Can we talk about the trick I found for finding tiny cracks in engine mounts?

Troy Morgan · 2026-09-21T19:55:04.333251+00:00

Last month I was doing a routine inspection on a Cessna 172 and could not find a crack in the engine mount that my supervisor swore was there. I tried a flashlight, a mirror, and even a magnifying glass, but the crack was hiding under a layer of grime and paint. Then a guy at the shop in Tulsa showed me to use a black light and a dab of fluorescent dye pen from the welding shop. I cleaned the area, sprayed the dye, wiped it off, and hit it with the black light. That hairline crack lit up like a neon sign in about 30 seconds. Now I keep a small UV flashlight in my box and it has saved me from missing stuff at least 3 times on other jobs. Has anyone else tried this on other parts like landing gear or wing spars?

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Can we talk about the trick I found for finding tiny cracks in engine mounts? | Aircraft Mechanics - The Community Guide