Data mining methods have been successfully applied to different fields. Aviation industry is one of these fields. There is a large amount of knowledge and data accumulation in aviation industry. These data could be stored in the form of pilot reports, maintenance reports, incident reports, component reports or delay reports. This paper explains the data mining application on the component reports of an airline company in Turkey. In this study, we applied data mining functions on the component reports. The purpose of our application is to find out a rule about the warning level of the components to do correcting operation before any fault. As a result we found out a meaningful rule that presents the formulation of the warning level of the components. The rules found are tested in terms of their accuracy and reliability.