Hawker 800 XP, Pilot Training Manual

Page: 281 / 504

INTRODUCTION
The Hawker 800 XP airplane incorporates a pneumatic system used for supplying engine
bleed air to the air-conditioning system, rudder bias system, hydraulic reservoir pres-
surization, and the pressurization system. The pneumatic system includes several valves,
a pressure regulator and shutoff valve, and operating controls. It also supplies bleed air
to other airplane systems.
DESCRIPTION AND
OPERATION
GENERAL
The pneumatic system receives low-pressure
(LP) and high-pressure (HP) air from both en-
gines when they are running. The bleed air pro-
vides the air supply used by other dependent
systems, which are:
• Air-conditioning system
• Pressurization system
• Rudder bias system
• Hydraulic reservoir pressurization
HP bleed air supplements the LP bleed air at
the mixing valve whenever the bleed-air pres-
sure drops to 27 psi, with the MAIN AIR VLV
switches selected to OPEN. This condition
normally occurs during descent of the air-
plane when the engine rpm is reduced. When
the LP bleed air drops to 27 psi, a pressure
switch causes the HP bleed-air valve to open,
allowing HP air to enter the mixing valve. A
temperature limiter in the mixer valve oper-
ates at 200° C (nominal) to reduce the HP air
bleed. Thus, the LP bleed air is supplemented
VA
LVE
L R
CO BLEED AIR
5
15
20
AIR
CHAPTER 9
PNEUMATICS
Revision 1 9-1
FOR TRAINING PURPOSES ONLY
HAWKER 800 XP PILOT TRAINING MANUAL
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