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View Full Version : A320: 1 Pack on if EXTRACT OVRD ON?

Bbow
12th Mar 2009, 00:10
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
IFixPlanes
12th Mar 2009, 06:48
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.
Bbow
12th Mar 2009, 23:37
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?
Swedish Steve
13th Mar 2009, 10:12
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.
IFixPlanes
13th Mar 2009, 17:58
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.

... 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:
http://img261.imageshack.us/img261/3731/conditionedairinletvalv.th.jpg (http://img261.imageshack.us/my.php?image=conditionedairinletvalv.jpg)

Edit: image added
Eric Janson
13th Mar 2009, 18:55
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.