Abstract: A method and apparatus for air-ground detection. A truck beam of a semi-levered landing gear is mounted on a pivot pin. The truck beam is configured to rotate about the pivot pin between a toes down position and a toes up position. A positioning mechanism is connected to a locking mechanism that secures an angle of the truck beam in the toes up position. The locking mechanism is secured in a steady state and configured to change from the steady state to a locked state in response to an initial ground contact. A sensor is connected to the locking mechanism. The sensor is configured to detect a change from the steady state to the locked state.

Abstract: A device including a first hydraulic piston, a second hydraulic piston disposed within the first hydraulic piston, and a third hydraulic piston disposed within both the first hydraulic piston and the second hydraulic piston. The first, second, and third hydraulic pistons are contained within a common outer wall. A manifold is connected to the first, second, and third hydraulic pistons. The manifold is disposed relative to the first, second, and third hydraulic pistons such that a fluid moving in the manifold can control positions of the first, second, and third hydraulic pistons.