An assembly for an aircraft engine mounting comprising an articulation axis supported by two plain bearings and a blocking device blocking the translation of the articulation axis in a direction which comprises a blocking screw that is screwed, in operation, into a first, tapped internal portion of a tubular extension secured to one of the two plain bearings, a first blocking system comprising an internal elastic stop ring housed in a groove formed in the tubular extension, and a second blocking system comprising a blocking screw which passes through first orifices passing through the second section of the blocking screw and second orifices passing through the tubular extension.