Abstract: The gas turbine engine can have an engine core; a core output shaft drivable by the engine core; a power output shaft; an auxiliary power shaft; and a reduction gearbox having gears, the gears drivingly connecting the core output shaft to the auxiliary power shaft. The gears can include an epicyclic gearing drivingly connecting the core output shaft and the auxiliary power shaft to the power output shaft. The gas turbine engine can further have a second auxiliary power shaft interconnected to the auxiliary power shaft, the power output shaft, and the core output shaft by the gears.

Abstract: A labyrinth seal assembly comprising: an outer seal having a radially inner cavity surface, and an axial cavity surface inward of the radially inner cavity surface; a floating seal received by the outer seal so as to be movable in a radial direction relative to the outer seal, the floating seal having a radially outer seal surface spaced inwardly from the radially inner cavity surface, a radially inner surface inward of the radially outer seal surface, and an axial seal surface bearing against the axial cavity surface; and an inner seal received by the floating seal, the inner seal having a radially outer surface spaced inwardly from the radially inner surface, a first one of the radially outer surface and the radially inner surface defining one tooth projecting toward a second one of the radially outer surface and the radially inner surface to inward of the axial seal surface.

Abstract: A method of operating a multi-engine system of a rotorcraft includes, during a cruise flight segment of the rotorcraft, controlling a first engine to provide sufficient power and/or rotor speed demands of the cruise flight segment; and controlling a second engine to by providing a fuel flow to the second engine that is between 70% and 99.5% less than a fuel flow provided to the first engine. A turboshaft engine for a multi-engine system configured to drive a common load is also described.

Abstract: The gas turbine engine can have an engine core; a core output shaft drivable by the engine core; a power output shaft; an auxiliary power shaft; and a reduction gearbox having gears, the gears drivingly connecting the core output shaft to the auxiliary power shaft. The gears can include an epicyclic gearing drivingly connecting the core output shaft and the auxiliary power shaft to the power output shaft. The gas turbine engine can further have a second auxiliary power shaft interconnected to the auxiliary power shaft, the power output shaft, and the core output shaft by the gears.

Abstract: An apparatus is provided for a gas turbine engine. This gas turbine engine apparatus includes a first platform, a second platform, a plurality of vanes and a plurality of beams. The first platform extends axially along and circumferentially about an axis. The second platform extends axially along and circumferentially about the axis. The vanes are arranged circumferentially about the axis. Each of the vanes extends radially across a gas path between the first platform and the second platform. The vanes include a first vane movably connected to the first platform. The beams are arranged circumferentially about the axis. The beams are fixedly connected to the first platform and the second platform. The beams include a first beam extending radially through the first vane.

Abstract: A gas turbine engine has a first spool having a low pressure compressor section disposed forward of an air inlet along a direction of travel of the engine, and a low pressure turbine section disposed forward of the low pressure compressor section and drivingly engaged thereto. A second spool has a high pressure compressor section disposed forward of the low pressure compressor section, and a high pressure turbine section disposed forward of the high pressure compressor section and drivingly engaged thereto. The high pressure turbine section is disposed aft of the low pressure turbine section. An output drive shaft drivingly engages the low pressure turbine section and extends forwardly therefrom to drive a rotatable load. A method of operating a gas turbine engine is also discussed.

Abstract: A gas turbine engine comprising: a duct extending about an axis, the duct including an outer-duct wall having an interior-duct surface circumscribing an interior of the duct and an exterior-duct surface radially outward of the interior-duct surface relative to the axis, the outer-duct wall defining an offtake opening extending from the interior-duct surface to the exterior-duct surface, the offtake opening in fluid communication between an offtake location inside the duct and outside the duct, and a bleed air offtake assembly including: an air line in fluid communication with inside the duct via the offtake opening, the air line having a first-line end defining a line inlet proximate to the outer-duct wall and a second-line end spaced from the first-line end; a valve located outside the duct and fluidly connected to the air line via the second-line end, and a conduit having a conduit inlet in fluid communication with inside the air line at a resonance location between the first-line end and the second-line en

Abstract: A labyrinth seal assembly comprising: an outer seal having a radially inner cavity surface, and an axial cavity surface inward of the radially inner cavity surface; a floating seal received by the outer seal so as to be movable in a radial direction relative to the outer seal, the floating seal having a radially outer seal surface spaced inwardly from the radially inner cavity surface, a radially inner surface inward of the radially outer seal surface, and an axial seal surface bearing against the axial cavity surface; and an inner seal received by the floating seal, the inner seal having a radially outer surface spaced inwardly from the radially inner surface, a first one of the radially outer surface and the radially inner surface defining one tooth projecting toward a second one of the radially outer surface and the radially inner surface to inward of the axial seal surface.

Abstract: A gas turbine engine has a first spool having a low pressure compressor section disposed forward of an air inlet along a direction of travel of the engine, and a low pressure turbine section disposed forward of the low pressure compressor section and drivingly engaged thereto. A second spool has a high pressure compressor section disposed forward of the low pressure compressor section, and a high pressure turbine section disposed forward of the high pressure compressor section and drivingly engaged thereto. The high pressure turbine section is disposed aft of the low pressure turbine section. An output drive shaft drivingly engages the low pressure turbine section and extends forwardly therefrom to drive a rotatable load. A method of operating a gas turbine engine is also discussed.

Abstract: An apparatus is provided for a gas turbine engine. This gas turbine engine apparatus includes a first platform, a second platform, a plurality of vanes and a plurality of beams. The first platform extends axially along and circumferentially about an axis. The second platform extends axially along and circumferentially about the axis. The vanes are arranged circumferentially about the axis. Each of the vanes extends radially across a gas path between the first platform and the second platform. The vanes include a first vane movably connected to the first platform. The beams are arranged circumferentially about the axis. The beams are fixedly connected to the first platform and the second platform. The beams include a first beam extending radially through the first vane.

Abstract: An apparatus is provided for a gas turbine engine. This gas turbine engine apparatus includes a hot section structure of the gas turbine engine. The hot section structure is configured with a plurality of surfaces respectively forming boundaries of a gas path through the hot section structure. The surfaces include a first surface and a second surface. The hot section structure includes metal and thermal barrier material. The first surface is formed by the metal. The second surface is formed by the thermal barrier material.

Abstract: A turboprop gas turbine engine mountable to an aircraft has an engine core and a gearbox driving a propeller, the engine core and the gearbox being enclosed within a nacelle. The propeller is located rearward of the gearbox and the engine core relative to a direction of travel of the aircraft. An air intake is disposed within the nacelle and formed to direct ambient air into the engine core. The air intake includes an air inlet duct, having a forward-facing intake inlet receiving the ambient air, with an upstream section and a downstream section. The upstream section is in fluid communication with the intake inlet and extends downstream from the intake inlet. The downstream section fluidly connects to and directs air from the upstream section into the engine air inlet. A second air outlet duct is located within the nacelle and directs air into an air-cooled-oil-cooler (ACOC).

Abstract: A turboshaft engine for a rotorcraft includes a first spool and an independently rotatable second spool. The first spool includes a low pressure compressor, a first set of variable guide vanes disposed at an entry of the low pressure compressor, and a low pressure turbine drivingly engaged to the low pressure compressor. The second spool includes a high pressure compressor, a second set of variable guide vanes disposed at an entry of the high pressure compressor, the second set of variable guide vanes independently operable relative to the first set of variable guide vanes, and a high pressure turbine drivingly engaged to the high pressure compressor. One or both of the low pressure compressor and the high pressure compressor includes a mixed flow rotor.

Abstract: In accordance with at least one aspect of this disclosure, there is provided a heat exchange system. The heat exchange system includes a first heat exchanger and a second heat exchanger. The first heat exchanger includes an engine fluid conduit fluidly connecting an engine fluid inlet to an engine fluid outlet. A first internal buffer fluid conduit fluidly connects a first buffer fluid inlet to a first buffer fluid outlet where the engine fluid conduit is in fluid isolation from the first internal buffer fluid conduit but is in thermal communication with the first internal buffer fluid conduit for heat exchange between the engine fluid and the buffer fluid.

Abstract: The gas turbine engine can have an engine core; a core output shaft drivable by the engine core; a power output shaft; an auxiliary power shaft; and a reduction gearbox having gears, the gears drivingly connecting the core output shaft to the auxiliary power shaft. The gears can include an epicyclic gearing drivingly connecting the core output shaft and the auxiliary power shaft to the power output shaft. The gas turbine engine can further have a second auxiliary power shaft interconnected to the auxiliary power shaft, the power output shaft, and the core output shaft by the gears.

Abstract: A gas turbine engine has a first spool having a low pressure compressor section disposed forward of an air inlet along a direction of travel of the engine, and a low pressure turbine section disposed forward of the low pressure compressor section and drivingly engaged thereto. A second spool has a high pressure compressor section disposed forward of the low pressure compressor section, and a high pressure turbine section disposed forward of the high pressure compressor section and drivingly engaged thereto. The high pressure turbine section is disposed aft of the low pressure turbine section. An output drive shaft drivingly engages the low pressure turbine section and extends forwardly therefrom to drive a rotatable load. A method of operating a gas turbine engine is also discussed.

Abstract: A gas turbine engine comprising: a duct extending about an axis, the duct including an outer-duct wall having an interior-duct surface circumscribing an interior of the duct and an exterior-duct surface radially outward of the interior-duct surface relative to the axis, the outer-duct wall defining an offtake opening extending from the interior-duct surface to the exterior-duct surface, the offtake opening in fluid communication between an offtake location inside the duct and outside the duct, and a bleed air offtake assembly including: an air line in fluid communication with inside the duct via the offtake opening, the air line having a first-line end defining a line inlet proximate to the outer-duct wall and a second-line end spaced from the first-line end; a valve located outside the duct and fluidly connected to the air line via the second-line end, and a conduit having a conduit inlet in fluid communication with inside the air line at a resonance location between the first-line end and the second-line en

Abstract: The turboshaft engine for a rotorcraft includes a low pressure spool having a low pressure compressor and a low pressure turbine section, and a high pressure spool having a high pressure compressor and a high pressure turbine section. The spools are independently rotatable relative to one another. The low pressure compressor section includes a mixed flow rotor. A set of variable guide vanes (VGVs) are discposed upstream of each of the low pressure and high pressure compressors, the VGVs being configured to be independently operable relative to one another.

Abstract: In accordance with at least one aspect of the present disclosure, there is provided a fuel system of an aircraft engine, comprising: a fuel conduit interface connecting a fuel conduit to a component of the fuel system; and a sweep line structure. The sweep line structure includes an inner surface facing toward, extending around, and defining a cavity around the fuel conduit interface, and an outer surface opposite the inner surface, the cavity being fluidly sealed relative to the outer surface.

Abstract: A system and method for measuring average temperature of gas in an axial cross-section of a gas turbine engine gas path, involving diverting gas samples from different positions in the axial cross-section to a gas mixing chamber and measuring a temperature of the resulting mixed gas.