Start cart running Packs A319/320
 

A319/320.

Occasionally we defer APU bleed air or the entire APU.

Obviously a start cart would be required in this instance. Is there any non published aircraft limitation/suggestions (min/max bleed pressure, time, single pack or two packs, intermittent use, etc.) using the start cart to run the packs? (running the pack/packs to cool the cabin while boarding)

Is anybody familiar with start carts - (general information only - there are probably a hundred variants) How long they can operate at high pressure? If it overheats how long is the cool down? Is there a lower pressure setting to run packs? Is it discouraged to run packs using a cart?

Thanks.

Hi CaptainMongo,

for the first question (if I understood it correctly) you will find the answer in FCOM PRO-SUP-21. For the second one I personally don't know for how long a HP cart can operate before it gets overheated.

It is allowed to run packs on hp pressure cart but it has to be free from oil contamination. Never done it as we usually use LP for a/c

Depends on the kind of "huffer-cart":

Modern, fancy-efficient ones use a diesel-driven air compressor and a holding tank to provide sufficient pressure and flow for an engine start. They are not designed to provide enough constant flow/pressure for prolonged Pack operation.

Turbine APU-style start carts are basically APUs on wheels - and most would have little issue running an air conditioning pack or two...

Digressing a little our airline had a distributed system of high pressure air hoses installed underground at each gate of our 'hottest hub'

These were accessed through a manhole type cover and connected to the aircraft, we used them to run packs and start engines with an inop APU.


It worked okay if not too many aircraft were connected (not nearly as effective as external conditioned air) but if every gate was occupied using the system pressure dropped and it lost its effectiveness.

Sonicbum,

I don't have access to the FCOM PRO-SUP-21, could you please cut/paste or paraphrase the wording.

Thanks,

Wasn't there some limitation that you shouldn't run packs from HP unit due to possible air contamination?

Hi,

see Lantirn reply. That's basically it.

CaptainMongo,

PRO-SUP-21:
"An external HP source may be used for air conditioning, provided the air supply is confirmed to be free from oil contamination."

That's all it says.

Thanks all.