A protective assembly and structural element for an aircraft comprising a portion of an attachment pylon primary structure is provided. The attachment pylon primary structure portion is at least partially covered by a protective assembly comprising a layer forming a firewall and a thermally insulating layer, the thermally insulating layer being located between the layer forming a firewall and the attachment pylon primary structure portion. The protective assembly is attached to the pylon primary structure by fasteners axially arranged in pairs, one of each pair extending through the protective assembly and the other of each pair extending through the pylon primary structure.