Patent ID: 8105021

Claim:
A seal assembly for a gas turbine engine comprising: a stator assembly and a rotor assembly configured to operatively engage each other to form a first seal and a labyrinth seal; the stator assembly including a carrier and an arm which is disposed opposite the carrier, together the arm and the carrier capture a piston ring therebetween; the first seal being provided by a hydrostatic seal having a seal face and a seal runner, the carrier mounting the seal face on a first face of the carrier, the carrier mounting a land of the labyrinth seal on a second face thereof; and the rotor assembly including an extension arm, together the extension arm and the carrier form an intermediate cavity and the extension arm supports a knife edge of the labyrinth seal to interface with the land to dispose the labyrinth seal between the intermediate cavity and a lower pressure cavity; wherein the labyrinth seal acts as a back-up seal 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.