When I was in the tech side we had a certain NDI inspector who could ground any aircraft for a crack if he was in the mood. Our job was to prep the areas that needed inspection by removing whatever was in the way, ( landing gear, hyd lines, etc.) then he’d set up and spend the rest of the day with his eddy current or penetrating dye, man we would groan when he rolled up because the jet was likely going to fail. Any jet has cracksif you look long enough, some obvious and some require a microscope, just an observation.