A320 APU Bleed after landing
Thread Starter
Joined: Jul 2014
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From: Jakarta
A320 APU Bleed after landing
Hi guys,
Apology for this silly questions.
During docking the aircraft, with a condition APU is available.
Some of my instructor, instructed me to turn on the APU BLEED after 3 minutes IDLE power have been reached after landing while and the aircraft is just couple meters from parking bay.
While others instructors, instructed me to turn on the APU BLEED once the aircraft is stoping with the condition parking break is SET.
As far as my understanding, the APU BLEED is used as an Air Condition, after the engine shut down.
My question is how is the APU BLEED connection with ENGINE BLEED related to safety before engine shutdown?
Thanks in advance guys
Apology for this silly questions.
During docking the aircraft, with a condition APU is available.
Some of my instructor, instructed me to turn on the APU BLEED after 3 minutes IDLE power have been reached after landing while and the aircraft is just couple meters from parking bay.
While others instructors, instructed me to turn on the APU BLEED once the aircraft is stoping with the condition parking break is SET.
As far as my understanding, the APU BLEED is used as an Air Condition, after the engine shut down.
My question is how is the APU BLEED connection with ENGINE BLEED related to safety before engine shutdown?
Thanks in advance guys
Joined: Jul 2008
Posts: 1,145
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From: Skating away on the thin ice of a new day.
For safety, they may want APU bleed available to spin an engine in the event of a tail pipe failure.
For pax comfort you would want the APU up and running bleed on / available before shutting engines down to keep the air con running.
When its started and when bleed is selected is an airline decision I would think. Pax comfort, safety, wear and tear, fuel savings etc. I'll leave that to A320 pilots.
For pax comfort you would want the APU up and running bleed on / available before shutting engines down to keep the air con running.
When its started and when bleed is selected is an airline decision I would think. Pax comfort, safety, wear and tear, fuel savings etc. I'll leave that to A320 pilots.
Joined: Mar 2006
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From: USA
At my company, we call that technique, not procedure. Particularly in IAE planes, I wait until N1 is below 5% so I don’t fill the cabin with exhaust fumes. Usually that coincides with the completion of the shutdown checklist. The interruption in the pack air flow is just a few seconds, and is much better (in my opinion) than inhaling exhaust gasses every leg.
Joined: Nov 1999
Aviation Qualifications: ATPL
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From: UK
I haven’t looked this up to check the detail, but I am fairly sure that if there is an interruption in the bleed air supply to the packs, it constitutes an extra pack cycle, which causes wear in the pack components.
(not sure how or why this wear occurs, but must be something to do with spinning up the air cycle machine).
This is why Airbus tell you to select APU bleed on just before turning off the engine masters.
Happy to be corrected.
(not sure how or why this wear occurs, but must be something to do with spinning up the air cycle machine).
This is why Airbus tell you to select APU bleed on just before turning off the engine masters.
Happy to be corrected.
Joined: Jun 2007
Posts: 3,443
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From: Wanderlust
Check airman
Main consideration for APU bleed is it sucks in engine fumes. APU starting takes 40 seconds and if you start it after engine shutdown till 5% N1 it has to be atleast close to one minute delay and it will recycle packs. So as Uplinked says it could bring in another aspect. So it's an issue which needs to be airline policy rather an individual technique. In Airbus best thing is to refer it to Airbus which will consider these aspects in their answer. Personally I would not cut it so fine. APU has nothing to do with 3mts.
Main consideration for APU bleed is it sucks in engine fumes. APU starting takes 40 seconds and if you start it after engine shutdown till 5% N1 it has to be atleast close to one minute delay and it will recycle packs. So as Uplinked says it could bring in another aspect. So it's an issue which needs to be airline policy rather an individual technique. In Airbus best thing is to refer it to Airbus which will consider these aspects in their answer. Personally I would not cut it so fine. APU has nothing to do with 3mts.
Joined: Jul 2006
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From: Somewhere over the rainbow
I just do exactly as per FCOM. Parking brake ON, APU Bleed ON, then engines shut down. Never heard any complains about smell of exhaust gasses in the cabin.
Last edited by pineteam; 13th November 2019 at 12:15. Reason: typo
Joined: May 1999
Posts: 165
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From: Europe
PRO-NOR-SOP-22
Your company procedures may vary but I doubt it's after ENG Shut down.
Hope this helps.
Only half a speed-brake
Joined: Apr 2003
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From: Commuting not home
FCOM rules. Reasons stated by vilas already.
I think C/A means he waits with bleed selection, not the APU start itself. Still a pack cycle.
Now, speaking of when to start the APU...
I think C/A means he waits with bleed selection, not the APU start itself. Still a pack cycle.
Now, speaking of when to start the APU...
Only half a speed-brake
Joined: Apr 2003
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From: Commuting not home
My question is how is the APU BLEED connection with ENGINE BLEED related to safety before engine shutdown?
Joined: Mar 2006
Posts: 2,633
Likes: 136
From: USA
Yes, I was referring to APU bleed selection. That thing with the fumes on the IAE is pretty annoying, and can’t be healthy in the long term. I’m surprised pineteam hasn’t experienced it. Unless the parking stand has a very strong tailwind, it’s almost guaranteed.
Joined: Mar 2012
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From: Having a margarita on the beach
