anti-g valve and remains constant until the g forces
As the g forces decrease, the downward force
on the activating weight diminishes to a point at
which the upper spring lifts the weight off the
exhaust valve. The pressure in the suit is then
vented through the exhaust port (fig. 1-4, view C)
into the cockpit.
Anti-G System Filter
Most anti-g systems use a filter to prevent
particles of dust, trash, and other foreign material
from entering the regulating valve. This filter may
be located in the supply line, as shown in figure
1-2, or it may be attached to the anti-g valve on
the inlet side. A typical anti-g system filter is
shown in figure 1-5.
The anti-g suit is connected to the anti-g
system by means of a quick-disconnect coupling.
This quick disconnect may be either a single unit
that connects the anti-g suit only, or it may be
a composite quick disconnect that connects the
pilot to the various personal service lines
(oxygen, ventilating air, anti-g system, and
The anti-g system quick disconnect is used on
aircraft that are not equipped with a composite
quick disconnect attached to the ejection seat.
This disconnect is on a hose that protrudes
through the pilots console. It is attached by a
Figure 1-5.Anti-g system filter.
flexible hose to the outlet port of the anti-g
pressure regulating valve. This disconnect may be l
pulled up to a bumper stop to aid in connecting
the anti-g suit hose. A spring-loaded cover on the
disconnect prevents the entry of foreign material
when the system is not in use.
Anti-g System Maintenance
Maintenance of the anti-g system consists
mainly of removal and installation of valves and
lines and servicing the filter. Component repair
of the anti-g valve is limited because of the equip-
ment necessary to test the valve. Component
repair of the dual range anti-g valve is not
recommended. The single-stage anti-g valve may
be repaired at intermediate maintenance activities
that have the necessary test equipment.
SERVICING. Replace the anti-g filter
element at periodic intervals, or when the element
becomes clogged or dirty. The replacement
interval is specified in the applicable maintenance
requirement cards. If the filter is removed from
the aircraft, ensure the filter is reinstalled
properly. The inlet and outlet ports are identified
as IN and OUT to facilitate installation for
proper direction of airflow. After replacing the
filter element, make a thorough check to ensure
that no air leaks exist.
OPERATIONAL CHECK. Perform an
operational check of the anti-g system with the
aircraft engine running by pressing the test
button on top of the valve to determine if there
is proper airflow from the system. When the test
button is depressed, the amount of airflow from
the disconnect should be proportional to the
amount the button is depressed. Greater airflow
with increased button depression indicates that the
anti-g valve is operating properly on aircraft with
dual range anti-g valves. This test should be
performed in both the high (HI) and low (LO)
Vent-air systems provide a flow of air to the
aircrafts seat or back cushions or to the
ventilating air connection of the antiexposure suit
when worn by the pilot and/or crew members.
The system provides a measure of personal
comfort, offsetting the discomfort caused by the
wearing of the antiexposure suit or heat created