Gas turbine engine configured for modular assembly/disassembly and method for same

1. A gas turbine engine having a rotational axis, comprising:

a first shaft connecting a compressor section and a first turbine section, which the first shaft is rotatable about the rotational axis;

a second shaft connected to a second turbine section, which the second shaft is rotatable about the rotational axis;

a shaft nut, having a castellated end surface, is threaded to the first shaft by a threaded surface of the shaft nut to secure the first turbine section; and

a flange attached to the second shaft having a castellated distal end surface that mates with the castellated end surface of the shaft nut;

wherein the second shaft, and the second turbine section together form a module that is adapted to be assembled with the gas turbine engine and disassembled from the gas turbine engine;

wherein the gas turbine engine is adapted to permit the second shaft and the second turbine section to selectively move axially forward within the gas turbine engine to a disassembly position;

wherein in the disassembly position, the castellated end surface of the shaft nut is engaged with the castellated distal end surface of the flange; and

wherein the flange attached to the second shaft is L-shaped, with a first leg and a second leg, wherein the second leg includes the castellated distal end surface.

2. A gas turbine engine having a rotational axis, comprising:

a first shaft connecting a compressor section and a first turbine section, which the first shaft is rotatable about the rotational axis;

a second shaft connected to a second turbine section, which the second shaft is rotatable about the rotational axis;

a third shaft connecting a second compressor section to a third turbine section, which the third turbine section includes a rotor stage;

a shaft nut, having a castellated end surface, is threaded to the first shaft by a threaded surface of the shaft nut to secure the first turbine section; and

a flange attached to the second shaft having a castellated distal end surface that mates with the castellated end surface of the shaft nut;

wherein the second shaft, the second turbine section, and the rotor stage of the third turbine section together form a module that is adapted to be assembled with the gas turbine engine and disassembled from the as turbine engine;

wherein the as turbine engine is adapted to permit the second shaft and the second turbine section to selectively move axially forward within the gas turbine engine to a disassembly position;

wherein in the disassembly position, the castellated end surface of the shaft nut is engaged with the castellated distal end surface of the flange; and

wherein the flange attached to the second shaft is L-shaped, with a first leg and a second leg, wherein the second leg includes the castellated distal end surface.

3. The gas turbine engine of claim 2 , wherein the gas turbine engine includes a shaft spacer, which the shaft spacer is removable to permit the module to selectively move axially forward within the gas turbine engine to the disassembly position.

4. The gas turbine engine of claim 2 , wherein the gas turbine engine includes a frame spacer that is removable to permit the module to selectively move axially forward within the gas turbine engine to the disassembly position.

5. The gas turbine engine of claim 2 , further comprising an inner radial seal configured to assume a non-interfering configuration in the disassembly position.

6. The gas turbine engine of claim 2 , further comprising an outer seal member configured to assume a non-interfering configuration in the disassembly position.

7. The gas turbine engine of claim 2 , further comprising a first frame having an attachment flange, a second frame having an attachment flange, and a frame spacer, which the frame spacer is configured to be disposed between the attachment flanges, and which the flange spacer is removable to permit the second turbine section and the second shaft to selectively move axially forward within the gas turbine engine to the disassembly position.

8. The gas turbine engine of claim 2 , further comprising a gearbox shaft connected to the second shaft.

9. The gas turbine engine of claim 2 , wherein the first leg extends radially outward from an outer diameter surface of the second shaft, and the second leg extends axially outward from the first leg, and a relief channel is disposed between the second leg and the outer diameter surface of the second shaft.

10. The gas turbine engine of claim 9 , wherein the second leg includes an inner radial surface, and a ramp surface extending between the castellated distal end surface and the inner radial surface.

11. A gas turbine engine having a rotational axis, comprising:

a first shaft connecting a compressor section and a first turbine section, which the first shaft is rotatable about the rotational axis;

a second shaft connected to a second turbine section, which the second shaft is rotatable about the rotational axis;

a third shaft connecting a second compressor section to a third turbine section, which the third turbine section includes a rotor stage;

a shaft nut, having a castellated end surface, is threaded to the first shaft by a threaded surface of the shaft nut to secure the first turbine section; and

a flange attached to the second shaft having a castellated distal end surface that mates with the castellated end surface of the shaft nut;

wherein the second shaft, the second turbine section, and the third turbine rotor stage together form a module that is adapted to be assembled with the gas turbine engine and disassembled from the gas turbine engine; and

wherein the flange attached to the second shaft is L-shaped, with a first leg and a second leg, wherein the second leg includes the castellated distal end surface.