The influence of SHM techniques on scheduled maintenance of aircraft composite structures

Scheduled maintenance procedures for civil aircraft structures went through decades of evolution from hard time replacement to time-based inspection. Currently, different inspection tasks are carried out at predetermined intervals to check the condition of structural components. If the condition of the structure exceeds a certain threshold, repair activities are initiated. The two key parameters in scheduled maintenance are the inspection interval and the repair threshold. The development of new materials such as composites and the introduction of advanced Structural Health Monitoring (SHM) techniques, will have a profound effect on scheduled maintenance. Considering the current level of maturity of SHM technologies, several combinations of SHM and scheduled maintenance are proposed in this paper and a probabilistic analysis is performed to quantify the savings on maintenance cost.