| CPC F02C 9/18 (2013.01) [F01D 21/003 (2013.01); F02C 7/06 (2013.01); F05D 2240/52 (2013.01); F05D 2240/55 (2013.01); F05D 2250/283 (2013.01)] | 20 Claims |

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1. A gas turbine engine, comprising:
an impeller;
a shaft coupled to the impeller;
an impeller inner cavity downstream of the impeller;
a thrust bearing assembly mechanically coupled to the shaft and configured to mitigate axial loads on the shaft during operation of the gas turbine engine;
a depressurizing seal assembly having a seal land; and
a controller configured to, by one or more processors, detect a loss of oil event to the thrust bearing assembly during operation of the gas turbine engine and, in response to detecting the loss of oil event, to:
actuate the depressurizing seal assembly to move the seal land toward a downstream face of the impeller such that the seal land forms a continuous axial seal about the impeller inner cavity;
vent gases from the impeller inner cavity to decrease a gas pressure in the impeller inner cavity to an extent less than an operating gas pressure of the impeller inner cavity; and
maintain the continuous axial seal and the gas pressure within the impeller inner cavity while the gas turbine engine is operating and thereby reduce the axial loads on the shaft.
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