Abstract: A thrust reversal system for a jet aircraft engine, comprising thrust reverser buckets movable between a stowed and a deployed position, an air motor operable under pilot's control to impart movement to the buckets, a piston movable in a cylinder having restricted outlet orifices for automatically decelerating the motor when the buckets approach both the stowed and the deployed position, a locking mechanism for locking the buckets in the stowed position and a flow control valve for controlling the direction of flow of operating air to the motor, the flow control valve, upon selection of deploy, initially occupying a position corresponding to movement of the motor in the direction to stow the buckets and, after release of the locking mechanism, moving to its alternative position to enable the motor to move the buckets to the deployed position.