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mats
Posts: 544
Joined: Sat Jul 05, 2003 11:20 pm

Boeing Doors

Sun Jun 24, 2007 11:35 pm

I am confused about how the doors on most Boeing aircraft operate.

My understanding is that aircraft doors are bigger trhan the opening. They serve as a "plug" to remain in place. This seems obvious if one looks at the doors on a DC-10, MD-11, or L1011: the door pops inside the cabin and goes up into the ceiling. (The same is true for the L1 door on a 767.)

The Airbus doors--I think--pop outside of the plane and slide toward the nose.

But what about the Boeing planes? I have seen how the doors "pop" inward, but outward as well. How can the door serve as a plug if it can pop inside and outside? Or do these doors not serve as plugs at all?
 
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Stitch
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RE: Boeing Doors

Sun Jun 24, 2007 11:38 pm

All Boeing doors are of the plug-design. With the exception of the 767, when opening, they must first be pulled into the cabin and then rotated to fit out through the opening. Only the 767 door retracts into the ceiling, but it too is a plug design in that one it is lowered into position, it then moves forward to press against the fuselage.
 
captaink
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RE: Boeing Doors

Sun Jun 24, 2007 11:51 pm

There is something like a flap at the top and the bottom of the door. Upon opening these flaps bend inward, making the door 'smaller' that way it can go thorugh the motion of opening. The right side goes toward the inside and the door is then push outside, left side first.

P.S. the door is held securely in place when closed by other mechanisms such as the girdle rod at the bottom etc.
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Tristarsteve
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RE: Boeing Doors

Mon Jun 25, 2007 1:12 am

The concept of plug doors is that pressure holds them in place. This is achieved by a row of stops down both sides of the door frame, and a row of stops down both sides of the door. These stops push together when the door is closed. Old Boeing doors B727 B737 B747 B757 are all similar and operate as described above. B777 and A320 doors use the same stops, but to open they are first lifted about an inch, then pushed out past the stops, but when closed the principle is the same.
B737 type cargo doors are true plug doors. they are bigger than the opening, but still sit on stops when closed.
The L1011 small cargo doors, and B767 small cargo doors operate like B777 pax doors. They are lifted then opened past the stops.
All these doors are called plug doors.
However the B747 fwd cargo door, L1011 fwd large cargo door, B767 fwd large cargo door (where fitted) ,B777 fwd cargo door (and rear door on BA aircraft) are NOT plug doors. The top hinge is a piano type hinge, and the bottom and sides of the door are held in place with hooks when closed. These doors are all similar design (and made by the same firm).
Some pax doors are not plug type. Usually when an airstair is built into the door like older F28 and F100 fwd pax doors. When doors are not plug type the locking and latching mechanism is quite complicated to try and make it foolproof, but it has been fooled. TK DC10 at Paris and the NW? B747 over the Pacific, both times the latching mech failed and the door opened under pressure.
 
Markhkg
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RE: Boeing Doors

Mon Jun 25, 2007 1:55 am

Quoting Stitch (Reply 1):
All Boeing doors are of the plug-design.

Actually, the new overwing B737-NG overwing exits, in addition to the B-747-400 upper deck exits, are not of plug-type design. If you notice, both swing out up and out when opened. Both can be opened in-flight if there is a low cabin pressure differential. However, both are also protected by locks, which has been discussed previously, and activate after the flight computer senses certain flight configurations.
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CanadianNorth
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RE: Boeing Doors

Mon Jun 25, 2007 11:42 am

Working as a groomer on 737s I use the doors on a regular basis (to use the door for loading/unloading our stuff, as well as on the 737-200 you have to open three of the doors to change the garbage bags, otherwise the slide would block the garbage can in its compartment) . How it is done is rotate the handle and the door comes inward a little, and then you manually rotate the door out of the aircraft untill it clicks into place. To close the door you push the button and rotate slightly to unlock it, and then continue rotating it into the galley, then rotate the handle and the door pushes itself into the doorframe and locks in place.

My understanding is that the door is actually slightly bigger than the opening, so when flying the pressure from the cabin holds the door against the fuselage, making it so the door will not open in flight. To open and close it I've been told that there are flap-like things which basically shrink the door enough to fit through the hole when you rotate the handle past a certain position.

However, I'm just a groomer and not a mechanic (yet), so anything past the how to operate the door I could easily be wrong on.


CanadianNorth
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HAWK21M
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RE: Boeing Doors

Mon Jun 25, 2007 7:17 pm

Quoting CanadianNorth (Reply 5):
My understanding is that the door is actually slightly bigger than the opening, so when flying the pressure from the cabin holds the door against the fuselage, making it so the door will not open in flight

The Door has Pins around its perimeter that rests on stops on the Frame.These pins/stops assy help transmit Door load to the Fuselage when pressurised.The Upper & lower flaps enable the door to slide into & out of the frame from Closed-cocked-open position & reverse.
regds
MEL
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CanadianNorth
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RE: Boeing Doors

Tue Jun 26, 2007 2:19 am

Quoting HAWK21M (Reply 6):
The Door has Pins around its perimeter that rests on stops on the Frame.These pins/stops assy help transmit Door load to the Fuselage when pressurised.The Upper & lower flaps enable the door to slide into & out of the frame from Closed-cocked-open position & reverse.

Thanks for correcting that. I knew the basic idea, but as for details it's as I said, I'm just the groomer.

Interesting system though I think...


CanadianNorth
Way to go, nice and slow, never late, 748!

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