ACCESSORY GEARBOX WITH SUPERPOSITION GEARBOX

A turbofan engine (20) includes 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) and an accessory gearbox (68) supporting a plurality of accessory components (72 ... 82) and a superposition gear system (66) disposed within the accessory gearbox (68). The superposition gear system (66) includes 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). The second tower shaft (78) is engaged to drive the sun gear (102); a starter (70) selectively coupled to the sun gear (102) through a starter clutch (112); a first clutch (114) for selectively coupling the first tower shaft (76) to the ring gear (108); a second clutch (116) for selectively coupling the ring gear (108) to a static structure (36) of the engine (20).