The project is adapted from the Chapter $4$ Case Study dealing with North$$South Airline In January $2012,$ Northern Airlines merged with Southeast Airlines to create the fourth largest U$.$S$.$ carrier. The new North$$South Airline inherited both an aging fleet of Boeing $727-300$ aircraft and Stephen Ruth. Stephen was a tough former Secretary of the Navy who stepped in as new president and chairman of the board. Stephen$$s first concern in creating a financially solid company was maintenance costs. It was commonly surmised in the airline industry that maintenance costs rise with the age of the aircraft. He quickly noticed that historically there had been a significant difference in the reported B$727-300$ maintenance costs $($from ATA Form $41$s$)$ in both the airframe and the engine