Plain English Meaning
A goo or paste used to seal gaps and protect surfaces on the aircraft so liquids cannot leak through or soak in.
Full Definition
A liquid or paste material applied to surfaces, seams, or fasteners on an aircraft to block the passage of air, fuel, water, or other fluids. On composite structures, sealant also serves as a protective coating that prevents spilled fluids from penetrating the material.
Context Anchor
Seen in aircraft structure and maintenance discussions, especially when checking composite surfaces after fuel, oil, or other fluid spills.
Derivation
From the verb 'seal,' meaning to close something tightly so nothing passes through. The '-ant' ending means a substance that performs the action -- so a sealant is literally 'a substance that seals.'
Why Pilots Care
Fluids such as fuel, oil, or hydraulic fluid can soften or weaken composite resins, reducing and .