A gas turbine engine for an aircraft comprises an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor, wherein a compressor exit temperature is defined as an average temperature of airflow at the exit from the compressor; and a fan located upstream of the engine core, the fan comprising a plurality of fan blades extending from a hub, each fan blade having a leading edge and a trailing edge, wherein a fan rotor entry temperature is defined as an average temperature of airflow across the leading edge of each fan blade at cruise conditions and a fan tip rotor exit temperature is defined as an average temperature of airflow across a radially outer portion of each fan blade at the trailing edge at cruise conditions. A core to fan tip temperature rise ratio is in the range from 2.845 to 3.8.

A power transmission system includes a shaft, a stator disposed within the shaft and substantially concentric with the shaft; and at least one supporting element positioned between the stator and the shaft and configured to support the shaft on the stator to reduce a vibration of the shaft and allow the shaft to rotate relative to the stator. A gas turbine engine including the power transmission system is also described.

A journal support pin to support intermediate gears for use in gas turbine engine comprises a titanium body, and an outer surface outside of the titanium body having a surface hardness that is harder than the body. A gas turbine engine and a method of forming a journal support pin to support intermediate gears for use in gas turbine engine are also disclosed.

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.

A gas turbine engine including a first rotor assembly comprising a first drive shaft extended along a longitudinal direction; a housing coupled to the first rotor assembly to provide rotation of the first rotor assembly around an axial centerline; a first accessory assembly, wherein the first accessory assembly sends and/or extracts energy to and from the first rotor assembly; and a first clutch assembly disposed between the first rotor assembly and the first accessory assembly. The first clutch assembly engages and disengages the first rotor assembly to and from the first accessory assembly.

An aircraft engine comprising a fan, the fan having a diameter D and including a plurality of fan blades, the fan blades having a sweep metric S.sub.tip, each fan blade having a leading edge, and a forward-most portion on the leading edge of each fan blade being in a first reference plane. The aircraft engine further comprises a nacelle, comprising an intake portion forward of the fan, a forward edge on the intake portion being in a second reference plane, wherein the intake portion has a length L measured along an axis of the aircraft engine between the first reference plane and the second reference plane, the aircraft engine having a cruise design point condition M.sub.rel, wherein M.sub.rel is between 0.4 and 0.93, L/D is between 0.2 and 0.45 and S.sub.tip is from −1 to 0.1.

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.

An assembly for a gas turbine engine includes a casing centered on a longitudinal axis and including an upstream portion, a central portion and a downstream portion arranged successively along the longitudinal axis, an attachment system include plural tie rods, and an accessory gearbox arranged within a space delimited axially by the upstream portion and the downstream portion and radially by the central portion, the accessory gearbox being solely attached to the upstream portion or solely attached to the downstream portion by the attachment system.

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.

Lubricant pump systems and associated methods for aircraft engines are provided. The method includes receiving an input torque, dividing the input torque between a first load path receiving a first portion of the input torque, and a second load path receiving a second portion of the input torque. A first lubricant pump of the aircraft engine is driven via the first load path using the first portion of the input torque. A second lubricant pump of the aircraft engine is driven via the second load path using the second portion of the input torque. When a malfunction of the second lubricant pump occurs, the method includes ceasing to drive the first lubricant pump and the second lubricant pump using the input torque.