Mid-turbine frame assembly
A method of cooling a portion of a gas turbine engine includes positioning a tie rod relative to an inner frame case. The tie rod includes a bushing opening and the inner frame case includes a fastener opening. A fastener is secured through the fastener opening in the inner frame case to a threaded bushing located in the bushing opening. The threaded bushing includes a distal end that forms a clearance gap with the inner frame case. Heat is transferred from the fastener through the threaded bushing to prevent the fastener from creeping.
1. A method of cooling a portion of a gas turbine engine comprising:
positioning a tie rod relative to an inner frame case, wherein the tie rod includes a bushing opening and the inner frame case includes a fastener opening;
securing a fastener through the fastener opening in the inner frame case to a threaded bushing located in the bushing opening, wherein the threaded bushing includes a distal end that forms a clearance gap with the inner frame case;
transferring heat from the fastener through the threaded bushing to prevent the fastener from creeping; and
preventing the threaded bushing from rotating relative to the tie rod with a tab on a bushing flange engaging a portion of the tie rod, wherein the tab includes an edge having a radius that is larger than a radius of an edge of the bushing flange opposite the tab.
2. The method of claim 1 , wherein the tie rod is made of a first material and the bushing is made of a second dissimilar material.
3. The method of claim 1 , wherein the tie rod includes a tie rod flange and a projecting portion.
4. The method of claim 3 , wherein the projecting portion extends upward from an upper surface of the tie rod flange.
5. The method of claim 4 , wherein the projecting portion at least partially defines an inlet passage through the tie rod.
6. The method of claim 1 , further comprising shielding the fastener from radiant heat exposure by recessing the fastener in the threaded bushing.
7. The method of claim 3 , wherein the bushing opening includes a first axial length and the bushing includes a cylindrical portion having a second axial length, with the first axial length greater than the second axial length to at least partially define the clearance gap.
8. The method of claim 7 , wherein the second axial length is between 80% and 95% of the first axial length.
9. The method of claim 1 , wherein the tab engages a projecting portion that extends upward from an upper surface of a flange on the tie rod.
10. The method of claim 1 , further comprising maintaining a roundness of a mid-turbine frame in the gas turbine engine with transferring the heat from the fastener to the threaded bushing.