A turbomachine engine can include a fan assembly, a pitch change mechanism, a vane assembly, a core engine, a gearbox, and a gearbox efficiency rating. The fan assembly can include a plurality of fan blades. The pitch change mechanism can be coupled to the fan assembly. The vane assembly can include a plurality of vanes. 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 twin-engine system includes a gas turbine engine comprising a core and a first output shaft drivable by the core. An electric engine has an electric motor configured to drive a second output shaft. A reduction gear box (RGB) has an RGB input drivingly engaged to both the first output shaft and the second output shaft. The RGB has an RGB output to provide rotational output to a rotatable load.

An air starter for an engine, such as a turbine engine, that includes a turbine for rotatably extracting mechanical power from a flow of fluid. The turbine includes a drive shaft that can be coupled to an output shaft to provide a rotational output. The interface between the drive shaft and the output shaft can be offset and include piloted portions.

An air starter for an engine, such as a turbine engine, that includes a turbine for rotatably extracting mechanical power from a flow of fluid. The turbine includes a drive shaft that can be coupled to an output shaft to provide a rotational output. The interface between the drive shaft and the output shaft can be offset and include piloted portions.

A turbomachine with a counter-rotating turbine for an aircraft includes a counter-rotating turbine and a mechanical reduction gear with an epicyclic, planetary-type gear train. The gear train includes a planet carrier secured to a stator housing of the turbomachine situated upstream from the counter-rotating turbine in relation to a direction of gas flow within the turbomachine. The planet carrier is secured to the stator housing by an annular part with an elongated shape extending inside the second shaft. The annular part includes an upstream end secured to the intermediate casing and a downstream end coupled to the planet carrier. The annular part also includes an integrated circuit for conveying lubrication oil from its upstream end to the planet carrier.

A turbomachine with a counter-rotating turbine for an aircraft includes a counter-rotating turbine and a mechanical reduction gear with an epicyclic, planetary-type gear train. The gear train includes a planet carrier secured to a stator housing of the turbomachine situated upstream from the counter-rotating turbine in relation to a direction of gas flow within the turbomachine. The planet carrier is secured to the stator housing by an annular part with an elongated shape extending inside the second shaft. The annular part includes an upstream end secured to the intermediate casing and a downstream end coupled to the planet carrier. The annular part also includes an integrated circuit for conveying lubrication oil from its upstream end to the planet carrier.

A starter-generator module for a gas turbine engine includes an inner stator portion with an armature defining a rotation axis and an outer rotor portion disposed about the rotation axis. The outer rotor portion includes a permanent magnet and a gear teeth member. The permanent magnet is disposed about the rotation axis and the gear teeth member is defined on the outer rotor portion such that the gear teeth member transmits rotational energy to an accessory gearbox in a start mode and receives rotational energy from the accessory gearbox in a generate mode.

An exemplary gas turbine engine includes a fan section including a fan rotor and at least one fan blade. A fan pressure ratio across the at least one fan blade is less than 1.45, noninclusive of the pressure across any fan exit guide vane system. The engine further includes a low-pressure compressor having a low-pressure compressor rotor that rotates together with the fan rotor at a common speed in operation, and a geared architecture that drives the low-pressure compressor rotor and the fan rotor. The geared architecture has a gear reduction ratio of greater than 2.5. The engine further includes a high-pressure compressor having a pressure ratio greater than 20, a low-pressure turbine having a pressure ratio greater than 5, and a bypass ratio greater than 10.

An exemplary gas turbine engine includes a fan section including a fan rotor and at least one fan blade. A fan pressure ratio across the at least one fan blade is less than 1.45, noninclusive of the pressure across any fan exit guide vane system. The engine further includes a low-pressure compressor having a low-pressure compressor rotor that rotates together with the fan rotor at a common speed in operation, and a geared architecture that drives the low-pressure compressor rotor and the fan rotor. The geared architecture has a gear reduction ratio of greater than 2.5. The engine further includes a high-pressure compressor having a pressure ratio greater than 20, a low-pressure turbine having a pressure ratio greater than 5, and a bypass ratio greater than 10.

A gas turbine engine includes a shaft and a hub supported by the shaft. A housing includes an inlet and an intermediate case that respectively provide an inlet and an intermediate case flow path. A rotor is connected to the hub and supports a compressor section arranged axially between the inlet and the intermediate case flow paths. A compressor section inlet has a radially inner boundary that is spaced a second radial distance from the rotational axis different from the first radial distance. First and second bearings support the shaft relative to the intermediate case and the inlet case, respectively. An inner race of the first bearing and an inner race of the second bearing engage and rotate with the hub. A fan shaft is drivingly connected to a fan having fan blades. A gear system is connected to the fan shaft and driven through a flex shaft.