For an effectively running maintenance organization, it is essential to retain any spare parts in the event that they are needed. However, it is not economical to keep more inventory than required. Considering those two contrasting requirements, trying to monitor all of stock items closely can lead to complexity and difficulty. Therefore, significant and relatively insignificant items are to be categorized by ABC Analysis. In this study, a maintenance organization of a major airline company is analyzed. ABC and XYZ classifications have been made to the materials and components used in maintenance operations by using annual data of the last two years. Class A materials have been examined in details and integrated with the maintenance plans in order to optimize order quantities and inventory levels. Results showed that joint optimization of order quantities with maintenance plans helps organization concurrently lower inventory levels and decrease the ratio of urgent orders. As being the first joint maintenance and inventory management study applied to an airline company with the help of ABC Analysis, this study contributes to the current literature.