The invention relates to an assembly (100) including a first part (10) made of a composite material and a second part (20), which parts are retained against one another by at least one attachment system (50) including a clamping element (30) comprising a head from which extends a rod (32). The attachment system further includes a sleeve (60) comprising a flange (61) having a conical inner surface (610) and a conical outer surface (611). The head (31) of the clamping element (30) abuts against the inner surface of the flange whereas the outer surface of the flange abuts against a countersink (12) provided in the first part (10).
