Reuters: Asiana passenger reportedly opens A321 emergency exit during approach
It's not intended to take loads under braking - it did take loads under landing and braking because the door was open; that is how it broke.
If that's considered a plug door then all doors on all aircraft are plug doors. Functionally it isn't a plug.
If that's considered a plug door then all doors on all aircraft are plug doors. Functionally it isn't a plug.
Perhaps best described as a hybrid plug door. Certainly not a traditional plug door; i.e., can only be opened inward due to the door dimensions relative to the opening. The Airbus door appears to elongate when latched but is that elongating structure part of the door or the door latching mechanism?
Perhaps best described as a hybrid plug door. Certainly not a traditional plug door; i.e., can only be opened inward due to the door dimensions relative to the opening. The Airbus door appears to elongate when latched but is that elongating structure part of the door or the door latching mechanism?
You are correct in saying that neither the height nor the width of the door is greater than the corresponding dimension of the opening, so describing it as plug (as Airbus does) is stretching it a bit (npi).
Sounds like OZ reaction to not sell exit row seats now is a ridiculous over reaction but as long as they are available for staff and interline ZED fares maybe it is a good idea!
Yes, having had a closer look at some clips of door opening from the outside, I see that there is a barely detectable inward movement (appears to be about one millimeter) before the door starts to lift. Obviously, given that the door is supposedly flush with the fuselage skin when closed, it can't move significantly inwards and then immediately upwards (unless it's an L1011-type door that retracts into the ceiling).
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.
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.
I will try to explain a bit about these doors - am unpleasently surprised that on PPRUNE we could not get the right information after full four pages, but there is a lot of misinformation and opinions. This fourm just to be full of experts, now it is full of wannabees, that should read and learn, not provide half informed opinions.
Door is not a typical plug type, as found on 737 or DC-9/MD-80. There are 14 door stops, that take the pressure load from door to door frame. There are 4 rollers, sticking out from the door to engage in roller guides on the frame, guiding doors into position (vertical movement and slight in/out movement, defined by geometry of roller guides) When opening, door is first lifted up via lever (with a minimal movement inwards to clear the door stops, onto which doors are pushed by inner pressure) then moved outwards. When doors are armed, lifting them upwards causes a disk in small pressure cylinder to be punctured and nitrogen under pressure is released into damper, thus making it pneumatic actuator, that forces doors outwards, at the same time pulling slide activating cord.
Pressure differential just before landing is minimal - in automatic mode, Cabin Pressure Controller will schedule the pressure differential down to 0,1 psi positive pressure on touchdown. (see diagram) When Weight on Wheels is sensed, this will be slowly released, so in 55 sec after touchdown, pressure is completelly equalized.
I can attest that this minimal pressure differential can be overcome, as my colleague unfortunatelly tested first hand in the hangar - he tried to open the door from the outside, not knowing that there is slight residual overpressure-(some testing of aircondition just finished). He managed to force the lever up, overlooked the red warning light in the window (cabin press) and door pushed him enough to tumble down the (improvised) steps. (just by pressure differential, actuator was not activated as door wasn`t armed)
So, yes, doors can be opened if pressure differential is small enough and enough force is exerted on door lever (and red flashing warning light is ignored). So this particular gentleman could not open it by just "touching" the lever. It was a deliberate action.
Thanks for that.
While most of the above has been covered in various posts (amid a number of red herrings), it's useful to have it all in one place.
Yes, I believe the guilty party has already acknowledged that it was intentional, albeit by someone not necessarily acting rationally.
Out of interest, do you have any feel for how much diff pressure would be enough to make forcing the door up to clear the stops impossible ?
While most of the above has been covered in various posts (amid a number of red herrings
), it's useful to have it all in one place.
So this particular gentleman could not open it by just "touching" the lever. It was a deliberate action.
Out of interest, do you have any feel for how much diff pressure would be enough to make forcing the door up to clear the stops impossible ?
Thanks for that.
While most of the above has been covered in various posts (amid a number of red herrings), it's useful to have it all in one place.
Yes, I believe the guilty party has already acknowledged that it was intentional, albeit by someone not necessarily acting rationally.
Out of interest, do you have any feel for how much diff pressure would be enough to make forcing the door up to clear the stops impossible ?
While most of the above has been covered in various posts (amid a number of red herrings
), it's useful to have it all in one place.Yes, I believe the guilty party has already acknowledged that it was intentional, albeit by someone not necessarily acting rationally.
Out of interest, do you have any feel for how much diff pressure would be enough to make forcing the door up to clear the stops impossible ?
Yes, I was so slow with preparing the photo, that in posts #85 and #86 the press. schedule was already published... getting lazy...
I could not find the definite answer to your question - I can only say that stronger you are on the door lever, more pressure you can overcome, as lifting the door out of closed position is purely mechanical (with some assisst of springs, that support the majority of the door weight)... I have heard a story from Toulouse from late eighties, when the type was new, where allegedly someone really forced the lever up from the outside, while the cabin was under some pressure and resultant violent opening of the door destructed door hinge and sent particular person flying down the stairs with serious injuries - but this is from my memory from over 30 years ago... The only number I have is warning at 0,037 psi delta - it is provided by a dedicated sensitive pressure switch, installed below cockpit. It is unfortunate, that these doors have no flap to relieve pressure, the same way as they are installed in cargo doors - there the flap is a must, as even slightest pressure differential will send the door into someone`s head upon opening.
