Plain English Meaning
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.
Full 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.
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.