PNEUMATICS
AIR CONDITIONING
AND PRESSURIZATION
AIRPLANE
OPERATIONS
MANUAL
2-14-10
Page
6
Code
01
REVISION 38
AOM-145/1114
AIR CONDITIONING DISTRIBUTION
The air conditioning distribution system provides conditioned air to the
cockpit and passenger cabin.
The main source of conditioned air to the cockpit is the left pack, with
a single distribution system for cooling or heating air.
The cockpit is provided with two FEET AIR handles and air outlets,
allowing each pilot to individually control the airflow.
For CRT displays ventilation, a shutoff valve on each side, electrically-
driven and independently controlled by a thermal switch, allows cold
air to be supplied for this function only.
The main source of conditioned air to the passenger cabin is the right
pack and partially by the left pack, through a cross connection duct.
The air distribution system for the passenger cabin is divided into three
lines. One line is distributed to the lower ducts, installed at the foot
level on both cabin sidewalls. The second line is for the upper ducts of
both sidewalls. The third line is dedicated to the gasper. If the duct
temperature is below 24°C (75°F), the associated temperature
switches command the recirculation fans to increase airflow.
The gasper air subsystem provides air to individual air outlets
(gasper), as well as for the rear electronic compartment, oxygen
cylinder compartment and relay box ventilation. The air to the gasper
is provided by a gasper fan and by one branch from the cross
connection of the general distribution system. The gasper fan is similar
to the recirculation fan, but it is operated in normal condition only. One
thermal switch is installed in the branch line to close fresh air in case
of heating condition (above 24°C). In this case, only air from the
gasper fan is available.
The recirculation air subsystem, consists of two recirculation fans, and
is usually operated to save the engine bleed. It must be kept off should
there be smoke in the cabin, or on hot days while on the ground. This
reduces the pull-down period and should be turned on in cold soak
conditions to reduce pull-up period.
The operational logic to open the Engine Bleed, Cross-bleed, APU
Bleed, and Pack Valves will be analyzed herein separately, for better
system comprehension. This system also actuates on the Anti-icing
System Valves. For further information, refer to Section 2-15 - Ice and
Rain Protection.
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