Alaska Airlines 737-900 MAX loses a door in-flight out of PDX
Psychophysiological entity
Firstly, is that from the exact same type?
The shadow top left and down a bit is deceiving. I thought it was a smooth surface, but there must be an inset strip following the curvature of the hull.
The bottom of the door doesn't have far to go down, yet needs to come out. Being on a hinge the bottom edge must be held out - apart from those slotted hinge bolts - and even they are settled into place by the 12 friction contact pads.
MechEngr
The shadow top left and down a bit is deceiving. I thought it was a smooth surface, but there must be an inset strip following the curvature of the hull.
The bottom of the door doesn't have far to go down, yet needs to come out. Being on a hinge the bottom edge must be held out - apart from those slotted hinge bolts - and even they are settled into place by the 12 friction contact pads.
MechEngr
There is a relief at the top edge of the door. It's not a tight joint all the way around on the outer skin.
Making too much fuss, we know already the plug needs to rise before disengaging its gides so there must be a space at the top, and we have seen the neoprene seal which sits at the top.
On many doors ( older designs needed an inflatable seal, Viscount comes to mind) they rely on the px diff to close the flexible seal and I recall using a body filler compound to sculpture the sealing, airframe side, surface for a door seal to seat better.
If the leading edge looks darker also look at the window leading edge and realise that photography can be misleading.
On many doors ( older designs needed an inflatable seal, Viscount comes to mind) they rely on the px diff to close the flexible seal and I recall using a body filler compound to sculpture the sealing, airframe side, surface for a door seal to seat better.
If the leading edge looks darker also look at the window leading edge and realise that photography can be misleading.
Don't know if it's from a 737 MAX 9, only that it's from an Alaska 737.
The sides - nothing said about the top.........
The sides - nothing said about the top.........
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My understanding of the logic involved is that this is not a 'one-off'. My understanding could be wrong.
As I understand it, the work required to remove the door-plug would have required formal recording in the CMES system. The work required to 'merely' open the door-plug did not, even though, in both cases the retaining bolts needed to be removed. 'Merely' opening the door-plug to replace a seal was co-ordinated through the non-official-system-of-record used for co-ordinating work, called 'SAT'.
This means that any work that was accomplished by 'merely' opening the door-plug would not necessarily end up with an associated CMES record. The retaining bolts would still need to be removed, and replaced, but no record of this removal and expected replacement of the retaining bolts would have happened.
This means that any (remedial) work that required opening the door-plug, but not its complete removal, is open to the bolts being removed and accidentally not replaced. As far as the CMES system is concerned, the bolts never changed status, which would have been a physical impossibility: and another example of where records and reality do not match, you need to trust reality.
If my logic is wrong, I apologise, and would be grateful for clearer thinkers and those in possession of more and better information to correct me.
As I understand it, the work required to remove the door-plug would have required formal recording in the CMES system. The work required to 'merely' open the door-plug did not, even though, in both cases the retaining bolts needed to be removed. 'Merely' opening the door-plug to replace a seal was co-ordinated through the non-official-system-of-record used for co-ordinating work, called 'SAT'.
This means that any work that was accomplished by 'merely' opening the door-plug would not necessarily end up with an associated CMES record. The retaining bolts would still need to be removed, and replaced, but no record of this removal and expected replacement of the retaining bolts would have happened.
This means that any (remedial) work that required opening the door-plug, but not its complete removal, is open to the bolts being removed and accidentally not replaced. As far as the CMES system is concerned, the bolts never changed status, which would have been a physical impossibility: and another example of where records and reality do not match, you need to trust reality.
If my logic is wrong, I apologise, and would be grateful for clearer thinkers and those in possession of more and better information to correct me.
Psychophysiological entity
One reason for 'merely' opening the plug/door was to replace a seal. Well, good luck with doing that with a gap you can just get your hands into. Really opening it raised a shed full of paperwork.
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The more I read, the more I understand why a supposedly new aircraft has hidden areas that looked daubed and painted over rather than a one time spray sequence.
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The more I read, the more I understand why a supposedly new aircraft has hidden areas that looked daubed and painted over rather than a one time spray sequence.
I know of one very large company that has an official channel that gets very specific, limited use, then separate channels (Slack, personal SMS, etc) where most communication happens. Seems many employees don't trust the official system to not be used against them.
Granted they aren't aerospace/aviation, but the mindset seems prevalent among the younger crowd (mid 30s and below).
This photo, posted earlier, shows the needed fittings on the frame.
https://cimg5.ibsrv.net/gimg/pprune....8b625c5127.jpg
Last edited by ST Dog; 23rd Jan 2024 at 16:13. Reason: Clarification.
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D Bru's post #1208 shows an image of a door from an Alaska 737, I can't say the fit is what I would expect. Lighting may not be helping, but the gap at the rear looks tighter & the forward end seems to be depressed & nowhere near flush with the fuselage, I imagine that front edge may need to be depressed slighly to avoid airflow getting under the door, but by this much? (not suggesting that this is related to the cause of the blow out, more that there may be general issue with door fitment / build quality)
Last edited by incompleteness; 23rd Jan 2024 at 15:23. Reason: Grammar
Yes, that's certainly feasible, but IMHO other suggested explanations are equally so.
The most obvious way (in both senses of the word) to hold the door plug temporarily would be a suitable screwdriver inserted into one of the upper or lower bolt holes. Clearly that would be most easily fitted with the handle inboard (as opposed to the bolts, which when fitted have their heads outboard).
But I'm struggling to see how, in the absence of the bolts being fitted, a screwdriver sticking out of the door plug could fail to be noticed. It would also very likely obstruct the fitting of the trim panel.
The most obvious way (in both senses of the word) to hold the door plug temporarily would be a suitable screwdriver inserted into one of the upper or lower bolt holes. Clearly that would be most easily fitted with the handle inboard (as opposed to the bolts, which when fitted have their heads outboard).
But I'm struggling to see how, in the absence of the bolts being fitted, a screwdriver sticking out of the door plug could fail to be noticed. It would also very likely obstruct the fitting of the trim panel.
Edited post to make it clearer that I was confirming the need for fittings to be added.
The Shadows
If you look at the shadow half way down the plug on the left, caused by the overlapping aluminium sheets. If the sheets are 2mm thick, the shadow looks to be 10mm. So is exaggerating the distance by x5.
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Editors are going to be very careful with a story like this. Fact checking, seeking corroboration, legal review, etc. all take time. No one wants to get it wrong and have to publish a retraction that's sure to get international attention and no one wants to be sued by Boeing.
If throwawayboeing is able to communicate and back up his/her claims, there will sooner or later be very big and bold headlines.
Reading the proceeding posts, I wonder if this becomes a nomenclature loophole - while there would certainly be paperwork associated with removing/replacing a door 'plug', opening/closing an actual door is unlikely to require paperwork. So by calling the 'plug' a 'door', they could avoid the paperwork when opening/closing it to do the needed rework (OTOH, there should have been paperwork associated with the seal rework).
Before I retired, there was a constant mantra regarding "process", and following the associated process(es). Further, if the process was broken or bad, take the steps needed to get the process changed so it made sense.
I wonder if that's been forgotten over the last seven years...
Before I retired, there was a constant mantra regarding "process", and following the associated process(es). Further, if the process was broken or bad, take the steps needed to get the process changed so it made sense.
I wonder if that's been forgotten over the last seven years...
Reading the proceeding posts, I wonder if this becomes a nomenclature loophole - while there would certainly be paperwork associated with removing/replacing a door 'plug', opening/closing an actual door is unlikely to require paperwork. So by calling the 'plug' a 'door', they could avoid the paperwork when opening/closing it to do the needed rework (OTOH, there should have been paperwork associated with the seal rework).
Before I retired, there was a constant mantra regarding "process", and following the associated process(es). Further, if the process was broken or bad, take the steps needed to get the process changed so it made sense.
I wonder if that's been forgotten over the last seven years...
Before I retired, there was a constant mantra regarding "process", and following the associated process(es). Further, if the process was broken or bad, take the steps needed to get the process changed so it made sense.
I wonder if that's been forgotten over the last seven years...
So have they hired people who hate paperwork? People who are illiterate? Or have they got management that can't stand waiting for paperwork?
If you want quality in a process, you run the process at the speed it can go. You don't run it at the speed you want it to go. If it's not fast enough to suit you, you improve the process. You don't whip the workers.
In my Big Company software job, the only time we caused customers problems is when we started skipping or fudging parts of our testing and deployment process. It wasn't one engineer's bugs that caused problems. It was other people deploying the bugs that caused problems.
Having recently read Flying Blind about the original 737Max debacle, it would seem following this thread that Boeing still doesn't believe this. It is easy to see how production pressure could lead to a change in shift missing the necessary continuity in the process as outlined in the Leeham News whistle blower article.
The Spirit warranty team was there to fix problems reported by Boeing, not to add to the list of discovered problems. No paperwork, no problems.