Systems and methods for mechanically rotating an aircraft about its center-of-gravity (C.sub.G) are disclosed. The system can enable the rear, or main, landing gear to squat, while the nose landing gear raises to generate a positive pitch angle for the aircraft for takeoff or landing. The system can also enable the nose gear and main gear to return to a relatively level fuselage attitude for ground operations. The system can include one or more hydraulically linked hydraulic cylinders to control the overall height of the nose gear and the main gear. Because the hydraulic cylinders are linked, a change on the length of the nose cylinder generates a proportional, and opposite, change in the length of the main cylinder, and vice-versa. A method and control system for monitoring and controlling the relative positions of the nose gear and main gear is also disclosed.

An active oleo system for an aircraft semi-levered landing gear system disclosed herein includes a main strut, an auxiliary strut, bogie beam, and a pressure boost mechanism. During a takeoff roll phase, the pressure boost mechanism may increase the pressure in the main strut, forcing the main strut piston to the fully extended length. Thru the action of main strut, auxiliary strut, and bogie beam this may increase the height of the aircraft above ground, providing for a larger achievable rotation angle of the aircraft.

An active oleo system for an aircraft semi-levered landing gear system disclosed herein includes a main strut, an auxiliary strut, bogie beam, and a pressure boost mechanism. During a takeoff roll phase, the pressure boost mechanism may increase the pressure in the main strut, forcing the main strut piston to the fully extended length. Thru the action of main strut, auxiliary strut, and bogie beam this may increase the height of the aircraft above ground, providing for a larger achievable rotation angle of the aircraft.

There is provided a control module for a hydraulic system. The module comprises a tank and a plurality of valves. The tank is configured to store hydraulic fluid and is substantially cylindrical. The plurality of valves fluidly connect with the tank and are configured to control distribution of hydraulic fluid from the tank to one or more components of the system. The plurality of valves are spaced around a circumference of the tank. One or more passages fluidly connect the tank with at least one of the plurality of valves and/or a first of the plurality of valves with a second of the plurality of valves.

A telescoping strut for a retractable landing gear in an aircraft. The telescoping strut comprises a pre-pressurized and central extension chamber extending along the telescoping strut and a surrounding retraction chamber. For retraction, an hydraulic generation architecture of the aircraft feeds a single input/output passage of the surrounding retraction chamber with a overcoming fluid pressure that overwhelms a extension positive pressure in the central extension chamber and opposes the effect of the pre-pressurizing. The retraction system is for instance for a rotorcraft.

A telescoping strut for a retractable landing gear in an aircraft. The telescoping strut comprises a pre-pressurized and central extension chamber extending along the telescoping strut and a surrounding retraction chamber. For retraction, an hydraulic generation architecture of the aircraft feeds a single input/output passage of the surrounding retraction chamber with a overcoming fluid pressure that overwhelms a extension positive pressure in the central extension chamber and opposes the effect of the pre-pressurizing. The retraction system is for instance for a rotorcraft.

An EHA system (10) for lifting or lowering a leg of an aircraft includes a hydraulic circuit (101) having a hydraulic actuator (a hydraulic cylinder 2) configured to lift or lower the leg, at least one electric hydraulic pump (3), and a hydraulic path, a pressure sensor (38, 83), a temperature sensor (84), and a control unit (a controller 9) configured to output a control signal for operating the electric hydraulic pump in leg lifting or lowering. The hydraulic circuit includes a pressure increasing element. The control unit performs health monitoring regarding the performance of the electric hydraulic pump based on the pressure of hydraulic fluid, the temperature of hydraulic fluid, and the speed of the electric hydraulic pump during operation of the electric hydraulic pump.

An EHA system (10) for lifting or lowering a leg of an aircraft includes a hydraulic circuit (101) having a hydraulic actuator (a hydraulic cylinder 2) configured to lift or lower the leg, at least one electric hydraulic pump (3), and a hydraulic path, a pressure sensor (38, 83), a temperature sensor (84), and a control unit (a controller 9) configured to output a control signal for operating the electric hydraulic pump in leg lifting or lowering. The hydraulic circuit includes a pressure increasing element. The control unit performs health monitoring regarding the performance of the electric hydraulic pump based on the pressure of hydraulic fluid, the temperature of hydraulic fluid, and the speed of the electric hydraulic pump during operation of the electric hydraulic pump.

An automatic engine driven pump (EDP) depressurization system for an aircraft is disclosed. The aircraft includes at least two EDPs driven by a main engine for converting mechanical power provided by the main engine into hydraulic power for distribution by a hydraulic system. The EDP depressurization system includes a depressurization device corresponding to each of the at least two EDPs and a control module. The depressurization devices are each energized to depressurize a respective EDP. The control module is in signal communication with each of the depressurization devices. The control module includes control logic for automatically generating a depressurization signal that energizes one of the depressurization devices based on a plurality of operational conditions of the aircraft.

An automatic engine driven pump (EDP) depressurization system for an aircraft is disclosed. The aircraft includes at least two EDPs driven by a main engine for converting mechanical power provided by the main engine into hydraulic power for distribution by a hydraulic system. The EDP depressurization system includes a depressurization device corresponding to each of the at least two EDPs and a control module. The depressurization devices are each energized to depressurize a respective EDP. The control module is in signal communication with each of the depressurization devices. The control module includes control logic for automatically generating a depressurization signal that energizes one of the depressurization devices based on a plurality of operational conditions of the aircraft.