A splined shaft includes splines evenly distributed over the periphery, wherein the splines being spaced apart from each other. At least one portion of the splines are spaced apart by a modified pitch p with respect to the nominal pitch pn of the splines. The ratio of the absolute value of the difference between the modified pitch and the nominal pitch, to the nominal pitch, i.e. |pn−p|/pn, is different from zero, for example between 0.5 and 5%.

A gas turbine engine includes a fan assembly having a plurality of fan blades; and a turbomachine. The turbomachine includes a compressor section, a combustion section, and a turbine section in serial flow order. The turbomachine further including a first input power source; a second input power source configured to counter-rotate relative to the first input power source; a power output component operably connected to the fan assembly; and a gear assembly located forward of the combustion section of the turbomachine, the gear assembly configured to receive power from the first input power source and the second input power source and provide power to the power output component, the gear assembly comprising a helical gear.

An oil collector for a mechanical reduction gear of a turbomachine, in particular for an aircraft, the reduction gear including a body having two opposite lateral faces configured to extend in part around planet gears of the reduction gear, the collector further including an internal oil circulation cavity connected firstly to oil inlets located on the faces, and on the other hand to at least one oil outlet, characterised in that at least one of the faces comprises includes columns and rows of several inlets each having a recess with a progressively increasing cross-section, each recess being delimited by walls, at least some of the walls having a hydrodynamic profile.

A turbomachine engine can include a fan assembly, a vane assembly, a core engine, a gearbox, and a gearbox efficiency rating. The fan assembly can include a plurality of fan blades. The vane assembly can include a plurality of vanes, and the vanes can, in some instances, be disposed aft of the fan blades. The core engine can include one or more compressor sections and one or more turbine sections. The gearbox includes an input and an output. The input is coupled to the one or more turbine sections of the core engine and comprises a first rotational speed, the output is coupled to the fan assembly and has a second rotational speed, and a gear ratio of the first rotational speed to the second rotational speed is within a range of 4.1-14.0. The gearbox efficiency rating is 0.10-1.8.

A method of providing an engine family includes providing a first engine having a low pressure turbine driving a low pressure compressor at a first speed ratio, and a high pressure turbine driving a high pressure compressor. The method includes providing a second engine by changing the first speed ratio of the first engine to a second speed ratio.

A propulsor section includes a propulsor having a plurality of blades rotatable about an engine longitudinal axis. A compressor section includes a low pressure compressor and a high pressure compressor. A turbine section includes a low pressure turbine that drives the propulsor through an epicyclic gear arrangement, and includes a second turbine that drives the high pressure compressor. A power ratio is provided by the combination of a first power input of the low pressure compressor and a second power input of the high pressure compressor. The power ratio is defined by the second power input divided by the first power input. The power ratio is equal to, or greater than, 1.0 and less than, or equal to, 1.4.

An apparatus and method for reducing edge contact stress concentrations in a press-fit. The apparatus and method of the present disclosure specifically provide for a press-fit collar having a channel circumscribing a collar axis. The channel having an asymmetrical cross-sectional profile in a radial face. The asymmetrical cross-sectional profile being configured to reduce an edge contact pressure.

A gas turbine engine includes a nacelle, and a bypass flow path in a bypass duct within the nacelle of the turbofan engine. A fan section includes a fan with fan blades. The fan section drives air along the bypass flow path. A fan shaft drives a fan that has fan blades and the fan rotates about a central longitudinal axis of the turbofan engine. A speed reduction device includes an epicyclic gear system. A turbine section is connected to the fan section through the speed reduction device and the turbine section rotates about the central longitudinal axis. A first fan bearing for supporting rotation of the fan hub is located axially forward of the speed reduction device. A second fan bearing for supporting rotation of the fan hub is located axially aft of the speed reduction device. A first outer race of the first fan bearing is fixed relative to the fan hub.

An example transmission comprising a lubricant feed passageway to receive lubricant; an input shaft having a cavity that defines a shaft collection trough to receive the lubricant from the lubricant feed passageway, the input shaft defining a radial passageway to enable the lubricant to flow from the shaft collection trough to an exterior surface of the input shaft; and a carrier to receive at least a portion of the input shaft, the carrier defining a carrier collection trough and channels formed in the carrier to distribute the lubricant to at least one of rotating components or non-rotating components in the carrier, the carrier collection trough to receive the lubricant from the shaft collection trough via the radial passageway in response to the input shaft rotating.

A propulsion system includes a drive shaft movable about an axis of rotation, a fan, a fan shaft that drives the fan, and a reduction device coupling the drive shaft and the fan shaft. The reduction device has first and second reduction stages and includes a sun gear, centered on the axis and driven by the drive shaft, a ring gear that is coaxial with the sun gear and that drives the fan shaft about the axis, and planet gears distributed circumferentially about the axis between the sun gear and the ring gear. Each planet gear includes a first portion meshed with the sun gear and a second portion meshed with the ring gear. A diameter of the first portion is different from a diameter of the second portion, and the first portion of the planet gears extend between the second portion of the planet gears and the fan.