A319/20/21
 

FROM YOUR EXPERIENCE OF AIRBUS FAMILY ,. .WHEN THE APU IS SUPPLING AIR THROUGH THE PACKS ,DO THE PACK VALVES OPEN STRAIGHT AWAY OR IS THERE A NOTICABLY DELAY BEFORE THE VALVES OPEN.

on a good morning (first flight of the day ) it can take about 20 mins to get a dodgy valve on line, once on line it works fine though , the only solution change it or live with it

They will be slow to open if you switch both packs at once. Select one pack & when open select the other. Not the most reliable of things the A320 FCVs. Often a valve stick in low flow, many people pen this off ( usually LGW) but the valve should be replaced ASAP in case the other valve fails.

As long as the packs are left selected 'on'when the final shutdown checks are done,then the next apu air 'on' selection will start the packs in a 1 then 2 delayed sequence(10secs).. .My outfit used to select the packs 'off' at the end of the day,the early morning start up was a tedious on & off rigmarole,until the temps equalised.. .Airbus'told us that with the "new" software the packs should be always left 'on',this has cured it for us in most cases.

Have been involved with similar problems regarding Pack problems especially on first flight of the day on the 319. There is a simple mod which has been designed to improve the reliability of the air conditioning system and is being incorporated on the BA fleet. It involves the removal of a sense line & fitment of a blanking plug at the FCV. Once this has been accomplished, the existing valves can then later be interchanged with an improved, later spec assy.

Yep, also had experience of this. I seem to remember that there is a TFU from Airbus about it and I believe the valves are being mod'ed. As far as I can remember the valves worked a lot better after the mod. If you are replacing the valves watch out, everyone I changed had damaged threads on one of the sense line connections so had to change that as well !

Sure you're not confusing sticky acm's with reluctant pack valves? Does the valve indicate 'open' but the pack is silent? The acm's can be a bitch to get started up first flight of the day - often a bit of apu boost on the eiu (or pulling the zone cntrlr cb's) to get a bit more chuff from the apu & some juggling of pack valve switches will get them going tho'.. .If the pack overheats with the pack valves 'on' its a stuck acm.. .As an aside, if you've got pfcv position indication probs - try a new sdac first. Might save a lot of grief.