Common Core Ground School 2 Exam Practice 2026 – Complete Prep Guide

The main idea is a staged path to keep the engine feed reliable and the airplane balanced as fuel is burned. Fuel moves from the aft main tank first, then into the forward main tank, and only after that into the supply tanks before it reaches the engines.

Starting with the aft main tank as the primary source makes the most sense because it provides the initial reservoir from which fuel is drawn. Transferring to the forward main tank next helps keep the aircraft’s weight distribution steady as fuel is used, helping maintain center of gravity. Finally, feeding the engines from the supply tanks ensures there is a stable, primed supply to the engine pumps, minimizing the chance of air in the lines or pump cavitation during different flight attitudes.

If the order were changed, you could deplete an essential feed too early or disrupt balance, which is why this sequence best supports a continuous, balanced engine fuel supply.