DUAL SPOOL POWER EXTRACTION WITH SUPERPOSITION GEARBOX

A turbofan engine according to an exemplary embodiment of this disclosure includes, among other possible things, a first spool (30) including a first turbine (46); a second spool (32) including a second turbine (54) disposed axially forward of the first turbine (46); a first tower shaft (76) engaged to the first spool (30); a second tower shaft (78) engaged to the second spool (32); a superposition gearbox (66) including a sun gear (102), a plurality of intermediate gears (104) engaged to the sun gear (102) and supported in a carrier (106) and a ring gear (108) circumscribing the intermediate gears (104), wherein the second tower shaft (78) is engaged to drive the sun gear (102); a first clutch (114) for selectively coupling the first tower (76) shaft to the ring gear (108); a second clutch (116) for selectively coupling the sun gear (102) to the carrier (106); and an accessory gearbox (68) driven by an output (118) of the superposition gearbox (66).