Adjustable flange material and torque path isolation for splined fan drive gear system flexible support

1. A gear assembly support for a gas turbine engine comprising:

a first portion engageable to a case of the gas turbine engine;

a second portion configured for supporting a gear assembly;

a torque reacting portion for transferring torque from the second portion to the first portion;

a forward flange disposed forward of the torque reacting portion, the forward flange defining a first interface to the case;

a forward undercut defining a first thickness within a forward axial width between the torque reacting portion and the forward flange;

an aft flange disposed aft of the torque reacting portion, the aft flange defining a second interface to the case; and

an aft undercut defining an aft thickness within an aft axial width between the torque reacting portion and the aft flange.

2. The gear assembly support as recited in claim 1 , wherein the forward flange and the aft flange include separately adjustable features for modifying the first interface and the second interface.

3. The gear assembly support as recited in claim 1 , wherein the first portion comprises a spline engageable with features defined within the case of the engine.

4. The gear assembly support as recited in claim 1 , wherein the torque reacting portion includes an axial width between the first portion and the second portion for defining torque transmitted to the case of the engine.

5. The gear assembly as recited in claim 1 , including a flex portion disposed between the second portion and the torque reacting portion.

6. The gear assembly as recited in claim 1 , wherein the forward flange comprises an annular lip extending radially outward that fits within the case.

7. The gear assembly as recited in claim 1 , including a plurality of flanges extending axially forward of the first portion.

8. A gear assembly support for a gas turbine engine comprising:

a first portion engageable to a case of the gas turbine engine;

a second portion configured for supporting a gear assembly;

a torque reacting portion for transferring torque from the second portion to the first portion;

a forward flange disposed forward of the torque reacting portion, the forward flange defining a first interface to the case; and

an aft flange disposed aft of the torque reacting portion, the aft flange defining a second interface to the case, wherein the forward flange and the aft flange include separately adjustable features for modifying the first interface and the second interface, the forward flange comprises a first diameter disposed forward of first portion, the aft flange comprises a second diameter aft of the first portion, wherein the separately adjustable features comprises a forward thickness of a forward tab under the first diameter and an aft thickness of an aft tab under the second diameter.

9. A turbofan engine comprising:

a fan including a plurality of fan blades rotatable about an engine axis;

a turbine section;

a geared architecture driven by the turbine section for rotating the fan about the engine axis; and

a support member that supports the geared architecture, the support member including a first portion engageable to a case of the turbofan engine, a second portion configured for supporting a gear assembly, a torque reacting portion for transferring torque from the second portion to the first portion, a forward flange disposed forward of the torque reacting portion, the forward flange defining a first interface to the case, and an aft flange disposed aft of the torque reacting portion, the aft flange defining a second interface to the case, a forward undercut defining a first thickness within a forward axial width between the torque reacting portion and the forward flange and an aft undercut defining an aft thickness within an aft axial width between the torque reacting portion and the aft flange.

10. The turbofan engine as recited in claim 9 , wherein the forward flange and the aft flange include separately adjustable features for modifying the first interface and the second interface.

11. The turbofan engine as recited in claim 9 , wherein the first portion comprises a spline engageable with features defined within the case of the engine.

12. The turbofan engine as recited in claim 9 , including a forward undercut and an aft undercut that are continuous about a circumference of the support.

13. The turbofan engine as recited in claim 9 , wherein the torque reacting portion includes an axial width between the first portion and the second portion for defining torque transmitted to the case of the engine.

14. The turbofan engine as recited in claim 9 , including a flex portion disposed between the second portion and the torque reacting portion.

15. The turbofan engine as recited in claim 9 , wherein the forward flange comprises an annular lip extending radially outward that fits within the case.

16. A turbofan engine comprising:

a fan including a plurality of fan blades rotatable about an engine axis;

a turbine section;

a geared architecture driven by the turbine section for rotating the fan about the engine axis; and

a support member that supports the geared architecture, the support member including a first portion engageable to a case of the turbofan engine, a second portion configured for supporting a gear assembly, a torque reacting portion for transferring torque from the second portion to the first portion, a forward flange disposed forward of the torque reacting portion, the forward flange defining a first interface to the case, and an aft flange disposed aft of the torque reacting portion, the aft flange defining a second interface to the case,

wherein the forward flange and the aft flange include separately adjustable features for modifying the first interface and the second interface, wherein the forward flange comprises a first diameter disposed forward of first portion and the aft flange comprises a second diameter aft of the first portion, wherein the separately adjustable features comprises a forward thickness of a forward tab radially inward of the first diameter and an aft thickness of an aft tab radially inward of the second diameter.

17. A method of supporting a gear assembly within a gas turbine engine comprising:

defining a forward interface between a support member and a static structure within the gas turbine engine with a flange portion;

defining an aft interface between the support member and the static structure;

defining a torque transfer path between a first portion between the forward interface and the aft interface and a second portion configured for attachment to the gear assembly independent of the flange portion;

defining moment loading with a forward undercut defining a first thickness within a forward axial width between the torque reacting portion and the forward flange and an aft undercut defining an aft thickness within an aft axial width between the torque reacting portion and the all flange;

attaching the gear assembly to the second portion; and

attaching the support member to the static structure such that the flange portion positions the support member relative to the static structure.

18. The method as recited in claim 17 , wherein defining the fit between the support member and the static structure comprises defining at least one of a forward thickness of a forward tab at a first diameter in the forward interface and an aft thickness of an aft tab of a second diameter.

19. The method as recited in claim 17 , wherein defining the torque transfer path comprises defining an axial thickness of the torque transfer path.