Methods and apparatus for assembling a gas turbine engine

A gas turbine engine turbine assembly comprising:

• a compressor;
• a high pressure turbine coupled to said compressor by a rotor shaft;
• and
• a low pressure turbine comprising at least one row of turbine stator blades spaced circumferentially apart and defining at least a portion of a flowpath extending through said low pressure turbine, said low pressure turbine further comprising a first rotor shaft coaxially aligned about second rotor shaft, said first rotor shaft comprising m first rows of turbine blades, said second rotor shaft comprising n second rows of turbine blades wherein m and n are different with respect to each other, said first rotor shaft rotatably coupled to a first compressor, said second rotor shaft rotatably coupled to a second compressor.

A gas turbine engine assembly comprising a counter-rotatable low pressure turbine comprising:

• a low pressure turbine flowpath;
• a first forward fan shaft comprising a forward fan coupled to a compressor end of said first forward fan shaft and m first low pressure turbine blade rows extending into said low pressure turbine flowpath;
• and
• a second aft fan shaft coaxially aligned about a longitudinal axis with said first forward fan shaft, said second aft fan shaft including n second low pressure turbine blade rows extending into said low pressure turbine flowpath wherein m and n are positive integers representing a number of blade rows, and wherein m and n are different with respect to each other.