Prognostics and health management: current state-of-the-art for optimizing aircraft structural maintenance
Résumé
Structural maintenance of civil transport aircraft is traditionally carried out within the framework of scheduled maintenance, in which the structure of the aircraft is inspected and possibly repaired according to a fixed schedule, identical for all aircraft of a same model. This strategy, combined with large variabilities, implies a significant level of overconservativeness for the majority of aircraft in a fleet. Advances in embedding sensors in the structure to track its structural health has a large potential for opening up new, more efficient, structural maintenance strategies. A first option would be to move from scheduled maintenance to condition based maintenance, in which the aircraft is monitored through its sensors and maintenance action triggered whenever necessary. A further option would consist in using the damage monitoring information to also carry out prognostics of the future damage evolution which will guide the maintenance process. After presenting these three different approaches to structural maintenance, we will briefly overview various prognostics methods for fatigue crack propagation. We will then present results of the application of the three considered maintenance strategies to the maintenance planning of fuselage panels of a short-range passenger aircraft. A comparison of the effectiveness and cost-efficiency of these strategies will be presented, which allows us to highlight the advantages of condition based and prognostics based maintenance, especially in cases where large variabilities are present.