monorail
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Door Seals On MD-88 And Others

Fri Nov 19, 2004 2:48 pm

I was looking at Seat Guru's map for a DL MD-88 and I noticed something curious on the note for the emergeny exit row.
"The aging door seals often make the area cold while in the air, grab a blanket."
Which leads me to ask how tight are door seals. I'm guessing this problem isn't specific to the MD-88? Do the door seals vary from emergency exit overwing to L1? How tight is the seal, really?

[Edited 2004-11-19 06:49:17]
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Starlionblue
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RE: Door Seals On MD-88 And Others

Fri Nov 19, 2004 6:39 pm

As I see it:

The seals will keep air in and out, but you only have the thickness of the seal between the -50 Celsius outside air and the +20 Celsius inside air. So while air does not leak (much) heat does. On the rest of the plane, you have the fuse, insulation, inside bulkhead and so on.
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monorail
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RE: Door Seals On MD-88 And Others

Sat Nov 20, 2004 2:45 am

So while air does not leak (much) heat does.

I understand what you're saying, but how does the age of the aircraft, as mentioned on seat guru, factor in to this?
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wbmech
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RE: Door Seals On MD-88 And Others

Sat Nov 20, 2004 4:03 am

I highly doubt the age of the aircraft or seals has anything to do with losing heat through the seals. It does depend on the type of aircraft. Some aircraft have door heater blankets around the emergency exit openings to counteract the effects of losing heat through the seals. The MD-80's do not have this installed. Seat guru might be experts on seat positioning, but they are not experts on aircraft systems by any means.
 
DeltaGuy
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RE: Door Seals On MD-88 And Others

Sun Nov 21, 2004 1:56 am

This is the first I've heard of this. Sometimes you'll get on a mad doggie, and there'll be a nice loud hissing noise coming from the seal until you get high/fast enough for it to go away, then it comes back as your're descending again. Can get quite annoying.

DeltaGuy
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Dalmd88
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RE: Door Seals On MD-88 And Others

Sun Nov 21, 2004 2:10 am

Most door seals are replaced at overhaul which is every six years. So even a twenty year old plane would have fairly new seals.
 
EMBQA
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RE: Door Seals On MD-88 And Others

Sun Nov 21, 2004 1:33 pm

Yea, I don't buy their response. A leaking door seal would scream worse then a crying baby and would be quickly written up by the crews to be fixed.
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Starlionblue
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RE: Door Seals On MD-88 And Others

Mon Nov 22, 2004 2:58 am

Depends on the size of the leak. Even spacecraft leak. It's just very very slow.

And I think Seatguru is talking about thermal leakage. Sitting in row 31 Window on AA 777s often requires a blanket because of the slightly chillier air around my feet-
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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Starlionblue
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RE: Door Seals On MD-88 And Others

Mon Nov 22, 2004 2:59 am

Depends on the size of the leak. Even spacecraft leak. It's just very very slow.

And I think Seatguru is talking about thermal leakage. Newer aircraft are better, but still not perfect. Sitting in row 31 Window on AA 777s often requires a blanket because of the slightly chillier air around my feet-
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Fly2HMO
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RE: Door Seals On MD-88 And Others

Tue Nov 23, 2004 5:59 am

I've sat on emergency exits in the mad dogs several times. It really feels colder if your next to the wall, and several times I've seen condensation forming on the door.
 
DC-10inLB
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RE: Door Seals On MD-88 And Others

Tue Nov 23, 2004 8:27 am

The doors aren't leaking, they'd whistle like a son of a b*tch. It's just cold there. I've sat on brand new 747s in the exit rows, had nothing but socks on, poked my toes under the life raft housing and it was freezing cold under there. It's just the fact that it is a very very remote part of the plane, not much circulation of the warmer cabin air.
 
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Starlionblue
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RE: Door Seals On MD-88 And Others

Tue Nov 23, 2004 11:12 am

The doors aren't leaking, they'd whistle like a son of a b*tch. It's just cold there. I've sat on brand new 747s in the exit rows, had nothing but socks on, poked my toes under the life raft housing and it was freezing cold under there. It's just the fact that it is a very very remote part of the plane, not much circulation of the warmer cabin air.

If I remember my high school physics correctly:
If there is a temperature gradient, an air current forms to correct the pressure imbalance. Thermal leakage is not the same as air leakage. Even with no air leakage the air closer to the seal would be colder since the seal does not insulate as well as the rest of the fuselage. An air current will form with warm air flowing towards the cold zone but heat will leech out through the seal. Note, heat flows out, not air.

[Edited 2004-11-23 03:16:33]
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
videns
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RE: Door Seals On MD-88 And Others

Wed Nov 24, 2004 11:24 am

I agree with Starlionblue... I've sat next to the emergency exit of many aircraft many times. It's always colder there... (In my experience, 757s have been the coldest so far)... In my opinion, leg room beats the cold...
Basically, you don't only get the cold from the metal door and floor, but also the air moving around there just to equalize the pressure because of the temperature difference. Nothing to worry about...
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