A variable displacement pump can include a rotor having a plurality of vanes, a cam ring surrounding the rotor and vanes, the vanes configured to extend from the rotor and contact an inner cam surface of the cam ring, and a retainer configured to contact the cam ring and to move the cam ring relative to the rotor to modify a pumping action. The pump can also include a direct actuation mechanism configured to control a position of the retainer to control a position of the cam ring and the pumping action.

A variable guide vane assembly is provided for a turbine defining a core air flowpath. The variable guide vane assembly includes an airfoil band defining a flowpath surface and a cavity. The variable guide vane assembly further includes an airfoil including a first end extending at least partially into the cavity of the airfoil band and an opposite second end, the airfoil extending generally along an axis between the first end and the second end and being moveable generally about the axis relative to the airfoil band. The variable guide vane assembly further includes a sealing element operable to form a seal between the first end of the airfoil and the airfoil band.

A hybrid electric engine including a gas turbine engine including a low speed spool, a high speed spool a fan section, a compressor section, a combustor section, and a turbine section. The hybrid electric engine further includes an electric generator configured to convert rotational power of the high or low speed spool to electricity and a variable area turbine control system electrically connected to the electric generator. The variable area turbine control system being configured to adjust a cross-sectional area of a core flow path of the hybrid electric engine. The variable area turbine control system including a plurality of variable turbine vanes located in the turbine section and a variable area turbine actuator configured to rotate each of the plurality of variable turbine vanes to adjust the cross-sectional area of the core flow path of the hybrid electric engine. The variable area turbine actuator is an electromechanical actuator.

There is provided a system and a method for operating a multi-engine rotorcraft. When the rotorcraft is cruising in an asymmetric operating regime (AOR) at least one engine is an active engine and is operated in an active mode to provide motive power to the rotorcraft and at least one second engine is a standby engine and is operated in a standby mode to provide substantially no motive power to the rotorcraft, at least one of a power level of the at least one second engine is increased and at least one variable geometry mechanism of the at least one second engine is moved to shed any ice accumulation on the at least one second engine.

There is provided a system and a method for operating a multi-engine rotorcraft. When the rotorcraft is cruising in an asymmetric operating regime (AOR) at least one engine is an active engine and is operated in an active mode to provide motive power to the rotorcraft and at least one second engine is a standby engine and is operated in a standby mode to provide substantially no motive power to the rotorcraft, at least one of a power level of the at least one second engine is increased and at least one variable geometry mechanism of the at least one second engine is moved to shed any ice accumulation on the at least one second engine.

A gas turbine engine is provided. The gas turbine engine includes a turbomachine having a low speed spool and a high speed spool; a rotor assembly coupled to the low speed spool; an electric machine rotatable with the low speed spool for extracting power from the low speed spool, for adding power to the low speed spool, or both; and an inter-spool clutch positioned between the low speed spool and the high speed spool for selectively coupling the low speed spool to the high speed spool.

A gas turbine engine is provided. The gas turbine engine includes a turbomachine having a low speed spool and a high speed spool; a rotor assembly coupled to the low speed spool; an electric machine rotatable with the low speed spool for extracting power from the low speed spool, for adding power to the low speed spool, or both; and an inter-spool clutch positioned between the low speed spool and the high speed spool for selectively coupling the low speed spool to the high speed spool.

Systems and methods for adjusting a variable geometry mechanism of an engine are described herein. An engine control request indicative of a desired output power for the engine is monitored. A rate of change of the engine control request is determined. The rate of change is compared to a threshold. Responsive to determining that the rate of change is beyond the threshold, a transient bias map is applied to a steady-state schedule to generate a variable geometry mechanism request indicative of a target position for the variable geometry mechanism. The variable geometry mechanism is adjusted toward the target position according to the variable geometry mechanism request.

Systems and methods for adjusting a variable geometry mechanism of an engine are described herein. An engine control request indicative of a desired output power for the engine is monitored. A rate of change of the engine control request is determined. The rate of change is compared to a threshold. Responsive to determining that the rate of change is beyond the threshold, a transient bias map is applied to a steady-state schedule to generate a variable geometry mechanism request indicative of a target position for the variable geometry mechanism. The variable geometry mechanism is adjusted toward the target position according to the variable geometry mechanism request.

A system includes a gas turbine system including a compressor, a combustor, a turbine, and an exhaust section. The system also includes multiple sensors coupled to components of the gas turbine system. The system further includes a controller communicatively coupled to the gas turbine system and the multiple sensors and configured to control operations of the gas turbine system, wherein the controller is configured to calculate a surrogate value for turbine exit Mach number based on the feedback from the multiple sensors and to utilize the surrogate value to derive a control action for the gas turbine system.