Reggaebird
Topic Author
Posts: 886
Joined: Tue Nov 02, 1999 7:43 am

Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 8:11 am

I shot the following airplane video recently in St. Maarten and a YouTube viewer pointed out something strange in the footage.

http://www.youtube.com/watch?v=vr5uLCmXJ4M

Look at the 1L cabin door from 0:04 to 0:22. It appears to, at best, have an odd alignment with the body of the aircraft. Is it possible for these doors to close improperly?
 
330guy
Posts: 239
Joined: Thu Nov 18, 2010 9:51 am

RE: Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 9:12 am

it does look odd... The only thing I can think is when the aircraft pressurises while climbing it pushes the door out and seals it. Doors are slightly larger than the hole they fit in, hence the odd opening techniques often seen i.e. door being pulled in before being pushed out
Aircraft flown: a300/10/20/21/30/40, b727/37/47/57/67/, DC9, MD80-90, l1011, f50, atr42/72, shorts360, pc12
 
GT4EZY
Posts: 511
Joined: Thu Dec 06, 2007 9:35 pm

RE: Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 11:22 am

I've noticed this on many MD's before now.
Proud to fly from Manchester!
 
Phen
Posts: 237
Joined: Mon Oct 29, 2007 7:05 pm

RE: Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 11:50 am

Quoting 330Guy (Reply 1):
The only thing I can think is when the aircraft pressurises while climbing it pushes the door out and seals it.

   Indeed I've noticed this before too- 330Guy's explanation would seem to be correct.
 
AA737-823
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RE: Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 12:54 pm

Greetings from a mechanic! And one that works on L1 doors way more often than he'd like to, at that!

The metal isn't what actually "seals" the door; it's the rubber seal that makes it airtight.
So the position of the door isn't really as critical as you'd think; so long as the stop are resting on the stop pads, then it's closed.

And no, the door isn't air tight until about 2 psid, that is, 2 psi higher inside than out. I'm not sure what altitude this occurs at, but I suspect it's about eight thousand feet.
 
Reggaebird
Topic Author
Posts: 886
Joined: Tue Nov 02, 1999 7:43 am

RE: Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 1:23 pm

Quoting AA737-823 (Reply 4):
Greetings from a mechanic! And one that works on L1 doors way more often than he'd like to, at that!

The metal isn't what actually "seals" the door; it's the rubber seal that makes it airtight.
So the position of the door isn't really as critical as you'd think; so long as the stop are resting on the stop pads, then it's closed.

And no, the door isn't air tight until about 2 psid, that is, 2 psi higher inside than out. I'm not sure what altitude this occurs at, but I suspect it's about eight thousand feet.

Thank you for the excellent information! However, this still begs the question..."shouldn't the door and be flush with the fuselage?". What are the ramifications of the door not being flush? Are there drag/friction/fuel penalties?
 
AIR757200
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RE: Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 1:36 pm

When I first started working with MD-80's myself, I too thought, "Is the door closed properly?" However, the bayonet (the piece on the door that says "Hands Off" will guide the door to properly close. The exterior door handle also won't properly close if it wasn't done correctly.

When that MD80, for example, arrives to its destination, the floor will be flush with the fuselage.

Here is an excellent video for the 717 door, which is the same design as the MD80 door.

http://www.youtube.com/watch?v=O3R9JCQbX9s
 
Reggaebird
Topic Author
Posts: 886
Joined: Tue Nov 02, 1999 7:43 am

RE: Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 11:04 pm

Quoting air757200 (Reply 6):
Here is an excellent video for the 717 door, which is the same design as the MD80 door.

http://www.youtube.com/watch?v=O3R9J...QbX9s

Thank you for the excellent video. I still think there must be some sort of penalty (aerodynamic or otherwise) for a door that is not flush with the body. Anyone else have insight?
 
PGNCS
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RE: Cabin Door Properly Sealed Or Not?

Wed Mar 09, 2011 11:09 pm

Quoting AA737-823 (Reply 4):
Greetings from a mechanic! And one that works on L1 doors way more often than he'd like to, at that!

The metal isn't what actually "seals" the door; it's the rubber seal that makes it airtight.
So the position of the door isn't really as critical as you'd think; so long as the stop are resting on the stop pads, then it's closed.

And no, the door isn't air tight until about 2 psid, that is, 2 psi higher inside than out. I'm not sure what altitude this occurs at, but I suspect it's about eight thousand feet.

I always wondered what PSID was required to seat the seals (other than by listening to the whistling!) I agree with you that there's pretty much no way on a DC-9 or MD-80 to close these doors incorrectly. They will leak on the ground, too, as will the cockpit windows!

Quoting Reggaebird (Reply 5):
Thank you for the excellent information! However, this still begs the question..."shouldn't the door and be flush with the fuselage?". What are the ramifications of the door not being flush? Are there drag/friction/fuel penalties?

It will be flush when the aircraft is pressurized. It isn't pressurized while taxiing.
 
580fa
Posts: 16
Joined: Wed Feb 03, 2010 11:48 pm

RE: Cabin Door Properly Sealed Or Not?

Thu Mar 10, 2011 12:09 am

MD-80 doors are a luxury!

I used to work on DC-9-10/15/30s. Those doors weren't closed right ever, even at altitude!

We used to wet bevnaps and push them in the doorsill.

I mean you could look outside and see birds!
 
Reggaebird
Topic Author
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RE: Cabin Door Properly Sealed Or Not?

Thu Mar 10, 2011 1:45 am

Quoting 580fa (Reply 9):
I used to work on DC-9-10/15/30s. Those doors weren't closed right ever, even at altitude!

We used to wet bevnaps and push them in the doorsill.

I mean you could look outside and see birds!

I really hope that you are joking!   These comments about MD-80/DC-9 doors is not very encouraging at all but I also know that they have a great safety record.
 
lowrider
Posts: 2542
Joined: Wed Jun 30, 2004 3:09 am

RE: Cabin Door Properly Sealed Or Not?

Thu Mar 10, 2011 2:32 am

The doors need not seal air tight. I have walked back to our main cargo door various times in flight and seen daylight around the edges of a few. All that happens is the outflow valves are a little more closed. One of the few advantages to letting people smoke on planes is that air leaks were easier to spot.
Proud OOTSK member
 
ImperialEagle
Posts: 2238
Joined: Sat Jan 14, 2006 10:53 am

RE: Cabin Door Properly Sealed Or Not?

Thu Mar 10, 2011 3:18 am

Quoting lowrider (Reply 11):
walked back to our main cargo door

I recall more than a few trips on NW 721C's when those cargo door seals were pretty well worn. I would usually end-up getting an extra blanket and wrapping my feet with it so they didn't freeze. A window seat on the port side in F did not always get you warmth!

Back when (you should pardon the expression) Lorenzo was busy making a mess of Continental, I recall a trip FLL-IAH when I sat just aft of L2 on a 722. That door seal was shot and I ended up moving up the aisle to get warm.
"If everything seems under control, you're just not going fast enough!"
 
PGNCS
Posts: 2249
Joined: Sun Apr 15, 2007 5:07 am

RE: Cabin Door Properly Sealed Or Not?

Thu Mar 10, 2011 3:45 am

Quoting Reggaebird (Reply 10):
These comments about MD-80/DC-9 doors is not very encouraging at all

Why? They are working as they are designed; if they weren't the aircraft wouldn't pressurize. You really want the plane unpressurized on the ground in the event of an evacuation.
 
IAHFLYR
Posts: 3944
Joined: Sat Jun 25, 2005 12:56 am

RE: Cabin Door Properly Sealed Or Not?

Thu Mar 10, 2011 4:02 am

Quoting ImperialEagle (Reply 12):
Lorenzo was busy making a mess of Continental, I recall a trip FLL-IAH when I sat just aft of L2 on a 722. That door seal was shot and I ended up moving up the aisle to get warm.

Well they have a new Lorenzo now at the helm........and I do remember doing exactly the same thing on a B722 from IAH to DEN, sure glad not many passengers back then on Continental. What a difference now.
Any views shared are strictly my own and do not a represent those of any former employer.
 
chuchoteur
Posts: 609
Joined: Tue Sep 12, 2006 9:17 pm

RE: Cabin Door Properly Sealed Or Not?

Thu Mar 10, 2011 5:45 pm

Quoting Reggaebird (Reply 5):
Thank you for the excellent information! However, this still begs the question..."shouldn't the door and be flush with the fuselage?". What are the ramifications of the door not being flush? Are there drag/friction/fuel penalties?

Indeed you are correct.
There is some residual parasitic drag if the door is not properly lined up.

I know that for a missing flap seal/misalignment it costs around $20.000 per year in fuel, but that's on the flying surfaces so I guess the value for a misaligned door is smaller.

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