dimensions are such as to withstand 1 1 times said limit loads for their part the pins and clevises of the attachments of the fusible connecting rods have dimensions such as not to break until the connecting rods have buckled the second connecting rods 40 e and 40 f have dimensions such as to resist and not break when they are subjected to said predetermined loads and to the loads corresponding to the loss of a blade it should be noted that the second connecting rods are amongst the connecting rods which form the link amongst those which are closest to the attachment 27 the path of forces which separates the point of convergence of the two second connecting rods 40 e and 40 f from the attachment is shorter than the path which the forces may travel between the points of convergence of the first attachments and the attachment 27 thus firstly the lever arm between the point of convergence and the attachment is minimal and secondly it is sufficient to reinforce this portion of the structural ring 21 which constitutes a possibility of global lightening of the structure when a fan blade breaks substantial imbalance is generated by the resulting lack of balance of the rotor this imbalance is transmitted downstream to the downstream securing plane according to the invention the first connecting rods buckle and the load is transmitted to the attachment by the second connecting rods 40 e and 40 f and the path along the outer structural ring 21 fig3 represents a variant embodiment in which the fusible elements are arranged in the attachments the link 140 between the two same rings 21 and 23 comprises three pairs of connecting rods the first connecting rods 140 a and 140 b are connected to the rings.