Turbine exhaust case and bearing housing assembly

1 . An exhaust case assembly for a gas turbine engine, comprising:

a turbine exhaust case (TEC) having an outer case extending around a central axis, an inner case concentrically disposed inside the outer case, an annular exhaust gas path radially between the outer case and the inner case, and a plurality of circumferentially spaced-apart struts extending across the annular exhaust gas path and structurally connecting the inner case to the outer case; and

a pair of bearings including a first bearing and a second bearing housed in a common bearing housing concentrically disposed inside the inner case of the TEC, the bearing housing having a tubular body extending around the central axis from a first axial end to a second axial end, the first bearing and the second bearing respectively disposed at the first axial end and the second axial end of the tubular body, the bearing housing integrally formed with an outer annular flange, the outer annular flange having:

a first segment projecting radially outwardly from the tubular body at an intermediate axial location between the first bearing and the second bearing,

a second segment projecting axially forwardly from the first segment to a distal end spaced axially forwardly from the intermediate axial location, and

a third segment projecting radially outwardly from the distal end of the second segment to a radially outer circumferential surface disposed axially between the first bearing and the second bearing,

the radially outer circumferential surface of the third segment joined to a corresponding radially inner circumferential surface of a mating flange projecting radially inwardly from the inner case of the TEC.

2 . The exhaust case assembly of claim 1 , wherein the plurality of circumferentially spaced-apart struts extends axially from a leading edge wall to a trailing edge wall, and wherein the mating flange of the inner case of the TEC is axially aligned with the trailing edge wall of the plurality of circumferentially spaced-apart struts and disposed axially between the first bearing and the second bearing.

3 . The exhaust case assembly of claim 2 , wherein the trailing edge wall merges with the inner case at a first axial location, and wherein the mating flange of the inner case is positioned at the first axial location.

4 . The exhaust case assembly of claim 1 , wherein the radially outer circumferential surface of the third segment is welded to the corresponding radially inner circumferential surface of the mating flange of the inner case of the TEC, the radially outer circumferential surface of the third segment and the radially inner circumferential surface of the mating flange forming a weld interface, the weld interface spaced axially from a first bent between the first segment and the second segment and radially outwardly from a second bent between the second segment and the third segment.

5 . The exhaust case assembly of claim 4 , wherein the first, second and third segments of the outer annular flange are configured to act as a hinge to accommodate temporary thermal expansion of the plurality of circumferentially spaced-apart struts of the TEC during engine transient events.

6 . The exhaust case assembly of claim 1 , wherein the outer annular flange of the bearing housing has a hairpin configuration including a first curvature from radial to axial between the first segment and the second segment and a second curvature from axial to radial between the second segment and the third segment.

7 . The exhaust case assembly of claim 1 , wherein the TEC and the bearing housing are made of nickel alloy materials, and wherein a niobium or tantalum content of the TEC is lower than the niobium or tantalum content of the bearing housing.

8 . The exhaust case assembly of claim 1 , wherein the TEC is casting, the bearing housing is a forging.

9 . The exhaust case assembly of claim 1 , wherein the TEC is a nickel-based superalloy casting, and wherein the bearing housing is a nickel-chromium-based superalloy forging.

10 . A gas turbine engine comprising:

a turbine exhaust case (TEC) including an outer case extending around a central axis, an inner case concentrically disposed within the outer case, an annular exhaust gas path radially between the inner case and the outer case, and a plurality of struts extending across the annular exhaust gas path from the inner case to the outer case; and

a pair of bearings including a first bearing and a second bearing housed in a common bearing housing concentrically disposed inside the inner case of the TEC; the bearing housing having a tubular body extending around the central axis and an outer flange projecting from a radially outer surface of the tubular body at an intermediate axial location between the first bearing and the second bearing, the outer flange having an axially extending segment spaced from the radially outer surface of the tubular body by an annular gap, the axially extending segment having a distal end spaced axially forwardly from the intermediate axial location, the distal end of the axially extending segment connected to a mating flange projecting radially inwardly from the inner case of the TEC at an axial location between the first bearing and the second bearing.

11 . The gas turbine engine of claim 10 , wherein the TEC and the bearing housing are made of nickel alloy materials, and wherein a niobium or tantalum content of the TEC is lower than the niobium or tantalum content of the bearing housing.

12 . The gas turbine engine of claim 10 , wherein the TEC is made of a casting, the bearing housing is a forging.

13 . The gas turbine engine of claim 10 , wherein the TEC is a nickel-based superalloy casting, and wherein the bearing housing is a nickel-chromium-based superalloy forging.

14 . The gas turbine engine of claim 10 , wherein a wall thickness of the axially extending segment of the outer flange is less than that of the tubular body of the bearing housing.

15 . The gas turbine engine of claim 10 , wherein the outer flange of the bearing housing comprises a first radial segment between the tubular body and the axially extending segment and a second radial segment between the axially extending segment and the mating flange of the inner case of the TEC, and wherein the second radial segment is welded to the mating flange of the inner case at an interface parallel to the central axis.

16 . The gas turbine engine of claim 10 , wherein the mating flange of the inner case is axially aligned with a trailing edge wall of the plurality of struts.