TEMP control may have to be adjusted periodically to
pressure relief valve begins to open at 10 psi and is fully
maintain desired temperature. Also, in this mode the
open at 18 psi.
vent suit system can be operated in a wider temperature
Vent Suit Air Hose Assembly
range.
Q5-23.
A vent-air system is used for what purpose?
The air hose assembly located on the left console is
made up of a manual flow control and a vent suit
Q5-24.
Where is the vent suit temperature sensor
disconnect. The manual flow control allows the pilot to
located?
manually regulate airflow entering the vent suit through
Q5-25.
Identify the six major components of a
the vent suit disconnect.
vent-air system.
OPERATION
Q5-26.
What are the two modes of operation for a
vent-air system?
The F-18 vent suit system operates when the air
cycle air-conditioning system is on. Vent suit system
RADAR LIQUID COOLING SYSTEM
operation is switched from automatic to manual when
the environmental control system (ECS) MODE switch
LEARNING OBJECTIVE: Describe the
on the ECS panel assembly (fig. 5-17) is set from
radar liquid cooling system and its compo-
AUTO to MAN.
nents.
The F-18 aircraft radar liquid cooling system (fig.
Automatic Mode
5-18) circulates liquid coolant to remove heat from the
radar transmitter high-voltage RF energy modules.
When the ECS MODE switch is in AUTO position,
Coolant heated by the transmitter is routed through a
the ACS temperature/flow controller modulates the
closed loop system to a heat exchanger. The heat
vent suit temperature control valve as required to
exchanger converts heated coolant to cooling air. A
maintain a constant temperature in the vent suit sensor
temperature control valve is integral to the heat
manifold. The vent suit temperature sensor signals the
exchanger to maintain a minimum coolant temperature
controller if manifold temperature changes and the
level. One of the three sources of air is induced across
controller makes torque motor current adjustments to
the heat exchanger to provide coolant temperature
the temperature valve accordingly. In this mode, the
control. During normal flight operations, ram air is
temperature selected on the SUIT TEMP control is
induced across the heat exchanger by an electrically
maintained without manual adjustments.
powered ram air scoop. At high ram air temperature
conditions (hot day-low altitude or high speed-high
Manual Mode
altitude), the ram air scoop is closed by a signal from
the air data computer (ADC), and conditioned air from
When the ECS MODE switch is in MAN position,
the ACS is delivered to the heat exchanger. For ground
the ACS temperature/flow controller adjusts and holds
operation, with aircraft weight on wheels, a cooling
the vent suit temperature valve torque motor in position
fan supplies cooling air to the heat exchanger.
determined by the SUIT TEMP control knob. In this
When cooling air is supplied from the ACS, a
mode, input from the vent suit temperature sensor is not
coolant temperature sensor operates through the
used by the ACS temperature/flow controller and SUIT
Figure 5-17.--ECS panel assembly, ECS MODE switch suit/cabin temp control.
5-16
