Which type of fuel tank is integrated with the aircraft structure and uses maximum empty space in a wing while adding minimum weight?

• A. Integral tanks
• B. Bladder tanks
• C. External tanks
• D. Sump box

Answer: (A)

Integral tanks are formed as part of the wing structure, using the hollow interior of the wing to hold fuel. By making the wing itself the tank, you place fuel in the maximum available space inside the wing and avoid adding separate tank walls, bladders, or external fittings. This combination uses the empty wing volume efficiently while keeping weight down, since there’s no extra bulky tank shell or bag system to carry. The fuel is distributed throughout the wing, which also helps with balance and structural integration.

Bladder tanks require a flexible bag inside the wing, adding weight from the bag material and fittings and not always using every inch of wing space. External tanks are mounted outside the wing and don’t utilize interior wing space. A sump box is only a small collection area, not a full-wing fuel container.