<p>Monitoring the current condition of the metal in aircraft load-bearing structural elements is an important component of ensuring the service reliability of aviation equipment and analyzing the causes of potential emergencies. Depending on the type of structures, materials, accessibility of elements, and the required degree of diagnostic detail, a wide range of non-destructive testing methods are used. Methods based on hardness measurement are quite common and relatively simple in terms of technical support. This paper presents the results of experimental studies aimed at assessing the current state of the surface of load-bearing structural elements of aircraft that have been subjected to overloads during operation. An analysis of the effect of static loads on the residual strains of structural elements was performed. Based on the LM hardness method, an approach to assessing the level of stresses that caused strains is proposed. A correlation has been established between the level of stresses arising in the structural element and the resulting changes in the hardness characteristics of the surface layer of the material, which allows the rapid assessment of the current state of damage to the structure.</p>