Aircraft hydraulic actuation system with chambers for hydraulic fluid

A method of moving a landing gear in an aircraft using an aircraft landing gear extension and retraction system that includes a supply line arranged to carry hydraulic fluid pressurized by a pump, a return line arranged to return hydraulic fluid to a reservoir, and a hydraulic landing gear retraction actuator configured to be connected to a first position fixed relative to a fuselage of the aircraft, wherein the actuator includes a first chamber and a second chamber separated by a piston configured to be connected to the landing gear,

• the method comprising:
• operating the landing gear extension and retraction system in a first mode to retract the landing gear, wherein the first mode includes supplying the first chamber with hydraulic fluid from the supply line to move the piston in a direction to retract the landing gear;
• and
• operating the landing gear extension and retraction system in a second mode to extend the landing gear, wherein the second mode includes isolating the first chamber from fluid communication with the supply line while the second chamber is in fluid communication with the return line such that the piston moves in a direction that allows the landing gear to extend by gravity acting on the landing gear,
• wherein the landing gear pivots about a second position, separate from the first position, fixed relative to the fuselage.

An aircraft landing gear extension and retraction system comprising:

• a supply line arranged to carry hydraulic fluid pressurized by a pump,
• a return line arranged to return hydraulic fluid to a reservoir, and
• a hydraulic landing gear retraction actuator comprising a first chamber and a second chamber separated by a piston configured to be attached to a landing gear of the aircraft, wherein the piston is moved during extension and retraction of the landing gear;
• the landing gear extension and retraction system being operable in a first mode to retract the landing gear, wherein in the first mode the first chamber is supplied with the hydraulic fluid from the supply line such that the piston is urged in a direction that causes the aircraft landing gear to be urged towards a retracted position;
• the landing gear extension and retraction system being operable in a second mode to allow the landing gear to extend, wherein in the second mode the first chamber is taken out of fluid communication with the supply line and the second chamber is in fluid communication with the return line such that the piston is moved by the landing gear as the landing gear extends at least partially due to gravity,
• wherein any fluid in the first chamber during the second mode does not provide a force sufficient to move the piston.

A method of extending a landing gear of an aircraft using an aircraft landing gear extension and retraction system that includes a supply line arranged to carry hydraulic fluid pressurized by a pump, a return line arranged to return hydraulic fluid to a reservoir, and a hydraulic landing gear retraction actuator including a first chamber and a second chamber separated by a piston configured to be connected to the landing gear of the aircraft,

• the method comprising:
• the landing gear extension and retraction system operating in a first mode to retract the landing gear and during the first mode the first chamber is supplied with hydraulic fluid from the supply line to urge the piston in a first direction that causes the landing gear to retract;
• the landing gear extension and retraction system operating in a second mode to extend the landing gear and during the second mode the first chamber is isolated from fluid communication with the supply line and the second chamber is in fluid communication with the return line such that the piston moves in a second direction, opposite the first direction, due to the force of gravity acting on the landing gear to extend the landing gear;
• and
• configuring the landing gear extension and retraction system into the second mode of operation by
• unlocking the landing gear from the retracted position;
• allowing the landing gear to extend under gravity;
• and locking the landing gear in an extended position.