pneumatically controlled canopy hydraulic ac-
tuator opens and closes the canopy. A canopy-
lock pneumatic actuator moves the canopy to the
locked or unlocked position. The canopy is locked
in the closed position by locking hooks that
engage latches on the cockpit sill. An inflatable
rubber seal in the canopy frame forms a pressure-
tight enclosure when the canopy is closed and
locked. Three rearview mirrors are mounted on
the pilot’s forward canopy frame and one on the
naval flight officer’s (NFO) forward canopy
frame. The canopy can be jettisoned for an
emergency on the ground and during the ejection
sequence.
The clamshell canopy pneumatic system
provides normal opening and closing of the
canopy. The system is controlled with the canopy
control handle at each crew station or with the
external canopy control handle on the fuselage left
side. Pneumatic pressure from externally serviced
reservoirs supply the power for the different
modes of canopy operation. The canopy can also
be manually opened and closed. A reference mark
is painted on the fuselage and canopy, and when
the canopy is closed and locked, the marks are
aligned.
SYSTEM OPERATION
The F-14 aircraft uses the clamshell canopy
system. This pneumatic system is operated by
setting any one of the three canopy control
handles, This action positions valves within the
pneumatic control module to route pneumatic
pressure to or from the system. The modes of
operation that can be selected are normal opening
mode, holding mode, normal closing mode, boost
closing mode, and auxiliary opening mode. The
function of all three control handles is the same.
Normal Opening Mode
Figure 2-2 (a foldout at the end of this chapter)
shows a schematic of the F-14 pneumatic canopy
system. Setting the pilot canopy control handle
to open pulls the lock lockpin and positions valves
No. 1,2, and 6 within the control module to direct
nitrogen at 325 psi through the C 1 and C3 ports
of the module, to the timer check valve, and to
the unlock port of the canopy-lock pneumatic
actuator. Simultaneously, the shutoff valves in the
open and close modules of the canopy hydraulic
actuator are vented to the atmosphere through the
C5 port of the actuator, through the canopy
pneumatic timer, and through valve No. 3 in the
control module. The lock port of the canopy-lock
pneumatic actuator is vented overboard through
the pneumatic timer. The piston of the actuator
extends and, by means of a torque tube, cranks,
and links, moves the canopy aft to unlock it from
the sill locks. When the extending piston reaches
the end of its stroke, ball locks engage to hold
it in that position. The extended piston also
actuates the timer check valve, which directs the
325-psi nitrogen to the C1 port of the canopy
hydraulic actuator. The nitrogen that enters the
hydraulic actuator acts against the piston of the
open transfer cylinder. This pressure, acting
against the piston, causes the hydraulic fluid on
the opposite side of the piston to extend the ac-
tuator. The extending actuator rotates the canopy
on the aft hinge to open the canopy. As the ac-
tuator extends, fluid displaced from the close side
of the actuator acts against the piston of the close
transfer cylinder. The nitrogen on the opposite
side of this piston is vented overboard through
the C2 port of the hydraulic actuator and through
valve No. 4 of the control module. Pulling the
lock lockpin at the beginning of the opening cycle
closes the canopy switch, which provides 28 volts
from the essential dc No. 2 bus, through the
CAN/LAD CAUTION/EJECT CMD IND
circuit breaker, to the canopy caution indicator
light on the pilot and NFO caution advisory
indicators.
Holding Mode
The HOLD position stops canopy motion at
any desired opening. Valve No. 3 in the control
module directs 325-psi nitrogen through the C5
port of the module, through the pneumatic timer,
to the C5 port of the hydraulic actuator. The
nitrogen that enters the C5 port closes the shutoff
valves in the open and close modules. The closed
shutoff valves trap hydraulic fluid on the open
and close side of the actuator piston, stopping
piston travel.
Normal Closing Mode
Setting the control handle to CLOSE positions
valves No. 1, 2, 4, and 5 in the control module
2-2
