A method and device for detecting an overstepping of design loads of the fin of an aircraft. The device includes a set of information sources and a section for determining, with the aid of information emanating from the set of information sources, a current bending moment. The device further includes a section for determining, with the aid of information emanating from the set of information sources, a current twisting moment, and a section for carrying out a comparison by comparing the pair formed by the current bending moment and the current twisting moment with a safety envelope representing a chart formed in a plane on the basis of pairs of values of bending and twisting moments and defined so that, for any pair which lies outside the safety envelope, there exists a risk of appearance of permanent deformation on the fin. The device further includes a section for determining whether a structural inspection of the fin has to be performed, at least on the basis of a comparison result provided by the comparison section.