TrisG, as
pilot and apprentice says
All to often people outside the business (passengers) overhear shop talk between crew and/or maintainers and develop a mental picture of problems that don't match reality
Cracks are normal in any metal aircraft structure, and it's one area of maintenance that keeps sheet metal workers in work. Rebuiding Bell tail booms was a constant source of effort. Having said that, cracks are definitely not normal within such items as gearboxes.