Bleed Air System
Air for the bleed air system can be supplied by the engines, APU, or an external
air cart/source. The APU or external cart supplies air to the bleed air duct prior to
engine start. After engine start, air for the bleed air system is normally supplied by
the engines.
The following systems rely on the bleed air system for operation:
Option - Aspirated TAT
Engine Bleed System Supply
Engine bleed air is obtained from the 5th and 9th stages of the compressor
section. When 5th stage low pressure bleed air is insufficient for the bleed air
system requirements, the high stage valve modulates open to maintain adequate
bleed air pressure. During takeoff, climb, and most cruise conditions, low
pressure bleed air from the 5th stage is adequate and the high stage valve
remains closed.
Engine Bleed Air Valves
The engine bleed air valve acts as a pressure regulator and shutoff valve. With
the engine bleed air switch ON, the valve is DC activated and pressure operated.
The valve maintains proper system operating pressure and reduces bleed air
outflow in response to high bleed air temperature.
Air for the bleed air system can be supplied by the engines, APU, or an external
air cart/source. The APU or external cart supplies air to the bleed air duct prior to
engine start. After engine start, air for the bleed air system is normally supplied by
the engines.
The following systems rely on the bleed air system for operation:
- Air conditioning/pressurization
- Wing and engine thermal anti-icing
- Engine starting
- Hydraulic reservoirs pressurization
- Water tank pressurization
Option - Aspirated TAT
- Aspirated TAT probe
Engine Bleed System Supply
Engine bleed air is obtained from the 5th and 9th stages of the compressor
section. When 5th stage low pressure bleed air is insufficient for the bleed air
system requirements, the high stage valve modulates open to maintain adequate
bleed air pressure. During takeoff, climb, and most cruise conditions, low
pressure bleed air from the 5th stage is adequate and the high stage valve
remains closed.
Engine Bleed Air Valves
The engine bleed air valve acts as a pressure regulator and shutoff valve. With
the engine bleed air switch ON, the valve is DC activated and pressure operated.
The valve maintains proper system operating pressure and reduces bleed air
outflow in response to high bleed air temperature.
