INTRODUCTION
The airplane pneumatic system consists of two independent engine bleed-air distribution sys-
tems. The bleed-air pneumatic system provides bleed-air for anti-icing, air conditioning and
pressurization.
Low pressure (LP) bleed-air from both en-
gines is used for cabin air conditioning and
pressurization. High pressure (HP) bleed-air
is automatically used on an as-needed basis for
pressurization when demand is high or LP
bleed-air supply is low. The bleed-air sup-
plied by a single engine is capable of provid-
ing all normal bleed-air needs.
HP bleed-air is also used for anti-icing of the
wings, horizontal stabilizer and the engine
nacelle inlets. A small amount of HP bleed air
is also used to pressurize the hydraulic reser-
voir, for CPCS jet pump operation, and as a
servo air source for operation of some valves
in the pneumatic system.
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