A bowed rotor prevention system for a gas turbine engine of an aircraft is provided. The bowed rotor prevention system includes a bowed rotor prevention motor operable to drive rotation of a starting spool of the gas turbine engine through an engine accessory gearbox. The bowed rotor prevention system also includes a controller operable to engage the bowed rotor prevention motor and drive rotation of the starting spool until a bowed rotor prevention threshold condition is met or a bowed rotor prevention shutdown request to halt rotation of the starting spool is received.

A bowed rotor prevention system for a gas turbine engine of an aircraft is provided. The bowed rotor prevention system includes a gear train and a bowed rotor prevention motor operable to drive rotation of a starting spool of the gas turbine engine through the gear train at a substantially constant speed upon engine shutdown until an energy storage source is depleted.

An engine starting system for a gas turbine engine is provided. The engine starting system comprising: a gas turbine engine including rotational components comprising an engine compressor, an engine turbine, and a rotor shaft operably connecting the engine turbine to the engine compressor, wherein each rotational component is configured to rotate when any one of the rotational components is rotated; a permanent magnet alternator operably connected to at least one of the rotational components, the permanent magnet alternator being configured to rotate the rotational components; and a motor controller in electronic communication with the permanent magnet alternator, the motor controller being configured to command the permanent magnet alternator to rotate the rotational components at a selected angular velocity for a selected period of time.

A method for supplying air to an engine of an aircraft via an air supply system of the aircraft. A dynamic air intake vent of the system can be closed by a closure member that is movable between a closed position and an open position. A static air intake vent is equipped with a filter medium. During flight, the method comprises an unfiltered operating mode that comprises the following steps: positioning of the closure member in the open position, and, during a phase of forward travel of the aircraft, dynamic intake of a flow of air, then transfer of a first portion of the flow of air to the engine and a second portion of the flow of air to the filter medium in order to clean the filter medium.

Method and system for controlling engine speed in a multi-engine aircraft, comprising monitoring a request for a first engine and a second engine to generate a given thrust and determining a corresponding engine speed for the first engine and the second engine in accordance with the given thrust. When the corresponding engine speed is outside of a selected speed range, a first engine speed and a second engine speed are allowed to track the corresponding engine speed. When the corresponding engine speed is within the selected speed range, a transition of the first engine speed and the second engine speed through the selected speed range is staggered by allowing one of the first engine speed and the second engine speed to transition through the selected speed range while holding the other of the first engine speed and the second engine speed outside of the selected speed range.

An aircraft gas turbine engine includes a fan system having a reverse traveling wave first flap mode, Fan RTW, and including a fan upstream of the engine core; a fan shaft; and a front engine structure to support the shaft and having a front engine structure nodding mode FSN including two modes at similar, but unequal, natural frequencies in orthogonal directions; and a gearbox. The engine includes a gearbox, and a gearbox output shaft to couple output of the gearbox to the fan shaft. An LP rotor system including the fan system and the gearbox output shaft has a first reverse whirl rotor dynamic mode, Rotor RW. A frequency margin of:

[00001]$\frac{\mathrm{the}\mathrm{frequency}\mathrm{difference}\mathrm{between}\mathrm{mode}\mathrm{FSN}\mathrm{and}\mathrm{the}\mathrm{highest}\mathrm{frequency}\mathrm{of}\mathrm{either}\mathrm{synchronous}\mathrm{Fan}\mathrm{RTW}\mathrm{or}\mathrm{synchronous}}{}$

An aircraft gas turbine engine includes a fan system having a reverse traveling wave first flap mode, Fan RTW, and including a fan upstream of the engine core; a fan shaft; and a front engine structure to support the shaft and having a front engine structure nodding mode FSN including two modes at similar, but unequal, natural frequencies in orthogonal directions; and a gearbox. The engine includes a gearbox, and a gearbox output shaft to couple output of the gearbox to the fan shaft. An LP rotor system including the fan system and the gearbox output shaft has a first reverse whirl rotor dynamic mode, Rotor RW. A frequency margin of: $\frac{\mathrm{the}\mathrm{frequency}\mathrm{difference}\mathrm{between}\mathrm{mode}\mathrm{FSN}\mathrm{and}\mathrm{the}\mathrm{highest}\mathrm{frequency}\mathrm{of}\mathrm{either}}{}$

A method for regulating the temperature of the exhaust gases of a turbomachine, the method including regulation of the injection of fuel into a combustion chamber of the turbomachine so that the turbomachine generates a target thrust; regulation of the injection of mechanical power by an electric motor onto a shaft driven in rotation by a turbine, the electric motor being activated when a clearance between a casing and the blades of the turbine exceeds a threshold value.

An axial fan rotates around a rotating shaft. The axial fan includes a hub, and a plurality of blades extending in a radial direction from the hub. Each blade includes a leading edge, a trailing edge including a depression, and a reinforcing protrusion located at least forwardmost and having a wall thickness thicker than a surrounding portion. As viewed along a rotating shaft direction, when a first virtual line and a second virtual line perpendicular to the radial direction are drawn, the reinforcing protrusion extends radially inside of the first virtual line and extends radially outside of the second virtual line, the first virtual line and the second virtual line respectively pass through a rearmost first endpoint in the rotation direction on a radially inside of a rear end that substantially overlaps the depression, and a rearmost second endpoint on a radially outside of the rear end.

A method of treating a component adapted for use in a gas turbine engine is described herein. The component may comprise ceramic matrix composite materials. The treatment to the ceramic matrix composite component may reduce or eliminate the wear or damage of crack propagation in the ceramic matrix composite component.