Preform crossovers for composite airfoils

1. A method of forming a ceramic matrix composite component having an internal cooling circuit, the method comprising:

wrapping a first sheet around a first mandrel;

subsequently, creating a first plurality of holes in the first sheet corresponding to a plurality of openings in the first mandrel;

wrapping a second sheet around a second mandrel;

subsequently, creating a second plurality of holes in the second sheet corresponding to a plurality of openings in the second mandrel;

subsequently aligning the first mandrel with the first sheet and the second mandrel with the second sheet such that the first plurality of holes face and are aligned with the second plurality of holes;

wrapping a third sheet around both the first mandrel and second mandrel to form a preform, the preform comprising each of the first sheet, the second sheet, and the third sheet; and

densifying the preform;

wherein the first sheet, second sheet, and third sheet are formed from a ceramic fiber material.

2. The method of claim 1 , wherein the ceramic fiber material comprises silicon carbide.

3. The method of claim 1 , wherein densifying the preform comprises one of a chemical vapor infiltration or chemical vapor deposition process.

4. The method of claim 3 and further comprising: removing the first mandrel and the second mandrel from the preform.

5. The method of claim 1 , wherein the step of creating the first plurality of holes in the first sheet and the second plurality of holes in the second sheet comprises:

removing a plurality of sections of the first sheet using a cutting or punching technique, the plurality of sections corresponding to the plurality of openings in the first mandrel; and

removing a plurality of sections of the second sheet using the cutting or punching technique, the plurality of sections corresponding to the plurality of openings in the second mandrel.

6. The method of claim 5 , wherein at least one of the first plurality of holes and at least one of the second plurality of holes has a dimension ranging from 0.010 inches to 0.200 inches, and wherein the dimension is a diameter or a length.

7. The method of claim 6 , wherein at least one of the first plurality of holes is aligned with a corresponding one of the second plurality of holes to form a channel through an internal preform wall orthogonal to a longitudinal axis of the preform.

8. The method of claim 6 , wherein at least one of the first plurality of holes is offset from a corresponding one of the second plurality of holes to form a channel through an internal preform wall angled away from a longitudinal axis of the preform less than 90° or greater than 90°.

9. The method of claim 6 , wherein the dimension of the at least one of the first plurality of holes is smaller than the dimension of the corresponding one of the second plurality of holes.

10. The method of claim 1 , wherein the step of creating the first plurality of holes in the first sheet and the second plurality of holes in the second sheet comprises:

inserting a pin through a plurality of sections of the first sheet corresponding to the plurality of openings in the first mandrel; and

inserting a pin through a plurality of sections of the second sheet corresponding to the plurality of openings in the second mandrel.

11. The method of claim 10 , wherein inserting the pin through the plurality of sections of the first sheet and the second sheet pushes fibers of each of the first sheet and the second sheet apart at a location of the pin.

12. The method of claim 10 , wherein at least one of the first plurality of holes and at least one of the second plurality of holes has a dimension ranging from 0.010 inches to 0.200 inches, and wherein the dimension is a diameter or a length.