Abstract: A gas turbine engine according to an example of the present disclosure includes, among other things, a propulsor section including a propulsor, a gear reduction, a first spool including a first compressor, a first turbine and a first shaft, and a second spool including a second compressor, a second turbine and a second shaft. The gear reduction includes a carrier and a plurality of gears. The plurality of gears include a sun gear, a ring gear, and a plurality of intermediate gears that engage the sun gear and the ring gear. At least two of the plurality of gears are double helical gears in meshed engagement.

Abstract: A gas turbine engine includes a fan shaft diving a fan having fan blades. The gas turbine engine also includes a gear system including a sun gear surrounded by a plurality of intermediate gear, a carrier at least partially supporting said plurality of intermediate gears, and a ring gear surrounding said plurality of intermediate gears, wherein said sun gear is driven by a turbine. The gas turbine engine also includes a flexible coupling fixing said ring gear from rotation relative to an engine static structure and a lubricating system for said gear system. Said lubricating system includes a lubricant input, there being a stationary first bearing receiving lubricant from said lubricant input. Said bearing has an inner first race in which lubricant flows, and a second bearing for rotation within said first bearing. Said second bearing has a first opening in registration with said inner first race such that lubricant may flow from said inner first race through said first opening into a first conduit.

Abstract: A fan drive gear system for a turbofan engine according to an exemplary embodiment of this disclosure, among other possible things includes a sun gear that is rotatable about an axis, a plurality of intermediate gears driven by the sun gear, and a baffle that is disposed between at least two of the plurality of intermediate gears for defining a lubricant flow path from an interface between the sun gear and at least one of the plurality of intermediate gears. The baffle includes a channel with at least one ramp portion directing lubricant.

Abstract: A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A rigid connection between a fan case and an inner core housing includes a plurality of A-frames connected at a connection point to the fan case. Legs in the A-frames extend away from the connection point in opposed circumferential directions to be connected to a compressor wall of the inner core housing. The rigid connection also includes a plurality of fan exit guide vanes rigidly connected to the fan case. A lateral stiffness ratio of the lateral stiffness of the plurality of fan exit guide vanes and a lateral stiffness of a combination of the plurality of A-frame, the compressor wall, and a fan intermediate case which is forward of the low pressure compressor being greater than or equal to 0.6 and less than or equal to 2.0.

Abstract: A turbofan engine according to an example of the present disclosure includes, among other things, a fan, a compressor section, a turbine section including a fan drive turbine and a second turbine, an epicyclic gear system with a gear reduction, first and second bearings, and a fan drive shaft interconnecting the gear system and the fan. The fan drive turbine has a first exit area at a first exit point and is rotatable at a first speed. The second turbine has a second exit area at a second exit point and is rotatable at a second speed. A first performance quantity is defined as the product of the first speed squared and the first area. A second performance quantity is defined as the product of the second speed squared and the second area.

Abstract: In an embodiment of the present disclosure, a gas turbine engine includes a fan, a first compressor stage and a second compressor stage, a first turbine stage and a second turbine stage, and wherein said first turbine stage drives said second compressor stage as a high spool, and wherein said second turbine stage drives said first compressor stage as part of a low spool, and a gear train driving said fan with said low spool, and such that said fan and said first compressor stage rotate in the same direction, and wherein said high spool operates at higher pressures than said low spool.

Abstract: A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A rigid connection between a fan case and an inner core housing includes a plurality of A-frames connected at a connection point to the fan case. Legs in the A-frames extend away from the connection point in opposed circumferential directions to be connected to a compressor wall of the inner core housing. The rigid connection also includes a plurality of fan exit guide vanes rigidly connected to the fan case. A lateral stiffness ratio of the lateral stiffness of the plurality of fan exit guide vanes and a lateral stiffness of a combination of the plurality of A-frame, the compressor wall, and a fan intermediate case which is forward of the low pressure compressor being greater than or equal to 0.6 and less than or equal to 2.0.

Abstract: A gear reduction for a gas turbine engine includes intermediate gears, a single structure establishing a carrier centered on an axis and having a pair of axially spaced apart side walls, axially extending circumferentially spaced connecting structure for connecting the pair of side walls, a central opening in at least one of the side walls, and circumferentially spaced smaller openings spaced radially outwardly of the central opening, with internal surfaces of the circumferentially spaced connecting structure defining intermediate gear pockets that extend away from the central opening to the circumferentially spaced openings. The intermediate gears are receivable through the central opening and are secured in the intermediate gear pockets. A ring gear includes a first ring gear half and a second ring gear half placed on an outer periphery of the intermediate gears such that ring gear teeth of the first and second ring gear halves engage with teeth of the intermediate gears.

Abstract: An exemplary gas turbine engine assembly includes a fan section including a fan, a first spool having a first turbine operatively mounted to a first turbine shaft, and a second spool having a second turbine operatively mounted to a second turbine shaft. The first and second towershafts are respectively coupled to the first and second turbine shafts. An accessory drive gearbox includes a set of gears. A compressor is driven by the first towershaft. A transmission couples a starter generator assembly to the set of gears. The transmission is transitionable between a first mode where the starter generator assembly is driven at a first speed relative to the second towershaft in response to rotation of the second towershaft, and a second mode where the starter generator assembly is driven at a different, second speed relative to the second towershaft in response to rotation of the second towershaft.

Abstract: A gas turbine engine includes a fan shaft diving a fan having fan blades. A gear system includes a sun gear surrounded by a plurality of intermediate gears. A carrier at least partially supports the plurality of intermediate gears. A ring gear surrounds the plurality of intermediate gears. The sun gear is driven by a turbine. At least one fan shaft support bearing is located forward of the gear system. A coupling fixes the ring gear from rotation relative to an engine static structure. A lubrication system lubricates components across a rotation gap. The lubrication system includes a lubricant input. A stationary first bearing receives lubricant from the lubricant input and has a first race in which lubricant flows. A second bearing rotates within the first bearing. The second bearing has a first opening in registration with the first race such that lubricant may flow from the first race through the first opening into a first conduit.

Abstract: A method of assembling a gear train includes providing a unitary carrier. The unitary carrier has a central axis that includes spaced apart walls and circumferentially spaced connecting structure defining spaced apart apertures provided at an outer circumference of the carrier, gear pockets provided between the walls and extending to the apertures, and a central opening in at least one of the walls. The method includes inserting a plurality of intermediate gears through the central opening and moving the intermediate gears radially outwardly into the gear pockets to extend into the apertures, placing a ring gear on an outer periphery of the intermediate gears to engage the intermediate gears, and securing the gear train to a fan shaft by a connection.

Abstract: A gas turbine engine according to an example of the present disclosure includes, among other things, a propulsor section including a propulsor supported on a propulsor shaft, a turbine section including a turbine shaft, a compressor section having a plurality of compressor hubs with blades driven by the turbine shaft about an engine axis, and an epicyclic gear train interconnecting the propulsor shaft and the turbine shaft. The epicyclic gear train includes a sun gear coupled to the turbine shaft, intermediary gears arranged circumferentially about and meshing with the sun gear, a carrier and a ring gear including first and second portions. The first and second portions have axially opposed faces abutting one another at a radial interface.

Abstract: A gas turbine engine includes a fan rotor driven by a fan drive turbine about an axis through a gear reduction. An inner core engine has an inner core engine housing surrounding a compressor section, including a low pressure compressor. A rigid connection between a fan case and the inner core engine includes A-frames rigidly connected at a connection point to the fan case. Fan exit guide vanes rigidly connect to the fan case, and to the inner core engine. A fan intermediate case is positioned forward of a first rotor stage in the low pressure compressor. A rigid structure is connected to the inner core engine and to the fan exit guide vanes. The rigid structure defines a structure moment stiffness. The fan intermediate case defines an intermediate case moment stiffness. A ratio of the structure moment stiffness to the intermediate case moment stiffness is between 5 and 15.

Abstract: A turbofan engine includes a propulsor section that has a propulsor shaft in driving engagement with a propulsor. An epicyclic gear system has a gear mesh lateral stiffness and a gear mesh transverse stiffness. A gear system input defines a gear system input lateral stiffness and a gear system input transverse stiffness. The gear system input lateral stiffness is less than 5% of the gear mesh lateral stiffness. A first turbine section rotates at a first speed, and a second turbine rotates at a second speed that is faster than the first speed. A first performance quantity is defined as the product of the first speed squared and the first area of the first turbine, a second performance quantity is defined as the product of the second speed squared and the second area of the second turbine, and a performance quantity ratio is between 0.5 and 1.5.

Abstract: A gas turbine engine includes a fan rotor driven by a fan drive turbine about an axis through a gear reduction. An inner core engine has an inner core engine housing surrounding a compressor section, including a low pressure compressor. A rigid connection between a fan case and the inner core engine includes A-frames rigidly connected at a connection point to the fan case. Fan exit guide vanes rigidly connect to the fan case, and to the inner core engine. A fan intermediate case is positioned forward of a first rotor stage in the low pressure compressor. A rigid structure is connected to the inner core engine and to the fan exit guide vanes. The rigid structure defines a structure moment stiffness. The fan intermediate case defines an intermediate case moment stiffness. A ratio of the structure moment stiffness to the intermediate case moment stiffness is between 5 and 15.

Abstract: A gas turbine engine includes a propulsor and a fan drive turbine. The fan drive turbine drives the propulsor through a geared architecture. The geared architecture includes a sun gear, a ring gear, and intermediate gears supported on journal support pins. The sun gear engages the intermediate gears and the intermediate gears engages the ring gear. The journal support pins include a titanium body and an outer surface outside of the titanium body that has a surface hardness that is harder than the titanium body. The outer surface is provided by a steel sleeve. Oil supply holes extend from a central bore in the titanium body through the steel sleeve. At least one pin extends through the steel sleeve to secure the steel sleeve to the titanium body.

Abstract: A gas turbine engine according to an example of the present disclosure includes, among other things, a fan shaft configured to drive a fan, a support configured to support at least a portion of the fan shaft, the support defining a support transverse stiffness and a support lateral stiffness, a gear system coupled to the fan shaft, and a flexible support configured to at least partially support the gear system. The flexible support defines a flexible support transverse stiffness with respect to the support transverse stiffness and a flexible support lateral stiffness with respect to the support lateral stiffness. The input defines an input transverse stiffness with respect to the support transverse stiffness and an input lateral stiffness with respect to the support lateral stiffness.

Abstract: A gas turbine engine includes a propulsor and a drive gear system. The drive gear system includes at least one ring gear, a plurality of intermediate gears positioned between and enmeshing with a sun gear and the at least one ring gear, with the plurality of intermediate gears carried by a gear carrier. A first bearing is configured to rotate with the gear carrier. A second bearing is on an opposite side of the drive gear system from the first bearing.

Abstract: A gas turbine engine according to an example of the present disclosure includes, among other things, a propulsor section including a propulsor supported on a propulsor shaft, a turbine section including a turbine shaft, a compressor section, and an epicyclic gear train interconnecting the propulsor shaft and the turbine shaft. The gear train includes a sun gear coupled to the turbine shaft, intermediary gears arranged circumferentially about and meshing with the sun gear, a carrier supporting the intermediary gears, and a ring gear including first and second portions each having an inner periphery with teeth intermeshing with the intermediate gears. The first and second portions have axially opposed faces abutting one another at a radial interface. The first and second portions have grooves at the radial interface that form a hole that expels oil through the ring gear.

Abstract: A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A rigid connection between a fan case and an inner core housing includes a plurality of A-frames connected at a connection point to the fan case. Legs in the A-frames extend away from the connection point in opposed circumferential directions to be connected to a compressor wall of the inner core housing. The rigid connection also includes a plurality of fan exit guide vanes rigidly connected to the fan case. A lateral stiffness ratio of the lateral stiffness of the plurality of fan exit guide vanes and a lateral stiffness of a combination of the plurality of A-frame, the compressor wall, and a fan intermediate case which is forward of the low pressure compressor being greater than or equal to 0.6 and less than or equal to 2.0.