Ever wonder what caused your flight cancellation due to "mechanical failure?" Chances are an aircraft mechanic found a malfunction that could have (or definitely would have) jeopardized the safety of the plane and its passengers. An unexplained electrical problem, jammed landing gear, or faulty brakes might all be the cause of a potential accident. Once in a while there is a mysterious creature on the wing of the plane intent on tearing out one of the engines. FAA regulations (and the mechanic's own common sense) dictate that the plane be grounded until the problem is fixed, or the creature can be tazed and detained.
Now here comes your potential power trip. Yes, a commercial aircraft mechanic can take a revenue-producing aircraft, one carrying hundreds of passengers every day, out of service if he feels the plane is unsafe. A private jet maintenance mechanic can inform an impatient executive that he'll have an unexpected layover in the pilots' lounge. Many aircraft maintenance facilities employ a Director of Maintenance, who has the thankless job of handling the customer abuse that's otherwise directed at the mechanic. Regardless of the circumstances, a reputable mechanic won't compromise his standards and allow a mechanically unsafe aircraft to fly.
"So what's the big deal? Let somebody fix it the next time," you shrug. What happens if you DON'T ground that plane, if you DON'T exert your power? What if the plane flies and crashes, and people die? How do you feel now? You must have the personality—and personal strength—to stand up to the pressure from impatient pilots, rude executives, and maintenance shop owners who want the plane out the door. "Not over my dead body —or yours." Let them be ticked off while they live to kiss their wife and grandkids.