An aircraft landing gear assembly comprising a centre biased actuator (10, 20), the centre biased actuator comprising: an outer cylinder; a slave cylinder arranged to be linearly transposed within the outer cylinder; a rod assembly (120, 26, 122), a piston of which is arranged to be linearly transposed within the slave cylinder and a rod (120, 26) of which extends from the outer cylinder; one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder; one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder; and a gas chamber (13, 23) comprising a sealed expandable chamber (14, 24) containing gas, the expandable chamber being arranged to act on hydraulic fluid within the centre biased actuator to bias the centre biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition, wherein the centre biased actuator (10, 20) is arranged to bias a first part of the assembly to assume a predetermined position relative to a second part of the assembly, and wherein the assembly is arranged, in use, to force the actuator (10, 20) to assume a first condition when in a first state and wherein the actuator (10, 20) is adapted to move the first part of the assembly to assume the predetermined position relative to the second part in a second state, and wherein the first part comprises a bogie beam and the second part comprises a main strut, characterised in that: the expandable chamber comprises metal bellows. an outer cylinder; a slave cylinder arranged to be linearly transposed within the outer cylinder; a rod assembly (120, 26, 122), a piston of which is arranged to be linearly transposed within the slave cylinder and a rod (120, 26) of which extends from the outer cylinder; one or more first dynamic seals arranged to act on a sidewall of the rod to inhibit hydraulic fluid leaking from the outer cylinder; one or more second dynamic seals arranged to act on a sidewall of the slave cylinder or an inner surface of the outer cylinder to inhibit hydraulic fluid leaking from the outer cylinder; and a gas chamber (13, 23) comprising a sealed expandable chamber (14, 24) containing gas, the expandable chamber being arranged to act on hydraulic fluid within the centre biased actuator to bias the centre biased actuator to assume an intermediate condition which lies between a compressed condition and an extended condition, wherein the centre biased actuator (10, 20) is arranged to bias a first part of the assembly to assume a predetermined position relative to a second part of the assembly, and wherein the assembly is arranged, in use, to force the actuator (10, 20) to assume a first condition when in a first state and wherein the actuator (10, 20) is adapted to move the first part of the assembly to assume the predetermined position relative to the second part in a second state, and wherein the first part comprises a bogie beam and the second part comprises a main strut, characterised in that: the expandable chamber comprises metal bellows.