Copyright D.P. Browne 2011
Pneumatics Bleed Air System
Pre Cooler
Eng 2 Bleed Valve
HP Valve
Cross Feed Valve
APU
Bleed
Air
Ground
cart
Bleed
Air
Eng 1 IP Air
Eng 1 HP Air
Eng 2 IP Air
Eng 2 HP Air
Pressurized air, from the engines, APU or ground service cart, is supplied for air
conditioning, air starting, wing anti-
The bleed air system is electrically controlled by the Bleed Monitoring Computers (BMC). These BMCs, are interfaced to the flight crew via the air overhead panel.
The bleed air sources are :
Engine 1 bleed air
Engine 2 bleed air
APU bleed air
Ground air from a ground cart
The APU bleed air supply has priority. If the APU bleed air is selected then the APU provides bleed air to the aircraft. When the engines are running, they supply bleed air to the pre cooler. If the engine low pressure bleed is insufficient, the BMC will open the High pressure bleed valve as well. The low pressure bleed air from the engine is annotated as IP air and the high pressure bleed from the engine is annotated as HP air.
A cross bleed valve separates the left and right sides of the bleed system. The cross feed valve is controlled by the BMC when the cross bleed valve selector on the over head panel is set to AUTO.
When ground air is supplying the aircraft, the APU bleed air must not be used, in case it damages either the APU bleed air components or the ground air components, since they are connected in series.
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