Development of methods for reducing scheduled maintenance downtime of aircraft

Maximization of aircraft utilization is one of the most important issues for airline companies. By accumulating more flight hours in a certain period of time, direct operating costs per flight hour can be reduced. Achieving more flight hours depends on aircraft availability for flight. One of the methods for increasing aircraft availability for flight is to reduce scheduled maintenance downtime of the aircraft. Methods of reducing maintenance downtime of an aircraft were examined in the scope of this thesis. By means of these methods, scheduled maintenance downtime of the aircraft is reduced, aircraft availability for flight is increased and a cost based structure has been established for the airline companies. Today many airline companies perform maintenance checks in predetermined intervals. Maintenance tasks given in maintenance programs are performed during these maintenance checks. However, this method used by many airline companies remains currently insufficient to prevent earlier accomplishment of maintenance tasks. Due to the rigid structure of this maintenance concept and fixed intervals, such airlines are subjected to enormous loss of material, man hour etc… This cause the aircraft to be kept much more time on gorund for maintenance purposes, consequently the aircraft availability for flight decreases. In the method proposed in this thesis, a more flexible structure has been developed to perform the maintenance not only during periodic checks but also whenever the aircraft is on the ground for any reason. In this method, a single task-oriented maintenance concept has been proposed. The method proposed in this thesis has been supported with some case studies performed in an airline company. In the scope of this thesis, a software which will help to increase the aircraft availability for flight has been developed to calculate more accurate and appropriate letter check alternatives according to real-time utilization values accumulated by each aircraft. This software allows us to use real-time utilization values for all aircraft and therefore it may suggest different appropriate letter check alternatives for each aircraft. Maintenance tasks which are planned in maintenance checks without taking into account the real-time utilization of the aircraft cause losses because of potential earlier accomplishment of these tasks and therefore decrease the aircraft availibility eventually. For these purposes, the accomplishment of maintenance tasks in the most appropriate letter check alternatives according to real-time utilization values and the suggestion of different appropriate letter check alternatives for each aircraft are studied in the software developed in this thesis. Single task-oriented maintenance concept, the accomplishment of maintenance tasks in the most appropriate letter check alternatives according to the real-time utilization values and the calculation of different appropriate letter check alternatives for each aircraft are subject of this thesis. With this method and maintenance concept, it is intended to decrease maintenance scheduled downtime of the aircraft, to accomplish maintenance tasks on time and to prevent losses and earlier accomplishment, to reduce maintenance cost of airline companies, to increase aircraft availability for flight and to maximize aircraft utilization, therefore to increase the flight hour in a certain period of time.