The aim of this paper, is to propose a solution for the model adequacy verification in indirect adaptive control beside the classical known validation tests. The dynamic system that was selected to verify the proposed solution, is represented by a flexible transmission described by a complex four order model. Using the selected model adequacy index, it is studied the influence of the SPAB signal and perturbation amplitude on the model adequacy and control solution, for two different tracking performances selections. The proposed solution, comes to overcome the model validation problems encountered in real-time applications, with the main advantage of improving the model identification and control solutions.