dry nitrogen for unlocking the canopy in the auxiliary
CANOPY PNEUMATIC CONTROL MODULE
mode. The reservoir is serviced, through the filler
The canopy pneumatic control module (fig. 3-1,
manifold, to 3,000 psi.
Item C) regulates pressure from the canopy pneumatic
Auxiliary Pneumatic Reservoir Filler Manifold
reservoir and directs it to the canopy pneumatic timer,
the timer check valve, canopy hydraulic actuator, and
The auxiliary pneumatic reservoir filler manifold
the canopy-lock pneumatic actuator. The module
(fig. 3-1, Item J) is connected to the auxiliary
contains a filter, a restrictor, two pressure reducers, two
pneumatic reservoir. It consists of a nitrogen filler valve
relief valves, a low-pressure sensor, and control valves.
and pressure gauge.
If canopy pneumatic reservoir pressure drops below
225 pounds per square inch (psi), the low-pressure
Auxiliary Pneumatic Reservoir Relief Valve
sensor causes the module valves to lock the remaining
pressure in the canopy hydraulic actuator to
The auxiliary pneumatic reservoir relief valve (fig.
counterbalance the weight of the canopy. Canopy
3-1, Item H), adjacent to the auxiliary pneumatic
unlocking is done by the auxiliary unlock mode.
reservoir, is connected to the reserve outlet port. It is a
spring-loaded poppet valve that prevents over-
CANOPY PNEUMATIC RESERVOIR
Valve cracking pressure is 4,500 pounds per square
The canopy pneumatic reservoir (fig. 3-1, Item A)
inch gauge (psig); full flow occurs at 5,100 psig. The
stores high-pressure dry nitrogen for operation of the
valve reseats when the auxiliary pneumatic pressure
canopy pneumatic system. The reservoir is serviced to
drops to 4,100 psig.
3,000 psi; it has a 225-cubic inch capacity. Servicing is
done through the pneumatic servicing charging
Auxiliary Pressure Reducer
module, which is remote from the reservoir.
The reservoir relief valve (fig. 3-1, Item A), on the
The auxiliary pressure reducer (fig. 3-1, Item H) is
canopy pneumatic reservoir, prevents overpressuriza-
downstream of the auxiliary pneumatic reservoir. It
tion of the reservoir. The valve opens at 4,500 psi and
reduces pneumatic pressure to 760 ± 30 psi applied to
reseats at 4,100 psi.
the auxiliary unlock pneumatic release valve.
PNEUMATIC SERVICING CHARGING
Auxiliary Unlock Pneumatic Release Valve
The auxiliary unlock pneumatic release valve (fig.
The pneumatic servicing charging module contains
3-1, Item G) is a lever-operated shutoff valve that is
a filler valve, a filter, two check valves, and two
connected by a cable and pulley assembly to the canopy
pressure gauges. The filler valve enables filling both the
control handle in the pilot and NFO stations. It is a
canopy pneumatic reservoir and the emergency landing
gear reservoir from a single point. The check valve
which maintains it in the open position. An internal
prevents reverse flow when one reservoir has a lower
vent releases pneumatic pressure when the auxiliary
pressure than the other.
mode is not selected. When the auxiliary mode is
selected to unlock the canopy, the vent port is blocked
to permit pneumatic pressure application to unlock
shuttle valve. After each auxiliary mode operation, the
The canopy switch (fig. 3-1, Item G) is actuated by
cam must be reset manually to return the system to
the canopy locking mechanism lock pin. The switch
closes when the canopy unlocks. This completes a
circuit to the canopy caution indicator lights on the pilot
UNLOCK SHUTTLE VALVE
and NFO caution advisory indicators. When the canopy
locks, the switch opens.
The unlock shuttle valve (fig. 3-1, Item G) is a
three-port, pressure-operated valve. An internal spool
AUXILIARY PNEUMATIC RESERVOIR
is shuttled by pneumatic pressure at either end of the
valve housing to block one of the two end inlet ports.
The auxiliary pneumatic reservoir (fig. 3-1, Item H)
When the canopy control handle is moved to the OPEN
has a 14.6-cubic-inch capacity. It stores high-pressure