A turbofan engine has a fan drivingly engaged by a shaft for rotation about a rotation axis and having: fan blades circumferentially distributed about the rotation axis and drivingly engaged by the shaft; an ice-accruing feature located on a surface of the fan exposed to an air flow flowing between the fan blades, the ice-accruing feature having a shape providing a non-axisymmetric ice accumulation on the fan to create a rotational imbalance; a balancing feature secured to the fan or to the shaft to counteract the ice-accruing feature such that the fan is rotationally balanced when the fan is free of ice, the balancing feature being located such as to be outside the air flow; an aircraft controller; and a sensor operatively connected to the fan and operable to send a signal to the aircraft controller, the signal indicative of the rotational imbalance caused by the ice-accruing feature.

A gas turbine engine includes: a fan rotating about an engine main axis; a core duct; an engine core; an Engine Section Stator (ESS) including a plurality of ESS vanes and arranged in the core duct downstream of the fan; and a plurality of variable inlet guide vanes (VIGV) adapted to rotate about a pivot axis and arranged in the core duct downstream of the ESS. The VIGV vanes are arranged angularly rotated with respect to the ESS vanes such that the VIGVs are shielded by the ESS, thereby protecting the VIGVs from icing and from ice shedding from the ESS vanes.

A pressure regulating valve assembly includes: a valve having an upstream side receiving an input flow and a downstream side providing an output flow, an actuator for opening and closing the valve, including partially opening the valve, and a regulator controlling the actuator to open, close or partially open the valve. The regulator includes a sense pressure port, wherein pressure at the port is maintained constant by the regulator. A chamber has a first entry orifice, a second entry orifice and an exit orifice. The first entry orifice is connected to the upstream side, the second entry orifice is connected to the downstream side, and the exit orifice is connected to the port. The exit orifice provides that the pressure at the exit orifice lies between the pressure at the first entry orifice and the pressure at the second entry orifice.

A pressure regulating valve assembly includes: a valve having an upstream side receiving an input flow and a downstream side providing an output flow, an actuator for opening and closing the valve, including partially opening the valve, and a regulator controlling the actuator to open, close or partially open the valve. The regulator includes a sense pressure port, wherein pressure at the port is maintained constant by the regulator. A chamber has a first entry orifice, a second entry orifice and an exit orifice. The first entry orifice is connected to the upstream side, the second entry orifice is connected to the downstream side, and the exit orifice is connected to the port. The exit orifice provides that the pressure at the exit orifice lies between the pressure at the first entry orifice and the pressure at the second entry orifice.

A system and method of increasing the temperature of oil that is used to anti-ice a gas turbine propulsion engine includes supplying oil from an oil supply system to an anti-ice oil circulation system that is disposed within the front frame of the gas turbine propulsion engine, and selectively injecting compressed air from the gas turbine propulsion engine into the oil supply system.

A system and method of increasing the temperature of oil that is used to anti-ice a gas turbine propulsion engine includes supplying oil from an oil supply system to an anti-ice oil circulation system that is disposed within the front frame of the gas turbine propulsion engine, and selectively injecting compressed air from the gas turbine propulsion engine into the oil supply system.

Methods, apparatus, systems, and articles of manufacture to provide damping of an airfoil are disclosed. An example airfoil is disposed in a flow path, the airfoil including a shell defining an exterior surface of the airfoil and forming a cavity in an interior surface of the airfoil, and a lattice damper disposed in the cavity, the lattice damper to reduce vibrational loads exerted on the airfoil.

Methods, apparatus, systems, and articles of manufacture to provide damping of an airfoil are disclosed. An example airfoil is disposed in a flow path, the airfoil including a shell defining an exterior surface of the airfoil and forming a cavity in an interior surface of the airfoil, and a lattice damper disposed in the cavity, the lattice damper to reduce vibrational loads exerted on the airfoil.

A system for lubricating components of a gas turbine engine includes a supply pump to pump lubricant from a reservoir through a supply conduit to lubricated component. An outer body deicing circuit is fluidly coupled in series with the supply conduit. Moreover, a scavenge conduit extends from the lubricated component to the reservoir and a scavenge pump pumps the lubricant from the lubricated component through the scavenge conduit. In addition, a valve is fluidly coupled in series with the supply conduit and the scavenge conduit and a bypass conduit extends from the valve to a location on the supply conduit downstream of the deicing circuit. When the lubricant is supplied to the valve, the valve directs the lubricant flowing through the scavenge conduit into the reservoir. When the supply of lubricant to the valve is halted, the valve directs the lubricant flowing through the scavenge conduit into the bypass conduit.

There is provided a system and a method for operating a multi-engine rotorcraft. When the rotorcraft is cruising in an asymmetric operating regime (AOR) at least one engine is an active engine and is operated in an active mode to provide motive power to the rotorcraft and at least one second engine is a standby engine and is operated in a standby mode to provide substantially no motive power to the rotorcraft, at least one of a power level of the at least one second engine is increased and at least one variable geometry mechanism of the at least one second engine is moved to shed any ice accumulation on the at least one second engine.