air bleed A 320

[avionneta]

hello,
according to MMEL you can dispatch without any restrictions any A320 showing a maintenance message on the status page EXCEPT when the maintenance is AIR BLEED
then you have to apply the operational procedure that wants you to take-off bleeds off ONLY if you feeds the packs with the APU.
the reason of the preceding is a bit obscure to me !!

[františek dobrota]

If I remeber MEL correctly, it is true only at high altitude airports.

[františek dobrota]

FYI
http://www.ukazto.com/img/1645929,airbleed..jpg

[gearpins]

Normal ops:when apu bleed selected on the eng bleed valves auto close.
since with maint msg air bleed cannot assure the same we select the bleeds off manually.:)

[CAT3C AUTOLAND]

františek dobrota, think you are right. We had this on Dispatch from LHR the other day. That operational procedure is for airfields with Pressure Altitude of 8000ft or more.

[avionneta]

sorry guys, but there is a OR between the two cases of the mel

[Johnman]

I can't see where the confusion is .It looks clear to me.

[avionneta]

I'm happy for you

[františek dobrota]

sorry guys, but there is a OR between the two cases of the mel

Yes, you are right. A/C can be dispatched under this MEL with no operational procedure I.A.W. a) if airport elevation is less than 8000'
OR
under b) can be dispatched with procedure without airport elevation restriction (FM limit 9200' ?).

My explanation: STS AIR BLEED is displayed, if some of CLASS 2 failure is present in BLEED system (more than 40 possible faults generate this message).It means higher possibility of automatic apu bleed valve closure during take off. In that case engine bleed valves reopens automatically, as function of normal logic. Such condition can significantly change engine parameters, especially at high altitude. I cannot confirm this idea by docs, unfortunately. Any other idea? (Sorry for my English)

[naceur]

I really prefer t/o packs off, apu bleed off.
when t/o with apu bleed on feeding the packs if a problem occurs to that apu bleed, engine bleed will take over and the ears will suffer.

[avionneta]

@ františek dobrota
it's an interesting track i've been told by other pilots too.
the two cases of the MEL probably responds to different failures ?
apu bleed take-off is probably synonymous of high temperature (that justifies the use of APU) and poor thrust with limitation. a situation that doesn't allow any failure in the apu bleed during take-off.
the right explanation of those two cases are still unknown anyway if if we might have good clues

[Don Coyote]

The two cases of the MEL do not apply to different failures, just different conditions.

I totally agree with the view of františek dobrota.