They are, and now this is just an additional thing that's inspected for and dealt with as part of the regular service life. Every plane you've ever flown in has

They are, and now this is just an additional thing that's inspected for and dealt with as part of the regular service life. Every plane you've ever flown in has had an unexpectedly high failure rate of some component that wasn't discovered until it was in service, which resulted in a modification to the published inspection/maintenance/replacement routine.