Influence of secondary damage on flight cycles and inspection interval for an aircraft wing panel

The present paper discusses the methodology for analytical estimation of an aircraft wing bottom panel flight cycles (FC) and inspection interval (II) at primary damage location based on critical value of FC due to secondary damage. The repeated type of fatigue spectrum is generated using the Air Force Fracture Mechanics and Fatigue Crack Growth Analysis software, which is further used for prediction of FC, and II of a finite Aluminum alloy plate (Al alloy: 2014 T-351) using Nasgro model. The influence of combined load, compressive load, composite reinforcement and delamination on critical FC, and II at primary damage location of wing bottom panel are investigated based on critical flight cycle due to secondary damage. The present methodology for estimation of FC and II is validated w.r.t. analytical estimation and published experimental results.