A method for manufacturing a composite part of an aircraft comprising the steps of placing a prepreg preform in a molding die between at least a molding die base part and a molding die upper part, debulking the air trapped in the prepreg, displacing the molding die upper part against the molding die base part in a direction perpendicular to the plane of the prepreg preform such that the molding die upper part presses the laminated perform until it reaches a blocking arrangement defining the position of the upper part relative to the base part for giving the prepreg preform the nominal thickness of the cured part, wherein said displacement is achieved by bolting the different parts of the molding die against each other, providing an elevated temperature to the preform such that it is cured.