If the center tank transfer switches are both OFF, ____________________.

If the center tank transfer switches are both OFF, ____________________.

• A. The FOB is halfboxed in amber
• B. The FOB is green
• C. The FOB is fully boxed in amber
• D. The FOB is zero

Answer: (A)

Center tank transfer switches control moving fuel from the center tank to the wing tanks, and the FOB (fuel on board) display uses color and boxing to show the transfer status. When both center tank transfer switches are OFF, the center tank is isolated from the transfer path. The FOB indication then appears as a half-filled amber box, signaling a non-active (inhibited) transfer state—fuel is still on board, but it is not being transferred from the center tank. This is a caution condition rather than a normal operating state. If the displays were green, that would imply normal or active transfer status; if the FOB showed zero, there would be no fuel on board; a fully amber box would reflect a different, not-this OFF isolation condition.

Center tank transfer switches control moving fuel from the center tank to the wing tanks, and the FOB (fuel on board) display uses color and boxing to show the transfer status.

When both center tank transfer switches are OFF, the center tank is isolated from the transfer path. The FOB indication then appears as a half-filled amber box, signaling a non-active (inhibited) transfer state—fuel is still on board, but it is not being transferred from the center tank. This is a caution condition rather than a normal operating state.

If the displays were green, that would imply normal or active transfer status; if the FOB showed zero, there would be no fuel on board; a fully amber box would reflect a different, not-this OFF isolation condition.