Review of fatigue monitoring of agile military aircraft

Fatigue monitoring of airframes has developed over the decades to the stage where it is now incumbent for all fighter type aircraft to be fitted with an airborne fatigue monitoring system. These systems typically collect operational data for the calculation of the safe-life or the inspection interval of the airframe. This paper presents a state-of-the-art review of fatigue monitoring systems of agile military aircraft. It reviews and comprehensively examines the techniques used in individual aircraft fatigue monitoring programs, and examines current systems and practises. Based on experience from Australian fatigue monitoring programs, it highlights some of the potential pitfalls in the systems and techniques. It also investigates the issues of strain gauge utilization and calibration, collection of flight parameter data, data integrity, comparisons with fatigue test results and fatigue damage models. Some of the problems with current systems are highlighted and requirements for future fatigue monitoring systems are suggested. This review has determined that there is little uniformity in the fatigue management practices of operators and that many aspects of the fatigue management process have been overlooked by some structural integrity managers. Also, very few of the papers reviewed specified the philosophy or aims of their monitoring systems.