In accordance with at least one aspect of this disclosure, there is provided a drive shaft system. In embodiments, the drive shaft system includes a generator shaft extending along a longitudinal axis with a longitudinal bore defined through the generator shaft. A thru shaft extends through the longitudinal bore of the generator shaft. In embodiments, the thru shaft includes, a front coupler mount at a first end operative to receive torque input, and a rear coupler mount at a second end opposite the first end.

A method for monitoring a fluid system for lubricating a mechanical system. The fluid system comprises a spraying circuit connected to a main fluid circuit and to a back-up fluid circuit. The back-up fluid circuit comprises a back-up check valve closed in a nominal operating mode. The method comprises a monitoring phase comprising the generation of a first alert in the presence of the detection of a malfunction making the main fluid circuit inoperative and the back-up check valve in an open state and the generation of a second alert different from the first alert in the presence a malfunction and the back-up check valve in a closed state.

A drivetrain for an aircraft includes an engine, a driveshaft to receive rotational energy from the engine and a gearbox including a multistage planetary gear system to receive rotational energy from the driveshaft. The multistage planetary gear system includes an integral multistage ring gear system having flanged and cantilevered ends. The integral multistage ring gear system forms a first stage ring gear at the cantilevered end and a second stage ring gear interposed between the flanged end and the first stage ring gear. The multistage planetary gear system includes a first stage sun gear, first stage planet gears and a first stage carrier. The first stage planet gears mate with the first stage ring gear. The multistage planetary gear system includes a second stage sun gear, second stage planet gears and a second stage carrier. The second stage planet gears mate with the second stage ring gear.

The aircraft motor architecture comprises two reversible electric machines (3, 4), the rotors (10) of which are linked both to the low pressure shaft (1) and to the high pressure shaft (2) by transmissions (11, 12, 13, 14) alternately disengaged depending on the direction of rotation of the rotor (10), the transmissions comprising passive one-way clutches (15, 16, 17, 18), the engagement directions of which are opposed. Independent modes of operation of the machines, as a starter or as an electric generator of each of the shafts, are thus provided.

The aircraft motor architecture comprises two reversible electric machines (3, 4), the rotors (10) of which are linked both to the low pressure shaft (1) and to the high pressure shaft (2) by transmissions (11, 12, 13, 14) alternately disengaged depending on the direction of rotation of the rotor (10), the transmissions comprising passive one-way clutches (15, 16, 17, 18), the engagement directions of which are opposed. Independent modes of operation of the machines, as a starter or as an electric generator of each of the shafts, are thus provided.

A method for detecting wear before failure of a free-wheel, the free-wheel comprising a driving part integrated into an upstream mechanical power transmission system and a driven part integrated into a downstream mechanical power transmission system. The method comprises determining an oscillation measurement of a monitoring parameter within the upstream or downstream mechanical power transmission system, determining a value of at least one dynamic parameter characteristic of the oscillation measurement or of a transform of the oscillation measurement in a frequency reference frame, and generating an alarm when the value of the dynamic parameter reaches at least one wear threshold.

There is described a method and system for operating a hybrid electric aircraft propulsion system. The method comprises modulating AC electric power applied to a first electric propulsor or a second electric propulsor from at least one motor inverter to synchronize the frequency of the first electric propulsor or the second electric propulsor with the frequency of a generator.

There is described a method and system for operating a hybrid electric aircraft propulsion system. The method comprises modulating AC electric power applied to a first electric propulsor or a second electric propulsor from at least one motor inverter to synchronize the frequency of the first electric propulsor or the second electric propulsor with the frequency of a generator.

A clutch that has a synchronizer for matching a rotational velocity of a drive input with a rotational velocity of a driven output prior to engagement of a locking mechanism.

A clutch that has a synchronizer for matching a rotational velocity of a drive input with a rotational velocity of a driven output prior to engagement of a locking mechanism.