A turbomachine, a computing system for a turbomachine, and a method for overspeed protection are provided. The turbomachine includes a first rotor assembly interdigitated with a second rotor assembly together operably coupled to a gear assembly. A plurality of sensors is configured to receive rotor state data indicative of one or more of a speed, geometric dimension, or capacitance, or change thereof, or rate of change thereof, relative to the first rotor assembly or the second rotor assembly. A controller executes operations including receiving rotor state data from the plurality of sensors; comparing rotor state data to one or more rotor state limits; and contacting one or more of the first rotor assembly or the second rotor assembly to a contact surface adjacent to the respective first rotor assembly or the second rotor assembly if the rotor state data exceeds the rotor state limit.

A gas turbine engine, includes: an engine core including a turbine, compressor, and shaft system connecting the turbine to the compressor, and forming a torque path therebetween. The shaft system is axially located by a thrust bearing located forward of the turbine, and the engine is configured, in the event of a shaft break which divides the shaft system into a front portion located by the thrust bearing and a rear portion unlocated by the thrust bearing, the rear portion is free to move axially rearwardly under a gas load. The engine further includes a shaft break detector having a forward speed sensor configured to measure a rotational speed of the front portion of the shaft system, and a rear microwave sensor configured to measure a rotational speed of the rear portion of the shaft system, wherein a shaft break can be detected based on differences in the measured speeds.

A gas turbine engine, and an aircraft including the gas turbine engine. The gas turbine engine comprising: an engine core comprising a turbine, a compressor, and a shaft system connecting the turbine to the compressor. The shaft system is axially located by a thrust bearing located forward of the turbine, and the engine is configured such that, in the event of a shaft break which divides the shaft system into a front portion located by the thrust bearing and a rear portion unlocated by the thrust bearing, the rear portion is free to move axially rearwardly under a gas load; and the engine further comprises an axial movement sensor configured to register a shaft break when it detects the axial movement of the rear portion of the shaft system.

A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a fan and a braking system. The braking system is configured to selectively engage the fan during ground windmilling to apply a first level of braking to slow rotation of the fan. Further, when the rotation of the fan sufficiently slows, the braking system is further configured to apply a second level of braking more restrictive than the first level of braking.

A method of operating a twin engine helicopter power plant, the power plant comprising: two turboshaft engines each having an engine shaft with a turbine at a distal end and a one-way clutch at a proximal end; a gear box having an input driven by the one way clutch of each engine and an output driving a helicopter rotor; a bypass clutch disposed between the proximal end of each engine shaft and the input of the gear box; and power plant management system controls for activating the bypass clutch; the method comprising: detecting when a rotary speed of an associated engine shaft is less than a rotary speed of the gear box input; activating the bypass clutch to drive the associated engine shaft using the rotation of the gear box input; and starting an associated engine by injecting fuel when the bypass clutch is activated.

A gas turbine engine has an engine static structure. At least one component rotatable relative to the engine static structure about an engine axis of rotation. A fan is coupled to at least one component for rotation about the engine axis of rotation. An actuator is mounted to the engine static structure, wherein the actuator is activated to prevent the fan from rotation and is inactivated to allow the fan to rotate. A method for preventing rotation of a fan in a gas turbine engine is also disclosed.

A gas turbine engine includes a compressor having a first compressor section and a second compressor section, a combustor fluidly connected to the compressor, and a turbine fluidly connected to the combustor. The turbine has a first turbine section and a second turbine section. A first shaft connects the first compressor section and the first turbine section. A second shaft connects the second compressor section and the second turbine section. A fan is connected to the first shaft via a geared architecture. A low speed accessory gearbox is interfaced with the first shaft via a mechanical interface. The low speed accessory gearbox includes a mechanical brake.

An in-line propeller gearbox of a turboprop gas turbine engine includes an epicyclic gearing arrangement that has a sun gear, a ring gear and at least one planet gear disposed between and meshing with both the sun gear and the ring gear. The propeller gearbox includes a disk brake that can be operated to slow down or stop altogether the rotation of the propeller. The disk brake has an axially extending shaft having at one end a disk and at the opposite end a gear having teeth that engage with one of the gears in the epicyclic gearing arrangement. The disk brake includes an hydraulic caliper or an electric caliper that can be actuated to slow down rotation of the disk to an eventual full stop and to hold the disk at full stop to thereby stop rotation of the propeller.

A method and system improving energy efficiency of a turbojet engine by optimizing rotating speed of a fan and operability of an engine, by freeing the fan from exclusive control of a low-pressure (LP) shaft by providing combined control with a high-pressure (HP) shaft when cruising power has been reached. The turbojet engine include at least one LP turbine and one HP turbine coupled to coaxial LP shafts and HP shafts, respectively, which can drive LP and HP compressors, respectively. The LP compressors include a fan that forms a first primary air-intake compression stage. The LP and HP shafts are mounted on one of two driving mechanisms, an inner ring gear, and a planet carrier for a planetary gear train for driving the fan, the HP shaft being mounted on a disengagement mechanism and the fan being coupled to the planetary gear train via an outer driven ring gear.

A toothed coupling mechanism for an assembly of rotating elements of an aircraft gas turbine engine includes a pair of coupling halves having an axial toothed coupling interface therebetween. Each coupling half has a plurality of splined teeth inter-engaged about an axis for transmitting torque therebetween. A protrusion is located on one of the splined teeth of one of the coupling halves. A splined tooth of the other coupling half comes into contact with the protrusion in a situation of uncoupling of said coupling halves.