Definition
Fuel tanks formed by sealing off a section of the aircraft structure itself — most commonly the inside of the wing — so that the structure becomes the tank. There is no separate container; the wing skin, ribs, and spars form the walls of the fuel space, with all seams sealed against leaks. Often called 'wet wings.'
Plain English
The fuel is held directly inside a sealed-up part of the airframe, usually the wing, instead of in a separate tank that was installed inside it.
Context Anchor
Seen in aircraft descriptions, weight-and-balance examples, and fuel capacity information.
Derivation
Integral' comes from the Latin integer, meaning 'whole' or 'complete.' An integral tank is part of the whole structure rather than a separate piece added in. That origin captures the idea exactly: the tank isn't a component sitting inside the wing — it is the wing.
Why Pilots Care
Affects total fuel capacity, aircraft empty weight, and how leaks or structural damage are handled since the tank is part of the airframe.
Intuition Check
Integral does not just mean important here. It means built in as part of the aircraft structure.
Example Sentence 1
Most modern transport-category aircraft use integral tanks in the wings to maximize fuel capacity.
Example Sentence 2
During the preflight inspection the pilot checked the seams of the integral tanks for signs of leakage.