Reuters: Asiana passenger reportedly opens A321 emergency exit during approach
N.B. the photo I posted in #46 is unrepresentative (it's a cabin trainer) - at L3, the A321 has the triple on the left and the double (plus F/A seat) on the right.
Clearly, the stops prevent direct outward motion of the door (whether or not there is cabin pressure). The door therefore needs to move upwards in order to clear the stops before moving outwards and then forwards.
How much resistance the stops present to upward movement of the door is a function not just of the pressure on the door forcing it against the stops, but also the friction between the door and the stops. The countless videos of A32x door operation don’t appear to show any appreciable inward movement of the door prior to lifting, so I doubt there is any geometric interference. The mechanical advantage provided by the handle is another factor, bearing in mind that raising the handle by approximately a foot appears to only lift the door by the 3 cm or so necessary to clear the stops.
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Eliminate seat occupancy
Asiana's immediate response appears to be to stop the seat in question being occupied:
https://www.aljazeera.com/news/2023/...ane-door-opens
https://www.aljazeera.com/news/2023/...ane-door-opens
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Originally Posted by EddyCurr
You are saying that in-flight repositioning of an object with the dimensions and aerodynamics of an A321 cabin door, one that has to extend outward from the hull and articulate forward to fully open, is a trivial matter?
The design of the cabin door hinge mechanism is such that upon actuation, the hinge mechanism extends the door outward from the hull and articulates it forward to the fully open position while maintaining the door (mostly) parallel to the hull.
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Cabin videos of this event illustrate the extent of buffeting around the door opening. Projecting something the size of a cabin door out and forward into that air stream, even "on edge", is non-trivial. When I posted my earlier remark I overlooked the fact that door opening assist devices are armed in flight. It was unnecessary for the perpetrator to manually provide the considerable effort required to move the door to the fully open position.
I would be interested to know if there was any malfunction or manual adjustment of the pressurisation system on this flight... Having flown Airbus of many years I would have sworn that this could not happen without non-standard pressurisation.
I also hope someone covering Korean media can update us all on the further repercussions for the passenger concerned. Please....
I also hope someone covering Korean media can update us all on the further repercussions for the passenger concerned. Please....
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Is this the same door?
(YouTube video, A321 L3 door trainer, SIM Tech manufacturing, in case the link doesn’t work)
If so, in light of recent events, maybe the short term solution is a burly cabin crew member stationed at these doors. 757 5th cabin crew (a very vague recollection) was sat at or near the corresponding location. Maybe.
(YouTube video, A321 L3 door trainer, SIM Tech manufacturing, in case the link doesn’t work)
If so, in light of recent events, maybe the short term solution is a burly cabin crew member stationed at these doors. 757 5th cabin crew (a very vague recollection) was sat at or near the corresponding location. Maybe.
Last edited by Lancelot de boyles; 29th May 2023 at 03:20. Reason: YouTube link not displaying
What are all other operators of this design doing? Any word from Airbus?
I would be interested to know if there was any malfunction or manual adjustment of the pressurisation system on this flight... Having flown Airbus of many years I would have sworn that this could not happen without non-standard pressurisation.
I also hope someone covering Korean media can update us all on the further repercussions for the passenger concerned. Please....
I also hope someone covering Korean media can update us all on the further repercussions for the passenger concerned. Please....
Above 10,000ft or so there is obviously positive pressure inside compared to outside. Once the aircraft starts descending below that height does the cabin pressure just track the outside atmosphere or is there a lag? If it lags you’d get a slight negative pressure inside the cabin wouldn’t you?
(I would assume there would be a lag to manage the rate of pressure change for passenger comfort.)
Either way, haven’t you lost any positive pressure locking effect?
There are of course 8 of these doors on an A321ceo, so an F/A adjacent to each door isn't going to happen.
S Korea's Asiana Airlines bans emergency seats after door opens
Note also the video a couple of posts back showing that it's not just seat A that can reach the handle easily.
I have a feeling this is going to run and run, with some fairly profound implications for the industry ...
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It is a plug type door. The first motion of the door opening is the the top and bottom section of the door move inwards, the door then moves slightly up off of the stops, the door then moves out. Normally cabin pressure prevents the top and bottom section moving inwards, preventing the door moving at all, let alone inwards.
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I’d want to know a lot more about the door mechanics before concurring with that.
Clearly, the stops prevent direct outward motion of the door (whether or not there is cabin pressure). The door therefore needs to move upwards in order to clear the stops before moving outwards and then forwards.
How much resistance the stops present to upward movement of the door is a function not just of the pressure on the door forcing it against the stops, but also the friction between the door and the stops. The countless videos of A32x door operation don’t appear to show any appreciable inward movement of the door prior to lifting, so I doubt there is any geometric interference. The mechanical advantage provided by the handle is another factor, bearing in mind that raising the handle by approximately a foot appears to only lift the door by the 3 cm or so necessary to clear the stops.
Clearly, the stops prevent direct outward motion of the door (whether or not there is cabin pressure). The door therefore needs to move upwards in order to clear the stops before moving outwards and then forwards.
How much resistance the stops present to upward movement of the door is a function not just of the pressure on the door forcing it against the stops, but also the friction between the door and the stops. The countless videos of A32x door operation don’t appear to show any appreciable inward movement of the door prior to lifting, so I doubt there is any geometric interference. The mechanical advantage provided by the handle is another factor, bearing in mind that raising the handle by approximately a foot appears to only lift the door by the 3 cm or so necessary to clear the stops.
No - the slide would not reach the engine. As it extends it will be bent back by the slipstream to lie along the fuselage until it extends far enough to have enough drag to tear it loose. There have been deployments where ground winds were enough that the slide was pushed out of position. If you don't look first it might be a jump straight to the pavement.
The link that broke takes tension load when the plane decelerates. I don't think uniform/constant braking alone would be enough, but if the brakes are applied and then eased, the mechanism is sufficiently springy that the door would swing backwards, and then re-applying the brakes would give the door a running start to hit the travel hard stop in the links. There is a mention of the gust lock, but that might only provide control to keep the door from closing and might not be rigid enough to prevent it from moving.
I noticed a striped bar across the opening - is that part of the door assembly so that the exit can be marked as not suitable in the event the door opens and the slide fails? If so, Airbus almost thought of everything.
That pin-in-groove could be made to take a substantial force.
I would not call it a plug door or semiplug door. A plug door seal should be compressed by the inside air pressure. The door is prevented from moving outward because that seal is in contact with the sealing surfaces. This is a finger capture door with pins extending like fingers. Internal pressure will tend to decrease the compression on the seal and failure of the fingers will allow the door to exit the fuselage.
For example of plug vs non-plug:
The 737 Classic (?) overwing emergency exits are plug doors - noted on one flight by the way that daylight through a 1/4 inch seal gap went away as the plane was pressurized and the plug forced into position. The NG changed it to an interlocked non-plug door.
See
The 737 main doors are plug doors - first having to come entirely into the plane before going edgewise out to clear the seals.
For all one ever wanted to know about 737 doors:
Seems like Airbus should have an electro-mechanical interlock on the non-plug doors.
The link that broke takes tension load when the plane decelerates. I don't think uniform/constant braking alone would be enough, but if the brakes are applied and then eased, the mechanism is sufficiently springy that the door would swing backwards, and then re-applying the brakes would give the door a running start to hit the travel hard stop in the links. There is a mention of the gust lock, but that might only provide control to keep the door from closing and might not be rigid enough to prevent it from moving.
I noticed a striped bar across the opening - is that part of the door assembly so that the exit can be marked as not suitable in the event the door opens and the slide fails? If so, Airbus almost thought of everything.
That pin-in-groove could be made to take a substantial force.
I would not call it a plug door or semiplug door. A plug door seal should be compressed by the inside air pressure. The door is prevented from moving outward because that seal is in contact with the sealing surfaces. This is a finger capture door with pins extending like fingers. Internal pressure will tend to decrease the compression on the seal and failure of the fingers will allow the door to exit the fuselage.
For example of plug vs non-plug:
The 737 Classic (?) overwing emergency exits are plug doors - noted on one flight by the way that daylight through a 1/4 inch seal gap went away as the plane was pressurized and the plug forced into position. The NG changed it to an interlocked non-plug door.
See
The 737 main doors are plug doors - first having to come entirely into the plane before going edgewise out to clear the seals.
For all one ever wanted to know about 737 doors:
Seems like Airbus should have an electro-mechanical interlock on the non-plug doors.
So the $64K question is whether, even with a modest amount of cabin pressure hindering that mm of inward movement, it's still possible to graunch the door up while overcoming the friction between the stops until it's free to move outwards, at which point the actuator takes over and drives the door forwards.
No doubt other explanations for what happened are available.
I would indeed be interested in seeing the AMM.
A bit like the annoying belt barriers that make you walk in unnecessary zigzags when checking in.
No - the slide would not reach the engine. As it extends it will be bent back by the slipstream to lie along the fuselage until it extends far enough to have enough drag to tear it loose. There have been deployments where ground winds were enough that the slide was pushed out of position. If you don't look first it might be a jump straight to the pavement.
The link that broke takes tension load when the plane decelerates. I don't think uniform/constant braking alone would be enough, but if the brakes are applied and then eased, the mechanism is sufficiently springy that the door would swing backwards, and then re-applying the brakes would give the door a running start to hit the travel hard stop in the links. There is a mention of the gust lock, but that might only provide control to keep the door from closing and might not be rigid enough to prevent it from moving.
I noticed a striped bar across the opening - is that part of the door assembly so that the exit can be marked as not suitable in the event the door opens and the slide fails? If so, Airbus almost thought of everything.
That pin-in-groove could be made to take a substantial force.
I would not call it a plug door or semiplug door. A plug door seal should be compressed by the inside air pressure. The door is prevented from moving outward because that seal is in contact with the sealing surfaces. This is a finger capture door with pins extending like fingers. Internal pressure will tend to decrease the compression on the seal and failure of the fingers will allow the door to exit the fuselage.
For example of plug vs non-plug:
The 737 Classic (?) overwing emergency exits are plug doors - noted on one flight by the way that daylight through a 1/4 inch seal gap went away as the plane was pressurized and the plug forced into position. The NG changed it to an interlocked non-plug door.
See
https://www.youtube.com/watch?v=2sj53BawjQg
https://www.youtube.com/watch?v=9Zyxy3naQh0
The 737 main doors are plug doors - first having to come entirely into the plane before going edgewise out to clear the seals.
For all one ever wanted to know about 737 doors:
https://youtu.be/WLfT5WJz-6s?t=205
Seems like Airbus should have an electro-mechanical interlock on the non-plug doors.
The link that broke takes tension load when the plane decelerates. I don't think uniform/constant braking alone would be enough, but if the brakes are applied and then eased, the mechanism is sufficiently springy that the door would swing backwards, and then re-applying the brakes would give the door a running start to hit the travel hard stop in the links. There is a mention of the gust lock, but that might only provide control to keep the door from closing and might not be rigid enough to prevent it from moving.
I noticed a striped bar across the opening - is that part of the door assembly so that the exit can be marked as not suitable in the event the door opens and the slide fails? If so, Airbus almost thought of everything.
That pin-in-groove could be made to take a substantial force.
I would not call it a plug door or semiplug door. A plug door seal should be compressed by the inside air pressure. The door is prevented from moving outward because that seal is in contact with the sealing surfaces. This is a finger capture door with pins extending like fingers. Internal pressure will tend to decrease the compression on the seal and failure of the fingers will allow the door to exit the fuselage.
For example of plug vs non-plug:
The 737 Classic (?) overwing emergency exits are plug doors - noted on one flight by the way that daylight through a 1/4 inch seal gap went away as the plane was pressurized and the plug forced into position. The NG changed it to an interlocked non-plug door.
See
https://www.youtube.com/watch?v=2sj53BawjQg
https://www.youtube.com/watch?v=9Zyxy3naQh0
The 737 main doors are plug doors - first having to come entirely into the plane before going edgewise out to clear the seals.
For all one ever wanted to know about 737 doors:
https://youtu.be/WLfT5WJz-6s?t=205
Seems like Airbus should have an electro-mechanical interlock on the non-plug doors.
The Airbus door is still considered a 'plug' type.
I agree however that the door flight locks as fitted to the bigger Boeings should be mandated on all types.