Aircraft landing gear structural health monitoring using a loads monitoring approach

For aircraft landing gear structural health monitoring, it is important to be able to detect overload occurrences as well as to know the fatigue state of the landing gear at any point in its life cycle. With this knowledge, it would be possible to calculate the remaining useable life in the components of the landing gear, enabling lightly used components to have an extended life. Different approaches can be taken when determining in-service landing gear loads, such as the use of kinematics (accelerations, velocities and displacements) or the use of force measurements (pressure or strain). Since a landing gear is a complicated structure with moveable elements and energy absorption capabilities, each landing gear structure has specific requirements when monitoring its loads. This paper will outline the loads monitoring approach that was taken for a business jet type landing gear structure. The self-contained data acquisition electronics as well as the sensors that were used to collect the in-service loads will be explained. The data reduction process and the flight test results will be reviewed. Finally, the post processing analysis required to calculate the damage in a landing gear component will be discussed.