I recall 707s (E-6 Navy) that had vertical stabilizers snapping off in flight. It happened twice. Neither aircraft crashed, in fact one test crew had to be advised by their chase plane that “1/2 of your tail just broke off” because they didn’t feel it in the controls.
Anyway, looking for the problem we got down on the manufacturing floor and found that in the tail cone of the airframe where things got narrow, every other internal rivet was missing
. When asked why machinists hadn’t installed the required fasteners we were told (anonymously) that
“nobody could see they were/weren't installed unless you crawled back into the tail cone; and putting them (fasteners) in was uncomfortable in the cramped cone section”.………
ahhh Union Labor.
Good news is that A.I. is gonna be a huge benefit to all manufacturing particularly QC. If a guy consistently finishes a piece of work 3 seconds faster than average. That person is gonna be automatically evaluated to determine if he/she is working really smart……or is doing something really stupid/lazy/evil.