Counterrotatable booster compressor assembly for a gas turbine engine

A counterrotatable booster compressor assembly (36) for a gas turbine engine having a counterrotatable fan section with a first fan blade row (18) connected to a first drive shaft and a second fan blade row (22) axially spaced from the first fan blade row (18) and connected to a second drive shaft (48). The counterrotatable booster compressor assembly (36) includes a first compressor blade row connected to the first drive shaft, a plurality of fan shaft extensions (100) connected to the second drive shaft (48) for driving the second fan blade row (22), and at least one compressor blade (124) integral with each fan shaft extension (100) so as to form a second compressor blade row interdigitated with the first compressor blade row. The counterrotatable booster compressor (36) further includes a first platform member (116) integral with each fan shaft extension (100) at a first location (118) so as to form a portion of an inner flowpath for the counterrotatable booster compressor (36) and a second platform member (120) integral with each fan shaft extension (100) at a second location (122) so as to form a portion of an outer flowpath for the counterrotatable booster compressor (36), where each compressor blade (124) of the second compressor blade row is positioned between the first and second platform members (116,120).