The keys slide into annular slots when the sidebrace actuator reaches full extension. The sidebrace hydraulic piston and actuator arm extends the main landing gear outboard and down from the wheel well and locks the landing gear in the down position using internal locking keys located in the lower end of actuator cylinder. Indication of landing gear position is provided to the flight crew through lights on the landing gear control panel, an aural warning horn, and by messages on the CAS in the event of malfunction. When the nose gear is retracted and seated in the uplock hook, the doors close to cover the forward wheel well, with the fairing panel linked to the rear of the nose gear drag brace enclosing the aft portion of the wheel well. Timing valves integrated into the extension/retraction cycle operate the hydraulic door actuating cylinder in the correct sequence. Two symmetrical nose wheel doors, hinged on the outside of the nose wheel well are mechanically linked together. A hydraulically actuated pushrod then rotates the uplock hook upward to provide positive nose gear latching. As the nose gear reaches the fully retracted position, a roller attached to the dual wheel axle assembly pushes aside a spring latch and engages an uplock hook, with the spring latch then falling into place securing the roller into the uplock hook. When the nose gear retracts, the downlock actuator arm moves aft, allowing the forward and aft portions of the truss brace to fold at the hinge point. Springs are also incorporated in the over center downlock to maintain the over center lock in the event of hydraulic failure. A downlock hydraulic cylinder extends an actuating arm placing the truss brace in the over center position. When the nose gear is fully extended, the forward and aft sections of the truss brace move over center to lock the nose gear down. The truss brace and trunnion pivot axes allow the hydraulic actuator cylinder to retract the nose gear assembly forward and up and extend the gear aft and down. A drag brace between the truss brace and the shock strut provides additional structural support. The nose gear assembly includes steerable dual wheels mounted on a shock strut attached to a trunnion and a hinged two piece truss brace. The main landing gear door, hinged at the inboard side of the wheel well, closes after the gear retracts and mates with the fairing door panel linked to the outside of the main gear assembly to seal the wheel well. An uplock roller mounted on the dual wheel axle assembly engages an uplock hook in the wheel well and rotates to latch the main gear in the uplocked position. In gear retraction, hydraulic pressure compresses the springs, displaces the downlocks and allows gear retraction inward into the wheel well in the wing root next to the fuselage keel. The downlocks include mechanical springs loads that maintain the locked position without hydraulic pressure. In the extended position, mechanical downlocks prevent gear retraction. A side brace hydraulic actuator/downlock extends and retracts the main gear. The pneumatic/hydraulic shock strut is attached between the wheel end of the articulated trailing arm and the top of the structural post. Each of the main landing gear assemblies has dual wheels with integrated brakes mounted on an articulated trailing arm attached to the landing gear structural post. The major components of each main landing gear assembly are: a landing gear door, a shock strut, a sidebrace actuator/downlock mechanism and an uplock mechanism.
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