valves close after the center tank is empty?

• A. 5 minutes after
• B. Immediately when empty
• C. 2 minutes after
• D. Never

Answer: (A)

In AUTO mode, with the center tank transfer switches ON, the fuel transfer system manages how fuel moves from the center tank to the wing tanks to keep the airplane balanced. When the center tank becomes empty, the system does not close the center tank transfer valves immediately. Instead, there is a built-in delay of five minutes before the valves close. This five-minute hold serves to stabilize the system. It prevents valve cycling due to transient readings, fuel slosh, or momentary pump behavior that might falsely indicate a need to reopen the transfer path. The delay ensures the center tank is truly empty and that no small amount of residual fuel or measurement variation could cause unwanted transfer or re-opening. So, the center tank transfer valves close five minutes after the center tank is empty in AUTO mode with the switches ON. The other options would either risk premature closure or ignore the deliberate delay designed to stabilize fuel balance.

In AUTO mode, with the center tank transfer switches ON, the fuel transfer system manages how fuel moves from the center tank to the wing tanks to keep the airplane balanced. When the center tank becomes empty, the system does not close the center tank transfer valves immediately. Instead, there is a built-in delay of five minutes before the valves close.

This five-minute hold serves to stabilize the system. It prevents valve cycling due to transient readings, fuel slosh, or momentary pump behavior that might falsely indicate a need to reopen the transfer path. The delay ensures the center tank is truly empty and that no small amount of residual fuel or measurement variation could cause unwanted transfer or re-opening.

So, the center tank transfer valves close five minutes after the center tank is empty in AUTO mode with the switches ON. The other options would either risk premature closure or ignore the deliberate delay designed to stabilize fuel balance.