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Bleed Air
Engine bleed air
Taken from both the 5th (low pressure) and 9th (high pressure) stages in order to regulate the pressure and temperature for different power settings. A low stage bleed check valve prevents 9th stage air back-pressuring the 5th stage. The high stage bleed valve regulates bleed air at low power settings, and the engine bleed valve regulates bleed air at high power settings. Temperature is regulated through a precooler.
Note that the E170LR takes air from the 6th and 10th stages.
The engine bleed valve opens automatically when:
- respective bleed switch is AUTO
- respective engine bleed is available
- no fire is detected in the respective engine
- no bleed duct leak is detected
APU bleed air
A check valve prevents back-pressuring the APU when engines are running. APU bleed air cannot be used for anti-ice system operation inflight.
The APU bleed valve opens automatically when:
- APU bleed switch is AUTO
- APU bleed is available
- no APU and left bleed duct leak is detected
- left engine bleed is unavailable
- anti-ice system is not requested, or is requested on but failed
The APU bleed air is prioritised by the AMS controller when:
- engine bleed pressure is below the minimum for start
- on the ground
- ground speed <50kt
- altitude <15,000'
- APU bleed is available
- the crossbleed valve is operating normally
Schematic
