A turbine engine assembly comprising: a low spool including a low spool accessory drive gear driven by a low rotor shaft; a high spool including a high spool accessory drive gear driven by a high rotor shaft, the high rotor shaft concentric around a portion of the low rotor shaft; and a differential gear assembly adapted to offtake power from rotation of one or both of the low spool and the high spool to drive one or more accessory loads, the differential gear assembly comprising: a first idler gear and a second idler gear, each including a plurality of teeth meshed with the low spool accessory drive gear and the high spool accessory drive gear, and a bearing surface; and a differential bull gear including a plurality of teeth and a corresponding at least one bearing surface engaging with the bearing surface of each of the first and second idler gears, the plurality of teeth adapted to mesh with an accessory drive system to transfer the power offtake and drive the one or more accessory loads, characterized in that the low spool accessory drive gear comprises a ring gear assembly including a ring gear supported to the low rotor shaft by a first plurality of bearings and a pinion gear meshed with the ring gear, and in that the ring gear assembly is radially inward of the one or more idler gears. a low spool including a low spool accessory drive gear driven by a low rotor shaft; a high spool including a high spool accessory drive gear driven by a high rotor shaft, the high rotor shaft concentric around a portion of the low rotor shaft; and a differential gear assembly adapted to offtake power from rotation of one or both of the low spool and the high spool to drive one or more accessory loads, the differential gear assembly comprising: a first idler gear and a second idler gear, each including a plurality of teeth meshed with the low spool accessory drive gear and the high spool accessory drive gear, and a bearing surface; and a differential bull gear including a plurality of teeth and a corresponding at least one bearing surface engaging with the bearing surface of each of the first and second idler gears, the plurality of teeth adapted to mesh with an accessory drive system to transfer the power offtake and drive the one or more accessory loads, characterized in that the low spool accessory drive gear comprises a ring gear assembly including a ring gear supported to the low rotor shaft by a first plurality of bearings and a pinion gear meshed with the ring gear, and in that the ring gear assembly is radially inward of the one or more idler gears. a first idler gear and a second idler gear, each including a plurality of teeth meshed with the low spool accessory drive gear and the high spool accessory drive gear, and a bearing surface; and a differential bull gear including a plurality of teeth and a corresponding at least one bearing surface engaging with the bearing surface of each of the first and second idler gears, the plurality of teeth adapted to mesh with an accessory drive system to transfer the power offtake and drive the one or more accessory loads, characterized in that the low spool accessory drive gear comprises a ring gear assembly including a ring gear supported to the low rotor shaft by a first plurality of bearings and a pinion gear meshed with the ring gear, and in that the ring gear assembly is radially inward of the one or more idler gears.