My dad was in the airline industry. Engineers kept lots of secret techniques to prevent them from being replaced. One had to due with adding strings to some f

My dad was in the airline industry. Engineers kept lots of secret techniques to prevent them from being replaced. One had to due with adding strings to some foam mixture to get it to set correctly. Not documented anywhere. When cheap labor was brought in they couldn’t reproduce the work. So old people had to be hired back at a lot more