Airline fleet maintenance: Trade-off analysis of alternate aircraft maintenance approaches

Abstract

Airline maintenance is a significant contributor to the overall operating costs of airlines, making up 11% of the total operating costs. In fact, the cost of airline maintenance has steadily increased in recent years. An improvement in the approach airlines take to maintain aircraft is needed to reverse this trend. Currently, aircraft operators use a preventative maintenance approach, where parts are replaced on a schedule. The purpose of this project is to examine the effectiveness of utilizing a condition-based approach, which considers the actual physical condition of the parts onboard the aircraft to dictate the time at which they are replaced. This additional information would allow parts to be replaced when they near the end of their actual usable life, thus reducing unnecessary replacements. These two approaches of maintenance were decomposed into three alternatives. The first alternative uses a preventative approach whereas the other two alternatives are condition-based. The preventative alternative involves the transmission of maintenance data to maintenance personnel when the aircraft is out of service. The second alternative, Condition-Based with Flight Line Transfer, involves the transmission of part condition information in between flights. The third alternative, Condition-Based with Airborne Transfer, provides a near realtime condition monitoring system during flight operations. The three design alternatives were compared in a discrete event simulation, using ARENA®, to determine the overall benefits of each maintenance approach. They were then evaluated using a utility function to determine their overall value to the system's stakeholders. Based on the results from the simulation, the Flight Line alternative ranked first out of the three considered alternatives. However, the aircraft operators could realize the most benefit by applying the condition-based process to parts with a high infant mortality failure pattern with low mean times between failure given that the other costs (shipping, storage, ordering, etc.) remain the same. The preventative alternative, though it had a very low implementation cost, resulted in more total replaced parts and a lower percentage of parts replaced with notification. While the Airborne alternative provided nearly perfect notification for part replacements, the high implementation and operating costs greatly offset its overall value to the stakeholders.