A turbofan engine comprising: a turbine engine; a nacelle surrounding the turbine engine and defining an annular bypass duct between the nacelle and the turbine engine and extending through the turbofan engine to define a generally forward-to-aft bypass air flow path; a thrust reverser having at least one movable control surface, movable to and from a reversing position where at least a portion of the bypass air flow is at least partially reversed; a thrust reverser actuation system having multiple actuators with each actuator having a piston being axially movable within a cylinder of the actuator and being operably coupled to the at least one movable control surface to move the at least one movable control surface into and out of the reversing position, a lead screw rotating at a speed proportional to the velocity of the piston when in use, and a synchronization mechanism to synchronize the multiple actuators; and a lockout mechanism; characterized in that: the lockout mechanism is selectively coupled to the lead screw of one of the multiple actuators and movable between an inhibit condition, wherein movement of the multiple actuators is prevented, and a permit condition, wherein movement of the multiple actuators is permitted; the lockout mechanism further comprises a handle for moving the lockout mechanism between the inhibit condition and the permit condition; the turbofan engine further comprises a door located adjacent the handle and moveable between a closed position and an opened position wherein access to the handle is provided; wherein when the door is moved to the closed position it contacts the handle to move the lockout mechanism to the permit condition; wherein the lockout mechanism further comprises a piston axially moveable between a first position and a second position where the piston selectively couples with the lead screw; wherein the handle is operably coupled to the piston of the lockout mechanism and the handle is moveable between a first position where the lockout mechanism is in the permit condition and a second position where the lockout mechanism is in the inhibit condition; wherein when the lockout mechanism is in the inhibit condition, the piston of the lockout mechanism operably couples with the lead screw and prevents rotation of the lead screw; wherein the piston of the lockout mechanism comprises teeth that engage portions of the lead screw and prevent rotation of the lead screw when the piston is in the second position that corresponds to the inhibit condition. a turbine engine; a nacelle surrounding the turbine engine and defining an annular bypass duct between the nacelle and the turbine engine and extending through the turbofan engine to define a generally forward-to-aft bypass air flow path; a thrust reverser having at least one movable control surface, movable to and from a reversing position where at least a portion of the bypass air flow is at least partially reversed; a thrust reverser actuation system having multiple actuators with each actuator having a piston being axially movable within a cylinder of the actuator and being operably coupled to the at least one movable control surface to move the at least one movable control surface into and out of the reversing position, a lead screw rotating at a speed proportional to the velocity of the piston when in use, and a synchronization mechanism to synchronize the multiple actuators; and a lockout mechanism; the lockout mechanism is selectively coupled to the lead screw of one of the multiple actuators and movable between an inhibit condition, wherein movement of the multiple actuators is prevented, and a permit condition, wherein movement of the multiple actuators is permitted; the lockout mechanism further comprises a handle for moving the lockout mechanism between the inhibit condition and the permit condition; the turbofan engine further comprises a door located adjacent the handle and moveable between a closed position and an opened position wherein access to the handle is provided; wherein when the door is moved to the closed position it contacts the handle to move the lockout mechanism to the permit condition; wherein the lockout mechanism further comprises a piston axially moveable between a first position and a second position where the piston selectively couples with the lead screw; wherein the handle is operably coupled to the piston of the lockout mechanism and the handle is moveable between a first position where the lockout mechanism is in the permit condition and a second position where the lockout mechanism is in the inhibit condition; wherein when the lockout mechanism is in the inhibit condition, the piston of the lockout mechanism operably couples with the lead screw and prevents rotation of the lead screw; wherein the piston of the lockout mechanism comprises teeth that engage portions of the lead screw and prevent rotation of the lead screw when the piston is in the second position that corresponds to the inhibit condition.