REVIEW SUBSET NUMBER 2
selector valve allows the system to pressurize and
run the hydraulic motor. When de-energized, the
Q1. The science of liquid pressure and flow is
valve blocks off hydraulic pressure, stopping the
motor. The flow regulator compensates for the
varying hydraulic system flow and pressures by
metering the fluid flow to the hydraulic motor.
Thus, excessive speed variation and/or over-
Q2. As an AE your primary concern with
spending of the compressor is prevented. A check
valve in the motor bypass line prevents system
return line pressure from entering the motor and
Q3. In a hydraulic system, what unit creates
The air compressor is the pneumatic system's
pressurizing air source. The compressor activation
switch, an integral part of the moisture separator
Q4. What does the hydraulic actuating unit
convert fluid pressure into?
The moisture separator assembly is the
pneumatic system's pressure sensor-regulator and
relief valve. The manifold pressure switch governs
air compressor operation. When manifold
pressure drops below 2,750 PSI, the pressure
Q5. Why does the arresting gear hook relay have
a 1.1 second delay?
sensing switch closes, energizing the separator's
moisture dump valve and hydraulic selector valve,
activating the air compressor. When manifold
pressure reaches 3,150 PSI, the pressure sensing
switch opens, de-energizing the hydraulic selector
Q6. What system provides the pilot with
adequate directional control during ground
valve. The deactivated dump valve vents
overboard any moisture in the separator. The
separator includes a thermostat and heating
e l e m e n t . The thermostatically controlled
wraparound blanket heating element prevents
Q7. During emergency retraction, what is used
to close the speed brake?
moisture from freezing within the reservoir in low-
temperature atmospheric conditions.
The safety fitting, at the moisture separator
inlet port, protects the separator from internal
explosions due to hot carbon particles or flames
on when system pressure drops below what
that the air compressor may emit.
A chemical drier further reduces the moisture
content of the air emerging from the moisture
An air charge valve provides the entire
Learning Objective: Recognize terms,
pneumatic system with a single external ground
definitions, components, and aircraft
servicing point. An air pressure gauge, near the
air charge valve, is for servicing the pneumatic
environmental systems operating principles
system. This gauge shows manifold pressure.
a n d features including controls for
temperature, pressure, and icing.
The ground air charge line air filter prevents
The proper operation of today's aircraft
requires maintaining a proper environment not
the ground servicing power source.