Patent ID: 7600978

Claim:
A method of forming a CMC airfoil, comprising: forming with a CMC material a leading edge, a trailing edge, a pressure wall between the leading and trailing edges, and a suction wall between the leading and trailing edges; forming a hole in the pressure wall and forming a generally opposed hole in the suction wall; and passing a bundle of ceramic fibers through the holes to form a stitch of ceramic fibers between the pressure and suction walls; wherein the forming step comprises impregnating CMC fabric with a first ceramic matrix, shaping the impregnated fabric to form the leading and trailing edges and the pressure and suction walls, and drying the impregnated fabric prior to the hole forming step; wherein the passing step further comprises infusing the ceramic fibers with a second ceramic matrix; and further comprising curing the stitched walls and the stitch together after the passing step; and at least partially curing the impregnated fabric prior to curing the stitched walls and the stitch together in order to generate a preload in the stitch due to differential curing shrinkage.