An uplock assembly for retaining and releasing landing gear systems, said uplock assembly comprising: a thermal actuator comprising: a chamber configured to contain expansible material therein; a heating mechanism coupled to said chamber for heating said expansible material and causing volumetric expansion thereof; a piston slidably coupled to said chamber and adapted to extend in response to said volumetric expansion; and an uplock release mechanism releasably engaged by said piston when extended such that said engaged uplock release mechanism causes the release of said landing gear.