NORMAL OPENING MODE
position, pneumatic pressure flows from the canopy
pneumatic control module, through the shuttle valve
Setting the pilot canopy control handle to OPEN
and the unlock actuator restrictor, to the unlock side of
pulls the lock pin and positions valves no. 1, 2, and 6
the canopy-lock pneumatic actuator. In the auxiliary
within the control module. This directs nitrogen (325
mode (AUX OPEN), auxiliary pneumatic pressure
psi), through the C1 and C3 ports of the module, to the
shuttles the valve spool in the opposite direction to
timer check valve and unlock port of the canopy lock
route auxiliary pneumatic flow from the auxiliary
pneumatic actuator. Simultaneously, the shutoff valves
unlock release valve to the unlock end of the
in the open and close modules of the canopy hydraulic
canopy-unlock release valve to the unlock end of the
actuator are vented to atmosphere through the C5 port
canopy-lock pneumatic actuator.
of the actuator, through the canopy pneumatic timer,
and through valve no. 3 in the control module. The lock
LOCK ACTUATOR CHECK VALVE
port of the canopy lock pneumatic actuator is vented
The lock actuator check valve (fig. 3-1, Item G)
overboard through the pneumatic timer; the piston of
prevents nitrogen from venting overboard during the
the actuator extends and, by means of torque tube,
canopy normal closing and holding modes.
cranks, and links, moves the canopy aft to unlock it
from the still locks. When the extending piston reaches
Q3-3. The canopy is made of what type of material?
the end of its stroke, ball locks engage to hold it in that
Q3-4. How is the canopy actuator locked?
position. The extended piston also actuates the timer
check valve, which directs the 325-psi nitrogen to the
Q3-5. Describe the function of the lock actuator
C1 port of the canopy hydraulic actuator. The nitrogen
restrictor.
that enters the hydraulic actuator acts against the piston
Q3-6. At what pressure does the low-pressure
of the open transfer cylinder. This pressure, acting
sensor cause the module valves to lock the
against the piston, causes the hydraulic fluid on the
remaining pressure in the canopy hydraulic
opposite side of the piston to extend the actuator. The
actuator?
extending actuator rotates the canopy on the aft hinge to
open the canopy. As the actuator extends, fluid
Q3-7. The canopy pneumatic reservoir is (a) what
displaced from the close side of the actuator acts
cubic capacity and (b) serviced to what psi?
against the piston of the close transfer cylinder. The
Q3-8. What item prevents overpressurization of the
nitrogen on the opposite side of this piston is vented
reservoir?
overboard through the C2 port of the hydraulic actuator
and through valve no. 4 of the control module. Pulling
Q3-9. Where is the auxiliary pressure reducer?
the lock pin at the beginning of the opening cycle closes
Q3-10.
What type of valve is the unlock shuttle valve?
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
OPERATION
canopy caution indicator light on the pilot and NFO
LEARNING OBJECTIVE: Describe the
CAUTION ADVISORY indicators.
modes of operation of the pneumatic canopy
system.
HOLDING MODE
The canopy pneumatic system is operated by
The HOLD position stops canopy motion at any
setting any one of the three canopy control handles,
desired opening. Valve no. 3 in the control module
which positions valves within the pneumatic control
directs 325-psi nitrogen through the C5 port of the
module to route pneumatic pressure to or from the
module, through the pneumatic timer to the C5 port of
system. The modes of operation that can be selected
the hydraulic actuator. The nitrogen that enters the C5
are: normal opening mode, holding mode, normal
port closes the shutoff valves in the open and close
closing mode, boost closing mode, and auxiliary
modules. The closed shutoff valves trap hydraulic fluid
opening mode. The function of all three control handles
on the open and close side of the actuator piston,
is the same; the following modes describe the operation
stopping piston travel.
using the pilot handle.
3-4
