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Cabin Door Properly Sealed Or Not?  
User currently offlineReggaebird From Jamaica, joined Nov 1999, 1176 posts, RR: 0
Posted (3 years 9 months 3 weeks 5 days ago) and read 4644 times:

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?

15 replies: All unread, jump to last
 
User currently offline330Guy From Ireland, joined Nov 2010, 453 posts, RR: 2
Reply 1, posted (3 years 9 months 3 weeks 4 days 23 hours ago) and read 4539 times:

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
User currently offlineGT4EZY From United Kingdom, joined Dec 2007, 1804 posts, RR: 3
Reply 2, posted (3 years 9 months 3 weeks 4 days 21 hours ago) and read 4350 times:

I've noticed this on many MD's before now.


Proud to fly from Manchester!
User currently offlinePhen From Ireland, joined Oct 2007, 319 posts, RR: 0
Reply 3, posted (3 years 9 months 3 weeks 4 days 21 hours ago) and read 4265 times:

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.


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5948 posts, RR: 12
Reply 4, posted (3 years 9 months 3 weeks 4 days 20 hours ago) and read 4121 times:

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.


User currently offlineReggaebird From Jamaica, joined Nov 1999, 1176 posts, RR: 0
Reply 5, posted (3 years 9 months 3 weeks 4 days 19 hours ago) and read 3995 times:

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?


User currently offlineair757200 From United States of America, joined Jul 2000, 1579 posts, RR: 7
Reply 6, posted (3 years 9 months 3 weeks 4 days 19 hours ago) and read 3949 times:

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


User currently offlineReggaebird From Jamaica, joined Nov 1999, 1176 posts, RR: 0
Reply 7, posted (3 years 9 months 3 weeks 4 days 9 hours ago) and read 3476 times:

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?


User currently offlinePGNCS From United States of America, joined Apr 2007, 2858 posts, RR: 49
Reply 8, posted (3 years 9 months 3 weeks 4 days 9 hours ago) and read 3474 times:

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.


User currently offline580fa From United States of America, joined Feb 2010, 90 posts, RR: 0
Reply 9, posted (3 years 9 months 3 weeks 4 days 8 hours ago) and read 3442 times:

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!


User currently offlineReggaebird From Jamaica, joined Nov 1999, 1176 posts, RR: 0
Reply 10, posted (3 years 9 months 3 weeks 4 days 7 hours ago) and read 3411 times:

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.


User currently offlinelowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 11, posted (3 years 9 months 3 weeks 4 days 6 hours ago) and read 3393 times:

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
User currently offlineImperialEagle From United States of America, joined Jan 2006, 2630 posts, RR: 21
Reply 12, posted (3 years 9 months 3 weeks 4 days 5 hours ago) and read 3372 times:

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!"
User currently offlinePGNCS From United States of America, joined Apr 2007, 2858 posts, RR: 49
Reply 13, posted (3 years 9 months 3 weeks 4 days 5 hours ago) and read 3364 times:

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.


User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 14, posted (3 years 9 months 3 weeks 4 days 4 hours ago) and read 3355 times:

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.
User currently offlinechuchoteur From France, joined Sep 2006, 774 posts, RR: 0
Reply 15, posted (3 years 9 months 3 weeks 3 days 15 hours ago) and read 3192 times:

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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