In 1994, one of AC's DC-9's (the MD-80 is actually a DC-9-80) suffered a ruptured component in the high pressure turbine section of its JT8 engine which resulted in a very serious rejected takeoff incident at YQR just before V1. A TSB investigation determined that AC failed to comply with an AD (airworthiness directive) relating to inspection intervals and the need for more precise inspection of some engine parts for cracking.

AC removed the fleet of engines from service and inspected them.

Same deal at AA. Maintenance was done improperly, and they have to fix the aftermath. It might be inconvenient for passengers, but the alternative, I would surmise, would be far more so. (I was one of the passengers on the DC-9 that suffered the failure at YQR -- but disembarked at Regina before the plane attempted to leave for Calgary/Vancouver)