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 hydraulically lock the canopy actuator in any position when the canopy pneumatic control module is in the neutral position. Flow regulators control actuator speed by permitting free flow of hydraulic fluid to the actuator and restricted flow from the actuator. Thermal relief valves relieve pressure from the double-acting cylinder to the transfer cylinders. The canopy hydraulic actuator is accessible from the NFO station when the canopy is opened and the NFO ejection seat is removed.

Canopy-Lock Pneumatic Actuator

The canopy-lock pneumatic actuator locks and unlocks the canopy. It operates with nitrogen pressure from the canopy pneumatic control module and the canopy pneumatic timer. The actuator moves the canopy for-ward or aft to the RETR (locked) or EXT (unlocked) position, respectively. When the ac-tuator piston reaches its full EXT (unlock) travel limit, the timer check valve permits pneumatic pressure flow from the canopy pneumatic control module to the open side of the canopy hydraulic actuator. While the canopy closes, the timer check valve vents pneumatic pressure from the canopy hydraulic actuator through the canopy pneumatic control module. When the canopy-lock pneumatic actuator piston moves toward the RETR (locked) position, the timer check valve reseats.

Lock Actuator Restrictors

The lock actuator restrictors regulate the speed of the canopy-lock pneumatic actuator during canopy locking and unlocking.

Canopy Pneumatic Timer

The canopy pneumatic timer permits pneu-matic pressure flow from the canopy pneumatic control module to the lock side, of the canopy-lock pneumatic actuator and vents or pressurizes the canopy hydraulic actuator shutoff valves. The last closing motion of the canopy actuates the timer.

Canopy Pneumatic Control Module

The canopy pneumatic control module regulates pressure from the canopy pneumatic reservoir and directs it to the canopy pneumatic timer, timer check valve, canopy hydraulic actuator, and canopy-lock pneumatic actuator. The module contains a filter, restrictor, two pressure reducers, two relief valves, low-pressure sensor, and control valves. If canopy pneumatic reservoir pressure drops below 225 psi, the low-pressure sensor causes the module valves to lock the remaining pressure in the canopy hydraulic actuator to counterbalance the weight of the canopy. This allows manual opening and closing of the canopy. Canopy unlocking is accomplished by the auxiliary unlock mode.

Canopy Pneumatic Reservoir

The reservoir stores high-pressure dry nitrogen for operation of the canopy pneumatic system. The reservoir is serviced to 3,000 psi; it has a 225-cubic-inch capacity. Servicing is accomplished through the pneumatic servicing charging module, which is remote from the reservoir.

Reservoir Check Valve

The reservoir check valve is in the servicing line to the canopy pneumatic reservoir. The valve prevents nitrogen flow from the reservoir to the pneumatic servicing charging module.

Reservoir Relief Valve

The reservoir relief valve, on the canopy pneumatic reservoir, prevents overpressurization of the reservoir. The valve opens at 4,500 psi and reseats at 4,100 psi.

Pneumatic Servicing Charging Module

The pneumatic servicing charging module is in the nosewheel well. This module contains a filler valve, filter, two check valves, and two pressure gauges. The filler valve allows filling both the canopy pneumatic reservoir and the emergency landing gear reservoir from a single point. The check valves prevent reverse flow when one reservoir has a lower pressure than the other.

Canopy Switch

The canopy switch is actuated by the canopy locking mechanism lock lockpin; the switch closes when the canopy unlocks. This completes a circuit to the canopy caution indicator light on the pilot and NFO CAUTION ADVISORY indicators. When the canopy locks, the switch opens.

Auxiliary Pneumatic Reservoir

The auxiliary pneumatic reservoir, aft of the canopy, has a 14.6-cubic-inch capacity. It stores high-pressure dry nitrogen for un-locking the canopy in the auxiliary mode. The reservoir is serviced, through a filler manifold, to 3,000 psi.

Auxiliary Pneumatic Reservoir Filler Manifold

The auxiliary pneumatic reservoir filler manifold is connected to the auxiliary pneumatic reservoir. It consists of a nitrogen filler valve and pressure gauge.

Auxiliary Pneumatic Reservoir Relief Valve

The auxiliary pneumatic reservoir relief valve, adjacent to the auxiliary pneumatic reservoir, is connected to the reservoir outlet port. It is a spring-loaded poppet valve that prevents overpressurization of the auxiliary pneumatic reservoir. Valve cracking pressure is 4,500 psi; full flow occurs at 5,100 psi. The valve reseats when the auxiliary pneumatic pressure drops to 4,100 psi.

Auxiliary Pressure Reducer

The auxiliary pressure reducer, located downstream of the auxiliary pneumatic reservoir, reduces pneumatic pressure (to 325 psi) applied to the auxiliary unlock pneumatic release valve.

Auxiliary Unlock Pneumatic Release Valve

The auxiliary unlock pneumatic release valve, aft of the canopy, is a lever-operated shutoff valve that is connected by a cable-and-pulley assembly to the canopy control handle in the pilot and NFO stations. It is a two-position valve operated by an eccentric cam mechanism and detented to main-tain the open position. An internal vent releases pneumatic pressure when the auxiliary mode is not selected. When the auxiliary mode is selected to unlock the canopy, the vent port is blocked to per-mit pneumatic pressure application to the un-lock shuttle valve. After each auxiliary mode operation, the cam must be reset manually to return the system to normal.

Unlock Shuttle Valve

The unlock shuttle valve, aft of the canopy, is a three-port, pressure-operated valve. An in-ternal spool is shuttled by pneumatic pressure at either end of the valve housing to block one of the two end inlet ports. When the canopy control handle is moved to the OPEN position, pneumatic pressure flows from the canopy pneumatic control module, through the shuttle valve and the unlock actuator restrictor, to the unlock side of the canopy-lock pneumatic actuator. In the auxiliary mode (AUX OPEN), auxiliary pneumatic pressure shuttles the valve spool in the opposite direction to route auxiliary pneumatic flow from the auxiliary unlock release valve to the unlock end of the canopy-lock pneumatic actuator.