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A mid-turbine frame located in a gas turbine engine axially aft of a high-pressure turbine and fore of a low-pressure turbine includes an outer frame case, an inner frame case, and at least a first spoke connecting the outer frame case to the inner frame case. The first spoke includes a tie rod havi

A mid-turbine frame located in a gas turbine engine axially aft of a high-pressure turbine and fore of a low-pressure turbine includes an outer frame case, an inner frame case, and at least a first spoke connecting the outer frame case to the inner frame case. The first spoke includes a tie rod having a first threaded surface and a connector having a second threaded surface. The first and second threaded surfaces overlap partially but not completely.

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1. A gas turbine engine comprising: a combustor;a first turbine section in fluid communication with the combustor;a second turbine section in fluid communication with the first turbine section; anda mid-turbine frame located axially between the first turbine section and the second turbine section, t

1. A gas turbine engine comprising: a combustor;a first turbine section in fluid communication with the combustor;a second turbine section in fluid communication with the first turbine section; anda mid-turbine frame located axially between the first turbine section and the second turbine section, the mid-turbine frame comprising: an outer frame case;an inner frame case; andat least a first spoke connecting the outer frame case to the inner frame case, the first spoke comprising: a tie rod having a first threaded surface; anda connector having a second threaded surface, wherein the first and second threaded surfaces overlap partially but not completely; and wherein the connector is a retaining nut comprising a flange extending outward from an outer surface of the retaining nut; and wherein a fastener extends through the flange into the outer frame case. 2. The gas turbine engine of claim 1, wherein the retaining nut is positioned in a hole of the outer frame case, with the flange positioned radially outward of the outer frame case and the second threaded surface positioned radially inward of the outer frame case. 3. The gas turbine engine of claim 1, wherein the first threaded surface is on an outer surface of the tie rod, wherein the second threaded surface is on an inner surface of the retaining nut. 4. The gas turbine engine of claim 1, wherein the tie rod comprises a flange fastened to an outer diameter portion of the inner frame case. 5. The gas turbine engine of claim 1, wherein the tie rod comprises a third threaded surface at a first end of the tie rod opposite a second end of the tie rod having the first threaded surface, the gas turbine engine further comprising: a retaining nut having a fourth threaded surface engaged with the third threaded surface. 6. The gas turbine engine of claim 5, wherein the tie rod extends through a hole in the inner frame case such that the first end of the tie rod and the retaining nut are positioned radially inward of the inner frame case. 7. The gas turbine engine of claim 1, wherein the first spoke is one of a plurality of spokes connecting the outer frame case to the inner frame case. 8. The gas turbine engine of claim 1, wherein each of the connector and the tie rod are hollow. 9. The gas turbine engine of claim 1, wherein the first spoke extends through a hole in at least one of the inner frame case and the outer frame case. 10. The gas turbine engine of claim 1, wherein the connector does not bottom-out when threaded on the tie rod. 11. The gas turbine engine of claim 1, wherein the first spoke extends through an airfoil having a hollow interior. 12. A mid-turbine frame located in a gas turbine engine axially aft of a high-pressure turbine and fore of a low-pressure turbine, the mid-turbine frame comprising: an outer frame case;an inner frame case; andat least a first spoke connecting the outer frame case to the inner frame case, the first spoke comprising: a tie rod having a first threaded surface; anda connector having a second threaded surface, wherein the first and second threaded surfaces overlap partially but not completely; and wherein the connector is a retaining nut comprising a flange extending outward from an outer surface of the retaining nut; and wherein a fastener extends through the flange into the outer frame case. 13. A method of assembling a mid-turbine frame for use in a gas turbine engine axially aft of a high-pressure turbine and fore of a low-pressure turbine, the method comprising: positioning an outer frame case radially outward of an inner frame case;attaching the outer frame case to the inner frame case via a plurality of spokes; andtightening the plurality of spokes to center the inner frame case with the outer frame case. 14. The method of claim 13, wherein tightening the plurality of spokes comprises: rotating spoke retaining nuts threadedly engaged with spoke tie rods so as to increase tension. 15. The method of claim 13, wherein each of the plurality of spokes extends through a hole in at least one of the inner frame case and the outer frame case. 16. The method of claim 13, wherein each of the spoke retaining nuts, the spoke tie rods, the inner frame case, and the outer frame case are manufactured to tolerances of 5 thousandths of an inch (0.127 mm) or greater, and wherein the inner frame case is centered with respect to the outer frame case with a tolerance of 5 thousandths of an inch (0.127 mm) or less. 17. The method of claim 16, wherein the plurality of spokes consists of an odd number of spokes in the mid-turbine frame. 18. The method of claim 13, wherein attaching the outer frame case to the inner frame case comprises rotating spoke retaining nuts, comprising a flange extending outward from an outer surface of the retaining nut and positioned at the outer surface of the outer frame case, threadedly engaged with spoke tie rods. 19. The method of claim 18, wherein attaching the outer frame case to the inner frame case comprises attaching the flange of the retaining nut to the outer frame case with a fastener that extends through the flange into the outer frame case.