But these intermittent failures lead to delays and worse. The sheer cost of repeat events leads to action. If deferrable at all the standard troubleshooting is mostly remove and replace. The repair and reliability processes identify these rogue units fairly fast and the actual rates of that in a well functioning airline are very low.

Yes, I remember a flight that sat at the gate past departure time, the explanation to the passengers was that some essential piece of equipment wasn't functioning, they had tried restarting it, and it was going to be replaced. About 30 minutes late, we were on our way.