To emphasize the importance of monitoring the structural integrity of
aging aircraft, some accidents involving structural failure in flight are
reviewed in this paper. Since the nondestructive inspection techniques are
time-consuming, as a complementary monitoring method it is proposed to
utilize the digital flight data for this purpose. A theory in static aeroelasticity is reviewed in this paper. Aerodynamic models of normal force and pitching moment coefficients are established through fuzzy logic modeling of the flight data. Stability and control derivatives with aeroelastic effects are then calculated by using these aerodynamic models to indirectly predict possible problems in the wing structure as well as the empennage structure. Three examples, one involving a newer twin-engine passenger jet transport, and the other two for four-engine old passenger jet transport airplanes, are presented in this paper.