Can any fuel tank feed any engine, or combination?

• A. Yes, cross-feed allows any tank to feed any engine or combination
• B. No, each engine must be fed by its respective tank only
• C. Yes, but only when the center tank is full
• D. Yes, but only during ground operations

Answer: (A)

Cross-feed capability is what enables multiple fuel tanks to support any engine or combination of engines. In a multi-tank system, there are separate tanks (for example, left, right, and center) and a network of cross-feed lines and valves that can connect the outlet of one tank to the intake of any engine. With the cross-feed valve set appropriately, fuel can be drawn from any tank to feed any engine, or even supply multiple engines from a single tank as needed. This flexibility helps balance fuel load and keep engines supplied if a pump or line in one tank is out of service.

The idea that a specific tank must feed a specific engine is not correct, because the system is designed to route fuel where needed through cross-feed. It does not require the center tank to be full to feed engines, and it is not limited to ground operations only; cross-feed is used in flight to manage balance and reliability as well.