Hawker Beechcraft Hawker 800XP, Руководство по эксплуатации для пилотов

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Page 10-3
Pilot’s Operating Manual
Revision A1: Nov, 2002
Sub-section 10
ENVIRONMENTAL
Hawker 800XP Pro Line 21
Section III - SYSTEMS DESCRIPTION
GENERAL
Bleed air is tapped from both engines and conditioned to acceptable temperature levels by an air
conditioning pack incorporating a three-wheel air cycle machine. Conditioned air is ducted to the flight
compartment and passenger cabin to provide ventilation, heating and pressurization. Temperature
levels, set manually, are automatically controlled.
Pneumatic controls automatically maintain required pressurization (cabin altitude) while manual
controls provide emergency selections of air conditioning and pressurization. On the ground,
conditioned air is supplied by the APU (if installed) and the air cycle machine when the main engines
are not running.
BLEED AIR SYSTEM
ENGINE AIR BLEED
Bleed air from each engine enters the rear equipment bay via two ducts in each pylon. Low Pressure
(LP) air is ducted from a flow limiting venturi to a mixing valve. When both Main Air Valves (MAV) are
selected open, High Pressure (HP) air is ducted from a flow limiting venturi to a solenoid-operated shut-
off valve then to the mixing valve.
MIXING VALVE
The mixing valve regulates HP air (when it is demanded by LP air low pressure) and mixes the HP and
LP air supplies to maintain at the outlet of the valve a minimum pressure of 20 psi and limits the
temperature to approximately 270° C.
The amount of HP air used is dependent on the LP air pressure available. When the LP air pressure
falls to 30 psi, the HP valve is opened but the mixing valve does not mix any HP air into the system until
the LP air pressure falls to 22 psi and below.
MAIN AIR VALVE
Air from each mixing valve is fed through an electrically actuated main air valve (MAV) and a non return
valve (NRV) into a common supply duct. The MAV and HP valve selections are made by means of two
switches, MAIN AIR VLV 1 and MAIN AIR VLV 2, on the overhead roof panel.
The switch selections of CLOSE, LP and OPEN affect the system as follows:
• CLOSE - MAV and HP valve are both selected closed.
• LP ON - MAV selected open and HP valve selected closed.
• OPEN - MAV selected open.
HP valve ‘armed’ but the valve position is controlled by the LP duct pressure switch.