Air intake structure for an airplane engine

The structure has an annular part which defines a fan case ducting that includes inner and outer casings (16, 17). A rigidifying bar (20) has ends (24, 22) integrated to the respective casings and to front and rear stiffening frames (18, 19) respectively. The ends (22, 24) are integrated to an inlet end of the fan case ducting and to an attachment zone (30) of the casing (16), respectively, and the bar is fixed by utilizing rivets.