Mid turbine frame including a sealed torque box

1. A mid-turbine frame for a gas turbine engine comprising:

an inner frame case defining a sealed torque box cavity;

a plurality of spokes protruding radially outward from the inner frame case, each of said spokes including a cooling passage extending from a radially outward end of the spoke toward the inner frame case, wherein the cooling passage is sealed at a joint between the inner frame case and the spoke;

at least one service line connected to the inner frame case; and

wherein an opening between said cooling passage and said torque box at the joint between the inner frame case and the spoke is sealed via a plug seal.

2. The mid-turbine frame of claim 1 , wherein said plurality of spokes are distributed circumferentially about said inner frame case, and wherein a joint between a radially inward end of each of said spokes and said inner frame case is sealed such that fluid transfer into said torque box at said joint is minimized.

3. The mid-turbine frame of claim 1 , wherein each of said spokes further comprises a redirection tube directing cooling fluid flowing through said cooling passage aft such that said cooling fluid bypasses the torque box.

4. The mid-turbine frame of claim 3 , wherein said redirection tube extends axially from a radially aligned portion of the cooling passage.

5. The mid-turbine frame of claim 1 , wherein said at least one service line is connected to the inner frame case via a connection feature, the connection feature interfacing the service line with a corresponding bearing support passage in the torque box.

6. The mid-turbine frame of claim 5 , wherein the connection feature includes:

a flange portion and an extension portion, the extension portion extending radially into said bearing support passage;

a seal plate radially outward of said flange portion; and

a seal element sealing said seal plate to said inner frame case.

7. The mid-turbine frame of claim 6 , wherein the seal element sealing said seal plate to said inner frame case is a piston seal.

8. The mid-turbine frame of claim 6 , further comprising a service line seal disposed between an outward facing surface of said extension portion and an inward facing surface of said bearing support passage.

9. The mid-turbine frame of claim 5 , wherein said bearing support passage includes at least a first opening for providing fluid from said bearing support passage to a component disposed radially inward of the mid-turbine frame.

10. The mid-turbine frame of claim 9 , wherein said at least a first opening is sealed to said inner frame case, such that fluid passing through said opening does not pass into said torque box.

11. The mid-turbine frame of claim 1 , wherein the inner frame case is configured such that all cooling air provided to an engine segment adjacent to said inner frame case bypasses the torque box.

12. A method comprising:

sealing a torque box such that passage of fluid from a mid-turbine frame into said torque box is minimized, wherein the sealing includes at least sealing a cooling passage in a spoke at a joint between the spoke and an inner frame case of the mid-turbine frame, wherein sealing a cooling passage in a spoke at a joint between the spoke and an inner frame case comprises sealing a radially inward end of said cooling passage such that fluid is not exchanged between said torque box and said cooling passage;

sealing said torque box such that passage of fluids inside said torque box to adjacent portions of a gas turbine engine is minimized; and

providing cooling air to a turbine section through a mid-turbine frame, said cooling air bypassing a torque box of said mid-turbine frame by passing cooling air through the cooling passage in at least one spoke and redirecting said cooling air from said spoke to said turbine section via a redirection tube prior to said cooling air entering said torque box.

13. The method of claim 12 , further comprising sealing every opening in said torque box.

14. A mid-turbine frame for a gas turbine engine comprising:

an inner frame case defining a sealed torque box cavity;

a plurality of spokes protruding radially outward from the inner frame case, each of said spokes including a cooling passage extending from a radially outward end of the spoke toward the inner frame case, wherein the cooling passage is sealed at a joint between the inner frame case and the spoke, each of said spokes further comprises a redirection tube directing cooling fluid flowing through said cooling passage aft such that said cooling fluid bypasses the torque box;

at least one service line connected to the inner frame case; and

wherein said redirection tube is fluidly connected to a radially aligned portion of the cooling passage upstream of the inner frame case.