BA380
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Coldness Near Doors On A/C

Sun Apr 20, 2008 9:40 pm

I have heard several people talking about the fact that they perceive it to be cold near the doors on A/C during flight (eg people posting in trip reports or on seatmaps)....

at the risk of getting flamed, is this possible? presumably the doors are a perfect seal, aren't they? otherwise things would be getting sucked towards the door!?! or have I misunderstood?
cabin crew: doors to automatic and cross-check...
 
FlyingColours
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RE: Coldness Near Doors On A/C

Sun Apr 20, 2008 9:58 pm

This would be best in Tech Ops.

Yes it can get cold by the doors in flight, I know it does happen from my experience working in the gallies inflight  Smile I'm not sure on the technical aspect of it but I think the main reason for the chill is if there is a little bit of a leak (a very tiny one which has no detrimental effect on the pressure).

I'd suggest moving it to tech and someone with some technical knowledge will answer, rather than me (apparently a Cart Tart)...

Phil
FlyingColours
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UAL747
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RE: Coldness Near Doors On A/C

Sun Apr 20, 2008 10:01 pm

For the timid flyer, worse than the cold, is the sound of rushing air that you hear sometimes around the door areas. LOL, I know I've heard it before.

I find though, it get's fairly cold on longhaul flights such as DFW-NRT or ORD-HKG, though I think that has something to do witht the way hot air rises and cold air falls. It's usually my feet that get cold.

UAL
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AA737-823
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RE: Coldness Near Doors On A/C

Sun Apr 20, 2008 10:01 pm

Well, yeah, they're a DECENT seal (Air does leak a little, and sometimes you can hear it leak A LOT). But they're not as well insulated as the rest of the cabin walls, so they're a bit colder.
The 767's actually have electric heaters in the door areas to combat the cooling tendency. I suspect other aircraft do as well.
 
roseflyer
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RE: Coldness Near Doors On A/C

Sun Apr 20, 2008 10:18 pm

The insulation blankets do not cover around the doors as well as in other places, which will make it colder. Most notably areas around doors, exit windows and tight curves such as the flight deck are not as well insulated.

Quoting BA380 (Thread starter):
at the risk of getting flamed, is this possible? presumably the doors are a perfect seal, aren't they? otherwise things would be getting sucked towards the door!?! or have I misunderstood?

People think that airplanes are perfectly sealed pressure vessels, but they are far from it. Not only are the seals not perfect at doors, but there are leaks at every wire, tube, cable, hose and various other items as they run through the pressure bulkheads. Airplanes will not hold pressure without the constant addition of air via the pressurization system.
If you have never designed an airplane part before, let the real designers do the work!
 
SlamClick
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RE: Coldness Near Doors On A/C

Mon Apr 21, 2008 2:26 am



Quoting RoseFlyer (Reply 4):
The insulation blankets do not cover around the doors as well as in other places

That is the most pertinent remark so far.

Airleaks at the doors could not produce cold cabin because the air will always leak OUT and never IN. Remember - the thing is pressurized. So the cabin might be warming the upper atmosphere ever so slightly but the reverse will never be true.  Smile

Less insulation blanket, gaps in insulation, and lack of sidewall hot air vents probably the big factor. Another is that metal exposed to the outside might wrap around to the interior surfaces of the window frame and create a pocket of sub-freezing air there. Bodies of air at differing temperatures tend not to mix.

Also flight attendants are most aware of it because of this: They drag out the serving carts during the climb and drag them UP the aisle. Then they deal drinks and snacks left and right down the aisle, working up a small sweat. Then they retire to the galley, pull the curtain, take off their serving smocks and sit down in the coldest place in the cabin in damp shirts. Now I'm betting that I'll get a call over the interphone within three minutes asking me to 'warm it up' back there.
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MQTmxguy
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RE: Coldness Near Doors On A/C

Mon Apr 21, 2008 6:23 am



Quoting RoseFlyer (Reply 4):
The insulation blankets do not cover around the doors as well as in other places, which will make it colder. Most notably areas around doors, exit windows and tight curves such as the flight deck are not as well insulated.

And inversely, there is more metal there than in most places so it conducts more heat away.

Quoting BA380 (Thread starter):
at the risk of getting flamed, is this possible? presumably the doors are a perfect seal, aren't they? otherwise things would be getting sucked towards the door!?! or have I misunderstood?

If that were true, every time you fly you should be seeing things sucked towards the cabin outflow valve.

Quoting SlamClick (Reply 5):
Now I'm betting that I'll get a call over the interphone within three minutes asking me to 'warm it up' back there

Your aircarft doesn't have an F/A temp control?
Well at least we can all take comfort in the fact that NW will never retire their DC-9s
 
kaddyuk
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RE: Coldness Near Doors On A/C

Mon Apr 21, 2008 8:00 am



Quoting MQTmxguy (Reply 6):
Your aircarft doesn't have an F/A temp control?

Flight deck has the master control...
Whoever said "laughter is the best medicine" never had Gonorrhea
 
MQTmxguy
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RE: Coldness Near Doors On A/C

Mon Apr 21, 2008 8:18 am



Quoting Kaddyuk (Reply 7):
Flight deck has the master control...

Of course. I don't know about your a/c, but on the ERJ you can set the master temp control knob to "FA" and it gives the F/A temperature control.
Well at least we can all take comfort in the fact that NW will never retire their DC-9s
 
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HAWK21M
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RE: Coldness Near Doors On A/C

Mon Apr 21, 2008 10:20 am

Most Commercial Aircraft have Dected Heated Air flowing near Doorways to provide warmth.
regds
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zeke
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RE: Coldness Near Doors On A/C

Mon Apr 21, 2008 11:13 am

Another factor is that galleys are generally near doors, the chillers in the galleys do drop the temperature of the surrounding area as well.
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readytotaxi
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RE: Coldness Near Doors On A/C

Mon Apr 21, 2008 4:02 pm

Prefer a cool seat near an exit myself, always too warm on aircraft for a blanket and a good sleep.
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