Abstract: A selectively actuatable pressure relief valve (110) includes a housing (112) that defines an annular projection (118), an inlet port (120) in the lower surface (122), and a relief vent (124) in the sidewall. A first plunger (128) and a second plunger (138) are longitudinally disposed within the housing and are actuatable between an open position and closed position. The valve is normally biased in the open position by a pair of springs (136 and 146). The valve may be actuated between the open and closed positions by a solenoid (148) or may be locked into the closed position by the manual override device (154). When the valve is in the closed position, the spring may be overcome by the fluid pressure exceeding a predetermined limit, thereby displacing the valve into the open position and providing high pressure relief.

Abstract: A thrust reverser synchronization shaft lock system that includes a sync lock control valve (50) and two hydraulically controlled sync locks (60) attached to the synchronization shafts (5) of a jet engine thrust reverser system, is disclosed. The thrust reverser system further comprises an isolation valve (45), a directional control valve (47), a plurality of actuators (19), and synchronization shafts (5). The sync locks (60) are capable via the synchronization shafts (5) of preventing the actuators (19) from deploying the thrust reversers of the jet engines. The sync locks (60) remain in a locked state until an independent control signal sent from the flight deck positively instructs the sync lock control valve (50) to unlock the sync locks (60), ensuring that the unlocking of the sync locks (60) corresponds to a valid thrust reverser deploy signal.