WINDSHIELD ANTI-ICE/RAIN
During normal operation of the anti-icing system,
REMOVAL SYSTEM
all four-engine bleed air valves are open to supply bleed
air to the cross-ship manifold, and both fuselage bleed
LEARNING OBJECTIVE: Recognize the
air shutoff valves are closed. The modulating valves,
components and operating principles for a
which are controlled by pneumatic thermostats,
windshield anti-ice/rain removal system.
maintain a controlled flow of bleed air to the leading
This system is designed to provide a means of
edge distribution system. The complete system is
maintaining visibility from the aircraft. The F-18
monitored for hot spots by heat-sensing switches.
windshield anti-ice/rain removal system is typical of
systems found in jet aircraft. This system supplies
Before flight, the anti-icing manifold system may
controlled temperature air from the air cycle
be tested for leakage. This leak test is performed by
air-conditioning system (ACS) to provide airflow over
pressurizing the system: OPEN the No. 4 engine bleed
the external surface of the windshield for rain removal
air valve; the Nos. 1, 2, and 3 engine bleed air valves
and windshield anti-icing.
remain CLOSED, and both fuselage shutoff valves are
in the OPEN position. When the bleed air pressure on
COMPONENTS
the bleed air manifold reads 70 psi, the No. 4 engine
Components of the windshield anti-ice/rain
bleed air valve is closed and the leak test switch is
removal system include a warm air temperature control
actuated. As the bleed air pressure drops, the
valve, temperature sensors, a flow/temperature limiting
time-delay relay will illuminate the ACCEPT light after
anti-ice modulating valve, an air control regulating
an 8-second delay if the system is tight. The light will
valve, and an anti-ice/rain removal switch.
go out when the test switch is released.
Warm Air Temperature Control Valve
Q5-7. Describe the difference between an anti-icing
The warm air temperature control valve operates to
system and a deicing system.
control temperature entering the windshield anti-ice
Q5-8. In an anti-ice system, what method(s) are
and rain removal ducts. The valve is modulated by
used to remove ice formation?
muscle pressure, which is controlled by the warm air
temperature sensor.
Q5-9. Identify the four major components of a P-3
anti-ice system.
Warm Air Temperature Sensor
Q5-10.
The OPEN light on the ice protection panel
The warm air temperature sensor (fig. 5-7, item A)
will illuminate when what condition occurs?
is located downstream of the warm air temperature
Figure 5-7.--Windshield anti-ice and rain removal system component locator.
5-9
