5 ms·

If this is true, it is impressive the door stayed attached to the plane as long as it did. If they really forgot to install all of the bolts intended to hold it

If this is true, it is impressive the door stayed attached to the plane as long as it did. If they really forgot to install all of the bolts intended to hold it in place, I would have expected to to fail much sooner.

jurassicfoxy 3y ago
One thing I don't understand is the why the door isn't designed so that pressure doesn't seal it tighter. Like a manhold cover. It seems at least the door needs to be "lifted" to be removed, so the missing bolts hold it down (but presumably do not hold against outward pressure). I guess that's why it doesn't immediately fall out. Has anyone seen mechanical or assembly drawings of these things?
- TaylorAlexander 3y ago
  My guess is a combination of it would be harder to install that way and designers never considered people would leave the bolts out! Hard to design a plane for such serious assembly oversight.
  - uoaei 3y ago
    Competent designers do think about those things.
    - icegreentea2 3y ago
      Competent designers and engineers consider the risks of incorrect assembly, and depending on risk assessment (probability vs severity of failure), and cost-benefit assessment (cost of redesign vs cost of inspection), and based on that decide on if further mitigations are required.
      - TaylorAlexander 3y ago
        Sure that makes sense.
      - uoaei 3y ago
        Generally if it's possible that a complete failure of process happens, designers will plan for that. Anything outside of fully automated assembly processes with interlocks and safety checks warrant that to a decent designer. You cite cost of redesign but we're talking design in the first place. What's on the table in this discussion is design, not response to failures.
- serf 3y ago
  >One thing I don't understand is the why the door isn't designed so that pressure doesn't seal it tighter. I guess presumably because the plug does double-duty as a door depending on the floor plan.
- thsksbd 3y ago
  My understanding, reading this, is that it is the pressure that holds it in place. The bolts just keep is from sliding off. The doors are very heavy, the pressure keeps them in place in only one direction. Without the bolts, only friction from the pressure would hold them up.
- Zigurd 3y ago
  based on the Blancolirio explanation, it would have been held in place by the pressure differential, except that on this flight it got jostled just right at a low enough altitude. What seems odd is the springs that assist opening an emergency exit are left in place. Might not have made a difference.
- ooboe 3y ago
  Chris Brady has a video explaining it: https://www.youtube.com/watch?v=5FcyvFfHsjQ https://www.youtube.com/watch?v=5FcyvFfHsjQ
- dboreham 3y ago
  It's like a flaky test in CI -- it worked for so many flights because the door is held on rails, and then by pressure at altitude.
- mikewarot 3y ago
  The door plug does seal tighter under pressure, but it has to be in the right position to do that. It's up to chance that the door plug could bounce up, and thus ready to open when the pressure builds.
mardifoufs 3y ago
Yes exactly, that's what makes me super doubtful of this story. Im mostly familiar with testing in the manufacturing process, but still, even for "in the field" post sales repair this would be very very hard to believe. Badly installed, not up to spec repairs? Sure! Forgetting about... literally all the bolts, in the factory, and then lying about it (???) for a repair that can take a day longer with 0 issues? Then tampering records? This is like 4 tiers of management, workers, inspectors colluding. Again, still possible, not super familiar with that but very very unlikely especially since they claim the door was basically not attached and painted over them bolts (again, ???). What would the endgoal even be at that point for the people who covered this up before it got sent to the airline ? I would completely believe it if they claimed that they didn't manufacture up to specs, didn't install it correctly, cheaped out on the materials.. but painting over the plugs? Yeah....
- dgoodell 3y ago
  I think you read Boeing engineer's post a bit too quickly, because that's definitely not quite what it said. That said, I worked in commercial aircraft engine component repair for years and everything I read in this is 100% plausible to me. One time we shipped a part back to the customer before it was even done being repaired. It had labels and stickers marking stuff that needed to be done still on it. When the customer got it they emailed us some photos of the markings and said "It doesn't look done to us...". We had to tell them to send it back so we could finish it. Whoops!
  - mardifoufs 3y ago
    What did I get wrong? I read his two comments but it's very possible I misunderstood something. I agree that the situation you are describing is very plausible. But correct me if I'm wrong but he's saying that Boeing knew (as in, their systems were aware) about it, even after the botched repair that there was no bolt. In this case, it would be closer to the customer knowing the repair wasn't done and still going forward with not sending it back. No checks are done even after malicious actions from spirit: >the reason the door blew off is stated in black and white in Boeings own records. It is also very, very stupid and speaks volumes about the quality culture at certain portions of the business >This entire sequence is documented in the SAT, and the nonconformance records in CMES address the damaged rivets and pressure seal, but at no point is the verification job reopened, or is any record of removed retention bolts created, despite it this being a physical impossibility. Finally with Spirit completing their work to Boeing QAs satisfaction, the two rivet-related records in CMES are stamped complete, and the SAT closed on 19 September 2023. No record or comment regarding the retention bolts is made. To me that's just hard to believe. Errors happen, but this involves fraud from spirit and also just no process at all from Boeing. I get that the system that deals with this for the 737 is apparently bad, but this just very very basic process management (aka step y needs to be done so that step x can be marked as started or confirmed). In this case, Spirit earlier lied about repairing it, then still didn't repair it... for reasons (hard to procure parts for a manufacturer is an... odd reason to just not fix a critical part especially since it would mean that they actively decided to not install the missing parts). And Boeing caught it the first time but then stopped caring the second? Idk, possible, but I'll wait for sure for more info before drawing conclusions

jurassicfoxy 3y ago

One thing I don't understand is the why the door isn't designed so that pressure doesn't seal it tighter. Like a manhold cover. It seems at least the door needs to be "lifted" to be removed, so the missing bolts hold it down (but presumably do not hold against outward pressure). I guess that's why it doesn't immediately fall out. Has anyone seen mechanical or assembly drawings of these things?

TaylorAlexander 3y ago
My guess is a combination of it would be harder to install that way and designers never considered people would leave the bolts out! Hard to design a plane for such serious assembly oversight.
- uoaei 3y ago
  Competent designers do think about those things.
  - icegreentea2 3y ago
    Competent designers and engineers consider the risks of incorrect assembly, and depending on risk assessment (probability vs severity of failure), and cost-benefit assessment (cost of redesign vs cost of inspection), and based on that decide on if further mitigations are required.
    - TaylorAlexander 3y ago
      Sure that makes sense.
    - uoaei 3y ago
      Generally if it's possible that a complete failure of process happens, designers will plan for that. Anything outside of fully automated assembly processes with interlocks and safety checks warrant that to a decent designer. You cite cost of redesign but we're talking design in the first place. What's on the table in this discussion is design, not response to failures.
serf 3y ago
>One thing I don't understand is the why the door isn't designed so that pressure doesn't seal it tighter. I guess presumably because the plug does double-duty as a door depending on the floor plan.
thsksbd 3y ago
My understanding, reading this, is that it is the pressure that holds it in place. The bolts just keep is from sliding off. The doors are very heavy, the pressure keeps them in place in only one direction. Without the bolts, only friction from the pressure would hold them up.
Zigurd 3y ago
based on the Blancolirio explanation, it would have been held in place by the pressure differential, except that on this flight it got jostled just right at a low enough altitude. What seems odd is the springs that assist opening an emergency exit are left in place. Might not have made a difference.
ooboe 3y ago
Chris Brady has a video explaining it: https://www.youtube.com/watch?v=5FcyvFfHsjQ https://www.youtube.com/watch?v=5FcyvFfHsjQ
dboreham 3y ago
It's like a flaky test in CI -- it worked for so many flights because the door is held on rails, and then by pressure at altitude.
mikewarot 3y ago
The door plug does seal tighter under pressure, but it has to be in the right position to do that. It's up to chance that the door plug could bounce up, and thus ready to open when the pressure builds.

mardifoufs 3y ago

Yes exactly, that's what makes me super doubtful of this story. Im mostly familiar with testing in the manufacturing process, but still, even for "in the field" post sales repair this would be very very hard to believe. Badly installed, not up to spec repairs? Sure! Forgetting about... literally all the bolts, in the factory, and then lying about it (???) for a repair that can take a day longer with 0 issues? Then tampering records? This is like 4 tiers of management, workers, inspectors colluding. Again, still possible, not super familiar with that but very very unlikely especially since they claim the door was basically not attached and painted over them bolts (again, ???). What would the endgoal even be at that point for the people who covered this up before it got sent to the airline ? I would completely believe it if they claimed that they didn't manufacture up to specs, didn't install it correctly, cheaped out on the materials.. but painting over the plugs? Yeah....

dgoodell 3y ago
I think you read Boeing engineer's post a bit too quickly, because that's definitely not quite what it said. That said, I worked in commercial aircraft engine component repair for years and everything I read in this is 100% plausible to me. One time we shipped a part back to the customer before it was even done being repaired. It had labels and stickers marking stuff that needed to be done still on it. When the customer got it they emailed us some photos of the markings and said "It doesn't look done to us...". We had to tell them to send it back so we could finish it. Whoops!
- mardifoufs 3y ago
  What did I get wrong? I read his two comments but it's very possible I misunderstood something. I agree that the situation you are describing is very plausible. But correct me if I'm wrong but he's saying that Boeing knew (as in, their systems were aware) about it, even after the botched repair that there was no bolt. In this case, it would be closer to the customer knowing the repair wasn't done and still going forward with not sending it back. No checks are done even after malicious actions from spirit: >the reason the door blew off is stated in black and white in Boeings own records. It is also very, very stupid and speaks volumes about the quality culture at certain portions of the business >This entire sequence is documented in the SAT, and the nonconformance records in CMES address the damaged rivets and pressure seal, but at no point is the verification job reopened, or is any record of removed retention bolts created, despite it this being a physical impossibility. Finally with Spirit completing their work to Boeing QAs satisfaction, the two rivet-related records in CMES are stamped complete, and the SAT closed on 19 September 2023. No record or comment regarding the retention bolts is made. To me that's just hard to believe. Errors happen, but this involves fraud from spirit and also just no process at all from Boeing. I get that the system that deals with this for the 737 is apparently bad, but this just very very basic process management (aka step y needs to be done so that step x can be marked as started or confirmed). In this case, Spirit earlier lied about repairing it, then still didn't repair it... for reasons (hard to procure parts for a manufacturer is an... odd reason to just not fix a critical part especially since it would mean that they actively decided to not install the missing parts). And Boeing caught it the first time but then stopped caring the second? Idk, possible, but I'll wait for sure for more info before drawing conclusions