Abstract: An inertial coupling is provided for substantially preventing rotational speed variations of a free power turbine in a multiple shaft gas turbine engine in response to a transient load condition. The inertial coupling comprises a gear assembly having first and second rotatable components driven respectively by the free power turbine and by the gas generator section of the gas turbine engine to cooperatively drive a free-wheeling inertial mass. The inertial mass is rotated at a constant speed during steady-state engine operation and provides sufficient rotational inertia during a transient load condition to couple the free power turbine temporarily to the gas generator section to maintain free power turbine speed substantially constant during adjustment of an engine fuel control to accommodate the changed engine load.

Abstract: A shaft sealing apparatus utilizing a flow of sealing fluid to block leakage of a second fluid; and including a valve element controlling the flow of sealing fluid as a function of shaft rotational speed.

Abstract: A gas turbine engine exhaust duct of combination circular and rectangular configuration, and accompanying muffler which provides cooling and silencing of exhaust flow from the gas turbine engine. The arrangement utilizes minimum space without sacrifice of performance.