21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-5.1.3

A UNIFIED APPROACH TO FATIGUE USAGE MONITORING OF FIGHTER AIRCRAFT BASED ON F/A-18 EXPERIENCE

Molent L.
Defence Science and Technology Organisation, Australia

Keywords: fatigue monitoring, fighter aircraft, f/a-18

In the current environment of decreasing budgets, the need for an accurate and reliable fatigue usage monitoring system is of ever increasing importance to ensure the safe and economical utilisation of aircraft which are expected to last longer than ever before. Strain based in-flight data recorders are perceived to provide an increase in accuracy over the traditional fatigue g meter, and have thus been implemented by many military fleet operators worldwide particularly for agile aircraft. Although this may be the case, these new generation recorders and the systems required for fatigue damage interpretation are complex, and many problems are associated with their use. Military design requirements mandate the incorporation of fatigue monitoring data recorders, however the specifications allow much scope in the implementation of the system and interpretation of the data. Therefore, there exist numerous and varied philosophies for the usage monitoring of aircraft worldwide. This paper proposes a unified approach for fatigue usage monitoring of modern fighter aircraft and is based on experience primarily with the F/A-18, and discusses the requirements for future fatigue monitoring systems based on strain and flight parameter measurements. Areas covered include the choice of gauge locations, need for flight parameters, data collection rates, calibration of damage models to durability tests, reliability of strain sensors, data integrity, and the in-flight calibration of strain sensors. The review also addresses the significance of each step in the fatigue damage calculation procedure.

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