STRUCTURAL LIFE MONITORING OF THE V–22

With the high cost of life-limited components, many manufacturers are studying and implementing monitoring systems on both commercial and military aircraft to optimize retirement times. A Vibration, Structural Life, and Engine Diagnostics recorder, called VSLED, was in the original specification of the V-22. This paper addresses the structural life aspects of VSLED as it is now implemented. Using the transducer signals available on the MIL-STD-1553B bus, VSLED calculates and records time in maneuver, component synthetic load histograms, peak and valley history, and aircraft usage data. A ground-based computer program, compatible with the Navy’s SAFE program, is being developed to analyze VSLED data. The ground-based system will be used to track fatigue damage accumulation on an individual aircraft basis. Flight condition recognition data will be used in conjunction with load values from flight load survey data to calculate high-cycle fatigue damage on rotor components. Peak and valley data will be used to calculate low-cycle damage accumulation on the airframe and landing gear structure. When component synthetic load algorithms have been developed to a sufficient accuracy level, they will be used to evaluate loading levels on fleet aircraft and compared to loading levels in the flight stress survey data. Inspection intervals for components will be evaluated based on measured, rather than estimated, usage data. The VSLED represents the high end of flight data recorders both in functionality and complexity. It has the potential to greatly enhance safety of flight by providing a mechanism to identify problem areas with flight critical components. By tracking each aircraft’s flight profile on a flight-by-flight basis, many component lives will be extended beyond that obtained from a traditional generic fleetwide spectrum. As an added benefit, the Navy will have enhanced asset management capabilities through the use of component usage projections based on historical data.