Patent ID: 7409819

Claim:
A method of assembling a gas turbine engine, said method comprising: rotatably coupling a first low-pressure turbine rotor to a high-pressure turbine using a first differential bearing coupled between the first low-pressure turbine rotor and the high-pressure turbine, wherein the first low-pressure turbine rotor includes a first plurality of turbine blades, each of the first plurality of blades extending radially outwardly from a root end toward a low-pressure turbine casing; rotatably coupling a second low-pressure turbine rotor to the first low-pressure turbine rotor using a second differential bearing coupled between the first low-pressure turbine rotor and the second low-pressure turbine rotor, wherein the second low-pressure turbine rotor includes a second plurality of turbine blades, each of the second plurality of blades extending radially outwardly from a root end toward the low-pressure turbine casing; and rotatably coupling the second low-pressure turbine rotor to a turbine rear-frame such that the weight of the high-pressure turbine is transmitted to the turbine rear-frame.