A320: APU BLEED with LP ground air unit?
Thread Starter
Joined: Jul 2006
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From: Somewhere over the rainbow
A320: APU BLEED with LP ground air unit?
Hello everyone,
In the FCOM-PRO-NOR-SOP-04- AIR CON it says:
No doubt about the HP unit, but what about the LP unit connected with APU Bleed ON and packs OFF? Should not be an issue isn't it? Since the LP is connected downstream of the packs.
No bleed No coffee!
Thank you.
In the FCOM-PRO-NOR-SOP-04- AIR CON it says:
Do not use APU BLEED if the ground personnel confirms that a LP or HP ground air unit is connected to the aircraft
No bleed No coffee!
Thank you.
Last edited by pineteam; 21st May 2019 at 15:55. Reason: TYPO
Joined: Mar 2000
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From: Sunrise Senior Living
Are you sure Pineteam?
HP/LP air will pressurise the pneumatic system just the same as the APU bleed would so I think your coffee is safe with Gnd air connected.
Of course, I could be wrong!!
mcdhu
HP/LP air will pressurise the pneumatic system just the same as the APU bleed would so I think your coffee is safe with Gnd air connected.
Of course, I could be wrong!!
mcdhu
Joined: Mar 2012
Posts: 2,605
Likes: 154
From: Having a margarita on the beach
Hello everyone,
In the FCOM-PRO-NOR-SOP-04- AIR CON it says:
No doubt about the HP unit, but what about the LP unit connected with APU Bleed ON and packs OFF? Should not be an issue isn't it? Since the LP is connected downstream of the packs.
No bleed No coffee!
Thank you.
In the FCOM-PRO-NOR-SOP-04- AIR CON it says:
No doubt about the HP unit, but what about the LP unit connected with APU Bleed ON and packs OFF? Should not be an issue isn't it? Since the LP is connected downstream of the packs.
No bleed No coffee!
Thank you.
Joined: Feb 2017
Posts: 1,013
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From: Isla Grande
Joined: Nov 2010
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From: USA
Joined: May 2004
Posts: 496
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From: Ziltoidia... indeed'd.
I believe that is limitation is to prevent the packs from getting contamination from external sources, i.e. the air conditioning from the external unit might carry oil, dust, particles, etc... that might be absorbed by the packs if they are switched on.
And airplane coffee sucks big time.
And airplane coffee sucks big time.
Joined: Jul 2010
Aviation Qualifications: ATPL
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From: Asia
I was informed by an engineer that the HP air cart could run the packs in the absence of APU bleed air but it would soon over heat and there is the issue of contamination as external HP air is meant for engine starting not breathing.
Joined: Mar 2006
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From: USA
I was informed by a pilot that it will indeed run the packs, but after inhaling that air, you won't run them for very long!
Eidolon
Joined: May 2001
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From: Some hole
interesting tidbit, some airports in the US had ground HP air that was reticulated like ground power.
Joined: Nov 2006
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From: Tropics
This shouldn’t be an issue, as Long as the packs are selected OFF with the HP unit on, as the pack valves would be closed.
In fact, at where I work we would be in this configuration whilst performing the Engine Start with External Pneumatic Power procedure. The procedure calls for the Packs to be OFF, before powering up the HP unit. The LP unit would still be connected to the aircraft at this stage to provide Air Conditioning.
In fact, at where I work we would be in this configuration whilst performing the Engine Start with External Pneumatic Power procedure. The procedure calls for the Packs to be OFF, before powering up the HP unit. The LP unit would still be connected to the aircraft at this stage to provide Air Conditioning.
Joined: Nov 1999
Aviation Qualifications: ATPL
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From: UK
We were told that the non return valve in the external LP port will chatter, (i.e. vibrate rapidly), if external LP air and APU bleed are used together; which could reduce the life of the valve.
I can’t see a mention of this now in the FCOM.
.
I can’t see a mention of this now in the FCOM.
.
Last edited by Uplinker; 22nd May 2019 at 15:04.
Joined: Mar 2012
Posts: 2,605
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From: Having a margarita on the beach
‐ Do not use conditioned air simultaneously from packs and LP ground unit (to avoid chattering of
the non return valves).
‐ Airflow supplied by the ground cart shall not exceed 1.2 kg/s (2.60 lb/s).
