gas turbine engine systems involving hydrostatic face seals with integrated back - up seals are provided . in this regard , a representative seal assembly for a gas turbine engine includes : a stator assembly and a rotor assembly configured to operatively engage each other to form a first seal and a second seal ; the first seal being provided by a hydrostatic seal having a seal face and a seal runner ; and the second seal being provided by a back - up seal such that responsive to a failure of the first seal , the back - up seal maintains at least a portion of a pressure differential established by the first seal prior to the failure .