A "Tap test"?? My life is hanging on a simple tap test? That's nuts. I was on an A320 this week sitting in 7A right next to the engine nacelle. On climb out, a sudden and loud vibration started, went away, came back and repeated a few more times. It continued through most of the flight. I was sure glad to get back down.
What is a "tap test"? Is that kind of like "knock on wood?"