to vent both transfer cylinders and the unlock port of the canopy-lock pneumatic actuator overboard. The weight of the canopy closes it; pneumatic power is not required. The closing time, approximately 10 seconds from the fully open position, is controlled by the flow regulators in the open and close control modules of the hydraulic actuator. The final closing motion of the canopy actuates the pneumatic timer to direct 325-psi nitrogen from valve No. 2 of the control module to the lock port of the canopy-lock pneumatic actuator, unlatching the ball locks. The actuator piston retracts and, by reverse action, moves the canopy forward to engage the canopy hooks in the sill locks. With the canopy in its full forward positions, the lock lockpin engages and prevents aft movement of the canopy. The final motion of the lock lockpin opens the canopy switch, breaks the circuit to the canopy caution indicator light on the caution advisory indicators, and the lights go off. Boost Closing Mode To close the canopy under high headwind conditions, the canopy control handle must be moved to BOOST. On aircraft not modified by AFC 95, the control handle must be rotated out- board to move the handle pasta stop to BOOST. Valve No. 4 in the control module is positioned to direct 790-psi nitrogen through the C2 port of the canopy hydraulic actuators to the close transfer cylinder. This nitrogen, acting against the transfer cylinder piston, causes the hydraulic fluid on the opposite side of the piston to retract the actuator. The other valves in the control module are positioned the same as when CLOSE is selected, and the system functions in the same manner to lock the closed canopy. The closing time for this mode of operation is also controlled by the flow regulators in the open and close control modules of the hydraulic actuator. Auxiliary Opening Mode The auxiliary opening mode is used to unlock the canopy when normal pneumatic system reservoir pressure drops below 225 psi. To prevent further depletion of nitrogen pressure in the normal system, a low-pressure sensor repositions valves No. 5 and No. 6 in the control module. The canopy must now be unlocked by activating the auxiliary opening mode. To set the canopy control handle to AUX OPEN on aircraft not modified by AFC 95, the handle must be rotated outboard to move past a stop (the handle will remain in the AUX OPEN position). When the control handle is set to AUX OPEN, the auxiliary unlock pneumatic release valve releases pressurized nitrogen from the auxiliary pneumatic reservoir. Nitrogen pressure from this reservoir flows through a 325-psi pressure reducer, through the release valve and pneumatic unlock shuttle valve, to shift position of the shuttle valve internal spool. This directs nitrogen pressure to the unlock port of the canopy-lock pneumatic actuator, unlocking the canopy. Valve No, 1 in the control module directs reservoir pressure to the open transfer cylinder of the canopy hydraulic actuator. This low-pressure nitrogen, acting against the transfer cylinder piston, counter- balances the weight of the canopy. The canopy can then be easily opened and closed manually. The canopy cannot be locked closed under these conditions. To return the system to normal operation, the control handle must be set to OPEN and, on aircraft not modified by AFC 95, rotated outboard to move past a stop. The release valve eccentric cam must be manually reset to block auxiliary nitrogen pressure flow to the shuttle valve and to vent the pressure in the canopy-lock pneumatic actuator. SYSTEM COMPONENTS The purpose of each of the major components of the F- 14 clamshell canopy system is presented in the following paragraphs. Refer to figure 2-2 to see how each component fits into the overall system. Canopy Hydraulic Actuator The canopy hydraulic actuator opens and closes the canopy. It consists of a double-acting hydraulic cylinder, two transfer cylinders, and two hydraulic control modules. The transfer cylinders convert pneumatic pressure from the canopy pneumatic control module to hydraulic power. The hydraulic control modules contain pneumatically actuated shutoff valves that 2-3