kimon
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Cabin Air Toxicity

Sat Dec 26, 2009 11:39 pm

do the 380 and 350 xwb have the same bleed-free system as the 787?
ditto for the 747-800?

http://www.telegraph.co.uk/travel/tr...s-a-breath-of-fresh-cabin-air.html

[Edited 2009-12-26 15:42:39 by kimon]
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Fly2HMO
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RE: Cabin Air Toxicity

Sun Dec 27, 2009 2:44 am

I *think* both airbii planes you mentioned are conventional.

One thing I know for sure is that the article mentioning the whole "cabin toxicity" thing is a hoax. Average aircraft cabins get completely new air every 15 minutes or some, doesn't get cleaner than that.
 
Mir
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RE: Cabin Air Toxicity

Sun Dec 27, 2009 3:30 am

The 380 still has conventional engine bleeds - not sure about the 350.

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HAWK21M
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RE: Cabin Air Toxicity

Sun Dec 27, 2009 4:36 am

Is there no Recirculation system on the B787.If so.what will be the pumping capacity of those Air Compressors.

regds
MEL.
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747classic
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RE: Cabin Air Toxicity

Sun Dec 27, 2009 8:43 am

B-787 only uses "bleedless"engines.
The air-conditioning system will not take bleed air from the engines. Rather, four large electrically driven air compressors will feed ambient air to the air-conditioning packs. Boeing engineers believe this system has a number of advantages to siphoning inlet air off the engines.

First, the engines will be more efficient, as all air sucked into them will contribute to thrust. Also, oil and other contaminants will not be sucked into a bleed air system, thus eliminating engine-related fumes in the cabin. By foregoing bleed air, leaks in hot duct work are avoided. And finally, Boeing engineers regard the electrically-driven air compressors as more reliable.

The compressors are independently monitored, however; and Hale said they "swap out as a unit." With four compressor motors, one can be off-line until repaired or replaced, and the airplane can continue flying, relying on the remaining three for necessary redundancy.

Both A-380 and future A-350XWB use a conventional pneumatic system to deliver bleed air to the airconditioning system.
The 747-8 uses the "proven"pneumatic bleed system from the 747-100/200/300/400 series to power the 3 airconditioning packs..

[Edited 2009-12-27 00:46:05]

[Edited 2009-12-27 01:13:42]
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tdscanuck
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RE: Cabin Air Toxicity

Sun Dec 27, 2009 9:46 pm



Quoting HAWK21M (Reply 3):
Is there no Recirculation system on the B787

787 has recirculation. Nobody wants to fly an airplane with zero recirculation...the air would be phenomenally dry.

Tom.
 
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HAWK21M
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RE: Cabin Air Toxicity

Mon Dec 28, 2009 6:11 am



Quoting Tdscanuck (Reply 5):

787 has recirculation.

If So.What capacity is the Four Air driven compressors & any details on the Airflow provided.Would Two u/s compressors be a NO GO.

regds
MEL.
I may not win often, but I damn well never lose!!! ;)
 
tdscanuck
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RE: Cabin Air Toxicity

Mon Dec 28, 2009 6:55 am



Quoting HAWK21M (Reply 6):
If So.What capacity is the Four Air driven compressors & any details on the Airflow provided.Would Two u/s compressors be a NO GO.

Airflow rate is pretty much pinned down by FAR's and smoke evacuation requirements...I don't have those on the top of my head, but it's going to get certified so you can easily figure out the lower boundary. And, since it's ETOPS certified, it should be able to do it on a single engine, although with all electric power you could theoretically run all four compressors on one engine.

I suspect two dead compressors would be no-dispatch, but you could continue flying with it if it happened in flight.

Tom.
 
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747classic
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RE: Cabin Air Toxicity

Mon Dec 28, 2009 7:38 am

Quoting HAWK21M (Reply 6):
If So.What capacity is the Four Air driven compressors & any details on the Airflow provided.Would Two u/s compressors be a NO GO.

This is one of the things, that has to be approved during testing of the 787.
All items in the MEL have to be checked or demonstrated to the authorities.
Personally I think one compressor U/S will be a dispatch item.
Two U/S will be a NOGO or departure with no passengers or severe passenger number limitations.
But all above is only speculation, because no (provisional) 787-MEL is published, as far as i know.

[Edited 2009-12-27 23:39:28]
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klemmi85
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RE: Cabin Air Toxicity

Mon Dec 28, 2009 12:36 pm

What exactly is meant by MEL?

Read that a few times already but couldn't figure out so far...
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747classic
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RE: Cabin Air Toxicity

Mon Dec 28, 2009 1:08 pm

Quoting Klemmi85 (Reply 9):
What exactly is meant by MEL?

Sorry, I thought that MEL was ready knowledge on the tech/ops forum.

MEL = Minimum Equipment List, see :

http://en.wikipedia.org/wiki/Minimum_equipment_list

[Edited 2009-12-28 05:11:29]
Operating a twin over the ocean, you're always one engine failure from a total emergency.
 
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HAWK21M
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RE: Cabin Air Toxicity

Mon Dec 28, 2009 5:34 pm



Quoting Klemmi85 (Reply 9):
What exactly is meant by MEL?

Minimum Equipment List.
A Document containing units & systems that may be Inoperative for a limited period of time without adversly affecting the safety & airworthiness of the Aircraft.

http://dgca.nic.in/ftppub/D2B-B1.pdf

regds
MEL.
I may not win often, but I damn well never lose!!! ;)
 
Tod
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RE: Cabin Air Toxicity

Tue Dec 29, 2009 5:53 pm



Quoting Tdscanuck (Reply 7):
Airflow rate is pretty much pinned down by FAR's and smoke evacuation requirements

14CFR25.831

"the ventilation system must be designed to provide each occupant with an airflow containing at least 0.55 pounds of fresh air per minute."


http://ecfr.gpoaccess.gov/cgi/t/text...ode=14:1.0.1.3.11.4.179.68&idno=14
 
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HAWK21M
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RE: Cabin Air Toxicity

Wed Dec 30, 2009 6:42 am



Quoting Tod (Reply 12):

"the ventilation system must be designed to provide each occupant with an airflow containing at least 0.55 pounds of fresh air per minute."

Exactly....So the Air compressors on the B787 will need to cater to minimum 0.55lbs/min fresh airflow.
regds
MEL.
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tdscanuck
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RE: Cabin Air Toxicity

Wed Dec 30, 2009 6:19 pm



Quoting HAWK21M (Reply 13):
Exactly....So the Air compressors on the B787 will need to cater to minimum 0.55lbs/min fresh airflow.

Actually, it's some subset of the compressors. I don't know what the exact failure conditions and MEL relief will be but, if we assume you can dispatch with one compressor inop, then you'd have to get 0.55 lbs/min/person from 3 compressors.

Tom.
 
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readytotaxi
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RE: Cabin Air Toxicity

Wed Dec 30, 2009 8:04 pm



Quoting HAWK21M (Reply 13):

So if the bloke next to me has flu I will not get next time the air comes round? Big grin
you don't get a second chance to make a first impression!
 
tdscanuck
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RE: Cabin Air Toxicity

Thu Dec 31, 2009 1:15 am



Quoting Readytotaxi (Reply 15):
So if the bloke next to me has flu I will not get next time the air comes round?

Typically not. The flu virus isn't particularly durable when airborne; I think it can only live in droplets. Droplets are easily caught by HEPA filters, and they evaporate fast (airliner air is pretty dry, even with recirculation).

You're way (way way way) more likely to get sick from surface contact that a lot of other people have touched (lavatory sinks, tray tables, etc.) than recirculated air.

Tom.
 
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readytotaxi
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RE: Cabin Air Toxicity

Thu Dec 31, 2009 6:51 pm



Quoting Tdscanuck (Reply 16):
You're way (way way way) more likely to get sick from surface contact that a lot of other people have touched (lavatory sinks, tray tables, etc.) than recirculated air.

You just made air travel so much more romantic.  Wink
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HAWK21M
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RE: Cabin Air Toxicity

Thu Dec 31, 2009 9:39 pm



Quoting Readytotaxi (Reply 15):

So if the bloke next to me has flu I will not get next time the air comes round? 

Depending on the Airflow between you both  wink 

On the B787 topic......I wonder if Boeing will get approval for havig two u/s air compressors under MEL.

regds
MEL.
I may not win often, but I damn well never lose!!! ;)

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