Of austenitic stainless steel grades, corresponding to AISI types 304, 304L, 316, 316L, 316Ti, 321 and 321H and their equivalent in the other norms, with a greatest external diameter not exceeding 406.4 mm and a wall thickness of 16 mm or less, with a roughness average (Ra) of the internal surface not less than 0.8 micrometres, not flanged, whether or not finished — Other — For use in certain types of aircraft