Oleo-pneumatic Prognostic and Health Management Design Methodology

Abstract

The oleo-pneumatic shock absorber is one of the most critical components in the landing gear system due to its essential job: absorbing the total aircraft weight in such a harsh environment during landing events. The reliability and availability of the oleo strut are vital to meet the flight safety criteria. However, the most frequent failure of the oleo strut is the leakage of its hydraulic fluid, whether oil or gas. This thesis aims to enhance the oleo-pneumatic shock strut dependability by developing a prognostic and health management (PHM) system to track the oleo strut health status during running time. PHM technology enables transferring the monitored real-time status data into maintenance helpful information, including the estimation of Remaining Useful Life (RUL) to help to improve the reliability factors and reduce the operation and maintenance costs. The first chapter in this thesis gives a general overview of the topic, including the introduction, background, and thesis structure. The second, third and fourth chapters review the literature on the reliability and maintainability of engineering, the Fault Tree Analysis (FTA) technique, and the landing gear system. The fifth chapter discusses the risk assessment of the oleo strut leakage failure by computing a FTA diagram to understand how and why the fluid leakage occurs. The sixth chapter consists of the monitoring sensors, diagnostic and prognostic techniques to design the PHM architecture of the oleo-pneumatic shock strut. Finally, the last chapter concludes the research with some recommendations for future study related to this topic.