Definition
The unwanted entry and absorption of water into a composite aircraft structure, typically through small cracks, damaged paint, or unsealed edges. Once inside, the water can soak into the core material or sit between layers, where freezing temperatures at altitude expand the trapped water and progressively separate the bonded layers, weakening the structure.
Plain English
Water getting into a composite part where it shouldn't be. Over time, especially when it freezes at altitude, that trapped water pushes the layers of the part apart and weakens it.
Context Anchor
Seen in discussions of composite aircraft structures, inspections, and damage that may not be easy to see from the outside.
Derivation
From Latin 'ingressus,' meaning 'entry' or 'a going in.' So 'water ingress' literally means 'water going in' — water entering somewhere it isn't supposed to be.
Why Pilots Care
Water inside composites can cause delamination, corrosion of internal components, and loss of structural strength.
Analogy
It is like water getting behind a wall in a house. The outside may look almost normal, but the hidden moisture can cause damage where you cannot easily see it.
Grounding Statement
If rainwater can get through a small crack or unsealed edge, it may collect inside the structure instead of draining away.
Intuition Check
Water ingress does not mean ordinary rain sitting on the surface. It means water has entered into an area or material where it should not be.
Example Sentence 1
The mechanic warned that even a small unsealed chip in the composite cowling could lead to water ingress and eventual delamination.
Example Sentence 2
The inspection revealed water ingress in the honeycomb core, requiring the panel to be dried and repaired.