US Patent 7493753 Gas turbine engine assembly and methods of assembling same

A method facilitates assembling a gas turbine engine. The method comprises coupling a low-pressure turbine rotatable about a drive shaft to a counter-rotating fan assembly including a first fan assembly and a second fan assembly wherein the first fan assembly rotates in a first direction and the second fan assembly rotates in an opposite second direction. The method also comprises coupling a planetary gearbox substantially circumferentially about the drive shaft such that an input of the gearbox is coupled to the low-pressure turbine and an output of the gearbox is coupled to the counter-rotating fan assembly, and such that the gearbox is positioned within a lubrication fluid sump that substantially circumscribes the gearbox.