Gas turbine engine assembly and method of assembling same

Abstract

A method for assembling a gas turbine engine assembly includes coupling a fan assembly to a core gas turbine engine such that the fan assembly is upstream from the core gas turbine engine, coupling a fan assembly to a core gas turbine engine such that the fan assembly is upstream from the core gas turbine engine, wherein the core gas turbine engine includes a high-pressure turbine, coupling a low-pressure turbine downstream from the core gas turbine engine such, wherein the low-pressure turbine includes a disk and a plurality of splines formed in the disk, providing a shaft that includes a first end and a second end that includes a plurality of splines, coupling the shaft between the low-pressure turbine and the fan assembly, and coupling a differential bearing between the shaft and the high-pressure turbine such that the shaft provides rotational support for the high-pressure turbine.

1 . A method for assembling a gas turbine engine assembly, said method comprising:
 coupling a fan assembly to a core gas turbine engine such that the fan assembly is upstream from the core gas turbine engine, wherein the core gas turbine engine includes a high-pressure turbine;   coupling a low-pressure turbine downstream from the core gas turbine engine such, wherein the low-pressure turbine includes a disk, a flange formed with the disk, and a plurality of splines formed in the flange;   providing a shaft that includes a first end and a second end that includes a plurality of splines;   coupling the shaft between the low-pressure turbine and the fan assembly; and   coupling a differential bearing between the shaft and the high-pressure turbine such that the shaft provides rotational support for the high-pressure turbine.   
   
   
       2 . A method in accordance with  claim 1 , further comprising coupling a differential bearing between the shaft and the downstream side of the high-pressure turbine such that the shaft substantially supports the high-pressure turbine. 
   
   
       3 . A method in accordance with  claim 1 , further comprising coupling the shaft second end to the low-pressure turbine such that the shaft splines mesh with the flange splines such that torque is transmitted from the low-pressure turbine to the fan assembly via the shaft during engine operation. 
   
   
       4 . A method in accordance with  claim 1 , wherein providing a shaft further comprises providing a shaft that includes a first portion having an outer diameter and a second portion having an outer diameter that is less than the first portion outer diameter. 
   
   
       5 . A method in accordance with  claim 1 , wherein providing a shaft further comprises providing a shaft that includes a first portion having a first length and a second portion having a second length that is less than the first length. 
   
   
       6 . A method in accordance with  claim 5 , wherein providing a shaft further comprises providing a shaft that includes a first portion and a second portion that is formed unitarily with the first portion. 
   
   
       7 . A method in accordance with  claim 5 , wherein providing a shaft further comprises providing a shaft includes a first portion having a length that is approximately equal to an axial distance between the fan assembly and a high-pressure turbine. 
   
   
       8 . A method in accordance with  claim 5 , wherein the core gas turbine engine includes a high-pressure turbine including a disk having a bore extending therethrough, said method further comprising providing a shaft that includes a first portion having an outer diameter that is greater than an inner diameter of the high-pressure turbine disk bore. 
   
   
       9 . A method in accordance with  claim 1 , wherein the core gas turbine engine includes a high-pressure turbine, said method further comprising coupling the high-pressure turbine downstream from the shaft first portion. 
   
   
       10 . A method in accordance with  claim 1 , wherein providing a shaft further comprises providing a shaft that includes a first portion having an outer diameter that is between approximately four and five inches, and a second portion having an outer diameter that is between approximately three and four inches. 
   
   
       11 . A gas turbine engine assembly comprising:
 a core gas turbine engine comprising a high-pressure turbine;   a fan assembly coupled to said core gas turbine engine such that said fan assembly is upstream from said core gas turbine engine;   a low-pressure turbine coupled to said core gas turbine engine, said low-pressure turbine coupled downstream from said core gas turbine engine, said low-pressure turbine comprising a disk, a flange formed with said disk, a plurality of splines formed in said flange; and   a shaft comprising a first end coupled to said fan assembly and a second end that comprises a plurality of splines; and   a differential bearing coupled between said shaft and said high-pressure turbine, said differential bearing configured to provide rotational support for the high-pressure turbine.   
   
   
       12 . A gas turbine engine assembly in accordance with  claim 11 , wherein said differential bearing is coupled between said shaft and a downstream side of said high-pressure turbine. 
   
   
       13 . A gas turbine engine assembly in accordance with  claim 11  wherein said shaft splines are configured to mesh with said flange splines such that torque is transmitted from said low-pressure turbine to said fan assembly via said shaft. 
   
   
       14 . A gas turbine engine assembly in accordance with  claim 11 , wherein said shaft comprises:
 a first portion having an outer diameter; and   a second portion having an outer diameter that is less than said first portion outer diameter.   
   
   
       15 . A gas turbine engine assembly in accordance with  claim 14 , wherein said first portion has a first length and said second portion has a second length that is less than said first length. 
   
   
       16 . A gas turbine engine assembly in accordance with  claim 14 , wherein said first portion and said portion are formed unitarily. 
   
   
       17 . A gas turbine engine assembly in accordance with  claim 15 , wherein said fan assembly and said high-pressure turbine are separated by a distance that is approximately equal to said first length. 
   
   
       18 . A gas turbine engine assembly in accordance with  claim 14 , wherein said core gas turbine engine comprises a high-pressure turbine comprising a disk having a bore extending therethrough, said bore having an inner diameter that is smaller than said shaft first portion outer diameter. 
   
   
       19 . A gas turbine engine assembly in accordance with  claim 14 , wherein said core gas turbine engine comprises a high-pressure turbine that is coupled downstream said shaft first portion. 
   
   
       20 . A gas turbine engine assembly in accordance with  claim 11 , wherein said shaft comprises:
 a first portion having an outer diameter that is between approximately four and five inches; and   a second portion having an outer diameter that is between approximately three and four inches.