Indeed. It appears that the plug did move upwards against mechanical restraint in the process of exiting the aircraft.
Agreed.
The Alaska jet that lost the door inflight was 2 months old. I don’t know that anyone knows how old was the United jet where the pictures were taken of the intact but misassembled door.
This has been discussed upthread.
On most airliners the passenger and galley doors on the main deck are the type that swing inside the door frame and then seal from the inside. So air pressure is holding the larger door fast against the smaller fuselage opening.
Conversely, in almost all cases cargo doors and emergency exit hatches are purely outward opening. They do not translate inside, rotate, then plug the hole. They are hatches held in place only by various latches and dogs while the air pressure inside is trying to swing them open.
I’m not sure I follow you.
We are looking at pictures of loose bolts. We do not know what the other end looks like. You don’t safety wire bolts that have nuts on the other end. You safety wire (or cotter-pin) the nuts. OTOH, if those bolts go into threaded cavities then yes, safety wire on the bolt heads would 100% be expected. And would be required by FAA certification standards.
IMO for now, the fact we see a bolt with no provisions for safety locking all but proves the design has a nut on the back side with some sort of locking on that nut. But which nut and / or locking was omitted during assembly.
With the completely predictable results, as you say, that the nuts backed off then the bolts backed out then shit happened.
AKA percussive maintenance.
About 30 mph, according to a postdoctoral researcher at the Institute of Theoretical Astrophysics at the University of Oslo. Scroll down about half way. (Gift link.)
The fuselage in that area is basically the same in the -900 and the -9.
Just read it was loose bolts that caused the issue. Loose bolts have been found in 6 other -9’s at this point. I can honestly say this could be a result of some engineering changes made over the years. There have been changes made to certain Engineering and Quality Assurance specifications that may have been the cause of this, I can’t, well I won’t say anymore based on the NDA I signed when I left the company. I am sure the FAA will find the root cause for this problem and they will let the public know.
Seems like the NTSB has concluded that all 12 stop pins failed, which is what allowed the pressure differential to shove the plug upward and disengage from the frame, allowing it to open as if it were intentional and appropriate.
The structure group’s exam to date showed that the door did translate upward, meaning all the stop pads became disengaged, fracturing the fittings and allowing the plug to blow out of the fuselage.
ISTM what that says is not that all 12 stop pads failed, but that they became disengaged due to the door moving up when it should not have. Is it failing if what it’s supposed to hold is no longer where it’s supposed to be held? What would have failed would have been the 4 bolts that should prevent the doorplug from sliding on its tracks, wouldn’t it?
I agree w this interpretation.
The stops on the door and the frame were each individually fine. The problem was the dummy door panel was wrongly allowed to translate upwards at which point the parts disengaged from each other and the dummy door panel opened outwards as designed.
Thanks. I’m impressed by the free flow of information from the NTSB during the investigation.
Yes, the door stops aren’t bolted to any part of the door, as I understand it, and only “failed” in the sense that the door had moved up and cleared the stops. They didn’t fail structurally.
And I appreciate you probably have a lot more you could say, but it would be inappropriate to do so, NDA or no NDA.
Okay, I was using the diagram above and the picture and misunderstood where those bolts were. I was assuming they were into threaded cavities.
Thank you! I knew there was a term for it and just blanked on it.
The president of Emirates seems to be getting fed up with Boeing’s quality control problems …
Since none of the .JP dopers have risen to this, I thought I’d give it a try. Was actually kinda scary to watch that, even knowing that everybody (in the video at least) made it out Ok.
This is my short summary:
There is a picture in this thread that shows bolts going into the door stop mounts on the inside frame of the plug. It was stated that these are adjusting mechanisms? But the plug and frame mounts for these are through holes. I assume therefore that the bolts, twelve of them, go through the mounts in some way. Holes in the plug mounts, holes in the frame mounts. They can indeed be used to align the plug. But seem to also be a block to movement. How did all twelve of them fail to not only stop lateral movement but also fail to stop outward movement. It has been reported they failed. Looking at the picture of the open plug hole, it seems it must have been all the plug mounted mounts that failed?
I hope they post a picture of the inside of the plug at some point. And/or better explain how twelve devices all failed.
I linked this video upthread, it’s a very good description of the door including photos. The link below should take you to the part where he is describing the 4, only 4, bolts that secure the door. The photo shows all of the stop pads and you can see the adjusting bolts are fitted to each of 12 “stop fittings” on the door itself and the “stop pads” are connected to the door frame. Those bolts do not attach the door in any way to the door frame, they are just to get a nice fit with the fuselage skin. https://youtu.be/maLBGFYl9_o?si=JGeLYfvbYvGVX2w7&t=472
@racer72, who is intimately familiar with these doors also described:
The tabs sticking out in the pictures have nothing to do with the hatch being held in place. They are used with threaded adjusters on the hatch to adjust the hatch to flush with the exterior skin panels.
So when the NTSB say the tabs failed, what they’re saying is they failed to hold the door in place because the door had slid upwards as it is designed to do when fitted as an actual emergency exit. They didn’t structurally fail and you can see them intact in photos of the incident aircraft,
Edit for clarity: The tabs DO hold the door against pressurisation forces, but they are not physically attached to the door by any bolt or anything, they simply form a barrier against the door falling directly out. Instead it must be lifted up to clear the tabs and then it will open outwards.
problem is: ther’s only Coca-Cola or Pepsi in this market … and from neither of those you can walk out with an airplane …
so AL also have limited option-space in terms of purchases… and need to “navigate” those situations …
but my gut feeling is : Boeing might move into the equivalent of “italian car” mental-space-territory (lots of problems and hidden cost later on) … so many AL might weigh more towards airbus in the medium-long term (strategic decision)
Thank you.
At what point do air carriers suffer from customer rejection of Boeing 737 MAX aircraft? They’d better not get too many more bad headlines about quality, or the carriers using those planes will run into trouble and it’ll kill Boeing’s sales.