Definition
The progressive extension of a small fracture in a material under repeated loading, vibration, or stress cycles. In aircraft structures, crack growth refers to how an existing flaw spreads over time until it can threaten the strength or integrity of the part.
Plain English
A tiny crack in a part slowly gets bigger each time the part is stressed, flexed, or vibrated. Given enough cycles, that small crack can grow into a serious one.
Context Anchor
Seen in discussions of aircraft structures, composite materials, inspections, and damage tolerance.
Why Pilots Care
It determines how quickly damage can spread and how often parts must be inspected for safety.
Analogy
Think of a small tear in the corner of a plastic bag. Each time you tug on the bag, the tear gets a little longer until the bag finally splits. Aircraft parts behave the same way under repeated load.
Intuition Check
Do not assume crack growth means the crack is always easy to see. In aircraft materials, crack growth can happen slowly and may be hidden until an inspection finds it.
Example Sentence 1
One advantage of composite materials is that they resist crack growth better than many metals under repeated loading.
Example Sentence 2
Engineers chose a material with slow crack growth to reduce the need for frequent structural checks.