Figure 12-42.--Ram air turbine-control system schematic.
then compressed further to the required pressure for
operating the system. Compressors of this type are
capable of maintaining up to and above 3,000 psi
pressure during flight.
On some aircraft, the compressor is operated by an
electric motor. On others, a hydraulic motor is used to
drive the compressor. Compressors must be serviced
with oil periodically, as outlined in the aircraft MIM.
An oil level sight gauge is provided on the compressor
(fig. 12-43).
AIR FILTERS.--An air filter is usually located in
t h e l i n e l e a d i n g i n t o t h e s y s t e m c o m p r e s s o r.
Additional filters may be located at various points in
the system lines to remove any foreign matter that may
enter the system.
Like hydraulic filters, air filters have a removable
element and a built-in relief valve. The relief valve is
Figure 12-43.--Air compressor.
designed to open and bypass the air supply around the
filter element should the element become clogged.
compressor; however, it may be incorporated within
Some air filters are equipped with the micronic-type
the system moisture separator. Its purpose is to
element, which must be replaced periodically. Others
regulate the pressure of the supply air before it enters
have the screen mesh type, which requires periodic
the system compressor. The pressure regulator
cleaning. The latter type may be reinstalled after
maintains a stable outlet pressure regardless of the inlet
cleaning and drying.
pressure.
AIR PRESSURE REGULATORS.--A pressure
MOISTURE SEPARATORS.--The moisture
regulator is generally located in the line between the
separator in a pneumatic system is always located
engine compressor and the pneumatic system
downstream of the compressor. Its purpose is to
12-41
