A low pressure turbine rotor disk for a small twin spool gas turbine engine in which the rotor disk includes a forward side cavity large enough to allow for the bearing assembly that rotatably supports the rotor disk to fit within the cavity in order to shorten the axial distance between the bearings that support the inner rotor shaft on which the turbine rotor disk is secured. Minimizing the bearings spacing allows for a high critical speed for the inner rotor shaft and therefore allows for the small twin spool gas turbine engine to operate at this small scale. The turbine rotor disk also includes a plurality of axial aligned cooling air holes to allow for cooling air from the bearings to flow out from the aft end of the rotor disk. The inner surface of the cavity is an annular surface that forms a seal with knife edges extending outward from the bearing support plate also located within the cavity. The rotor disk includes an annular groove facing outward and on the rear side of the disk to allow for a tool to be inserted for removing the rotor disk from the shaft. An axial central opening in the rotor disk allows for insertion of the shaft and is formed with a bearing race abutment surface on the forward side and a nut abutment surface of the aft side used to compress the rotor disk assembly on the inner rotor shaft.