[Yo-Yo]

There was a 747 in 1989 that had its cargo door blow out after several flights showed pressurization problems.

https://en.wikipedia.org/wiki/United_Airlines_Flight_811

[HamiltonJay]

Actually the 1989 blowout was due to a design flaw, the locking mechanism could get damaged, and the indicators that it was properly locked would show it was properly secured even when due to the damage it was not properly locked, if memory serves.

I am also pretty sure that this design flaw, that allowed the locks to become damaged and not lock properly but still indicate they were was raised beforehand and dismissed.