A320 After ENG SHUT DOWN procedure
 

In procedure it is written that XBLEED should be selected OPEN under conditions one pack off(WING A.ICE ON), FIRE P/B not pressed, perf permits. What is the reason for X-BLEED to be OPEN if no need for WING A.ICE and for ENG RELIGHT? Just always to be ready for icing conditions or for both pack operation or what?
More have I: why XBLEED should be shut if FIRE P/B pressed and no APU bleed?
Thanks

To be able to crank the engine in case of tailpipe fire...

Thanks. Is it for sure or just thinking? And what about SHUT?

...for the event that APU bleed is introduced at some later point (bleed failure? After shutdown?) which would OPEN the XBLEED if it was left in AUTO.

As for opening it if no eng fire, you can run both packs from 1 eng bleed (though not recommended at high altitude, in my experience), so perhaps as well as the reasons you suggest, it is to improve cabin ventilation and/or pressurisation. Just a guess.

ECAM is (quite) clever. It knows that, if you have not pressed the Eng Fire Pb following an eng failure, you have decided on 'No Damage'. Therefore it is fine for the Status Page to suggest:

''If Performance Permits.............X-Bleed ON''

This permits the running of both packs from the live eng bleed with the caveat of: ''One Pack Only if WAI ON'' because the remaining eng bleed is not up to running 2 Packs, WAI, probably Eng AI plus all the other pneumatics.

In the event of a failure with damage or a fire, the Eng Fire Pb is pressed and the Status Page will not make the above suggestion because we do not want to run the risk of hot bleed air entering a damaged engine and/or of contamination of bleed air - depends on where and what the damage is.

Caution! If you are considering running the packs from the APU following an eng fail as called for in the Overweight Landing Procedure, pressing the APU Bleed Pb will open the X-Bleed if it is at Auto. Therefore, if Eng1 has failed with damage, we cannot protect it, but if we are considering Eng2, we can use the APU Bleed, but only with the X-Bleed Closed.

Hope that is fairly clear!!

Cheers
mcdhu

Thanks a lot