TIL a flashlight trick that saves my eyes on night shifts

Last night I was doing a preflight in a dark hangar and kept missing hairline cracks on the wing skins with my standard flashlight. A guy from the line crew told me to hold the light sideways, so the beam hits the surface at a shallow angle instead of straight on. It makes every tiny scratch cast a shadow and they pop right out. I checked three panels in half the time, and my eyes weren't fried after. Anyone else use an angled light trick for composite inspections?

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aaron_foster201mo ago

Whoa, hold on there! That angled light trick is great, but it's not really about making shadows with the beam itself. The real magic is that you're using what's called "grazing light," and it works way better for finding stuff like dents or wrinkles, not so much for hairline cracks. Cracks in composite material usually show up better with a bright light coming from the opposite side or from behind the panel, if you can get to it, because they let light through. The sideways trick will definitely make scratches and surface scuffs stand out, which is awesome, but for actual cracks you gotta look for a change in the reflection or a dark line that breaks the surface. Don't get me wrong, the line guy gave you a solid tip, but just don't rely on it as your only method for finding cracks. I'd say use the angled light to spot the suspect areas, then bust out a magnifying glass or a borescope to confirm it's actually a crack.

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