The pressure transmitter senses the bleed-air pres-
sure in the duct upstream from the bleed-air flow
control and shutoff valve. The pressure transmitter
transmits the pressure indication to the bleed-air
pressure indicator on the environmental panel.
Learning Objective: Identify the operating
principles and components of an air-
The air-conditioning system consists of two
subsystems: refrigeration and cabin temperature
control. These subsystems and their components
are discussed in the following paragraphs.
The refrigeration subsystem, shown in figure
4-6, consists of two physically separated packages:
refrigeration and cabin air/water separator. The
refrigeration subsystem operates on bleed air,
which is temperature and pressure regulated.
Passage through the ram air-cooled heat
exchanger reduces the bleed-air temperature to
Figure 4-6.-Refrigeration subsystem schematic.