Aerospace - Hairline Crack
A crack is a type of discontinuity brought about by tensile stress the result being that things are no longer held together. Hairline crack is a very thin crack that sometimes some of them cannot be seen with naked eyes.In aerospace field, hairline crack is not some mere problem that can be ignored.
During flight, airplanes experience significant loads and stresses, and over time these loads can lead to cracks forming in high-stress areas of planes. If there is some hairline crack on plane body, there's a posibillity that the plane will be unsafe to fly.
Here are some Dino-Lite Microscope recommended for hairline crack inspection :