Wrapped a wrench in tape to find a hydraulic leak and it worked on the first shot
Had a 737 nose gear actuator weeping fluid somewhere I couldn't pin down, and I was tired of wiping everything dry just to watch it fog up again with no clear trail. So I cleaned the whole area down with solvent, wrapped the suspect fitting in plain white shop tape, and left it overnight. Came in the next morning and the leak path was printed right on the tape, running down 2 inches from the flare. It took me 10 minutes instead of the 2 hours I burned the day before chasing it with a flashlight. Anyone got a better trick for those slow leaks that only show up under pressure?