Hydraulic actuator

Abstract

A hydraulic actuator for an aircraft. The hydraulic actuator comprises: a housing to accommodate hydraulic fluid; an extension chamber and a retraction chamber each defined by the housing; and a bypass line in fluid communication with the extension chamber and the retraction chamber, wherein the bypass line comprises a flow restrictor and a bypass valve, wherein the flow restrictor restricts a rate of fluid flow through the bypass line, wherein the bypass valve has material defining a port that is openable to allow the hydraulic fluid to flow through the bypass line, and wherein the material is configured to change shape, as a temperature of the material reduces to below a predetermined temperature, to thereby open the port. Also disclosed is a hydraulic actuation system, in the form of a landing gear system, comprising the hydraulic actuator, and an aircraft comprising the hydraulic actuation system.

Dependencies are inferred from the claim text.