A method of manufacturing spars, longerons and fuselage beams having a variable H cross-section

A beam (A) of fibre-reinforced curable thermosetting composite material is preliminarily assembled in an uncured condition. The beam is placed between two forming tools, namely a lower (10) and an upper (11) tool, shaped in such a way as to give the lower (G) and upper (F) flanges a predetermined shape, at least one of the flanges having a non-rectilinear profile viewed in a longitudinal vertical plane. Two longitudinally elongate rigid inserts (12, 13) are placed between the flanges at the sides of the web and are covered in respective airtight tubular bags (14, 15). The spaces between the upper tool (11) and the lower tool (10) on the two opposite longitudinal sides are sealed. The open opposite ends of the tubular bags are also sealed in such a manner that the pressure applied in an autoclave during the step of curing causes the tubular bags to swell and presses them against the two opposite faces of the web and against the flanges of the beam. On completion of curing, the upper forming tool (11) is removed and the inserts (12, 13) are extracted sideways.