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A320: 1 Pack on if EXTRACT OVRD ON?

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Old 12th March 2009 | 00:10
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A320: 1 Pack on if EXTRACT OVRD ON?

Hi guys,

I seem to remember we had to have at least one a/c pack on if you selected the EXTRACT pushbutton to OVRD, to aid cooling of the E&E bay. I can't seem to find any reference for this.

Does someone know where this is written down?

Many thanks,

Bbow
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Old 12th March 2009 | 06:48
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Originally Posted by Bbow
Does someone know where this is written down?
FCOM 1.21.30 P6
BLOWER FAULT or EXTRACT FAULT warning

When the BLOWER or the EXTRACT pushbutton is set to OVRD (override)
position, the system is in closed-circuit configuration and adds the air from the air conditioning
system
to the ventilation air.
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Old 12th March 2009 | 23:37
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Hi IFixplanes,

I noticed that bit in the FCOM, thanks for the copy/paste. Just to clarify, does this mean that you actually need to have at least 1 pack on?

I pressume this air gets fed through the Air Con inlet V/V, from the AirCon Duct? And this Duct is obviously downstream of the packs?
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Old 13th March 2009 | 10:12
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Yes, normally on the ground with OAT above about zero, air is drawn in from outside, and then exhausted overboard with two fans and two valves. If any of these fail, then air is drawn from the air conditioning system, downstream of the pack valves. ( The air upstream of the pack valves is too hot!)
This means that there are limits for how long you can have the aircraft powered with a AEVC failure with no packs running.
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Old 13th March 2009 | 17:58
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As you can see (on the already mentioned FCOM page) the system is in the closed circuit configuration and in addition the air it is in a (i would call it) closed loop. No air from the avionic bay area and no air to the cargo underfloor area. No system is 100% leakfree, so you have to add air.

Originally Posted by Bbow
... I pressume this air gets fed through the Air Con inlet V/V, from the AirCon Duct? And this Duct is obviously downstream of the packs? ...
The conditioned air inlet valve is installed in a duct which is connected to the cockpit main supply duct.

Location:


Edit: image added

Last edited by IFixPlanes; 13th March 2009 at 18:26.
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Old 13th March 2009 | 18:55
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Bbow,

You'll find this information in the MEL (I think it's under Operational Procedures)

Sorry - don't have a MEL reference for you.
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