In flight, what is the primary bleed souce?
Engine Bleed
What are the 2 compressor stages from the engines? Which stage is primary?
- Intermediate pressure stage (IP)
- High pressure stage (HP)
In flight IP stage is primary. HP stage only used when insufficent IP air such as engine at idle
What prevents HP air from entering the IP stage?
Check Valve
What stops HP air from entering system?
The High Pressure Valve
Can HP and IP air be used at the same time?
NEVER, always one OR the other
Where does air from either the HP or IP stage go?
Enters a common engine bleed valve which is also a shutoff and pressure regulating device. This valve can be controlled from the cockpit.
Can APU used for bleed air?
Yes, limited to 20,000 ft. The APU is the primary bleed source when the APU is running. Eng bleed valves close.
What system controls and monitors the pnumatic system?
BMC - Bleed Monitoring Computers. One for each engine bleed system. BMC 1 also controlls APU bleed.
Where are bleed leak detection loops installed?
- APU Ducting
- Eng Pylon Ducting
- Wing Ducting
If a leak is detected…
Signal sent to BMC wich will isolate the area and alert the crew via ECAM
How do the leak detection loops work?
Two independent loops installed and monitored by the BMCs. BOTH loops must sense heat rise before alert is sent. If one loop inop, a single loop will alert.
Closing an engine bleed valve…
- Shuts down associated pack
- Closes HP valve
Name the conditions under which the BMC would automatically close an engine bleed valve.
- Overtemp
- Over pressure
- Bleed leak detected
- Eng start sequence commanded
- APU bleed selected on
What position do the ENG bleed valves fail?
Fail closed. Spring loaded to close when engine not running or if reverse pressure sensed.
Can a single bleed supply both packs and anti-ice at the same time?
NO - if anti-ice is needed, one pack must be shut down.