An airfoil portion including an outer wall that defines a cavity for receiving cooling air. The airfoil portion includes a leading edge that resides in an upstream direction, a trailing edge that resides in a downstream direction, a convex suction side, and a concave pressure side. At least one insert disposed within the cavity is configured to initially receive at least a portion of the cooling air entering the chamber of the insert and direct the cooling air through a plurality of insert apertures to cool the inner surface of the outer wall of the airfoil portion. The insert further includes a configuration that generally conforms to the contour of the outer wall of the chamber but in spaced relation thereto. A portion of the cooling air exits the airfoil portion through a plurality of film cooling apertures formed through the outer wall. A main insert includes at least one additional insert which is inserted from the outside and transferred into the cavity at an intermediate position, and then moved in direction to the trailing edge and fixed to predetermined position The additional insert forms the size of the trailing edge channel inlet at the end of the main insert.