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Engine Bleed System
Air is bled from 2 compressor stages: the IP port (8th stage) and the HP port (6th stage). A HP valve can cut off bleed air from the HP port. This is automatically controlled by the system, as HP air is only used when IP air pressure is insufficient (ie. engines at idle). The combined IP/HP air from the compressor then goes to a bleed valve which acts as a shutoff valve and PRV, then through a pre-cooler (which uses engine fan air to regulate temperature to 200°C). The temperature may be regulated to 150°C when wing anti-ice is off.
Normal pressure is 44 to 52 psi. There is overpressure protection provided by the OPV, which closes at > 85 psi.
The engines 1 and 2 systems are connected via a crossbleed duct which has a crossbleed valve. APU bleed air and external GPU air connect to the left (#1) side of the duct.
Bleed valves are electrically controlled by their BMC and pneumatically operated.
Failures
If, for example, an overheat is detected in the engine bleed air duct, the engine bleed valve is automatically closed by the BMC, and the ECAM automatically displays the bleed page on the S/D. AIR ENG 1(2) BLEED FAULT will be displayed on the E/WD. To use wing anti-ice, one pack will need to be switched off.
If a leak was detected, AIR L(R) WING LEAK is displayed. In this case the crossbleed valve is closed to isolate the two sides of the duct, and wing anti-ice cannot be used.