Plug doors
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Plug doors
I've always understood that, at least on large Boeing airliners, the doors in the passenger cabin are designed so that they must be pulled inward in order to open them, which supposedly functions as a built-in way of preventing them from opening when the cabin is pressurized.
Today I read in several places that Airbus doesn't use plug doors, but instead has a different mechanism.
So, two questions: (1) Can someone confirm that Boeing doors really cannot be opened when the aircraft is normally pressurized in flight; and (2) is this also true for Airbus airliners, and if so, do they do it the same way, or in a different what (which way?)?
As SLF I recall that Boeing aircraft seem to have doors that move inward before opening. I recall seeing some aircraft that had doors that seemed to move inward and roll upwards (Boeing, or who?). I don't recall what Airbus doors look like when they open.
In cases where pressure alone does not hold a door shut, what other mechanisms are used to prevent accidental (or deliberate) opening of the door in flight? On some smaller pressurized aircraft, it looks like it's just a mechanical lock that has nothing to do with pressure at all.
I did search for previous discussions but couldn't find anything that seemed to cover the same ground.
Today I read in several places that Airbus doesn't use plug doors, but instead has a different mechanism.
So, two questions: (1) Can someone confirm that Boeing doors really cannot be opened when the aircraft is normally pressurized in flight; and (2) is this also true for Airbus airliners, and if so, do they do it the same way, or in a different what (which way?)?
As SLF I recall that Boeing aircraft seem to have doors that move inward before opening. I recall seeing some aircraft that had doors that seemed to move inward and roll upwards (Boeing, or who?). I don't recall what Airbus doors look like when they open.
In cases where pressure alone does not hold a door shut, what other mechanisms are used to prevent accidental (or deliberate) opening of the door in flight? On some smaller pressurized aircraft, it looks like it's just a mechanical lock that has nothing to do with pressure at all.
I did search for previous discussions but couldn't find anything that seemed to cover the same ground.
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I can only speak for the B737 as the Boeing or the MD-80 as to the Douglas side. Yes Boeing doors are of a plug type. You have to pull them in and then there is some articulation in the hinge system that allows the do to go back out through the opening when the door is fully open and outside the aircraft.
The Airbus does not use this system, it is not a plug door and it opens outward. There does not seem to be a problem with the Bus. It is my current assignment and we operate a large fleet and have not had any problems with the door. It is very robust and the lock system seems to work well.
To be honest we have had some problems with the Boeing doors. they have a very safe design philosophy in that they are plug doors but the mechanism and articulation is sensitive. These doors require more maintenance than I have seen so far on the Bus.
Please note our Boeings are old and the Buses are newer which could account for some of the difference.
The Airbus does not use this system, it is not a plug door and it opens outward. There does not seem to be a problem with the Bus. It is my current assignment and we operate a large fleet and have not had any problems with the door. It is very robust and the lock system seems to work well.
To be honest we have had some problems with the Boeing doors. they have a very safe design philosophy in that they are plug doors but the mechanism and articulation is sensitive. These doors require more maintenance than I have seen so far on the Bus.
Please note our Boeings are old and the Buses are newer which could account for some of the difference.
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Sorry, I only answered one of the questions.
The Boeing is almost impossible to open in flight because cabin pressure is holding the door closed. The bus, I believe has pressure switches on the handle which lock it and prevent operating the lever in flight with the cabin pressurized.
Here is all we have in pilot hand book:
7a.2.2 Passenger Doors. The cabin entry/service doors can be opened either from inside or outside. They incorporate a damper actuator which limits door travel; and in an emergency assists opening the door.
Each door is equipped with a single-lane escape slide or dual-lane slide-raft. A slide arming lever connects the slide to the floor brackets when in the ARMED position. If the door is opened from inside while the slide is armed, the
door is pneumatically-assisted and the slide will inflate and deploy automatically. The slide may be inflated manually if automatic inflation fails. Opening the door from outside disarms the door.
7a.2.3 Overwing Emergency Exits (A319/A320). The overwing emergency exits are equipped with a dual-lane escape slide mounted on the fuselage at the trailing edge of each wing. This slide is always armed. If an overwing
emergency exit is opened from inside, the slide will automatically deploy. The slide may be inflated manually if auto mode fails.
7a.2.4 A321 Emergency Exits. Two plug type doors on each side of the cabin are emergency exits. They open outward and forward. Each door has an escape slide stowed in a compartment below the cabin floor. Operation of
these exits is similar to that of passenger doors.
The Boeing is almost impossible to open in flight because cabin pressure is holding the door closed. The bus, I believe has pressure switches on the handle which lock it and prevent operating the lever in flight with the cabin pressurized.
Here is all we have in pilot hand book:
7a.2.2 Passenger Doors. The cabin entry/service doors can be opened either from inside or outside. They incorporate a damper actuator which limits door travel; and in an emergency assists opening the door.
Each door is equipped with a single-lane escape slide or dual-lane slide-raft. A slide arming lever connects the slide to the floor brackets when in the ARMED position. If the door is opened from inside while the slide is armed, the
door is pneumatically-assisted and the slide will inflate and deploy automatically. The slide may be inflated manually if automatic inflation fails. Opening the door from outside disarms the door.
7a.2.3 Overwing Emergency Exits (A319/A320). The overwing emergency exits are equipped with a dual-lane escape slide mounted on the fuselage at the trailing edge of each wing. This slide is always armed. If an overwing
emergency exit is opened from inside, the slide will automatically deploy. The slide may be inflated manually if auto mode fails.
7a.2.4 A321 Emergency Exits. Two plug type doors on each side of the cabin are emergency exits. They open outward and forward. Each door has an escape slide stowed in a compartment below the cabin floor. Operation of
these exits is similar to that of passenger doors.
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All Airbus and Boeing pax main entry doors are plug type.
Airbus doors are very similar to Boeing 777 doors.
The Airbus doors first move inwards and lift up slightly like the 777 doors do. That way they can get past the tabs that make them plug type doors.
Pre 777 Boeing A/C (except L1011 like doors on the 767) don't lift so they come inwards and articulate as stated to get past the same tabs that all main entry doors have.
If they weren't plug type doors they would require pull in hooks and multiple independent rotary locks like the main cargo doors.
Each of these doors is approximately 6' x 4' around 3,500 square inches, at a differential pressure of 8 psi makes that 28,000 pounds. No one will open that and the handle is not designed to, the mechanism will break long before any door opens.
Airbus doors are very similar to Boeing 777 doors.
The Airbus doors first move inwards and lift up slightly like the 777 doors do. That way they can get past the tabs that make them plug type doors.
Pre 777 Boeing A/C (except L1011 like doors on the 767) don't lift so they come inwards and articulate as stated to get past the same tabs that all main entry doors have.
If they weren't plug type doors they would require pull in hooks and multiple independent rotary locks like the main cargo doors.
Each of these doors is approximately 6' x 4' around 3,500 square inches, at a differential pressure of 8 psi makes that 28,000 pounds. No one will open that and the handle is not designed to, the mechanism will break long before any door opens.
Last edited by SMOC; 25th Jan 2010 at 03:53.
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Smoc said it rightly. If you notice at the interior edge of an Airbus door opening in the airframe, you will notice a number of squarish metal "tabs" sticking out of the door edge. These are the "tabs" that are preventing the door from blowing out in the air. I'll explain clearer if i can find a pic.
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I'm not too sure I would describe the 320 entry doors as plug type.
Boeing 737 have the tabs that fold in and with a convoluted mech action allows the door to come into then out of the cabin with the tabs folded down.
767 are internal and plug the opening when set closed.
320 doors push up against the pressure seals and then are locked with thumping big latches. From memory without the latches the door would just be free to blow out.Hence it will not plug the opening.
I think the issue is what defines a plug door.Too me it means a door thats basically larger than the hole it plugs like a plug in a sink and will not push thru the opening.
Boeing 737 have the tabs that fold in and with a convoluted mech action allows the door to come into then out of the cabin with the tabs folded down.
767 are internal and plug the opening when set closed.
320 doors push up against the pressure seals and then are locked with thumping big latches. From memory without the latches the door would just be free to blow out.Hence it will not plug the opening.
I think the issue is what defines a plug door.Too me it means a door thats basically larger than the hole it plugs like a plug in a sink and will not push thru the opening.
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Grey beard which door on the 146....they are all plug.....on the main entry doors the action of closing pulls the door in and then down behind the stops, also the door then goes slightly outward....a plug in my book....All the rest on the lower lobe and the flight deck are definite plugs....
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(1) Can someone confirm that Boeing doors really cannot be opened when the aircraft is normally pressurized in flight; and (2) is this also true for Airbus airliners
Some examples would include a Turkish Diesel-10; a United Airlines 747 and probably an Air India 747.
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Yeah, looks like a320 doors are not plug-type:
YouTube - Operacion Type C door
YouTube - Operacion Type C door
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A320 FCOM 1.52.10: "The aircraft has four plug-type doors that open outward and forward"
Either way, FAA doesn't define plug doors. The official term is "doors for which the initial opening movement is inwards". The Airbus doors qualify as inwards opening doors, otherwise they need locks and flags like the cargo doors. Part 25.783 is the applicable section.
I heard it's the same design on every Airbus product, including the Concorde.
Either way, FAA doesn't define plug doors. The official term is "doors for which the initial opening movement is inwards". The Airbus doors qualify as inwards opening doors, otherwise they need locks and flags like the cargo doors. Part 25.783 is the applicable section.
I heard it's the same design on every Airbus product, including the Concorde.
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IMO (not even humble, lol) if a door slaps up against the fuse from outside and is held in position with dirty big C latches, that aint a plug, and I dont care what airbus or BAe choose to call it.
next time I plug a sink from underneath I'll reconsider.
Dont get me wrong I like the bus (and its doors) , spent a long time working the 320 in the early days.
next time I plug a sink from underneath I'll reconsider.
Dont get me wrong I like the bus (and its doors) , spent a long time working the 320 in the early days.
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It's not the plug-type pax doors which cause the explosive decompression disasters. It's (almost) invariably the non-plug cargo doors which trigger those disasters, eg Air India 182, United 811 etc etc.
Combine non-plug electrically opened doors with Kapton or Poly-X wiring and you've got the recipe for a catastrophe. Added terrorists not necessary.
Combine non-plug electrically opened doors with Kapton or Poly-X wiring and you've got the recipe for a catastrophe. Added terrorists not necessary.
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Concord was built by Airbus?
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At the risk of oversimplification: Concorde was built by Aérospatiale and BAC. Aérospatiale was one of several companies in the original Airbus consortium that merged to form EADS, which now owns the Airbus brand and manufactures aircraft under that brand. I think.
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Plug doors
You will not open Boeing or Airbus doors in flight!! No matter how strong you are.
In a passed life I was closely involved with a smoke evacuation test on a B747-100. This meant I and another were lashed into the aircraft with 1.5" rope and body harness. The aircraft was depressurised at FL100 and the two redundant engineers tried to open door 1L, we managed to just crack the door and no more. I would even go to say it was the upper and lower gates that moved and not the actual door.
The idea being that in the event of cabin smoke the small cabin crew would crack open the forward and a rear door to create the draft and airflow to remove any smoke.....just like that
The noise from the airflow and roar was something I will always remember.
If a person was 'super human' the door handle would shear off first before any of these plug type doors began to open under pressurisation.
Well that was certainly kicked into touch.
But an idea that was explored, still alive to mention it - good plug!
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Actually, remember that Qantas 747-400 that blew an O2 bottle? It hit the door handle on the way up thru the floor and broke the handle shaft and cam. The door handle rotated to the open position, but the door didn't open.
And to add to AnthonyGA, BAC became BAe, who made Airbus wingsets in Filton, where they built the Concorde (the other Concorde line being Toulouse). That plant was sold by BAE Systems to EADS to become Airbus UK.
Checking out a picture (http://websites1st.co.uk/Websites/Co...rde%20door.jpg), it is the same system as the Airbus.
And to add to AnthonyGA, BAC became BAe, who made Airbus wingsets in Filton, where they built the Concorde (the other Concorde line being Toulouse). That plant was sold by BAE Systems to EADS to become Airbus UK.
Checking out a picture (http://websites1st.co.uk/Websites/Co...rde%20door.jpg), it is the same system as the Airbus.