Definition
Wet-wing fuel tanks are fuel tanks formed by sealing portions of the airplane's wing structure itself, so that the wing's internal cavities — between the spars, ribs, and skin — hold the fuel directly, with no separate tank or bladder inside.
Plain English
Instead of putting a fuel tank inside the wing, the inside of the wing is sealed up and used as the tank. The fuel sits directly against the wing's metal structure.
Context Anchor
Seen in airplane fuel system descriptions, aircraft manuals, and preflight inspection discussions.
Derivation
Called 'wet-wing' because the wing structure itself becomes wet with fuel — the fuel touches the wing's internal surfaces directly, rather than being held in a separate container.
Why Pilots Care
This design increases fuel capacity and reduces weight but requires careful sealing and inspection to prevent leaks.
Intuition Check
Do not read “wet-wing” as meaning the outside of the wing is wet. It means the wing itself is built and sealed to hold fuel inside it.
Example Sentence 1
The airplane's wet-wing fuel tanks gave it a longer range than the same model fitted with bladder tanks.
Example Sentence 2
During preflight the pilot checks the wing surfaces for any signs of seepage from the wet-wing fuel tanks.