Abstract: A gas turbine engine includes a first spool rotationally coupled to a plurality of accessories via a first gearing and a second spool rotationally coupled to a third spool via a second gearing. The first gearing and the second gearing rotate independently and are enclosed within a housing of an accessory gearbox. A method of operating the gas turbine engine includes supplying a first fuel flow rate to a primary combustor associated with the first and third spools and supply a second fuel flow rate a secondary combustor associated with the second spool based on a power lever angle within an intermediate power level range.

Abstract: A gas turbine engine includes a first spool associated with a diffuser and a primary combustor and a second spool associated with a secondary combustor. The first spool includes a first compressor and a first turbine mounted to a first shaft, and the second spool includes a second compressor and a second turbine mounted to a second shaft. An inlet duct fluidly connects the diffuser to the second compressor. An outlet duct assembly fluidly connects the second turbine to the diffuser and the primary combustor.

Abstract: A bearing assembly of a gas turbine engine includes a bearing inner race, a bearing outer race located radially outboard of the bearing inner race and a plurality of bearing elements located between the bearing inner race and the bearing outer race. A centering spring is operably connected to and supports the bearing outer race. The centering spring is an annular structure including a base portion, a tip portion, and a plurality of beams extending axially between the base portion and the tip portion.

Abstract: A propulsor includes a propulsor body and a prop assembly in rotational communication with the propulsor body. The prop assembly includes a plurality of prop blades configured for rotation about an axial centerline of the propulsor. The plurality of prop blades are rotatable between a deployed position and a stowed position. The propulsor further includes at least one linkage having a first linkage end and a second linkage end. The first linkage end of the at least one linkage is rotatably mounted to the propulsor body and the second linkage end is configured to be rotatably mounted to an aircraft body. The propulsor further includes a first motor coupled to the at least one linkage and configured to rotate the at least one linkage relative to the propulsor body between a first rotational position and a second rotational position.

Abstract: A gas turbine engine includes a first spool of a primary flow path and a second spool of a secondary flow path. The second spool is nonconcentric with the first spool. The second spool includes a boost compressor and a load compressor in fluid communication with an inlet plenum. An inlet duct assembly and an outlet duct assembly place the secondary flow path in communication with the primary flow path. The gas turbine includes a controller operable to vary open areas of variable inlet guide vanes to control a flow division between the boost compressor and the load compressor.

Abstract: Gas turbine engines and rotor arms thereof are described. The gas turbine engines include a first disk, a second disk, and a rotor arm arranged between and connecting the first disk to the second disk, wherein a cavity is defined at least between the rotor arm and the first disk. The rotor arm includes a radial portion having an inner diameter end and an outer diameter end, an axial portion having a first end and a second end, wherein the first end of the axial portion is connected to the outer diameter end of the radial portion, at least one entrance flow path defined within the radial portion extending from the inner diameter end to the outer diameter end, and at least one exit aperture arranged proximate the second end of the axial portion.

Abstract: A gas turbine engine includes a compressor section, a combustor, and a turbine section. The turbine section includes a high pressure turbine comprising a plurality of turbine blades. The gas turbine engine includes a tap for tapping air that is compressed by the compressor, to be passed through a heat exchanger to cool the air, the cooled air to be passed to the plurality of turbine blades. A sensor is located downstream of a leading edge of the combustor, and is configured to measure a characteristic of the cooled air. A controller is configured to compare the measured characteristic to a threshold and control an operating condition of the gas turbine engine based on the comparison.

Abstract: A gas turbine engine includes a fan positioned at an engine central longitudinal axis, and a fan drive turbine located at the engine central longitudinal axis and configured to drive rotation of the fan. A gas generator is non-coaxial with the fan drive turbine and operably connected to the fan drive turbine such that exhaust from the gas generator drives rotation of the fan drive turbine. An auxiliary power core is located at the engine central longitudinal axis, and one or more bleed passages connect the gas generator and the auxiliary power core. The one or more bleed passages are configured to selectably combine a bleed airflow from the gas generator and an auxiliary core airflow at the auxiliary power core to direct the combined airflow to the fan drive turbine to increase output of the fan drive turbine.

Abstract: A hybrid electric gas turbine engine includes a fan section having a fan, a turbine section having a turbine drivably connected to the fan through a main shaft that extends along a central longitudinal axis, a gas generating core extending along a first axis that is radially offset from the central longitudinal axis, a first electric motor drivably connected to the main shaft, wherein the electric motor is colinear with the main shaft, and an electric compressor extending along a second axis that is radially offset from the central longitudinal axis, the electric compressor in fluid communication with the second turbine section.

Abstract: A gas turbine engine includes a core section including a compressor, a main combustor, and a main turbine. Combustion products from the main combustor drive rotation of the turbine and the compressor. A power turbine is fluidly connected to the main turbine and driven by exhaust from the main turbine. The gas turbine engine further includes a fan section having a fan rotor located fluidly upstream of the core section. The power turbine is operably connected to the fan rotor to drive rotation of the fan rotor via rotation of the power turbine. The gas turbine engine includes a bleed arrangement having one or more bleed passages configured to divert a bleed airflow from the compressor around the main combustor and main turbine, and reintroduce the bleed airflow into the power turbine.

Abstract: A method of distributing power within a gas turbine engine is disclosed. In various embodiments, the method includes driving a high pressure turbine having a first stage and a second stage with an exhaust stream from a combustor, the first stage connected to a high pressure turbine first stage spool and the second stage connected to a high pressure turbine second stage spool; driving a high pressure compressor connected to a high pressure compressor spool via a differential system, the differential system having a first stage input gear connected to the high pressure turbine first stage spool, a second stage input gear connected to the high pressure turbine second stage spool and an output gear assembly connected to the high pressure compressor spool; and selectively applying an auxiliary input power into at least one of the high pressure compressor spool and the high pressure turbine.

Abstract: Gas turbine engines and rotor arms thereof are described. The gas turbine engines include a first disk, a second disk, and a rotor arm arranged between and connecting the first disk to the second disk, wherein a cavity is defined at least between the rotor arm and the first disk. The rotor arm includes a radial portion having an inner diameter end and an outer diameter end, an axial portion having a first end and a second end, wherein the first end of the axial portion is connected to the outer diameter end of the radial portion, at least one entrance flow path defined within the radial portion extending from the inner diameter end to the outer diameter end, and at least one exit aperture arranged proximate the second end of the axial portion.

Abstract: A gas turbine engine is disclosed. In various embodiments, the gas turbine engine includes a high pressure turbine having a first stage and a second stage, the first stage connected to a high pressure turbine first stage spool and the second stage connected to a high pressure turbine second stage spool; a high pressure compressor connected to a high pressure compressor spool; and a differential system having a first stage input gear connected to the high pressure turbine first stage spool, a second stage input gear connected to the high pressure turbine second stage spool and an output gear connected to the high pressure compressor spool.

Abstract: A method of distributing power within a gas turbine engine is disclosed. In various embodiments, the method includes driving a high pressure turbine having a first stage and a second stage with an exhaust stream from a combustor, the first stage connected to a high pressure turbine first stage spool and the second stage connected to a high pressure turbine second stage spool; driving a high pressure compressor connected to a high pressure compressor spool via a differential system, the differential system having a first stage input gear connected to the high pressure turbine first stage spool, a second stage input gear connected to the high pressure turbine second stage spool and an output gear assembly connected to the high pressure compressor spool; and selectively applying an auxiliary input power into at least one of the high pressure compressor spool and the high pressure turbine.

Abstract: A turboshaft engine includes a core section extending between an inlet and an outlet of the turboshaft engine. The core section includes a compressor, a main combustor, and a main turbine, such that combustion products from the main combustor drives rotation of the turbine and the compressor. A power turbine is fluidly connected to the main turbine and driven by exhaust from the main turbine. A primary bypass is fluidly connected to the inlet and the outlet. The primary bypass directs a portion of an airflow entering the inlet around the core section to the outlet. A secondary bypass is located in the core section and is configured to divert a portion of a core airflow of the core section around the main combustor and the main turbine to the power turbine.

Abstract: A cooling system for a component of a gas turbine engine includes a first airflow passage configured to direct a first airflow to a mixing chamber and a second airflow passage to configured direct a second airflow to the mixing chamber, the second airflow having a higher temperature than the first airflow, and a cooling airflow passage to direct a cooling airflow from the mixing chamber to the component, the cooling airflow comprising the first airflow and the second airflow. The airflow passages are configured and sized to allow an amount of cooling airflow for unrestricted engine operation. When the first airflow passage is disabled, the second airflow passage and cooling airflow passage are configured and sized to allow an amount of cooling airflow which is adequate to permit continued safe engine operation restricted to within only a portion of its normal parameters and operating envelope.

Abstract: A shaft and sleeve assembly of a gas turbine engine includes an outer shaft extending about an engine central longitudinal axis and having a radially inner shaft surface. The radially inner shaft surface has a shaft groove define therein. A sleeve is located radially inboard of the radially inner shaft surface. The sleeve includes a sleeve groove defined in a radially outer sleeve surface. The sleeve groove is formed at an axial location between a first axial end and a second axial end of the sleeve. A retaining element is installed in the shaft groove and the sleeve groove to retain the sleeve relative to the outer shaft. The sleeve includes one or more sleeve openings formed therein, and the sleeve groove is aligned with the one or more sleeve openings.

Abstract: A hybrid electric gas turbine engine includes a fan section having a fan, a turbine section having a turbine drivably connected to the fan through a main shaft that extends along a central longitudinal axis, a gas generating core extending along a first axis that is radially offset from the central longitudinal axis, a first electric motor drivably connected to the main shaft, wherein the electric motor is colinear with the main shaft, and an electric compressor extending along a second axis that is radially offset from the central longitudinal axis, the electric compressor in fluid communication with the second turbine section.

Abstract: A shaft and sleeve assembly of a gas turbine engine includes an outer shaft extending about an engine central longitudinal axis and having a radially inner shaft surface. The radially inner shaft surface has a shaft groove define therein. A sleeve is located radially inboard of the radially inner shaft surface. The sleeve includes a sleeve groove defined in a radially outer sleeve surface. The sleeve groove is formed at an axial location between a first axial end and a second axial end of the sleeve. A retaining element is installed in the shaft groove and the sleeve groove to retain the sleeve relative to the outer shaft. The sleeve includes one or more sleeve openings formed therein, and the sleeve groove is aligned with the one or more sleeve openings.

Abstract: A bearing assembly of a gas turbine engine includes a bearing inner race, a bearing outer race located radially outboard of the bearing inner race and a plurality of bearing elements located between the bearing inner race and the bearing outer race. A centering spring is operably connected to and supports the bearing outer race. The centering spring is an annular structure including a base portion, a tip portion, and a plurality of beams extending axially between the base portion and the tip portion.