Alaska Airlines 737-900 MAX loses a door in-flight out of PDX

[remi]

The failure that is outlined in the article is troubling, but it is also not unexpected. What is frustrating is that the process is done in such a haphazard manner, when the information exists within the system that all is not well. The rectification of a defect such as this should have been a routine matter, save for the constraints of production & delivery schedules. After "392" discrepancies in the same small component, which are admittedly not identified as to severity of non conformance, but somewhere, a proper QA system that is not just lip service to having processes that are not followed, and inspectors that are disincentivised to discover issues is not a healthy place to be.

The background problem is, how do you perform what is akin to cancer surgery on this problem to save the patient, when there is evidence that this is not isolated, the whole MDD takeover has resulted in metastasis throughout the program. The cure for this may well be to cut the head off this patient, and replace it with a head from a group that are going to look at the long term health of the company and to try and turn around SS BCA, which has icebergs ahead, and has had a management in corporate level, and a board that has been busy on the poop deck, pooping away the future of the company. IMHO.

This is no better than the debacle on the Ducommon ring frame fiasco which is still a black mark on the company.

The company will blame the component manufacturer, deflection is easy, however, it wasn't the supplier of the part that didn't put the bolts in, and it is improbable that the mechanic on the line did this deliberately, and that strongly suggests that production pressure plays a part in this event. The process is flawed, if the steps are not tracked, then the QA group is not likely to detect such errors.

BCA will survive, and it should survive, not because it is too big to fail, (there are eminently sound alternatives) but the turn around of this company is not impossible, it is just impossible with the current pathological management that exists in Chicago.
As someone who has worked in a massive, complex cloud computing environment, I am shocked that there would be both a "system of record" and a parallel "system of whatever" used to manage production.

I (and many many other people) used to pull metrics from a ticketing system of record, and so did management. That was just how to do it. We also used email, assorted chat systems, and eventually Slack, but those are just to chat with people. Every action associated with an event, a deployment, a major change, or something otherwise ticketed was updated in the ticket. That record was preserved for posterity. 10-20+ year old tickets are still around. Our controls didn't have federal legal liability attached, at least not at the "a deliberate omission is illegal" level, but it was just a straightforward, methodical way to work, and with rare exceptions due to security, anyone could see work in a ticket.

Replacing a system of record, especially in a regulated, safety-conscious environment, is a massive undertaking and I expect that a goal of 10 years would be achievable, but wouldn't happen, because these things always run into execution problems due to management and technical turnover. Unless something radical and transformative is already underway at Boeing, it will take 10 years, 15 years, more, for the company to straighten up and fly right. This could have been started in the mid 90s, or any time since, but ... has it?

Boeing is of course too big to fail, and aviation exports rank very high (often #1) in US exports by category, but someone, somehow, needs to get this company back on track if it's going to continue to be a legitimate competitor to Airbus.

[639]

Frankly, I don't like my scenario. I did at first, but almost deleted it before you posted. I like the concept of one item replacing 4 safety bolts but it still leaves the splitting issue which I find alarming.

Frankly, I'm still in the dark about how that top edge passes the lip of the fuselage. I've read every post and watched Chris Brady's items. I know the system must work, but I can't 'see' the roller pins and guides doing everything that has to be done.

It might not look like it as the roller guide does mean some straight upwards movement before the J shape of the guide channel moves the top outwards, but that is the only part that governs the track of the door as it moves upwards and is enough to just clear the lip.

[DaveReidUK]

One possible explanation has been expressed here several times and, to the best of my knowledge, has not been refuted.

A single temporary locating pin, bolt, or mandrel, was inserted in one guide hole. The expectation was that this temporary pin would be replaced by a bolts after the other three bolts had been inserted but the task was interrupted. The trim panel was replaced with only the temporary pin/bolt/mandrel in place and it eventually fell out.

In my opinion no other satisfactory explanation has been suggested.

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.

[SRMman]

Agree with all this post except, and I may be wrong, I think the door has to be pulled inwards for the roller pin to be at the back of the guide fitting ie. before the door is pulled down placing the pin at the top of the guide fitting (above where the stop bolt should be). Possibly. The way I see it the back of the guide fitting is on the outboard side of the door and as the pin is fixed, the door (and guide fitting) has to move inboard. Possibly.
What do you think ?
Also, as far as I can see from earlier pictures the stop pins are convex and the stop pads concave so we might need a tweak to cover the detail of how they engage / disengage

Europa01, thanks, you're quite right! I should have said pulled (inwards); I will amend my original post. But just regarding your last bit about the stop pins and pads, I'm not sure the shape of the mating surfaces is significant, I must admit I thought they were flat, but I may be wrong. In any case once the guide fitting locking bolt is inserted the stop pins and pads I assume are directly opposite each other, the only adjustment being to the stop pin longitudinally to ensure the 12 gaps are all the same.

Going back to my first post on this subject I'd said:
"The lift assist springs are resisting this downwards movement, and so the door needs to be held in place to allow the guide fitting locking bolts to be inserted under the guide pins, and the vertical movement arrestor bolts inserted through the hinge guide fittings"
In light of the latest news today (.https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspection-procedure-at-boeing/#comment-509962) the implication is increasingly that the lock bolts were absent in the Alaska incident, rather than had failed in some way. So it seems that the lift assist springs are NOT necessarily strong enough to resist the final downwards movement of the door and its guide track fittings up to contact with the roller pins, otherwise the locking bolts would HAVE to be fitted to ensure the whole door wouldn't just pop up to the "ready to push open" position.

In fact, maybe Boeing should now increase the lift springs rate such that the door guide track fittings MUST be forcibly held down to insert the locking bolts!

[SRMman]

Allowing and accepting the above explanation by throwawayboeingN704AL where does this leave the many other instances of door plug defects being reported in other aircraft

Yes, I'd wondered that. There was at least one photo of an untightened hinge guide fitting bolt.

[MikeSnow]

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).


Maybe they used one or more bolts with the their heads inboard, and without the nuts, to hold the plug temporarily. Which would also make it harder to notice that there is anything missing.

[Thrust Augmentation]

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)

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/852x887/door_1_98bbaca81a3d089a8e6241c5aa3695d6c35c7f41.jpg

[Semreh]

On the other hand, if true, then the problem with this particular door was a one-off. A result of needing to open the door to replace the seal, and then not reinstalling the bolts properly. It doesn't suggest a design flaw or a step that was missed in production, but a "loophole" in the rework requirements that did not require QA signoff if the door was opened, but not removed, and only affecting this particular aircraft.

Now, apparently other inspections have found other loose bolts, which may in fact suggest a more wide-reaching problem.

The NTSB report should be good reading, either way.

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.

[Jet Jockey A4]

I don't know if this information was posted here already but here is a copy and paste from the article...Boeing Whistleblower: Production Line Has “Enormous Volume Of Defects” Bolts On MAX 9 Weren’t Installedby Gary Leff (https://viewfromthewing.com/author/viewfromthewing/) on January 22, 2024
A reader at respected airline industry site Leeham News offered a comment (https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspection-procedure-at-boeing/#comment-509962) that suggests they have access to Boeing’s internal quality control systems, and shares details of what they saw regarding the Boeing 737 MAX 9 flown by Alaska Airlines that had a door plug detach inflight, causing rapid decompression of the aircraft.

The takeaway appears to be that outsourced plane components have so many problems when they show up at the production line that Boeing’s quality control staff can’t keep up with them all.
Current Boeing employee here – I will save you waiting two years for the NTSB report to come out and give it to you for free: 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.

…With that out of the way… why did the left hand (LH) mid-exit door plug blow off of the 737-9 registered as N704AL? Simple- as has been covered in a number of articles and videos across aviation channels, there are 4 bolts that prevent the mid-exit door plug from sliding up off of the door stop fittings that take the actual pressurization loads in flight, and these 4 bolts were not installed when Boeing delivered the airplane, our own records reflect this.

…As a result, this check job that should find minimal defects has in the past 365 calendar days recorded 392 nonconforming findings on 737 mid fuselage door installations (so both actual doors for the high density configs, and plugs like the one that blew out). That is a hideously high and very alarming number, and if our quality system on 737 was healthy, it would have stopped the line and driven the issue back to supplier after the first few instances.

…Now, on the incident aircraft this check job was completed on 31 August 2023, and did turn up discrepancies, but on the RH side door, not the LH that actually failed. I could blame the team for missing certain details, but given the enormous volume of defects they were already finding and fixing, it was inevitable something would slip through- and on the incident aircraft something did. I know what you are thinking at this point, but grab some popcorn because there is a plot twist coming up.

The next day on 1 September 2023 a different team (remember 737s flow through the factory quite quickly, 24 hours completely changes who is working on the plane) wrote up a finding for damaged and improperly installed rivets on the LH mid-exit door of the incident aircraft.

…Because there are so many problems with the Spirit build in the 737, Spirit has teams on site in Renton performing warranty work for all of their shoddy quality, and this SAT promptly gets shunted into their queue as a warranty item. Lots of bickering ensues in the SAT messages, and it takes a bit for Spirit to get to the work package. Once they have finished, they send it back to a Boeing QA for final acceptance, but then Malicious Stupid Happens! The Boeing QA writes another record in CMES (again, the correct venue) stating (with pictures) that Spirit has not actually reworked the discrepant rivets, they *just painted over the defects*. In Boeing production speak, this is a “process failure”. For an A&P mechanic at an airline, this would be called “federal crime”.

…finally we get to the damning entry which reads something along the lines of “coordinating with the doors team to determine if the door will have to be removed entirely, or just opened. If it is removed then a Removal will have to be written.” Note: a Removal is a type of record in CMES that requires formal sign off from QA that the airplane been restored to drawing requirements.

If you have been paying attention to this situation closely, you may be able to spot the critical error: regardless of whether the door is simply opened or removed entirely, the 4 retaining bolts that keep it from sliding off of the door stops have to be pulled out. A removal should be written in either case for QA to verify install, but as it turns out, someone (exactly who will be a fun question for investigators) decides that the door only needs to be opened, and no formal Removal is generated in CMES (the reason for which is unclear, and a major process failure). Therefore, in the official build records of the airplane, a pressure seal that cannot be accessed without opening the door (and thereby removing retaining bolts) is documented as being replaced, but the door is never officially opened and thus no QA inspection is required.

[DaveReidUK]

I don't know if this information was posted here already but here is a copy and paste from the article...Boeing Whistleblower: Production Line Has “Enormous Volume Of Defects” Bolts On MAX 9 Weren’t Installedby Gary Leff (https://viewfromthewing.com/author/viewfromthewing/) on January 22, 2024
A reader at respected airline industry site Leeham News offered a comment (https://leehamnews.com/2024/01/15/unplanned-removal-installation-inspection-procedure-at-boeing/#comment-509962) that suggests they have access to Boeing’s internal quality control systems, and shares details of what they saw regarding the Boeing 737 MAX 9 flown by Alaska Airlines that had a door plug detach inflight, causing rapid decompression of the aircraft.

The takeaway appears to be that outsourced plane components have so many problems when they show up at the production line that Boeing’s quality control staff can’t keep up with them all.
Current Boeing employee here – I will save you waiting two years for the NTSB report to come out and give it to you for free: 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.

…With that out of the way… why did the left hand (LH) mid-exit door plug blow off of the 737-9 registered as N704AL? Simple- as has been covered in a number of articles and videos across aviation channels, there are 4 bolts that prevent the mid-exit door plug from sliding up off of the door stop fittings that take the actual pressurization loads in flight, and these 4 bolts were not installed when Boeing delivered the airplane, our own records reflect this.

…As a result, this check job that should find minimal defects has in the past 365 calendar days recorded 392 nonconforming findings on 737 mid fuselage door installations (so both actual doors for the high density configs, and plugs like the one that blew out). That is a hideously high and very alarming number, and if our quality system on 737 was healthy, it would have stopped the line and driven the issue back to supplier after the first few instances.

…Now, on the incident aircraft this check job was completed on 31 August 2023, and did turn up discrepancies, but on the RH side door, not the LH that actually failed. I could blame the team for missing certain details, but given the enormous volume of defects they were already finding and fixing, it was inevitable something would slip through- and on the incident aircraft something did. I know what you are thinking at this point, but grab some popcorn because there is a plot twist coming up.

The next day on 1 September 2023 a different team (remember 737s flow through the factory quite quickly, 24 hours completely changes who is working on the plane) wrote up a finding for damaged and improperly installed rivets on the LH mid-exit door of the incident aircraft.

…Because there are so many problems with the Spirit build in the 737, Spirit has teams on site in Renton performing warranty work for all of their shoddy quality, and this SAT promptly gets shunted into their queue as a warranty item. Lots of bickering ensues in the SAT messages, and it takes a bit for Spirit to get to the work package. Once they have finished, they send it back to a Boeing QA for final acceptance, but then Malicious Stupid Happens! The Boeing QA writes another record in CMES (again, the correct venue) stating (with pictures) that Spirit has not actually reworked the discrepant rivets, they *just painted over the defects*. In Boeing production speak, this is a “process failure”. For an A&P mechanic at an airline, this would be called “federal crime”.

…finally we get to the damning entry which reads something along the lines of “coordinating with the doors team to determine if the door will have to be removed entirely, or just opened. If it is removed then a Removal will have to be written.” Note: a Removal is a type of record in CMES that requires formal sign off from QA that the airplane been restored to drawing requirements.

If you have been paying attention to this situation closely, you may be able to spot the critical error: regardless of whether the door is simply opened or removed entirely, the 4 retaining bolts that keep it from sliding off of the door stops have to be pulled out. A removal should be written in either case for QA to verify install, but as it turns out, someone (exactly who will be a fun question for investigators) decides that the door only needs to be opened, and no formal Removal is generated in CMES (the reason for which is unclear, and a major process failure). Therefore, in the official build records of the airplane, a pressure seal that cannot be accessed without opening the door (and thereby removing retaining bolts) is documented as being replaced, but the door is never officially opened and thus no QA inspection is required.

Link to original was posted yesterday.

[Loose rivets]

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
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.




https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/852x887/top_lip_cab4ff85d05587fdf4be4da7edf0d7bbeca8361d.jpg

[aeromech3]

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.

[Thrust Augmentation]

Firstly, is that from the exact same type?

Don't know if it's from a 737 MAX 9, only that it's from an Alaska 737.

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

The sides - nothing said about the top.........

[OldnGrounded]

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.

I think your logic is exactly right. And I think that the problem revealed is a fundamental and extremely serious process failure. Coupled with the (claimed by throwaway) use of a second, non-authoritative system to address the issue, it's a giant hole in the process of building airplanes that could easily result in more than door plugs falling out of the sky. That's why I said, above, that I think I'd suspend the production certificates.

[Loose rivets]

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.

_______________

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.

[ST Dog]

As someone who has worked in a massive, complex cloud computing environment, I am shocked that there would be both a "system of record" and a parallel "system of whatever" used to manage production.


I'm not at all surprised.

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).

[ST Dog]

I don't think there's a latch fitting on the frame. That would have to be installed which might be a big deal if the backup intercostals also need to be installed. That would be a large-ish structural mod (if needed).


Correct, the plug option doesn't have the latch fittings.

This photo, posted earlier, shows the needed fittings on the frame.
https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/664x558/737_door_2_6e87fca8f3091b54bf738601cc19c88b625c5127.jpg

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/664x558/737_door_2_6e87fca8f3091b54bf738601cc19c88b625c5127_49d7e9aa 640fd398c1ebfef4a5e59ad39cab5b84.jpg

[incompleteness]

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)

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/852x887/door_1_98bbaca81a3d089a8e6241c5aa3695d6c35c7f41.jpg

It is depressed WRT the skin because it moves outwards to nominally flush when pressurized. The light is from the front causing a shadow on the front edge but not the back, giving the illusion of unequal gaps.

...

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 shadows top left and mid left are lap joints. Top is where the crown skin goes over the window belt and mid is the belt going over the side skin.

[EXDAC]

This photo, posted earlier, appears to show fittings on the frame.

Yes, but that is a picture of a door which needs latch fittings. The question was whether those latch fitting would be installed for the plug and be available for retrofit of a door.

[Europa01]

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.

As a practising mechanical engineer of far too many years I can see the unpleasant attraction of inserting a handy (un)suitable screwdriver, mandrel, sprag, bolt or something when re closing the door. What’s also troubling me is - what happened to the bolts which were removed? Where were they put? Did they just kick around the fuselage floor until someone binned them, were they left in the bottom of the door to rattle around until the door ejected? I can’t believe that critical fasteners can be unaccounted for in any way on an aircraft production line. All of this points to a serious workforce culture problem and of course this comes from or is tolerated by those at the top.

[ST Dog]

Yes, but that is a picture of a door which needs latch fittings. The question was whether those latch fitting would be installed for the plug and be available for retrofit of a door.

They aren't installed for the plug, based on the numerous photos of that option, but would have to be added to convert it to a functional exit as shown in the photo of an actual exit door.

Edited post to make it clearer that I was confirming the need for fittings to be added.

[scifi]

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.
https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/852x887/door_1_98bbaca81a3d089a8e6241c5aa3695d6c35c7f41.jpg

[C2H5OH]

Seven days since posting under that Leeham article and yet no word in Seattle or NYT?
Could be good OpSec though, not calling the numbers provided. Wouldn’t do that either.

[OldnGrounded]

Seven days since posting under that Leeham article and yet no word in Seattle or NYT?
Could be good OpSec though, not calling the numbers provided. Wouldn’t do that either.

Right. If the reporters want whistleblowers to feel safe, they have to provide much more secure ways to contact and communicate. We know, though, that both the Times reporter and Gates are aware of that and are experienced in these things.

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.

[MarineEngineer]

No sane whistleblower is going to contact a reporter's public email!

[adnoid]

...Just to be sure Boeing doesn't have trouble finding them later...

I anticipate I will use this exact wording in some future correspondence. Well played.

[tdracer]

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...

[remi]

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...
The important question is why would someone be motivated to avoid the paperwork? Presumably if you are in aviation you have a very high tolerance for, and even like for, paperwork.

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.

[shinz0]

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.
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.

[MechEngr]

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.

[OldnGrounded]

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.

But the Spirit team didn't make the CMES entries related to the work on the seal and associated "opening" or "removal" of the plug, or determine how it would be characterized. They couldn't, because they don't have access.

[remi]

Alaska Airlines CEO: We found 'many' loose bolts on our Max 9 planes following near-disaster

"I'm angry," Ben Minicucci said. "This happened to Alaska Airlines. It happened to our guests and happened to our people."

https://www.nbcnews.com/business/business-news/alaska-airlines-found-more-loose-bolts-boeing-737-max-9-ceo-says-rcna135316

Note that as an investigation stakeholder he is legally constrained to be factual, not speculative.

Still waiting for the good news part.

[remi]

But the Spirit team didn't make the CMES entries related to the work on the seal and associated "opening" or "removal" of the plug, or determine how it would be characterized. They couldn't, because they don't have access.
Yeah this is a world class failure because among other things it's on its face inevitable. Or designed to fail.

Bear in mind that like many or most people here I love what Boeing used to do and the superb aircraft they made. It just seems like since 1997 that's not what they do or make any longer, and it makes me sad and upset.

A standby captain I used to golf with flew 757 domestic. He related that one day he was deadheading/relocating west from somewhere in Texas. Got ATC to clear him direct to something like 40k and flew straight up there like an F-4 on military power. Ah the good old days when the future of Boeing single aisle might have had main landing gear doors.

[eppy]

Throughout this thread there have been numerous terminology debates about Door Vs Plug that many people just rolled their eyes to and ignored as being pedantic.

Turns out it may be the one of the largest holes in the Swiss cheese if the recent anonymous account is correct.

Removing a plug requires an entry in the formal tracking and inspection system, with a full audit trail and validation of all processes undertaken.

Opening a door to perform an inspection or for maintenance doesn't. In this case it was classifed as a door being opened, even though it was bolted in. As such, there was no audit trail of the bolts, whose status remained unchanged in the system, which was a physical impossibility.

[remi]

Throughout this thread there have been numerous terminology debates about Door Vs Plug that many people just rolled their eyes to and ignored as being pedantic.

Turns out it may be the one of the largest holes in the Swiss cheese if the recent anonymous account is correct.

Removing a plug requires an entry in the formal tracking and inspection system, with a full audit trail and validation of all processes undertaken.

Opening a door to perform an inspection or for maintenance doesn't. In this case it was classifed as a door being opened, even though it was bolted in. As such, there was no audit trail of the bolts, whose status remained unchanged in the system, which was a physical impossibility.
One wonders if a tiny contribution to doing the right thing might be different terminology, e.g. "PORT COVER."

As someone at various times working on UIs, manuals, articles, and whatnot, I obsess over terminology.

It's not unreasonable to obsess. After all, a lot of thought went into the NATO/aviation phonetic alphabet, for the exact same reasons that it's important to communicate understandably and precisely to software users.

[tdracer]

The important question is why would someone be motivated to avoid the paperwork? Presumably if you are in aviation you have a very high tolerance for, and even like for, paperwork.

So have they hired people who hate paperwork? People who are illiterate? Or have they got management that can't stand waiting for paperwork?


Do you honestly know anybody who likes doing paperwork? Because in my 40-year career I never met one. Did the paperwork? Yes. Tolerated paperwork? Yes. Liked doing paperwork? NO!!!

[remi]

Do you honestly know anybody who likes doing paperwork? Because in my 40-year career I never met one. Did the paperwork? Yes. Tolerated paperwork? Yes. Liked doing paperwork? NO!!!
I have seen many people, and known a few, who find paperwork relaxing and/or gratifying. I don't, but I can accept that many people do.

[RickNRoll]

Air Alaska CEO states their own checks of 737 Max planes find many loose bolts.

[MechEngr]

But the Spirit team didn't make the CMES entries related to the work on the seal and associated "opening" or "removal" of the plug, or determine how it would be characterized. They couldn't, because they don't have access.
This is true. What is also true is Spirit should have their own system for tracking work that should parallel CMES. Still, they did not formally alert Boeing that additional work needed to be entered into CMES to reflect the additional defect.

[remi]

This is true. What is also true is Spirit should have their own system for tracking work that should parallel CMES. Still, they did not formally alert Boeing that additional work needed to be entered into CMES to reflect the additional defect.
How would anyone know that they formally alerted Boeing or anyone else? Is there any system of record more sophisticated than email or typed letters that documents that? Is there any mechanism that makes such communication "official" rather than "discussion"?

There are countless memos from management and engineers found in boxes of discovery material that have led to awards to plaintiffs, but pretty close to zero such memos result in regulatory action beforehand.

[OldnGrounded]

Air Alaska CEO states their own checks of 737 Max planes find many loose bolts.

Exclusive: Boeing presses suppliers on tightening bolts after loose parts found in 737 MAX 9 checks (https://www.reuters.com/business/aerospace-defense/boeing-presses-suppliers-tightening-bolts-after-loose-parts-found-737-max-9-2024-01-23/)

"[. . .]
Alaska Airlines CEO Ben Minicucci said in an NBC News interview that aired Tuesday that the airline found 'some loose bolts on many' MAX 9s during inspections.

'My demand on Boeing is, what are they going to do to improve their quality programs in house?' Minicucci said."

[OldnGrounded]

How does it happen that America's premier (and, formerly, the world's premier) commercial airframe manufacturer sets itself on a path into the wilderness, and 27 years later, no one is looking for the way back? Is it really as simple as a room full of financial elite are sucking out all the money they can from the former US #1 export industry, and aside from that they don't care?

If you had to pick one thing, that would have to be it.

[OldnGrounded]

Still, they [Spirit] did not formally alert Boeing that additional work needed to be entered into CMES to reflect the additional defect.

I don't understand which "additional defect" you mean. Spirit did, according to throwawayboeing, inform Boeing about the damaged seal. I don't think it's Spirit's job to tell Boeing what needs to be entered into CMES. Long quote:

Presented with evidence of their malfeasance, Spirit reopens the package and admits that not only did they not rework the rivets properly, there is a damaged pressure seal they need to replace (who damaged it, and when it was damaged is not clear to me). The big deal with this seal, at least according to frantic SAT postings, is the part is not on hand, and will need to be ordered, which is going to impact schedule, and (reading between the lines here) Management is Not Happy.

However, more critical for purposes of the accident investigation, the pressure seal is unsurprisingly sandwiched between the plug and the fuselage, and you cannot replace it without opening the door plug to gain access. All of this conversation is documented in increasingly aggressive posts in the SAT, but finally we get to the damning entry which reads something along the lines of “coordinating with the doors team to determine if the door will have to be removed entirely, or just opened. If it is removed then a Removal will have to be written.”

Note: a Removal is a type of record in CMES that requires formal sign off from QA that the airplane been restored to drawing requirements.

If you have been paying attention to this situation closely, you may be able to spot the critical error: regardless of whether the door is simply opened or removed entirely, the 4 retaining bolts that keep it from sliding off of the door stops have to be pulled out. A removal should be written in either case for QA to verify install, but as it turns out, someone (exactly who will be a fun question for investigators) decides that the door only needs to be opened, and no formal Removal is generated in CMES (the reason for which is unclear, and a major process failure).

Therefore, in the official build records of the airplane, a pressure seal that cannot be accessed without opening the door (and thereby removing retaining bolts) is documented as being replaced, but the door is never officially opened and thus no QA inspection is required.

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.

I told you it was stupid.

[chrisl137]

This is true. What is also true is Spirit should have their own system for tracking work that should parallel CMES. Still, they did not formally alert Boeing that additional work needed to be entered into CMES to reflect the additional defect.

How would anyone know that they formally alerted Boeing or anyone else? Is there any system of record more sophisticated than email or typed letters that documents that? Is there any mechanism that makes such communication "official" rather than "discussion"?

There are countless memos from management and engineers found in boxes of discovery material that have led to awards to plaintiffs, but pretty close to zero such memos result in regulatory action beforehand.

Everybody in aerospace has some kind of quality management system, and in general workers from any particular company are going to do work on their own paper, even if it's at a customer facility. Part of everybody's quality system is how non-conformances get communicated back and forth - customer (Boeing) notes a non-conformance with the plug bolts. That non-conformance is now tied to that fuselage and it doesn't get accepted with it open. So Spirit generates a non-conformance in *their* system (probably attaching Boeing's documentation of it) and generates a repair or rework order. Their people do the work on a Spirit work order, which may or may not require inspection. Then the confirmation that the work was done gets transmitted to Boeing, where someone reviews it and attaches it to the NC that was written up by Boeing QA. It may or may not trigger an inspection (apparently didn't in this case) and someone at Boeing has to close on the NC. But since Spirit discovered the problem with the seal in the course of the work, they probably generated an additional NC for that, which may not have required someone from Boeing to disposition, but which they probably were required to report up to Boeing. That probably should have triggered an inspection - maybe it would have if it had started with an NC noted by Boeing rather than Spirit.

All of the sequence above is a guess - I've never worked at or with Boeing, but have worked with a lot of other companies, and the process is similar everywhere. Everybody works on their own documentation, and the non-conformances and inspection evidence gets passed up and down the chain and attached to the part records at every step. We can be pretty sure that it works like that at Boeing because that would be how the anonymous Boeing person could tell the story (assuming it's true). It's all there in the documentation system. They probably even know the names of who did the work, though it really doesn't matter. It's a system failure for one reason or another, and the goal is to make it harder to make mistakes, not punish people for making them. People make lots of mistakes, you build knowledge of that into the system, and you don't let them get away from you. (as an aside, a distinction with a config management system for building stuff like airplanes vs. software is that for airplane builds the computers are live humans with all their foibles and they're running work orders by hand)

I do like the suggestions that it might have resulted from terminology confusion. I couldn't get multiquote to include enough quotes, but I had been thinking that it was related to interpretation of the word "remove" rather than "door". But either way, those kinds of things happen all too much. You have the best process in the world that works great for years. Then you hire a new tech, maybe even someone very experienced but in a different part of aerospace so they're unfamiliar with the local terminology. They dutifully follow the procedure as carefully as possible and completely break something. It's not their fault, and I've seen it happen more than once. It's a function of not realizing how much specialized terminology you use in your day to day life - it's just normal language to you and everybody you work with. But it's from another planet for the new tech.

[remi]

Exclusive: Boeing presses suppliers on tightening bolts after loose parts found in 737 MAX 9 checks (https://www.reuters.com/business/aerospace-defense/boeing-presses-suppliers-tightening-bolts-after-loose-parts-found-737-max-9-2024-01-23/)

"[. . .]
Alaska Airlines CEO Ben Minicucci said in an NBC News interview that aired Tuesday that the airline found 'some loose bolts on many' MAX 9s during inspections.

'My demand on Boeing is, what are they going to do to improve their quality programs in house?' Minicucci said."
What more straightforward task is there than verifying that bolts of the correct specs are (existing) in the right holes torqued to the right force? Sure, if you can't get to them, maybe not so simple. But let's assume they are right in front of you, like we've seen in the photographs of the structure in question.

This seems to be a failure on the order of a checkbox is missing and/or no one checked the checkbox. After several hundred airframes, no one noticed this? Or did people exploit the fact that it was missing or a common practice to ignore it? And if so, what other kind of work does Boeing (or Spirit) do this way.

Alaska painfully internally reworked itself following the first and one of the extremely rare US multiple fatality scheduled carrier accidents of the new millennium (so far), for which it was primarily at fault. After 24 years of exemplary safety afterward, Alaska has a near fatal accident entirely not of its own making.

If I were the CEO of that company, I would be thinking, at Boeing management: "We did what we had to. We f-ed up. Change was uncomfortable and a lot of work but as a result we're doing great now. Exactly what have you, our only aircraft vendor, upon whom we are dependent on every matter of safety out of our own control, been doing?"

[C2H5OH]

United Chief Executive Scott Kirby said during the airline’s earnings call on Tuesday that it wasn’t canceling its orders for the Max 10. But he said the airline was taking the jet “out of our internal plans.”

“We’ll be working on what that means exactly with Boeing,” he said. “But Boeing is not going to be able to meet their contractual deliveries on at least many of those airplanes.”

Translated in common language:
We don't cancel the order just yet, because we would have to pay contractual penalties. So we are waiting for Boeing to acknowledge that they cannot fulfill their contractual obligations, so that we can cancel for free.

How would anyone know that they formally alerted Boeing or anyone else? Is there any system of record more sophisticated than email or typed letters that documents that? Is there any mechanism that makes such communication "official" rather than "discussion"?

There are countless memos from management and engineers found in boxes of discovery material that have led to awards to plaintiffs, but pretty close to zero such memos result in regulatory action beforehand.
It's a feature of such processes, that the supplier closes their books when the intermediate product is delivered to the OEM, so Spirit should not be able to add any tasks to their flavor of "CMES" after the fuselage has arrived in Renton. Any work being done there is under the flag of Boeing and reimbursement is up to accountants and their commercial book keeping for warranty claims.

[chrisl137]

Translated in common language:
It's a feature of such processes, that the supplier closes their books when the intermediate product is delivered to the OEM, so Spirit should not be able to add any tasks to their flavor of "CMES" after the fuselage has arrived in Renton. Any work being done there is under the flag of Boeing and reimbursement is up to accountants and their commercial book keeping for warranty claims.

Physical location doesn't necessarily correlate with acceptance, and delivery doesn't necessarily lock a record. In other parts of aerospace it's not unusual for something to get delivered to the customer for tests that the supplier can't carry out themselves and acceptance only happens long after the item is physically with the customer. Rework/Repair/modification on a part can happen years after delivery and acceptance and the CM system should be able to tie the changes to the original record. It's not necessarily a common thing, but it's not unusual, either.

[remi]

Translated in common language:
It's a feature of such processes, that the supplier closes their books when the intermediate product is delivered to the OEM, so Spirit should not be able to add any tasks to their flavor of "CMES" after the fuselage has arrived in Renton. Any work being done there is under the flag of Boeing and reimbursement is up to accountants and their commercial book keeping for warranty claims.
Right, but my understanding is that there are Spirit personnel on site at the Renton assembly facility that are there to represent/facilitate/?? Spirit-the-vendor in some manner. I don't have any direct knowledge of this and my reading of previous comments may be incorrect or confused. (However, I was just at IKEA in Renton today. The checkout situation is even worse than its previously optimized-for-worst configuration. An omen?) Anyway, what do these Spirit people do? How do they communicate? Is it like that weird game of telephone I used to play with Indian engineers and their managers?

Me (X): I found XYZ and here's what to do
My manager: Good evening.
Indian manager: How are you?
Indian engineer: I read the email from X and he is absolutely right.
Indian manager: I'm well. And you?
My manager: Well, thank you. It's raining here.
Me: Mmm.
(This is literally four people on one phone call. Yes this is how these calls went. At 9PM my time.)

I've done a fair bit of consulting work but in general my customers have gone out of their way to give me as much access to communication, configuration management, etc., as possible. I can see how for CYA and BTV (blame the vendor) purposes it could be handy to have vendor representatives hanging around unable to do anything other than get sodas from the fridge.

I do genuinely wonder what the vendor reps are there for if they are not functionally integrated into the quality process.

[Pinkman]

Throwaways' description makes perfect sense and like me many of us with knowledge of ISO and other QMS type systems probably had their face in their hands - its a classic. Yes, in the first instance the ship should have been delivered defect free but given the situation BAC found themselves in what should have happened is that the spirit warranty/re-work team should have been employed under contract arrangements that permitted them to use CMES even if through a designated BAC employee. There is so much more around culture and enforcement but we are not even close to that yet.

[C2H5OH]

I do genuinely wonder what the vendor reps are there for if they are not functionally integrated into the quality process.
From what I read, they are there, to fix warranty claims on the cheap for and under the commercial control of the supplier - but under the supervision and technical control of the OEM.

[fgrieu]

We know with good confidence that the door plug's four locking bolts where not present at time of the accident, because the structural elements holding the door are essentially intact, and would not allow ejection of the door plug if these locking bolts had been present: perhaps even one, and most certainly two, are enough to prevent the door from sliding up and detach. Thus loose structural bolts are not the direct cause of the plug's ejection.

Alaska reportedly found "many" loose bolts in their inspections of the door plugs of their 79 grounded 737 MAX 9. I assume it's mostly structural bolts, not missing bolts nor missing castellated nuts on locking bolts. These findings finding seem largely unrelated to missing/lost locking bolts that have caused the plug's loss.

I ask: is such finding so abnormal/alarming ? Don't loose bolts happen all the time, and aren't they factored in the design ?

[fdr]

Throwaways' description makes perfect sense and like me many of us with knowledge of ISO and other QMS type systems probably had their face in their hands - its a classic. Yes, in the first instance the ship should have been delivered defect free but given the situation BAC found themselves in what should have happened is that the spirit warranty/re-work team should have been employed under contract arrangements that permitted them to use CMES even if through a designated BAC employee. There is so much more around culture and enforcement but we are not even close to that yet.

A production system doesn't have to cater for the normal only, it has to assume abnormalities will occur and is supposed to be robust enough in process to catch those. If not, then why waste the time and money on QA; just put it into slot machines at Vegas, at least they occasionally pay out.

[gambling is an addiction, Reach out and get help if you have a problem, free call: 1 (800) BOE-IN-GQA. Ask for Dave Calhoun] No furry animals or Airbuses were hurt with this message.

[SRMman]

We know with good confidence that the door plug's four locking bolts where not present at time of the accident, because the structural elements holding the door are essentially intact, and would not allow ejection of the door plug if these locking bolts had been present: perhaps even one, and most certainly two, are enough to prevent the door from sliding up and detach. Thus loose structural bolts are not the direct cause of the plug's ejection.

Alaska reportedly found "many" loose bolts in their inspections of the door plugs of their 79 grounded 737 MAX 9. I assume it's mostly structural bolts, not missing bolts nor missing castellated nuts on locking bolts. These findings finding seem largely unrelated to missing/lost locking bolts that have caused the plug's loss.

I ask: is such finding so abnormal/alarming ? Don't loose bolts happen all the time, and aren't they factored in the design ?

Simple answer to your 3 questions:
1. Very alarming
2. Certainly not
3. Absolutely not

[SRMman]

Another snippet from throwawayboeing's post I found astonishing was the bit about the rivets:

“We now return to our incident aircraft, which was written up for having defective rivets on the LH mid-exit door."
"Spirit has teams on site in Renton performing warranty work for all of their shoddy quality, and this SAT promptly gets shunted into their queue as a warranty item."

"Once they have finished (the rivets), they send it back to a Boeing QA for final acceptance, but then Malicious Stupid Happens! The Boeing QA writes another record in CMES (again, the correct venue) stating (with pictures) that Spirit has not actually reworked the discrepant rivets, they *just painted over the defects*. In Boeing production speak, this is a “process failure”
"Presented with evidence of their malfeasance, Spirit reopens the package and admits that …. they did not rework the rivets properly”

Am I being naïve in taking this at face value; that Spirit literally “painted over” the rivets instead of, presumably, replacing them? Just seems unbelievable....

[aeromech3]

I wonder, when in maintenance, if we removed a panel or assembly we would bag the attaching hardware and tie to the item; if we removed say an FCU and had multiple similar bolts of different length, we would make up a cardboard pattern template and insert in groups, saves a lot of faffing around.
Those of you still working aircraft, is this a taboo practice now?

[fdr]

I wonder, when in maintenance, if we removed a panel or assembly we would bag the attaching hardware and tie to the item; if we removed say an FCU and had multiple similar bolts of different length, we would make up a cardboard pattern template and insert in groups, saves a lot of faffing around.
Those of you still working aircraft, is this a taboo practice now?

That simple expediency would have gone a long way towards precluding the embarrassment of this event.

[fdr]

Another snippet from throwawayboeing's post I found astonishing was the bit about the rivets:

“We now return to our incident aircraft, which was written up for having defective rivets on the LH mid-exit door."
"Spirit has teams on site in Renton performing warranty work for all of their shoddy quality, and this SAT promptly gets shunted into their queue as a warranty item."

"Once they have finished (the rivets), they send it back to a Boeing QA for final acceptance, but then Malicious Stupid Happens! The Boeing QA writes another record in CMES (again, the correct venue) stating (with pictures) that Spirit has not actually reworked the discrepant rivets, they *just painted over the defects*. In Boeing production speak, this is a “process failure”
"Presented with evidence of their malfeasance, Spirit reopens the package and admits that …. they did not rework the rivets properly”

Am I being naïve in taking this at face value; that Spirit literally “painted over” the rivets instead of, presumably, replacing them? Just seems unbelievable....

Well, it worked on the B-17. where they only needed to last about 30 missions on average. Spirit heritage? BCA has noted that the problem with the quality of the door originated with the fabricator of that component, over the seas and far away in Malaysia. Which highlights the failings thereafter, at Spirit and at Renton. Deflection won't absolve BCA from the need to cogitate their navel and determine whether they are "in it for the huntin' ".

[SRMman]

Apologising in advance for thread drift, I don't think the Avro Lancaster had a "life" per se, but its survival rate averaged at 21 operational sorties. I was involved with one of the survivors PA474 in the early 80's !

[SLF3]

The issue for Boeing, the FAA and the NTSB is that this system failure is so fundamental to Boeing (and its subs) QA/QC that an analogue could happen anywhere on any 737. It is not unique to this ‘door’.

quadrupling the number of inspectors won’t make a difference if they don’t know what they are supposed to be looking at. They need to make fundamental changes to their production and quality systems. That’s a three year minimum project just for systems design followed by implementation with an associated learning curve and culture change.

what do you do in the interim? The pure answer is shut them down, but realistically that won’t happen.

[Less Hair]

AFAIK, they much relied on external senior instructors teaching "external" standards.

[DaveReidUK]

I wonder, when in maintenance, if we removed a panel or assembly we would bag the attaching hardware and tie to the item; if we removed say an FCU and had multiple similar bolts of different length, we would make up a cardboard pattern template and insert in groups, saves a lot of faffing around.

You beat me to it, we used little drawstring bags whenever the same loose fasteners were to be reinstalled.

[joe_bloggs]

You beat me to it, we used little drawstring bags whenever the same loose fasteners were to be reinstalled.

Our engineers have been using “ziplock” plastic bags in recent years. They have several drawers of different sizes. They can be written on with marker pen and “nested” inside each other if required.

[Yancey Slide]

Our engineers have been using “ziplock” plastic bags in recent years. They have several drawers of different sizes. They can be written on with marker pen and “nested” inside each other if required.

We’re presuming that there isn’t a neat and tidy bag of bolts that was tacked to the door which decided it wanted to go skydiving when the opportunity presented itself.

[remi]

Our engineers have been using “ziplock” plastic bags in recent years. They have several drawers of different sizes. They can be written on with marker pen and “nested” inside each other if required.
Or, basically anything that is the equivalent of a red lockout padlock that you use to indicate: Please do not turn on the power while I am working inside the high voltage cabinet (or please do not deliver this airplane until the bolts are back in).

[remi]

The issue for Boeing, the FAA and the NTSB is that this system failure is so fundamental to Boeing (and its subs) QA/QC that an analogue could happen anywhere on any 737. It is not unique to this ‘door’.

quadrupling the number of inspectors won’t make a difference if they don’t know what they are supposed to be looking at. They need to make fundamental changes to their production and quality systems. That’s a three year minimum project just for systems design followed by implementation with an associated learning curve and culture change.

what do you do in the interim? The pure answer is shut them down, but realistically that won’t happen.
This is when management puts workers through a bunch of slide shows and quizzes to fix the problem, with no change in management whatsoever.

[JRBarrett]

I wonder, when in maintenance, if we removed a panel or assembly we would bag the attaching hardware and tie to the item; if we removed say an FCU and had multiple similar bolts of different length, we would make up a cardboard pattern template and insert in groups, saves a lot of faffing around.
Those of you still working aircraft, is this a taboo practice now?

I work in maintenance at a corporate flight department, and this is exactly how we do it. A 24-month inspection requires removing multiple panels on the wing and fuselage, and the fasteners (screws) can often be of several different lengths on any one panel. We have pattern templates for every panel on the aircraft, labeled with the panel number. We have a log sheet with all panels listed, with entries for “removed”, “ok to close” “installed” and “inspected”.

The person who inspects a given panel after reinstallation cannot be the same person who installed it.

[xetroV]

We’re presuming that there isn’t a neat and tidy bag of bolts that was tacked to the door which decided it wanted to go skydiving when the opportunity presented itself.
Imagine finding that in your backyard.

I wonder, is there a formal process to document and deal with loose and excess parts found on an aircraft factory floor? After all, those bolts must have been found somewhere? They can’t just have disappeared in thin air, I’d imagine. (Barring some genuine Jedi tricks.)

[DaveReidUK]

Seattle Times today:

"The fuselage panel that blew off an Alaska Airlines jet earlier this month was removed for repair then reinstalled improperly by Boeing mechanics on the Renton final assembly line, a person familiar with the details of the work told The Seattle Times.

If verified by the National Transportation Safety Board investigation, this would leave Boeing primarily at fault for the accident, rather than its supplier Spirit AeroSystems, which originally installed the panel into the 737 MAX 9 fuselage in Wichita, Kan."

[WillFlyForCheese]

Seattle Times today:

That’s not the same as what Throwaway wrote . . . And perhaps is more damning.

[OldnGrounded]

Seattle Times today:

https://www.seattletimes.com/business/boeing-aerospace/boeing-not-spirit-mis-installed-piece-that-blew-off-alaska-max-9-jet/

[D Bru]

Re-examining some pictures I suddenly realised that the door plug wasn't intended to be fitted on N704AL (LN 8789), but on N705AL (LN8799), the latter delivered last December. Coincidence, normal practice? Original door plug intended for N704AL with issues, e.g. not a good fit?

If we take "Trowawayboeing" for his word, the door plug swap wasn't done at Renton, most certainly not by Boeing and neither by the Spirit "warranty team". Unless of course..... the Spirit "warranty team" "solved" the loose rivets (after they first attempted to "repair" them by "painting them over") as a last resort by taking out the door plug from N705AL a little down in the Renton line and installed it on N704AL, giving the "warranty team" a little bit more time to work on the original door. It would be interesting to know the line number written on the door plug that N705AL has been flying around with since last December.

But no, this scenario would have meant that the door plug on N704AL wasn't just opened, but removed, which would/should have triggered a QC in Boeing's system logic. That means the swap could only have taken place at Spirit Wichita. And taking into account that this second door plug installed had these issues (the loose rivets), failing Boeing's QC, what was wrong with the door plug originally intended for N704AL?

[OldnGrounded]

That’s not the same as what Throwaway wrote . . . And perhaps is more damning.

Isn't the only significant difference the assertion that it was BCA personnel who removed and replaced (or "merely" opened and closed) the plug? That's not insignificant, certainly, but it doesn't change who's responsible for properly documenting and inspecting work like that at Renton.

Here's what Gates wrote:

The published whistleblower account does not explicitly state who removed and reinstalled the door plug in Renton.

The information that it was Boeing mechanics who removed the plug is from a different source with knowledge of the repair, the person who cannot be identified because of the sensitivity of the ongoing investigation.

[Ivor_Bigunn]

The Washington Post has an article today about the remarks of the Alaska CEO.

It is a typically long but very flabby article , but a couple of hilites for me:

"I am more than frustrated and disappointed. I am angry,  said CEO Ben Minicucci, referencing the accident in which part of a Max 9 jet operated by his airline came loose in midflight early this month. This happened to Alaska Airlines. It happened to our guests and happened to our people. 

Inspections at United Airlines since the accident have turned up similar issues."

And:

"Minicucci told NBC that preliminary inspections have taken about 10 hours per door. Both carriers are still awaiting clearance from the FAA to complete formal inspections. Once the FAA issues its directive, Minicucci said, it will take several days to complete all the inspections. The FAA, for its part, has said there is no timeline for when the Max 9 jets will be cleared to resume flying. "

I think it has been reported before that the airline's inspections had turned up loose bolts, and this confirms it, and implies that the issue is widespread.

But also, it appears that all the Inspections have been "preliminary", and that the airlines expect the FAA to eventually issue a set of directives about what inspections, and/or modifications, are required before the Max 9 can return to service. So there is no clear path yet to solve the issue.

It looks like the Max 9's with plug doors may be grounded for a long time.

IB

[SRMman]

That’s not the same as what Throwaway wrote . . . And perhaps is more damning.

And there was that Reuters article 13th Jan, ref my #923

[roger4]

Ref your #923 and the Reuters article, there can't be many cabin interior pieces that would fit through the 4ft x 2ft hole in the fuselage?

[aeromech3]

Loose rivets: if they were of the solid annealed type then they are now age work hardened, but I doubt these were used in the door plug skin and should not be re worked; if they were standard, then likely a couple of rivet gun bursts with a block would solve the loose issue, followed then by a paint touch up.
Now if they are referring to hi lock type, then removal replacement would be necessary and I doubt a paint dub would pass muster.

[SRMman]

From Flight Global:

Boeing is to pause production and delivery of its 737 Max aircraft on 25 January, as it calls a “quality stand down” amid ongoing quality-control issues.

The airframer states that the one-day stand down will take place at its Renton, Washington facility, where its production, delivery and support staff will pause operations “so employees can take part in working sessions focused on quality”.

Boeing Commercial Airplanes chief Stan Deal says the sessions will allow workers involved in the 737 production to “pause, evaluate what we’re doing, how we’re doing it and make recommendations for improvement”.

According to internal employee communications, the airframer states: “During the stand downs, teammates will participate in hands-on learning, reflection and collaboration to identify where quality and compliance can be improved and create actionable plans that will be tracked to closure.” Boeing is expected to roll out these sessions across its other facilities covering its other aircraft programmes.

[MechEngr]

Poke a finger down my throat for the phrase “quality stand down”.
This comes across as "stop being distracted by continued schedule and performance based beatings and do better work with the garbage you're given while we hit you harder."

Note the "workers" are the ones to pause, to evaluate, to make recommendations. The root of the problem appears to be that Boeing management is allowing Spirit to ship so much garbage the Renton workers are drowning.

[C2H5OH]

The airframer states that the one-day stand down will take place at its Renton, Washington facility, where its production, delivery and support staff will pause operations “so employees can take part in working sessions focused on quality”.

According to internal employee communications, the airframer states: “During the stand downs, teammates will participate in hands-on learning, reflection and collaboration to identify where quality and compliance can be improved and create actionable plans that will be tracked to closure.” Boeing is expected to roll out these sessions across its other facilities covering its other aircraft programmes.
Yeah, have the shopfloor rats blame themselves in workshops and hands-on learning, „tracking“ ad-hoc made up BS actions „to closure“. That will get the spirit up and improve things, for sure :ugh:.

[MarineEngineer]

I think Boeing executives should close the factories for a week, give the workers a paid holiday and have a serious look at themselves and corporate culture. It needs to a top-down whooping.

[639]

A one day stand down to address decades of QA decline?, sack the management they are not fit for purpose.

[MarineEngineer]

The New York Times has a couple of excellent graphics showing the door closing and the function of the lift assist springs.

https://int.nyt.com/data/videotape/finished/2024/01/1706042765/macro_v13_prores422hq-640w.mp4

https://int.nyt.com/data/videotape/finished/2024/01/1706042765/detail_hinge_v12_prores422hq-640w.mp4

These may be paywalled, but you can normally access a few stories without a subscription.

There's a third on the action of the guide and rollers but it's not very good.

All in this story https://www.nytimes.com/interactive/2024/01/23/business/boeing-alaska-airlines-door-plug.html

[Filibust]

“During the stand downs, teammates will participate in hands-on learning, reflection and collaboration to identify where quality and compliance can be improved and create actionable plans that will be tracked to closure.”

Left unsaid: “Employees will implement these improved quality plans with no loss of productivity” :o

[Chipsaway]

Should be one of those things that never happen. Not even after a million planes are built because that should be the standard of safety. They are not making cars that can afford a recall. I know there were design flaws decades ago like cargo doors opening in midflight, but those were design flaws long ironed out. A plug door isn't a new design nor too complex. This is like 60 year design?? What is scary here is how they could have completely missed installing the 4 critical bolts at Spirit and then QC team couldn't catch it at Boeing!!!

If they can miss something so easy but critical due to "quality escape", I wonder what other quality escape are baked in already and we won't find out until quarter or half of "engineered lifespan" of the aircraft later.
​​​​​​
What if there was quality escape in the fuselage or wings?

Cracks and impurities in the composite or cured at wrong temperature? Cutting corners and shoddy inspections to save a buck? Instead of 30,000 cycle, they give out at 15K?

And why would the bean counters care? Management would have long retired 10-15 years later, with golden parachute, and kicked the can of junk and responsibility down the road. Heck, they don't even need 15 years. MCAS shown you can get a golden parachute in 2 years after criminal engineering was discovered.

​​​​​​It's tragic because I know there are alot of smart engineers and visionists at Boeing. I'm sure they have the answer how to turn Boeing around but I'm sure shareholders would just shuffle the MBA bean counters around, too big to failz same old song same old song.

​

[incompleteness]

Left unsaid: “Employees will implement these improved quality plans with no loss of productivity” :o

Do they get budget and schedule time for these quality reforms? Based on experience, I wonder.

Airbus has an anonymous tip line and specific training that nobody can be pushished for speaking up.

[remi]

I think Boeing executives should close the factories for a week, give the workers a paid holiday and have a serious look at themselves and corporate culture. It needs to a top-down whooping.
"Teacher work day"

[Old Ag]

Imagine finding that in your backyard.

I wonder, is there a formal process to document and deal with loose and excess parts found on an aircraft factory floor? After all, those bolts must have been found somewhere? They can’t just have disappeared in thin air, I’d imagine. (Barring some genuine Jedi tricks.)

I still stand by my post from the 8th:

I will say this. If I were the NTSB and I were looking for the four bolts, I would start with the bin marked “Extra 737 Parts” at the FAL in Renton.

[scifi]

I know they have found the door/plug, but have they found the interior trim panel yet..?
It might have floated much further away from the original site, or be hidden in the weeds.

[MJA Chaser]

Loose rivets: if they were of the solid annealed type then they are now age work hardened, but I doubt these were used in the door plug skin and should not be re worked; if they were standard, then likely a couple of rivet gun bursts with a block would solve the loose issue, followed then by a paint touch up.
Now if they are referring to hi lock type, then removal replacement would be necessary and I doubt a paint dub would pass muster.
Woud be interesting to read what the fault with the rivets was as presented to the person fixing the reported fault. Perhaps a repaint was all that was required to fix the fault??

[MechEngr]

The main rivet defects that are easily seen are that the stem of the rivet cracked or the rivet is bucked off center.

Of the two, trying to hide cracks by filling them with paint is the better fit for the report.

[OldnGrounded]

Woud be interesting to read what the fault with the rivets was as presented to the person fixing the reported fault. Perhaps a repaint was all that was required to fix the fault??

I can't remember coming across or hearing about a fastener fault that could be corrected with paint.

[A0283]

just from my own aerospace experience, no more no less… one will have to translate these to the Boeing specific situation and terminology … sorry if this post is too long …


#1287 (https://www.pprune.org/11582102-post1287.html) (permalink (https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx.html#post11582102))eppy 24th Jan 2024 01:09

“…Throughout this thread there have been numerous terminology debates about Door vs Plug that many people just rolled their eyes to and ignored as being pedantic. Turns out it may be the one of the largest holes in the Swiss cheese…”

My experience - The earlier you are involved in the integral design and manufacturing process, and/or the more experienced you get, the more important terminology. To get a feel for it, increase your impression of importance by one order of magnitude.

Example: Investigating the issues sketched by posters about a plug originally destined for another line number, and the statements by throw*704AL, will encounter the definition of what it is, and a categorisation. Can you exchange one plug for the other plug type, or is it an exchange plus making the interface to fit type, or is it the previous one but requiring “tooling””, etcetera…

The one requiring “”tooling”” in this specific case might require that Spirit shall do the work (for multiple reasons)… the definition will also include whether the plug is a serial numbered item (which activates other processes) or ‘just a piece of structure’ …

If Spirit shall do the work, this means that you get them inside your final assembly line process … if the work is not okay, or backlog work (by fup or ramping up production). Properly organising this will take senior experienced manufacturing engineering and tool engineering and production engineering and others’ involvement to design a process that QA/QC can monitor and report on. Here you meet IT systems and read and/or write issues as indicated by throw*704AL.

This is why I stated the label “quality escape” in other places would be considered ‘non-sensical’, and pushing cause too far downstream.

The Swiss cheese model is a gross simplification.


#1312 (https://www.pprune.org/11582304-post1312.html) (permalink (https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx.html#post11582304))SLF3 24Jan2024 10:12

“The issue for Boeing, FAA and NTSB is that this system failure is so fundamental to Boeing (and its subs) QA/QC “

My experience - This is the consequence of the loss of safety culture. Wise to assume (as posted before) it takes 10 years to get back to basics, that is, from the moment (untainted) top management puts itself behind making the change.


#1320 (https://www.pprune.org/11582494-post1320.html) (permalink (https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx.html#post11582494))xetroV 24Jan2024 14:02

“… loose and excess parts found on an aircraft factory floor…”

My experience - Once any part hits the floor on an “OEM commercial aircraft newbuild final assembly line” you SHALL not use them anymore. Follow up (dispose, replace, paperwork (or not), etc) will depend on the definition of type and specifics.


#1330 (https://www.pprune.org/11582617-post1330.html) (permalink (https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx-67.html?ispreloading=1#post11582617))SRMman 24Jan2024 16:33

“From Flight Global: Boeing is to pause…Boeing Commercial Airplanes chief Stan Deal says the sessions will allow workers involved in the 737 production to “pause, evaluate what we’re doing, how we’re doing it and make recommendations for improvement”. Acc to internal employee communications, Boeing states: “During the stand downs, teammates will participate in hands-on learning, reflection and collaboration to identify where quality and compliance can be improved and create actionable plans that will be tracked to closure.” …”

My experience - people responsible as well as involved in such statements permanently disqualify themselves from leadership positions in “OEM commercial aircraft newbuild operations“ in the minds of experienced professionals who DO understand safety culture. This is one of the reasons why it takes ‘10 years’.

[joe_bloggs]

From Seattle Times.FAA restricts Boeing MAX rate ramp up and lays out extensive inspection regimen.
…“Let me be clear: This won’t be back to business as usual for Boeing,” FAA Administrator Mike Whitaker said in a statement. “We will not agree to any request from Boeing for an expansion in production or approve additional production lines for the 737 MAX until we are satisfied that the quality control issues uncovered during this process are resolved.”…

https://www.seattletimes.com/business/boeing-aerospace/faa-restricts-boeing-max-rate-ramp-up-and-lays-out-extensive-inspection-regimen/

[beltz6]

I can't remember coming across or hearing about a fastener fault that could be corrected with paint.
Yeah, because that's what duct tape is for.

[Longtimer]

FAA halts Boeing 737 Max production expansion, but clears path to return Max 9 to service (msn.com) (https://www.msn.com/en-ca/travel/news/faa-halts-boeing-737-max-production-expansion-but-clears-path-to-return-max-9-to-service/ar-BB1hdjyW?ocid=msedgdhp&pc=EDGEXST&cvid=9c7091ca80a540d592830228d11443c8&ei=31)

FAA halts Boeing 737 Max production expansion, but clears path to return Max 9 to service


United plans to return the planes to service beginning on Sunday, according to a message to employees from Chief Operating Officer Toby Enqvist.

"In the days ahead, our teams will continue to proceed in a way that is thorough and puts safety and compliance first," Enqvist said in the internal message.

[remi]

Boeing states: “During the stand downs, teammates will participate in ...
This "teammates"/"partners" thing promulgates the fiction that line workers are somehow involved in determining the processes they are instructed to use.

When "teammates" can vote to determine how Boeing assembles aircraft, let me know, and I'll prepare my pig for her first solo flight.

[aox]

According to internal employee communications, the airframer states: “During the stand downs, teammates will participate in hands-on learning, reflection and collaboration to identify where quality and compliance can be improved and create actionable plans that will be tracked to closure.”

Do they still have real managers, or is it just AI chatbots?

[RatherBeFlying]

Nomenclature has been a subject of vigorous debate.


Doors are regularly opened in service and securely latched shut with a handle.
Emergency exits are periodically opened for inspection and subsequently latched shut with a handle.
Plugs require removal of retaining bolts to open for inspection or maintenance and the bolts must be put back in place

Whoever tasked to close the plug was not the person who opened the plug and may have thought it was just another door and did not know that retaining bolts were required after the plug snapped shut.

People seeing the plug back in place assumed it had been secured.

Possibly we will eventually see a placard on the plug describing placement and torque of retaining bolts, and transparent windows in the interior trim allowing inspection.


​​​​

[hunbet]

In the meantime, Delta Airlines inspected all of the plugs on their 737-900s and found no faults before the FAA issued their recommendation to inspect them.
Proactive Maintenance Department.

[Joe_K]

Nomenclature has been a subject of vigorous debate.​​​​

I find it interesting that the "Throwaway" whistleblower (or whatever we want call him/her), assuming they are real and actually have insight on what happens on the factory floor, is referring to a "door plug" a few times at the beginning of their lengthy post, but then quickly revert to calling it a "door" for most of the rest of the post. And asserts that the SAT entry makes reference to a "door" which was opened.

If that actually reflects how workers on the factory floor are used to thinking about these door plugs, ie. as "doors" that can be opened rather than panels which can be removed, then the issue goes beyond nomenclature and into conceptualisation. Ie. the nomenclature is just a symptom of the idea which workers have in their heads of what the object is and how it should be dealt with. Worst case scenario would be workers having the approach of "they're all doors, some have bolts, some have not, need to check the paperwork", leaving the door open for an erroneous install of a door plug as a door, simply because "the paperwork didn't say to install the bolts".

[SRMman]

Nomenclature has been a subject of vigorous debate.


Doors are regularly opened in service and securely latched shut with a handle.
Emergency exits are periodically opened for inspection and subsequently latched shut with a handle.
Plugs require removal of retaining bolts to open for inspection or maintenance and the bolts must be put back in place

Whoever tasked to close the plug was not the person who opened the plug and may have thought it was just another door and did not know that retaining bolts were required after the plug snapped shut.

People seeing the plug back in place assumed it had been secured.

Possibly we will eventually see a placard on the plug describing placement and torque of retaining bolts, and transparent windows in the interior trim allowing inspection.


​​​​
Going back to my earlier post 1257, I'd facetiously suggested that Boeing should increase the lift springs rate such that the door guide track fittings MUST be forcibly held down to insert the locking bolts . . .In other words, the door physically couldn't be closed without the locking bolts.

[Roger_Murdock]

I find it interesting that the "Throwaway" whistleblower (or whatever we want call him/her), assuming they are real and actually have insight on what happens on the factory floor, is referring to a "door plug" a few times at the beginning of their lengthy post, but then quickly revert to calling it a "door" for most of the rest of the post. And asserts that the SAT entry makes reference to a "door" which was opened.

If that actually reflects how workers on the factory floor are used to thinking about these door plugs, ie. as "doors" that can be opened rather than panels which can be removed, then the issue goes beyond nomenclature and into conceptualisation. Ie. the nomenclature is just a symptom of the idea which workers have in their heads of what the object is and how it should be dealt with. Worst case scenario would be workers having the approach of "they're all doors, some have bolts, some have not, need to check the paperwork", leaving the door open for an erroneous install of a door plug as a door, simply because "the paperwork didn't say to install the bolts".

Completely agree that inconsistent nomenclature contributed/contributes to the problem and even cognition that there is a problem. Even the NTSB has struggled with this in their communication.

[C2H5OH]

I'll extend that by saying, it is not good practice to have a non-functional removable item, that has to be removed for an inspection every 24 months, which would not be needed if that item wasn't there in the first place.
Don't have that hole in the fuselage in the first place or permanently close it forever.

[Peter H]

I find it interesting that the "Throwaway" whistleblower (or whatever we want call him/her), assuming they are real and actually have insight on what happens on the factory floor, is referring to a "door plug" a few times at the beginning of their lengthy post, but then quickly revert to calling it a "door" for most of the rest of the post. And asserts that the SAT entry makes reference to a "door" which was opened.

If that actually reflects how workers on the factory floor are used to thinking about these door plugs, ie. as "doors" that can be opened rather than panels which can be removed, then the issue goes beyond nomenclature and into conceptualisation. Ie. the nomenclature is just a symptom of the idea which workers have in their heads of what the object is and how it should be dealt with. Worst case scenario would be workers having the approach of "they're all doors, some have bolts, some have not, need to check the paperwork", leaving the door open for an erroneous install of a door plug as a door, simply because "the paperwork didn't say to install the bolts".

[SLF] Isn't the terminology even worse than that?

Besides ordinary doors and emergency exits you have
- "plug doors" that are both doors (providing ingress & egress) and plugs (fitting tightly into a hole blocking it up) -- which are self-tightening when pressurised.
- "door plugs" which are neither doors nor plugs.

[tsumini]

If it were me I would just call it whatever the blueprint calls it. QED

[C2H5OH]

[SLF] Isn't the terminology even worse than that?

Besides ordinary doors and emergency exits you have
- "plug doors" that are both doors (providing ingress & egress) and plugs (fitting tightly into a hole blocking it up) -- which are self-tightening when pressurised.
- "door plugs" which are neither doors nor plugs.

IMHO you have doors (functional for access) and plugs (non-functional) and you have "plug type" (surface mating, self-sealing & self locking under pressure) and "semi-plug type" (multi-point mating, self sealing but not self locking under pressure) and non-plug type (e.g. latched, pin locked). So in this case a semi-plug type plug.

[helispotter]

From Flight Global:

"...identify where quality and compliance can be improved and create actionable plans that will be tracked to closure.”

So what constutes "closure"? Some measures for improvement of quality and compliance would clearly need to be continuous while ever Boeing are building aircraft, so there is no "closure" in those cases... or is this mainly about public appearance?

[safetypee]

C2 :ok:
Les mots exacts; or ‘saying it like it really isʼ

WORDS MEAN SOMETHING (http://www.ludwigbenner.org/papers/Words.htm)

" When context is lost, words can be dangerous ".

[roger4]

IMHO you have doors (functional for access) and plugs (non-functional) and you have "plug type" (surface mating, self-sealing & self locking under pressure) and "semi-plug type" (multi-point mating, self sealing but not self locking under pressure) and non-plug type (e.g. latched, pin locked). So in this case a semi-plug type plug.

Surely the answer regarding ambiguous language is to simplify it, rather than complicate it. To me, in this context, it is simply a door if it can be opened and closed by hand, and it is a plug if you need to use tools to open/close it.

[remi]

Surely the answer regarding ambiguous language is to simplify it, rather than complicate it. To me, in this context, it is simply a door if it can be opened and closed by hand, and it is a plug if you need to use tools to open/close it.
I still think that "PORTAL COVER" is a better option for terminology than "DOOR PLUG." It's pretty darn clear that such a thing isn't a door and isn't opened and closed like a door.

[DaveReidUK]

A door plug isn't a door.

Any more than a bath plug is a bath.

[remi]

AWST isn't bullish on Boeing at the moment.

https://aviationweek.com/aerospace/manufacturing-supply-chain/opinion-can-boeings-misguided-leaders-be-stopped

As 2023 ended, the company’s strategy department was abolished. Unit strategy functions were also reduced. The company no longer wants a plan for company-wide new technology development, new product development or, most crucial, restoring the links between the people who design and build aircraft and the people who manage the company. There are also no plans to promote technical people to senior management positions. Stephanie Pope’s recent appointment as chief operating officer means another finance person has been made Calhoun’s heir apparent.

The future, if it can be called that, is simply to run the company for cash—deliver legacy jets, try to make existing defense programs profitable, and resume converting cash flow into shareholder returns. Management may also try to sell off parts of the company—or perhaps all of it. The implications of this for the U.S. aerospace industry, defense industrial base and even the broader economy are potentially enormous.

[remi]

A door plug isn't a door.

Any more than a bath plug is a bath.
If you really want to go there with grammar and semantics, a "door plug" is a plug that goes in a door, like a plug that goes in a bath(tub). But where's the door? It's actually a "door opening plug" or a "door frame plug."

It's like the difference between a divot (gouged out turf) and a divot hole (where the divot came from): When you take a divot, it leaves a divot hole.

[Joe_K]

A door plug isn't a door.

Any more than a bath plug is a bath.

True. But the point is that they may have treated it like a door on the factory floor.

We now return to our incident aircraft, which was written up for having defective rivets on the LH mid-exit door.
(…)

However, more critical for purposes of the accident investigation, the pressure seal is unsurprisingly sandwiched between the plug and the fuselage, and you cannot replace it without opening the door plug to gain access.

(…)

the damning entry which reads something along the lines of “coordinating with the doors team to determine if the door will have to be removed entirely, or just opened. If it is removed then a Removal will have to be written.”

(…)

If you have been paying attention to this situation closely, you may be able to spot the critical error: regardless of whether the door is simply opened or removed entirely, the 4 retaining bolts that keep it from sliding off of the door stops have to be pulled out. A removal should be written in either case for QA to verify install, but as it turns out, someone (exactly who will be a fun question for investigators) decides that the door only needs to be opened, and no formal Removal is generated in CMES (the reason for which is unclear, and a major process failure). Therefore, in the official build records of the airplane, a pressure seal that cannot be accessed without opening the door (and thereby removing retaining bolts) is documented as being replaced, but the door is never officially opened and thus no QA inspection is required.
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.


If that's the language used on the factory floor, then that is significant.

[remi]

So what constutes "closure"? Some measures for improvement of quality and compliance would clearly need to be continuous while ever Boeing are building aircraft, so there is no "closure" in those cases... or is this mainly about public appearance?
Literally the only thing Boeing management cares about is squeezing the remaining cash from its aging, weary, shriveling cash cow. You have to hear everything they say through that filter.

They don't build aircraft; they build durable goods. They aren't an aviation company. They are a liquidation business devoted to shutting down the former world leader in commercial aviation industry as profitably as possible.

[fotoguzzi]

Did Spirit fix the rivets and door plug seal before or after the interior paneling was installed? Would a Spirit rework person have had permission to remove interior paneling to complete the task?

Am I correct in understanding that after the interior was initially installed, the interior panel would have to be removed to gain access to the four bolts--the only way to partially open the door plug or to prepare it for removal from the plane?

Finally, at the time the paneling was initially installed, was there a step to inspect the door plug to insure that the bolts were present before the door was obscured by paneling?

[639]

If it were me I would just call it whatever the blueprint calls it. QED

Blueprint?:E

[A30yoyo]

Not trying to shift blame but could there have been a better response to the pressurisation warnings on this newly delivered aircraft?

[xetroV]

A door plug isn't a door.

Any more than a bath plug is a bath.
And a -900 isn’t a MAX… :8

[OpenCirrus619]

Travel Agent sees 15-fold increase in customers filtering out Boeing 737 Max planes (https://www.standard.co.uk/news/world/boeing-737-max-planes-alaska-airlines-kayak-travel-agent-b1134612.html)

[Europa01]

Going back to my earlier post 1257, I'd facetiously suggested that Boeing should increase the lift springs rate such that the door guide track fittings MUST be forcibly held down to insert the locking bolts . . .In other words, the door physically couldn't be closed without the locking bolts.

Excellent - almost certainly idiot proof mechanical interlock. On the subject of door mechanics, I think we're almost certain that there were no bolts and as far as I can see there is no convincing explanation for why the door / plug lasted as long as it did before it detached. Change analysis would ask “what was different about the condition of the door on the event flight”?

[chrisl137]

So what constutes "closure"? Some measures for improvement of quality and compliance would clearly need to be continuous while ever Boeing are building aircraft, so there is no "closure" in those cases... or is this mainly about public appearance?

Sounds like what happens in any kind of review - you get a bunch of action item assignments with varying degrees of specificity and then do whatever the assignment is and provide documentation that it's done in order to close it. But they really seem to need some actions assigned from outside the company to make some high level changes, as well as some detailed changes to how they work.

[MechEngr]

The door can be secured closed without the locking bolts by tightening the adjustable stops no matter how strong the springs are.

The better answer is to use a mechanism that doesn't require bolts at all - the latches on car doors and hood are examples of cheap and reliable mechanisms. Even pieces of spring steel that is attached to the door frame to hold against the tops of the door stops or some specifically created bracket.

[DaveReidUK]

Don't have that hole in the fuselage in the first place or permanently close it forever.

There are plenty of posts in the thread about the perceived advantages of having a single fuselage design for the MAX 9, in other words all aircraft having the MED opening, filled by either the E/E or the door plug.

[joe_bloggs]

Jon Ostrower summarises. https://theaircurrent.com/aviation-safety/127-days-the-anatomy-of-a-boeing-quality-failure/

127 Days: The anatomy of a Boeing quality failure

extract

…Boeing staff on Aug. 31 discovered (and later fixed) loose fasteners (https://theaircurrent.com/aviation-safety/undamaged-plug-exit-on-alaska-max-9-had-fasteners-tightened-during-assembly/) on the right-hand side plug exit.

…On the opposite side of the aircraft, next to the left-hand plug that failed on Alaska 1282, Boeing made another quality discovery. Rivets installed at Spirit in the fuselage structure just forward of the plug exit door frame weren’t installed properly in five locations and required rework. In documenting the defects, the quality control report observed four properly installed bolts were fitted to the exit plug, preventing its movement.

…On Sept. 7, the rivets in question were found to be painted over and the underlying issue with their improper installation not addressed. It is not clear at this point who specifically painted over the rivets, but Boeing quality control sent the fasteners back for rework to Spirit…

…On Sept. 12, Boeing conducted a standard test on the aircraft to confirm its structural integrity and its ability to be safely pressurized. 8789 passed successfully, TAC is told. During this period the damaged rivets remained unfixed and an additional five days passed while a final resolution was being planned by Boeing and Spirit.

The key moment, The Air Current has learned, came on Sept. 18 when the plug exit was opened by Boeing to give Spirit contracted staff access to fix the rivets. Whether the plug was removed or just opened remains unknown…

Regardless, the four key bolts that hold the plug in place must be removed to either open or remove the 63-pound plug. The whereabouts of the bolts, according to the NTSB, remain central to understanding what caused the explosive decompression aboard Alaska 1282.

The rivets were fixed fully the following day on Sept. 19. What happened next in the factory is not entirely clear, yet is just as essential to understanding the quality failures that led to the accident…

…Airplane 8789, now fully assembled, was seen outside the Renton factory on Oct. 8 and later moved to the flight line for its Oct. 15 maiden flight…

[chrisl137]

The door can be secured closed without the locking bolts by tightening the adjustable stops no matter how strong the springs are.

The better answer is to use a mechanism that doesn't require bolts at all - the latches on car doors and hood are examples of cheap and reliable mechanisms. Even pieces of spring steel that is attached to the door frame to hold against the tops of the door stops or some specifically created bracket.

Latches can also fail - example: my car has had a couple recalls related to latches. And safety critical latches normally have some additional active mechanism to keep them closed - cars have locks, climbers use locking carabiners, even with knots it's common to throw an extra locking half-hitch behind them to keep them from coming undone. It's not obviously safer or more reliable to replace something that once installed correctly has extremely unlikely failure modes with something that automatically latches and appears safe but still requires some active locking mechanism (more parts => more steps => more ways you can mess it up).

[639]

The door can be secured closed without the locking bolts by tightening the adjustable stops no matter how strong the springs are.

The better answer is to use a mechanism that doesn't require bolts at all - the latches on car doors and hood are examples of cheap and reliable mechanisms. Even pieces of spring steel that is attached to the door frame to hold against the tops of the door stops or some specifically created bracket.

If you mean the 12 adjustable pins that abut the stop pads I believe it was mentioned that they were rigged with a slight clearance that got closed up when pressurised.
Please correct me if I have that wrong, but if so the the stop pads would not restrict movement till a positive hull pressure differential was present

....or do you mean that they might be tightened in error?, that's another scary thought to add to the list

[tdracer]

Not trying to shift blame but could there have been a better response to the pressurisation warnings on this newly delivered aircraft?
It's been repeatedly reported (including statements from the NTSB) that there was NO relationship between the pressurization warnings and the door plug.
In short, the pressurization warnings were related to an electrical hiccup in the pressurization system, not a leak or lack of pressure.
Please quit with that dead end...

[WHBM]

United Airlines chief executive, Scott Kirby, also told CNBC that he is "disappointed".

"The Max 9 grounding is probably the straw that broke the camel's back for us," he said, adding that "we're going to build a plan that doesn't have the [Boeing] Max 10 in it".

737 Max 9: Boeing jets cleared to fly after mid-air incident - BBC News (https://www.bbc.co.uk/news/business-68090175)

I didn't see this discussed elsewhere. I believe United have 250 orders for the MAX10. Can it be that they are cancelling them ?

[fdr]

AWST isn't bullish on Boeing at the moment.

https://aviationweek.com/aerospace/manufacturing-supply-chain/opinion-can-boeings-misguided-leaders-be-stopped


That is a disturbing report. It puts the future of BCA into question, and that would rapidly convert to a further loss of confidence in the product range. It is essentially doubling down with the problem that exists from the corporate strategy to milk the cow dry, hasn't worked since 1997. Not a brilliant strategy, but then nor is the short sighted structure strategy of the investors

[A0283]

That is a disturbing report. It puts the future of BCA into question, and that would rapidly convert to a further loss of confidence in the product range. It is essentially doubling down with the problem that exists from the corporate strategy to milk the cow dry, hasn't worked since 1997. Not a brilliant strategy, but then nor is the short sighted structure strategy of the investors

Triggers me … maybe out of scope (for pilots) but perhaps offering a bit of context…

Clearly remember serious discussions starting in the 1970’s, turning in to fierce verbal ‘fights’ in the 1980’s centering on my persisting questioning of my seniors (manufacturing, engineering, pilots, speculators, investors, bankers) about how you could or should combine Financial Quarter driven thinking with the Long Cycle character of the aerospace industry. In the 70s and 80s I was often told (both sides of the ocean) that the Boeing Quarter driven approach was superior. This against my in-depth study based impression that the Airbus approach appeared to be beating the Americans on the conceptual family level (which in my view historically used to be the 40’s and 50’s strength of the Americans (boosted by the arrival of WW2 Germans)). In the 80’s the Boeing fans attacked composites and (even more surprising - think F16) fly by wire in airliners.

So you might conclude these discussions started much earlier … which might mean the McD guys did not invent ‘it’ but perhaps turned it into a beany obsession… maybe boosted later by a 3rd ‘rocket $tage’ when managers could extraordinarily benefit from making non-core decisions (sometimes hiding behind shareholders value) …

In the 90’s, involved in a brand new commercial aircraft (program) development, part based on platform to program data, I got the freedom to try find out how you could derive requirements based on a projected 75-year manufacturing life. Quite exiting. But sad not being able to share it with the seniors anymore. And sad that Boeing apparently killed certain strategy groups. The more competition the further we all get.

[LandIT]

Jon Ostrower summarises. https://theaircurrent.com/aviation-safety/127-days-the-anatomy-of-a-boeing-quality-failure/

127 Days: The anatomy of a Boeing quality failure

extract

......
…On Sept. 12, Boeing conducted a standard test on the aircraft to confirm its structural integrity and its ability to be safely pressurized. 8789 passed successfully, TAC is told. During this period the damaged rivets remained unfixed and an additional five days passed while a final resolution was being planned by Boeing and Spirit.

The key moment, The Air Current has learned, came on Sept. 18 when the plug exit was opened by Boeing to give Spirit contracted staff access to fix the rivets. Whether the plug was removed or just opened remains unknown…

....
The rivets were fixed fully the following day on Sept. 19. What happened next in the factory is not entirely clear, yet is just as essential to understanding the quality failures that led to the accident…

…Airplane 8789, now fully assembled, was seen outside the Renton factory on Oct. 8 and later moved to the flight line for its Oct. 15 maiden flight…

What sort of process control / QA permits sequencing of the pressurisation test while there is still outstanding rework required on skin rivets which could compromise pressurisation and to fix them opening or removal of the plug and replacing the seal which likewise and definitely could compromise pressurisation? Was the pressurisation test repeated? [ My head is shaking in amazement ]

[vikingivesterled]

What more straightforward task is there than verifying that bolts of the correct specs are (existing) in the right holes torqued to the right force? Sure, if you can't get to them, maybe not so simple. But let's assume they are right in front of you, like we've seen in the photographs of the structure in question.
"

How can some come around after the job is done and check that a castelated nut with a split pin is torqued to the right force. You would have to take the split pin out to cheque the torque. And then you would have to replace the split pin with a new one. So in practise redoing the job. No inspector / qualtity control person is going to do that so no wonder some of the bolts have been found to be loose. And you can in this case after they are mounted only see the head with hopefully a number (using something like a mirror or these days a snake cam) and the end of the bolts so that isn't a true check either.

[MikeSnow]

It's been repeatedly reported (including statements from the NTSB) that there was NO relationship between the pressurization warnings and the door plug.
In short, the pressurization warnings were related to an electrical hiccup in the pressurization system, not a leak or lack of pressure.
Please quit with that dead end...

To be fair, it has also been reported that Boeing doesn't open or remove the door plug on the assembly line, and it turns out they actually did.

I tried to find NTSB's Jennifer Homendy's quotes regarding this, and so far this is what I found (emphasis mine): "At this time, we have no indications whatsoever that this correlated in any way to the expulsion of the door plug and the rapid decompression". "At this time" doesn't exclude finding such indications in the future. She also said "it may have absolutely nothing to do with what occurred in the cabin of the aircraft during that event.". "May", meaning they are not sure yet. Finally, she said "The two could have been entirely separate". Again, "could", expressing lack of complete certainty.

So, unless there is anything more recent and more definitive from the NTSB, I think it's a bit too early to completely rule out any relation between these issues, since the NTSB can't completely rule it out.

On another note, regarding the door plug, I see The Air Current just found a new name for it: "the plug exit". Obviously, the correct terminology would be "the mid-cabin port side semi-plug type emergency exit door plug".

[WillowRun 6-3]

Committee Leaders’ Statement on the FAA’s Ungrounding of Boeing MAX-9 AircraftWashington, D.C., January 25, 2024 |Joint statement of Transportation and Infrastructure Committee Chairman Sam Graves (R-MO), Transportation and Infrastructure Committee Ranking Member Rick Larsen (D-WA), Aviation Subcommittee Chairman Garret Graves (R-LA), and Aviation Subcommittee Ranking Member Steve Cohen (D-TN) on the Federal Aviation Administration’s (FAA) announced ungrounding of the Boeing MAX-9 aircraft:

“Safety is and always will be our highest priority for the aviation system. The United States and the FAA remain the gold standard in aviation safety, and it’s important that we advance and uphold that standard.

“Yesterday’s approval of the MAX 9 inspection instructions via the Multi Operator Message is a positive step in getting these planes back in the air safely, ensuring our carriers have what they need to provide safe and reliable air service throughout the nation, and restoring passenger confidence.

“We support this decision by the FAA, as well as their announced audit of Boeing’s quality control and safety practices and investigation into Boeing’s 737 MAX 9 manufacturing, with more potential oversight actions to follow. These actions are designed to ensure that the highest manufacturing and quality control standards are maintained throughout our aviation ecosystem.

“Federal safety experts at the FAA and the NTSB briefed us, and we will continue to closely monitor their actions and investigations. In the meantime, the Senate should immediately pass our bipartisan House FAA reauthorization bill, which would ensure that the FAA and NTSB have the authorities and resources they need to continue this important work and make critical improvements to aviation safety that directly address many of the issues we’re seeing.”

[WHBM]

Travel Agent sees 15-fold increase in customers filtering out Boeing 737 Max planes (https://www.standard.co.uk/news/world/boeing-737-max-planes-alaska-airlines-kayak-travel-agent-b1134612.html)
The company has since enhanced the filter, making it appear more prominently on the search page and adding the ability to differentiate between 737 Max 8 and Max 9 planes.
Ironically, filtering out the Max9 would have been useless on the accident flight, as it was scheduled, and in fact operated every day until this one, for a Max8. It was only because this airframe had been removed from ETOPS flying that it was substituted on the day (and which fortunately provided empty seats).

[MechEngr]

How can some come around after the job is done and check that a castelated nut with a split pin is torqued to the right force. You would have to take the split pin out to cheque the torque. And then you would have to replace the split pin with a new one. So in practise redoing the job. No inspector / qualtity control person is going to do that so no wonder some of the bolts have been found to be loose. And you can in this case after they are mounted only see the head with hopefully a number (using something like a mirror or these days a snake cam) and the end of the bolts so that isn't a true check either.

No one knows what bolts have been found loose, but the arresting bolts don't need to be tight. The holes that match the slots in the castle nuts are far enough down the threads on the bolts that the nuts have to be fully engaged before the split pin can be installed. One cannot go much further or the slots won't line up. It is typical on torque controlled joints that the torque operation is witnessed by the inspector to ensure the inspector can verify the correct torque is set on the torque wrench and the slots line up with the hole. Then the split pin will be installed. The inspector will apply a torque-stripe, an adhesive but brittle material, across the nut, the pin, the neighboring washer, and structure, so that if the joint is undone by any reason the material will fracture in an obvious way. See https://www.google.com/search?q=torque-stripe+images and https://shop.boeing.com/aviation-supply/p/83317=33

The loose bolts that I have seen so far are ones that hold various brackets to the door; I have seen the hinge guide bracket bolts loose. They go into locking nutplates and appear to only have been installed finger tight, as if the assembler intended an inspector was to come witness the installation torque. That was in the Spirit factory or their supplier, so I don't know how they marked the operation complete when it clearly never was.

[MechEngr]

If you mean the 12 adjustable pins that abut the stop pads I believe it was mentioned that they were rigged with a slight clearance that got closed up when pressurised.
Please correct me if I have that wrong, but if so the the stop pads would not restrict movement till a positive hull pressure differential was present

....or do you mean that they might be tightened in error?, that's another scary thought to add to the list

I think error is on the table. Someone is looking at a door that springs up, never worked on the door before, and sees 12 screws that can do the job. Did they ask, what holds the door from springing up? It doesn't appear they did. That leads me to think, maybe they snugged a few of them and that with each jounced landing the door crept up. Going up is a lower energy state as the force becomes less as they go off-center; there is no going back.

[JetDesigner]

Regarding the terminology: my experience as an aerospace design engineer leads me to think the technical documents call it something like "Plug, Door." We might casually call it a 'Door Plug' but the documentation most likely always refers to it first and foremost as a Plug. I've designed parts, written design specifications, written related parts of component and aircraft maintenance manuals, etc. Using the wrong nomenclature in a technical document is a big deal. I found that out by trying to change the name of the first part I designed - within 2 days my manager told me the VP Engineering didn't like it. And this is exactly the reason why - there can't be confusion as to whether or not someone's installing a door or a plug.

[maxter]

The door can be secured closed without the locking bolts by tightening the adjustable stops no matter how strong the springs are.

The better answer is to use a mechanism that doesn't require bolts at all - the latches on car doors and hood are examples of cheap and reliable mechanisms. Even pieces of spring steel that is attached to the door frame to hold against the tops of the door stops or some specifically created bracket.

Or you just have a culture where the teams doing the work care about quality and do their jobs correctly and with pride/respect would be an even better solution. Guarantee this will not have been the only issue discovered over time that relates to culture of the company. Culture is driven by the leaders of a business in getting true engagement from their workforce. Maybe relates to old joke 'The beatings will stop when the morale improves'. Stop gap measures have no lasting impact as they will eventually be ignored/broken

[remi]

I think error is on the table. Someone is looking at a door that springs up, never worked on the door before, and sees 12 screws that can do the job. Did they ask, what holds the door from springing up? It doesn't appear they did. That leads me to think, maybe they snugged a few of them and that with each jounced landing the door crept up. Going up is a lower energy state as the force becomes less as they go off-center; there is no going back.
But ... but ... but the process is documented, right? The requirements for the work to be done and determined to be completed are documented, right?

Of course I wouldn't be surprised if the documentation is incomplete and/or unreadable and/or unnecessarily complex to execute, especially if the doc writers are now in India or somewhere else cheap that people have English-ish language skills.

Or you just have a culture where the teams doing the work care about quality and do their jobs correctly and with pride/respect would be an even better solution. Guarantee this will not have been the only issue discovered over time that relates to culture of the company. Culture is driven by the leaders of a business in getting true engagement from their workforce. Maybe relates to old joke 'The beatings will stop when the morale improves'. Stop gap measures have no lasting impact as they will eventually be ignored/broken
Non-unionized manufacturing employees in right to work, at will employment states know that their company has less concern for their well being than their executive office espresso drinks machine. So you will get Russian army conscript performance from them, not USAF career noncom performance.

[Keith.]

Would an X-ray check on a completed body be the final confirmation of bolt installation on this type of dummy door ?

[chrisl137]

The loose bolts that I have seen so far are ones that hold various brackets to the door; I have seen the hinge guide bracket bolts loose. They go into locking nutplates and appear to only have been installed finger tight, as if the assembler intended an inspector was to come witness the installation torque. That was in the Spirit factory or their supplier, so I don't know how they marked the operation complete when it clearly never was.

I think the few I've seen are the same ones and as far as I can tell aren't safety critical, but would mostly be annoying to a mechanic who had to pop the plug out if the had uncoupled the springs from the plug. I suspect they were past finger tight and into whatever self-locking/prevailing torque feature is in the nut plates, but as you say, not final torqued. If they had been only finger tight for 150 flights or whatever it was, they likely would have come completely out and not been hanging there to be seen in the inspections.

[DaveReidUK]

How can some come around after the job is done and check that a castellated nut with a split pin is torqued to the right force. You would have to take the split pin out to check the torque. And then you would have to replace the split pin with a new one. So in practice redoing the job. No inspector / quality control person is going to do that so no wonder some of the bolts have been found to be loose. And you can in this case after they are mounted only see the head with hopefully a number (using something like a mirror or these days a snake cam) and the end of the bolts so that isn't a true check either.

I'm struggling to remember ever having torqued a nut/bolt combination that was intended to be split-pinned.

[occasional]

Anyone care to explain how "misdrilled holes" and "improperly installed rivets" happen ?

[MechEngr]

The rivets is easier - if they are using ice-box rivets. These are annealed at a relatively high temperature and then flash frozen so the aluminum alloy doesn't self-harden. If they are kept too long in the freezer or left out too long they start to re-harden from a very soft state to their final high strength. If that hardening happens then instead of bucking them into a nice formed head, the aluminum rips/cracks at the periphery of the formed head. The rivet then needs to be carefully sheared off, so as to not damage the base parts that are being joined and the rivet body driven out and a new rivet installed. Process wise, it doesn't take much to get it wrong. 15 to 20 minutes out of the box, depending on how warm the factory is. If you've ever mixed up too much 5 minute epoxy for the time it takes to fit a bunch of pieces together and it hardens in the mixing cup - very similar error.

The misdrilled holes is more of a mystery to me. I thought with all the CNC equipment that mislocated holes would be a thing of the past; what has been described are "snowman" holes where a hole is drilled in the wrong location, off by a small amount, and another hole is drilled in the correct location, making what sort of looks like the two snowballs of a snowman instead of a single round hole.

[MechEngr]

Would an X-ray check on a completed body be the final confirmation of bolt installation on this type of dummy door ?
That is a large amount of airplane to X-ray, particularly on a factory floor with a lot of humans around and the extra intensity to penetrate metal.

[zueriflyer]

Would an X-ray check on a completed body be the final confirmation of bolt installation on this type of dummy door ?Charming idea with the X-rays as they offer the added advantage of spotting residual tequila bottles, pliers and spanners.

[DaveReidUK]

That is a large amount of airplane to X-ray, particularly on a factory floor with a lot of humans around and the extra intensity to penetrate metal.

Yes, even in a maintenance hangar any X-ray activity is hugely disruptive to any other work going on in the vicinity. Trying the same on a final assembly line, or having to move the aircraft elsewhere to do it, would cause chaos.

[sensor_validation]

I'm struggling to remember ever having torqued a nut/bolt combination that was intended to be split-pinned.
Car stub axle bolts, need torque to seat bearings/seals but may have to back off a bit to get pin in?

[Thrust Augmentation]

Car stub axle bolts, need torque to seat bearings/seals but may have to back off a bit to get pin in?
Torque or torque + degrees & then further tightening until hole alignment is achieved is common in the automotive world.

[hec7or]

It's been repeatedly reported (including statements from the NTSB) that there was NO relationship between the pressurization warnings and the door plug.
In short, the pressurization warnings were related to an electrical hiccup in the pressurization system, not a leak or lack of pressure.
Please quit with that dead end...
So this aircraft had an in-properly installed door plug and an electrical hiccup?

[wrench1]

I'm struggling to remember ever having torqued a nut/bolt combination that was intended to be split-pinned.
FYI: the prevailing mx guidance requires the use of at least the minimum standard torque when installing a bolt and castle nut unless specifically changed in the OEM install instructions. And the process to align the bolt hole with the castellation can vary from substituting a different washer/nut to tightening/loosing the nut until the hole aligns depending on the reference.

Non-unionized manufacturing employees in right to work, at will employment states know that their company has less concern for their well being than their executive office espresso drinks machine. So you will get Russian army conscript performance from them, not USAF career noncom performance.
FWIW: In my experience, I actually find the opposite to be true. And since the door plug incident is more a human factor issue at the hangar floor level than an accountant/engineer" issue at the C-suite level, I think it speaks volumes of the work being performed. Regardless, both the Spirit Aero and the Renton 737 shops are union shops for what it is worth.

[DaveReidUK]

So this aircraft had an in-properly installed door plug and an electrical hiccup?

I've never heard of an aircraft having two independent defects simultaneously.

[Maninthebar]

I've never heard of an aircraft having two independent defects simultaneously.

Um, are there not examples of aircraft despatched under MEL that then encounter a different failure? Not that rthis was the case here.

Could your point be expressed as "no 2 independent issues with similar symptons"

[hec7or]

I've never heard of an aircraft having two independent defects simultaneously.
are they independent? loose door plug and a pressurisation problem?

[remi]

I've never heard of an aircraft having two independent defects simultaneously.
Aircraft fly with multiple pending maintenance items All The Time.

Complex systems exhibit multiple unrelated failures All The Time.

[SRMman]

How can some come around after the job is done and check that a castelated nut with a split pin is torqued to the right force. You would have to take the split pin out to cheque the torque. And then you would have to replace the split pin with a new one. So in practise redoing the job. No inspector / qualtity control person is going to do that so no wonder some of the bolts have been found to be loose. And you can in this case after they are mounted only see the head with hopefully a number (using something like a mirror or these days a snake cam) and the end of the bolts so that isn't a true check either.

l’d be surprised if these lock bolts were required to be “torqued” at all. For me to torque a bolt (or nut) is to apply a specific clamping load, using a torque spanner to achieve a particular lb.ft (or N.m) value, a good example being to torque a vehicle’s cylinder head bolts. The lock bolts in question need to be tight yes, but applying anything much more than that could easily distort or plastically deform the guide tracks or hinge fittings.

I’d have thought the procedure would be to screw on the castellated nuts until tight, and then tighten further up to 1/6 of a turn to allow the split pins to be inserted. Any later inspection would be simply to check for the presence of the bolts, nuts and split pins.

[OldnGrounded]

Aircraft fly with multiple pending maintenance items All The Time.

Complex systems exhibit multiple unrelated failures All The Time.

I'm pretty sure the OP was making a point with humor.

[DaveReidUK]

Aircraft fly with multiple pending maintenance items All The Time.

Complex systems exhibit multiple unrelated failures All The Time.

At the point where a well-known airline was being formed by banging together two predecessors, with resulting industrial action by bolshie engineers, and was attempting for the first time to introduce a new wide-body on shorthaul routes, each one of the aforesaid aircraft was at times flying with well over a hundred ADDs ...

[Roger_Murdock]

ASA9802 OKC-SEA climbing to cruise with pressurization.

[tdracer]

I've never heard of an aircraft having two independent defects simultaneously.
DR - I had to admit I did a double take when I read that - irony indeed :cool:

[incompleteness]

The rivets is easier - if they are using ice-box rivets. These are annealed at a relatively high temperature and then flash frozen so the aluminum alloy doesn't self-harden. If they are kept too long in the freezer or left out too long they start to re-harden from a very soft state to their final high strength. If that hardening happens then instead of bucking them into a nice formed head, the aluminum rips/cracks at the periphery of the formed head. The rivet then needs to be carefully sheared off, so as to not damage the base parts that are being joined and the rivet body driven out and a new rivet installed. Process wise, it doesn't take much to get it wrong. 15 to 20 minutes out of the box, depending on how warm the factory is. If you've ever mixed up too much 5 minute epoxy for the time it takes to fit a bunch of pieces together and it hardens in the mixing cup - very similar error.

The misdrilled holes is more of a mystery to me. I thought with all the CNC equipment that mislocated holes would be a thing of the past; what has been described are "snowman" holes where a hole is drilled in the wrong location, off by a small amount, and another hole is drilled in the correct location, making what sort of looks like the two snowballs of a snowman instead of a single round hole.

By far the most common types of rivets in civil aluminium skin installation are MS20426AD (flush) and good old MS20470AD (protruding). AD means the material is 2117-T4 which is driven as-is (not icebox).

These are specified as BJ on the drawing. At one time or another I'm pretty sure most young structures engineers have dreamed about BJ-5's at night we deal with them so much.

MS204xxDD are 2024-T4 which are cold-storage rivets. They are less preferred in the shop because even though they are easier to buck, the out-time limitations are logistically painful.

I would say almost for sure the rivets in question are BJ's.

As for mis-drilling, without more info that's hard to speculate on. A misaligned jig or slight error in robot programming can lead to a whole field of mis-drilled holes.

Snowman or figure-8 or binocular holes are easy, you just install a special binocular fastener. Joke. But trust me we wish such things were possible.

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1583x890/b7nux_b8eeb7d27ac786869603871c178cdeea53e5671e.jpeg

[Roger_Murdock]

Now UAL3904 N37527 PSP-SFO flying pressurized.

[hec7or]

DR - I had to admit I did a double take when I read that - irony indeed :cool:
you missed this one too
Aeronautical Engineers and manufacturers go to great effort to "add lightness" (quote from colin chapman - lotus) so pilots can add fuel. :) (irony)

[remi]

Anyone care to explain how "misdrilled holes" and "improperly installed rivets" happen ?
Measure once, drill twice, I suppose?

[theFirstDave]

I’d have thought the procedure would be to screw on the castellated nuts until tight, and then tighten further up to 1/6 of a turn to allow the split pins to be inserted.

How is "tight" determined? By measuring the torque!

[fdr]

https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1583x890/b7nux_b8eeb7d27ac786869603871c178cdeea53e5671e.jpeg

I want one of these.


Originally Posted by Bradley Hardacre Aeronautical Engineers and manufacturers go to great effort to "add lightness" (quote from colin chapman - lotus) so pilots can add fuel.

"So beancounters can add payload"

[Loose rivets]

If I were fitting the top safety bolts, they would be scarcely tight enough to damage the paint - and then backed off for the castelation. Those guide should not be crushed. The bottom one could tolerate a bit more torque but it's not needed.

I thought I'd read every post but I'm not sure why there's been so much talk about rivets. Someone even quoted me on some point. The only place I would be concerned about is the fastening of the top skin to the plug frame where there's splitting - that may or may not have occurred before the accident. The top row of fasteners seem to be nuts and bolts while the sides are rivets.

I'd be interested to know what I've missed . . . he said, nudgingly. :confused:

[AerocatS2A]

If I were fitting the top safety bolts, they would be scarcely tight enough to damage the paint - and then backed off for the castelation. Those guide should not be crushed. The bottom one could tolerate a bit more torque but it's not needed.

I thought I'd read every post but I'm not sure why there's been so much talk about rivets. Someone even quoted me on some point. The only place I would be concerned about is the fastening of the top skin to the plug frame where there's splitting - that may or may not have occurred before the accident. The top row of fasteners seem to be nuts and bolts while the sides are rivets.

I'd be interested to know what I've missed . . . he said, nudgingly. :confused:

Fixing rivets was one of the reasons the door plug was opened/removed. The rivets themselves aren’t related directly to the failure.

[zueriflyer]

How is "tight" determined? By measuring the torque!With regards to nuts and bolts, the number of interpretations of the term "tight" equals the number of people on planet earth that feel qualified to hold a spanner in their hand.

[639]

If I were fitting the top safety bolts, they would be scarcely tight enough to damage the paint - and then backed off for the castelation. Those guide should not be crushed. The bottom one could tolerate a bit more torque but it's not needed.

Indeed, there is no need for the 4 bolts in question to be torqued or even tight. No clamping force is needed or desired as they are performing as simple pins.

Is "nipped up" still a recognised term?

[FlexibleResponse]

Boeing's fault...not Spirit?

https://www.adn.com/nation-world/2024/01/24/boeing-not-supplier-mis-installed-piece-that-blew-off-alaska-airlines-max-9-jet-industry-source-says/

[DaveReidUK]

Boeing's fault...not Spirit?

https://www.adn.com/nation-world/2024/01/24/boeing-not-supplier-mis-installed-piece-that-blew-off-alaska-airlines-max-9-jet-industry-source-says/

See post #1323 for a link to the original 24 Jan Seattle Times article.

[Europa01]

Indeed, there is no need for the 4 bolts in question to be torqued or even tight. No clamping force is needed or desired as they are performing as simple pins.

Is "nipped up" still a recognised term?

It is where I come from but how about:-

THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx
ALL STEPS TO BE CARRIED OUT AS SPECIFIED AND IN THE ORDER SPECIFIED
PLACE KEEPING TO BE USED AS FOLLOWS - circle step number at the start of each step and crosss slash the circled step number on completion

IF IN DOUBT STOP AND ASK

1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut, washer and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1/6 of a turn (one flat) or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completion : Signature ………….Date:……….
8 SUPERVISOR HOLD POINT : Task confirmed completed Signature ………..Date………..

[639]

It is where I come from but how about:-

THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx

1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1//6 of a turn or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completion

Exactly how I would write up this task for a worksheet.

[zueriflyer]

It is where I come from but how about:-

THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx

1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1//6 of a turn or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completionStraightforward worksheet, easily identifiable as 'fake' since it reflects an unusually high proportion of common sense in combination with too little red tape.

Jokes aside, do we actually know if Boeing specifies a tightening torque for this application?

There could be good reasons for torquing the bolts unrelated to their primary function .

[aeromech3]

Calling out Europa01 and 639.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.

[sealo0]

Calling out Europa01 and 639.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
reminds me of a US Paper Headline,

“Nut, Screws, Washer and Bolts”

[A0283]

Was expecting a clown joke or clowns remark when days ago someone fielded the question “Calhoun-Clon-Clown?“

Information that is coming out of Boeing/Spirit (not only now but also (years) before) is shockingly far away from the highest standards that I have seen for years in aerospace commercial new building. The width and depth of this @&#$ I have not even seen far less complex and far more forgiving industries, industries to which I regularly help translate and adapt aerospace standards (and test lessons learned in reverse). I sincerely hope that the general public will understand that this is certainly not normal. Have had to answer and try explain that multiple times already since AK 704 got unplugged.

This situation has far wider impact than a single event, wider than a single model, wider than Boeing/Spirit. In that sense the scope of the present NTSB investigation is far too limited. So hope they start another one in parallel. We should ask ourselves general but also personal questions, for example:

Do we have a global aerospace systemic problem ?

If the standards have sunk so low - and sunk so low especially after the unprecedented massive (also wide international) attention/scrutiny that Boeing and the MAX got after the two fatal crashes - questions could be:

For example, (FAA will become an investigation in itself), how could EASA have given the MAX a 100% clear and based on what?

For example, Who investigated What. With what we find now it seems like either information was suppressed or investigators fooled and/or incompetent?

These far below business practice standards are suggested to have been driven by corporate and management greed.

What has been done to diminish these drivers and by whom?

How is it possible that you can push a global giant to the brink and get away with 90+ million.

How is it possible to appoint a new CEO who has co-thrived for years on safety culture cutting.

What happened with the tough talk in US Congress after the crashes?

Has US Congress answered the question how much funding the FAA needs to become effective? Self-regulation is showning hard limits.

FAA managers In congressional hearings lacked engineering and certainly manufacturing knowledge and experience - did they recognise that themselves, how do they solve that?

Boeing has got away with this for years. This means that competitors had to compete with that for years. Has this introduced a systemic risk or systemic strength in these competing organisations? There must have been a significant impact.

My experience at the time Boeing had a better name was that we regularly put in a higher design and manufacturing standard than Boeing In multiple technical fields. That would be untenable with the present day standards to compete with.

Throw*794AL talked about ‘safety accepters and safety rejecters’. I wonder how people from each group go to work everyday? And what happens when they meet?

So many questions… !

(the aging workforce means it will get harder to develop and implement the proper (known) solutions … )

[639]

Calling out Europa01 and 639.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.

Not had one from me then

[SRMman]

How is "tight" determined? By measuring the torque!
No, perhaps I should have specifically said finger tight - we all know what that means.

[SRMman]

Indeed, there is no need for the 4 bolts in question to be torqued or even tight. No clamping force is needed or desired as they are performing as simple pins.

Is "nipped up" still a recognised term?
Yes, in my book!

[hec7or]

Here's another nut and bolt SNAFU by the manufacturer
Report 2020-014.pdf (aaiu.ie) (https://aaiu.ie/sites/default/files/report-attachments/Report%202020-014.pdf)

[Goth]

The issue with quality culture I've been mulling over (after the discussion about the "removal" vs "opening" classification) is comfort and familiarity. I am not an aerospace engineer or mechanic, but I'm interested in how processes work (by analogy with those that I follow).

If I am asked to perform an activity such as removing a few bolts do I have a mental model of how they are going to be replaced? If I'm removing these bolts as part of a written-up subtask I might just trust (or indeed know) that the higher-level task that demands their removal will also ensure their replacement. If I have bought into a quality and safety culture shouldn't it feel uncomfortable to be unbolting something outside of a process that I trust/expect to restore it?

I think it should be easy to distinguish in process terms between opening a standard passenger door using the handle (as flight crew would do) and opening a door by removing bolts with a tool?

[A0283]

Here's another nut and bolt SNAFU by the manufacturer
Report 2020-014.pdf (aaiu.ie) (https://aaiu.ie/sites/default/files/report-attachments/Report%202020-014.pdf)

Interesting “ no safety recommendation “ …

I am starting to wonder how the NTSB and other accident investigators today perceive causes in design and manufacturing.

If you want to understand what preceded this at this point in time you would probably have to rely on a whistleblower and a class action law suit. That’s weird.

[aeromech3]

My copy of CAIP's from 1971 (updated for some years and costs) which I studied and loaned out to promising mechanics for their preparation for Licensing exams, states clearly this is the minimum standard.
In regards to locking nuts BL/3-13 applies.
I respect the IAA, they kept the Licensed Engineer status for a long time and the the report AAIF 2020-014 pdf can hardly make a recommendation to adhere to basic standards.
My take on that incident is that the pin had some interference fit and though the nut was fitted as evidence by the tang washer inner face (hardly floating) remember that 271inlbf is hardly a grunt on a 1foot spanner, but that the cotter pin might well have passed through the nut slots, and the pre-drilled hole in the pin is not possible, my blunt side cutters are testament to the difficulty of removing split pins when even one leg is slightly bent; the correct diameter split pin was never there.
Not relevant to B737-9 incident where visual check was easy but same conclusion: the split pins were never there.

[Thirsty]

Sorry: I won't quote the other posts I am referring to - this thread is going the way of the AF447 one with hundreds of pages to read!

According to throwawayboeingN704AL comments section at leehamnews.com, the aircraft fuselage assembly airplane #8789 (to become N704AL) had issues with rivets, and the "the mid-cabin port side semi-plug type emergency exit door plug" pressure seal. The replacement seal was (presumably for expediency purposes) borrowed from another fuselage assembly #8799 (to become N705AL).

Question 1: Was the LHS door plug also urgently borrowed from another fuselage assembly (N705AL), possibly with the four retention bolts with castellated nut and split pin assemblies not yet fitted on that replacement assembly?

Question 2: Would four new retention bolts with castellated nut and split pin assemblies be fitted if the door plug needed to be removed (CMES)/opened (SAT) for any reason, before it left the factory or after, such as during scheduled maintenance, or would just the split pin be replaced?

Question 3: What of that 'other' aircraft assembly the pressure seal was borrowed from (N705AL) - who has that airframe right now, and has it been inspected with a little more thoroughness than all the others? What of the paperwork of the other airframe? Was that consistent with the story from throwawayboeingN704AL about SAT and CMES entries for that airframe as well?

Question 4: How do you align the door plug with the fuselage? Is appears to be a two person job, with one on the inside loosening the bolts on the top roller bracket and bottom spring loaded guides, and then moving the door in conjunction with the person outside until the two line up properly with the door seal before tightening them up on each side? That would involve the four roller guide bolts being a two step process: First to have the bolts holding the (slotted hole) roller guides in place loosely so the final bracket location can be adjusted within the slotted bolt holes, and then the final torque being applied to lock them into place permanently. I'm assuming the four retention bolts with castellated nut and split pin assemblies were missing, but the bolts that keep the roller guides in place are the ones that are loose on this airframe and have been discovered loose on other airframes, aren't they? Is this omitted second tightening step the smoking gun that defines the entire issue? A missing page in the manual maybe that defines this tightening step and insertion of the retention bolts, or the person that performs these steps is missing on the production line?

Question 5: Re post 1191 (fdr)
The four retention bolts with castellated nut and split pin assemblies that were missing do not have to be torqued to any major tightness. The function is to prevent the pin assembly from moving past them, and the stresses on the bolt are at right angles to the bolt. The nut is just there to prevent it from sliding out of the hole it is in, and the split pin is just to ensure the nut doesn't loosen. Being snug tight or very tight is not going to make that much of a difference as the bolts stop the door plug pins from sliding up-and-down within the roller guide brackets - only that it is there as an interference to prevent free up-and-down movement. This is consistent with the story the opposite right hand side door plug assemblies requiring tightening by Boeing. Are my assumptions valid?

Re post #1428 (Europa01)
QA Inspection procedure:
Outside:
Ensure even gap between door and frame, and seal and door plus assembly is flush with airframe.
Inside:
Confirm all four retention bolts are fitted, nuts are tightened so no thread is visible between nut and bracket and verify bolt does not have free play, and place daub of colored thread locker paint over split pin to confirm inspection. Repeat for other side of door plug.
Ensure all four bolts for each roller guide are torqued to specification.

Question 6: On the airframe N704AL, are all the doors (regular ones that open and close), and door plugs assemblies (that are semi-permanently closed) showing colored thread locker QA inspection paint? Both sides? How about the other airframe the door seal was borrowed from (N705AL)? How about all other airframes that have been inspected to date? Is the QA inspection paint daub present on each and every one (I'd love to see the FAA spreadsheet with the inspection ticks and crosses and look for any patterns)? Are the loose bolts that have been found on other airframes showing signs of QA daubing, indicating that at some stage they have been installed and QA inspected?

Question 7: Why aren't the NTSB looking for the missing door pressure seal as well? Surely any deformation imprints or tears in the flexible material on that would tell a story to clarify which angle the door plug departed the airframe?

Question 8: Where does one purchase a set of Specialist Bolts for British Industry alluded to in post 1416? I need a set for my workshop, to go with my left handed tools!

[Mutttley]

Incompleteness... If that diagram isn't from a Model Engineer article by Michael Oxley, then it ought to be...

[Europa01]

Calling out Europa01 and 639.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.

Whoops - forgot to include washer as about to lose Wi-Fi connection so was hurrying. A fine example of a) why critical procedures should not be prepared under unnecessary time constraints and b) the value of having critical procedures independently verified before being issued. Feedback noted and procedure revised accordingly.

[jimjim1]

See post #1323

Firstly Dave, thanks for all of your thoughtful posts, always a pleasure.

For everyone, Just a hopefully friendly reminder, the post# is not always preserved. I suspect that as posts are deleted by posters or by moderators that the numbers change. Long or contentious threads can be quite badly affected by this.

On the other hand, the adjacent "(permalink)" is always preserved and makes it very easy for readers to just click. To use it you could Right click on "(permalink)" and choose "Copy link address", then paste into new post. Of course while this is very easy on PC with mouse, it may not be quite as straightforward with touch. Long hold and "Copy link address", I guess.

Annoyingly, you need to remember to do this before starting your Reply, or if too late, open the post in another window.

Permalink to #1323
https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx-67.html?ispreloading=1#post11582556

[WillowRun 6-3]

Re: Thirsty's post listing questions

Can it be presumed that the FAA's investigation-with-audit will first of all, cover these questions, and second, have the insight and approach to identify other sets of similar questions as further facts, and further possibilities, are brought to light? I don't enjoy sounding cynical yet there are many who have contended that FAA has been lulled into ineffectiveness or complacency - or both - by several insidious layers of regulatory capture. Or that it lacks the qualified staff or required funding - or all of the above.

Incidentally, not that long ago the U.S. Senate was deciding whether to affirmatively advise and consent to nomination to the office of Administrator of an individual whose aviation sector experience was little more (if it was anything more at all) than serving for a few years as head of large airport in a major city. Much was made of this person's lack of "aviation safety" experience; likewise, many aspersions of political grandstanding were cast on those who opposed the nomination citing this lack of experience. The runway incursion incidents were bad enough, but the Safety Summit (and its readouts), and the ATO's effectiveness (and that of other FAA components) suggested saying "I told you so" to the White House seem like overkill. But now that Alaska Air has experienced a door-plug-door exiting a fuselage in mid-air, maybe a reckoning about the qualifications and experience essential for the Administrator role is in order.

(Note: the nominee who was eventually confirmed obviously has more than the sufficient relevant experience - this post absolutely cannot be and should not be read, interpreted or cited as any negative comment at all on Mr. Whitaker, none.)

[incompleteness]

Incompleteness... If that diagram isn't from a Model Engineer article by Michael Oxley, then it ought to be...

Different versions of that have been around for years, the one I posted is just what I happened to find first.

[scifi]

I think we all now know how the door/plug is located in the Up and Down direction, but nothing has been said about what locates it in the Left and Right direction, especially at the top, where it just hangs from the roller slots.

[shinz0]

At a guess the clearances in the lower hinges & the roller slots are such that they control the door within allowable tolerances while pressurisation loads are off it, the fixing pads would hold it in that location once the pressurisation forces come into play.

[Semreh]

It is where I come from but how about:-

THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx
ALL STEPS TO BE CARRIED OUT AS SPECIFIED AND IN THE ORDER SPECIFIED
PLACE KEEPING TO BE USED AS FOLLOWS - circle step number at the start of each step and crosss slash the circled step number on completion

IF IN DOUBT STOP AND ASK

1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut, washer and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1/6 of a turn (one flat) or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completion : Signature ………….Date:……….
8 SUPERVISOR HOLD POINT : Task confirmed completed Signature ………..Date………..

And presumably

9) Discard unused washer.

The next revision to include actual installation of the washer, somewhere between step (3) and step (4), perhaps?
I would also like to understand the reasons behind a single washer being used. I'm not saying it is wrong, but depending on the function of the bolted joint, it is sometimes the practice to have a washer between the head of the bolt and the surface with the through-hole in it, as well as between the nut and the the corresponding surface with the through-hole in it.

https://engineeringlibrary.org/reference/bolted-joint-design-analysis-sandia
https://www.kenenghardware.com/where-do-washers-go-on-bolts-a-clear-guide-for-the-proper-placement/

Obviously, additional washers add extra mass, so they should only be added where necessary.

But you probably need only a 'locking pin with folding latch', for example: https://www.kipp.com/gb/en/Products/Operating-parts-standard-elements/Spring-plungers-indexing-plungers-ball-lock-pins/K0776-Socket-pins-with-folding-latch.html - modified to take a lock (safety) wire to prevent the latch from folding back to the 'extract' position. The bolt is not there to hold parts together (there's no specific tension load here), but to prevent movement that would apply shear forces to the bolt. In fact a simple clevis (https://en.wikipedia.org/wiki/Clevis_fastener) pin ( https://www.mcmaster.com/products/lock-pins/precision-clevis-pins-7/ ) with a cotter pin or locking pin ( https://www.aircraftspruce.com/catalog/hapages/lockpins.php ) and washer(s) would work.

[Semreh]

reminds me of a US Paper Headline,

“Nut, Screws, Washer and Bolts”

Thus confirming that American and British punctuation practices are radically dissimilar. Punctuation can be important - there is a world of difference between: "Don't, stop!"; and "Don't stop!".

[MZoVrsmg]

nothing has been said about what locates it in the Left and Right direction, especially at the top, where it just hangs from the roller slots.

Comments made privately to me by someone who claims to have worked on this platform:


Per AMM the roller can protrude 0.03 - 0.065 in from the track (this is common roller engagement in door guide and latch tracks on Boeing cabin doors). Engagement is adjusted by shims under the white fitting the roller is attached to.
...
If rigged properly the door does not bounce around on the roller. There is a check in the rigging procedure that the roller must be engaged fore and aft in the track a certain dimension, and to a certain depth in the track. When you push the door down onto the track the lower hinges fittings sort of overcenter (and are then locked from movement by the lower spring lock bolts)


I'm having a hard time visualizing what those dimensions are describing. Is that how much roller we should see when the door is closed?

[MechEngr]

I think we all now know how the door/plug is located in the Up and Down direction, but nothing has been said about what locates it in the Left and Right direction, especially at the top, where it just hangs from the roller slots.
The door closes into a fuselage skin recess that has little clearance side to side, so the entire face of the door provides a location restraint.

[ScandinavianInterest]

The door closes into a fuselage skin recess that has little clearance side to side, so the entire face of the door provides a location restraint.
The picture on entry 1080 shows that there is a very tight fitting between the the roller guides and the roller plate.

[MechEngr]

The picture on entry 1080 shows that there is a very tight fitting between the the roller guides and the roller plate.
Even if the roller guide and the hinge guide didn't exist, the door fit would still provide the primary locating function. The door fit is unavoidably required; the roller guide and hinge guide are there for removal and installation simplification.

[639]

Per AMM the roller can protrude 0.03 - 0.065 in from the track (this is common roller engagement in door guide and latch tracks on Boeing cabin doors). Engagement is adjusted by shims under the white fitting the roller is attached to.
...
If rigged properly the door does not bounce around on the roller. There is a check in the rigging procedure that the roller must be engaged fore and aft in the track a certain dimension, and to a certain depth in the track. When you push the door down onto the track the lower hinges fittings sort of overcenter (and are then locked from movement by the lower spring lock bolts)

Highlighted comment is significant

[Loose rivets]

Here the a plug seems to be biased to the right. The left roller pin seems woefully short. The picture I posted needs a lot of zooming in but if you look very carefully at the 2nd picture, it shows the wear on the roller to be about half way along the roller. I'm mindful that this abrasive wear mark perhaps shows a constant vibratory movement.
.
.
https://cimg2.ibsrv.net/gimg/pprune.org-vbulletin/1164x1612/door_in_place_3b5d8ddd522e7df2de28ff15e570f8fe24dc6992.jpeg


https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/2000x1333/short_roller_pin_6d890aa975bb4cf600290f237fd88e096de0de38.jp g

It's not my imagination, is it - in the first picture the top left two pins look biased right compared to their pads?
.
.
.
.

[RickNRoll]

It's an incredibly intricate piece of kit for a door that isn't supposed to ever be used as a door.

[D Bru]

While “Throwawayboeing...” alleges that damaged and improperly installed rivets were recorded by Boeing to have been found on the door plug itself, The Air Current (TAC) reported (as posted here by joe_bloggs #1378 (https://www.pprune.org/11583452-post1378.html) (permalink (https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx-69.html#post11583452))**) on the basis of separate inside sources that these defects found by Boeing were “in the fuselage structure just forward of the plug exit door frame.” Both accounts date this recording on 1 Sept and note that Spirit “repaired” the issue by painting the affected rivets over, without addressing the underlying defects. TAC dates this recording by Boeing on 7 Sept and both accounts report that the defect was then sent back to Spirit to be readdressed.

Now it is IMO important to note that TAC further reports that the aircraft performed its maiden flight on 15 Oct still in its bare green coating applied by Spirit before delivery to Boeing. This implies that whether the defective rivets were found on the door plug itself or on the fuselage, the fact that they were “painted over” in any case means that they should be located on the inside of either the door plug, that is on it’s painted inside fringes or on the inside painted circumferences of the doorframe itself. This is supported by TAC reporting that “the crucial moment came” when on 18 Sept Boeing opened the door plug to give Spirit contractors access to fix the rivets (for the second time).

This brings me then to the question of how the defective rivets were discovered in the first place on 1 Sept, without opening the door plug. In Boeing’s documenting the original rivet defects discovery on 1 Sept, TAC notes that Boeing observed that four bolts were properly installed on the door plug, “preventing its movement”.

I had taken this Boeing observation about the properly installed bolts as the situation before opening the door plug on 1 Sept, that is in which state the installed plug door had arrived at Boeing from Spirit. Because, who would put the bolts fully fixed back on 1 Sept, if repair work would necessitate another opening of the plug (on 7 Sept) and the same for the second repair (rivets plus the defective seal which had been discovered on the initial “repair” of the rivets), when the door was yet opened for a third time on 18 Sept?

If, what is highly likely, they already opened the door plug on 1 Sept, it means that already then the four bolts had to be removed, while the final closure of the door plug only took place on 19 Sept, after Spirit contractors in a second instance had repaired the rivets to Boeing’s satisfaction and the door plug was closed. That’s a lot of time between removing the four bolts and the moment that they should’ve been reinstalled. A valid question is then indeed where four bolts were kept during that extended period of time, if they were not loosely put back into their slots, or were not put into string- or ziplock-bags and attached to the plug door (as some fellow commenters in this thread would have found an effective solution for the bolts not to get lost).

This then also raises another question, that whether or not the door plug under normal circumstances and according to procedure would have to be re-closed anyway on 1 Sept and 7 Sept, despite that the recorded defects would necessitate anyhow opening the door for (re-)repairs.

That the door was reported as actively being opened by Boeing on 18 Sept for the re-repair is because in all probability it had to be closed properly for the structural integrity and pressurisation test performed on 12 Sept. The question is then if the four bolts were installed for that occasion. It’s interesting that in any case the result of this test was recorded as positive, even if the defective door plug seal had not been yet replaced (the latter took only place on 18 & 19 Sept together with the re-repair of the defective rivets).

It is expected that the NTSB will address these issues in its (final) report.

**
https://theaircurrent.com/aviation-safety/127-days-the-anatomy-of-a-boeing-quality-failure/

[DaveReidUK]

It's an incredibly intricate piece of kit for a door that isn't supposed to ever be used as a door.

Think about it,

It's a door that isn't supposed to ever be used as a door.

Rather than a doorway that isn't supposed to ever be used as a doorway ...

[A0283]

Don’t know if we go far beyond the interest of pilots here, but …


Information is bubbling up slowly (still need to wait a week till expected NTSB prelim factual report) but much is still missing of course. To solve this puzzle we have to put what we have in the right order. So please more posts like #1458 (https://www.pprune.org/11585580-post1458.html) (permalink (https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx-73.html?ispreloading=1#post11585580))D Bru ref TAC and timing. Would be nice to include the url.


The right order in this case (simplified) might be sketched as: phase 1 design engineering plus manufacturing engineering (includes main tool engineering), phase 2 engineering drafting plus production procedures definition, phase 3 production execution (plug Malaysia, fuselage Spirit and final assembly Boeing with procedure and tool use), (phase 4 modification), phase 5 maintenance and operations,

In phase 1 you talk function (here terminology is key, and imho in this case already starts out quite weak).

Next to that in phase 1 you start for example defining “interchangeability”. Interchangeability will tell what you can take out, and what you can replace it with, doing what with what.

Example: can you take out the paxdoor from aircraft A and hang it in aircraft B, close the paxdoor, and fly away B. Or do you need to trim or shim (door or fuselage), or insert new seals or …, or use a range of tooling and tools.
Earlier post on where to shim is interesting.

So phase 1 determines the (digital and physical) tooling tree hierarchy, and will limit what you can do in which fase and in their lower level detailed procedures. And will show up in limited and translated form 4 phases later in for example the AMM (see earlier post) and SRM.

So it’s not only about what we do see, but also what we should or shall see.

We don’t have phase 1 information yet, and phases 2,3,4,5 are mixed in a soup.

Cause of the mix appear to be a another mix, one of terminology, stop and go’s of the program, delayed deliveries and work backlog, catching up production work in final assembly, substandard management and practices, production ramp up …


Some of the many questions:

So what function is it… a door, an escape, an “escape door replacement quick release fuselage panel”,… What are the associated interchangeability requirements… ?

Was the originally earmarked plug panel used, or one taken from another aircraft ?

Does every opening of the ‘plug panel’ require a seal check and/or always a seal replacement?

Was the cause of pressure issues the seal, or seating of the seal (when not the rivets)…? What was the quality of the seating structure there?

What were the rivet issues and could these even be properly solved on the final assembly line … think type of required tooling and final assembly throughput time requirements … were the rivets painted over to solve technical issues or to fit schedule…?

[WHBM]

Following on from United's comments about the MAX9 grounding, Ryanair : "If United cancel any MAX10 slots, we will have them ..."

Ryanair tells Boeing it would buy any MAX 10 orders dropped by US airlines (msn.com) (https://www.msn.com/en-gb/travel/news/ryanair-tells-boeing-it-would-buy-any-max-10-orders-dropped-by-us-airlines/ar-BB1hpkMj?ocid=entnewsntp&pc=U531&cvid=24796338d08843668e7a33b6877909b9&ei=61)

I'm sure "at a price".

[OpenCirrus619]

Following on from United's comments about the MAX9 grounding, Ryanair : "If United cancel any MAX10 slots, we will have them ..."

Ryanair tells Boeing it would buy any MAX 10 orders dropped by US airlines (msn.com) (https://www.msn.com/en-gb/travel/news/ryanair-tells-boeing-it-would-buy-any-max-10-orders-dropped-by-us-airlines/ar-BB1hpkMj?ocid=entnewsntp&pc=U531&cvid=24796338d08843668e7a33b6877909b9&ei=61)

I'm sure "at a price".

Kinda gives the lie to "Low fares, Great care" (latest advert) - they obviously aren't interested in safety ... rushing to buy aircraft where there is a demonstrated lack of quality in the build.

If for no other reason than this: Ryan Air if now firmly on my list of airlines to avoid.

[DaveReidUK]

So what function is it… a door, an escape, an “escape door replacement quick release fuselage panel”,… What are the associated interchangeability requirements… ?

I don't think there is any doubt or ambiguity over what it does, even if the terminology used is somewhat confusing.

The 737-9 (and the -900ER) are built with two additional large holes behind the wing, one each side, and obviously before flight, something has occupy those holes to stop passengers falling out ...

Customers take their pick as to what the "something" is: an active E/E (if the number of seats requires it), a deactivated E/E, or the stopper-upper© (technical term) that most airlines have chosen.

[Less Hair]

The point of the door-style plug is it can be reconfigured to become an emergency exit for future use. So the aircraft is more flexible if the next operator should intend to max out the possible max seat count.

[roger4]

Kinda gives the lie to "Low fares, Great care" (latest advert) - they obviously aren't interested in safety ... rushing to buy aircraft where there is a demonstrated lack of quality in the build.

If for no other reason than this: Ryan Air if now firmly on my list of airlines to avoid.

The Max10 has an emergency exit door in the hole behind the wing, not a plug like some 900ER and Max9s.

[incompleteness]

While “Throwawayboeing...” alleges that damaged and improperly installed rivets were recorded by Boeing to have been found on the door plug itself, The Air Current (TAC) reported (as posted here by joe_bloggs #1378 (https://www.pprune.org/11583452-post1378.html) (permalink (https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx-69.html#post11583452))**) on the basis of separate inside sources that these defects found by Boeing were “in the fuselage structure just forward of the plug exit door frame.” Both accounts date this recording on 1 Sept and note that Spirit “repaired” the issue by painting the affected rivets over, without addressing the underlying defects. TAC dates this recording by Boeing on 7 Sept and both accounts report that the defect was then sent back to Spirit to be readdressed.
...


Red emphasis mine. It think the attempt by Spirit to get away with a cosmetic 'repair' cuts right to the heart of the cultural conundrum that Boeing faces. I think we all realize this is about more than four bolts. There is something wrong with Boeing & it's supply chain.

In business, it's considered normal to try to get away with ethically grey things. "Let's try literally painting over the problem and see if we get away with it. If not, hey, we had to try." In business, that is considered virtuous, but it's poison for safety culture. Everyone from Boeing to subcontractors working for Spirit have got to be motivated, incentivized, trained, and rewarded for doing it right and erring on the side of caution.

I think the feeling of doom a lot of us feel is due to the fact that it's hard to imagine Boeing giving up its addiction to gross margin for anything. That's why Aviation Week expressed the opinion that over the coming years Boeing would give up on civil aviation, as impossible as that is to imagine.

[WHBM]

Red emphasis mine. It think the attempt by Spirit to get away with a cosmetic 'repair' cuts right to the heart of the cultural conundrum that Boeing faces. I think we all realize this is about more than four bolts. There is something wrong with Boeing & it's supply chain.
Something I've come across in various process/engineering situations is the whole mainstream Method Statement and QA checklist is thoroughly documented and watertight. However, this may not extend to the handling of QA failures, which may just rely at best on inspectors then using their ability for the process now needed to retest everything that needs retesting, down to the repairer just reporting back "fixed", without documenting what they did, or how.

I suspect few of us anticipate that someone formally reported "painted over it".

[DaveReidUK]

The point of the door-style plug is it can be reconfigured to become an emergency exit for future use. So the aircraft is more flexible if the next operator should intend to max out the possible max seat count.

Yes, that has been mentioned a number of times earlier in the thread. Aimed at lessors, obviously.

[D Bru]

"Aviation Flights" has all kind of photos per airline of 737 MAX's coming out of Renton, whether it's being spotted first time outside the facility or first, second test flight, third and fourth test/acceptance flight. On their page for Alaska Airlines (https://aviation.flights/boe/customer/ASA-35/all/all/0,15) the green primer photos (when being spotted first time coming fresh out of the facility) are very interesting. Most primer aircraft are shown with already then fully installed, flush, apparently ready to fly mid-aft door plugs. For the accident aircraft N704AL (LN 8789) however, the mid-aft doors on these photos are tape sealed all around. This raises the question whether even at that stage there were some remaining issues and at the same time puts doubts whether the four bolts even at that late stage would or should have been definitely been installed. According to the website referred to, the photos of N704AL (LN8789) below were taken on 23 Sept, that is four days after Spirit contractors had completed the repair works on/or around the door plug and Boeing accepted as done. For comparison, the last two photos are from other green, just out of the factory aircraft from the same website around the same time (hence the same test registration). Tape, no tape = Work unfinished, work finished = Bolts not yet installed, bolts installed???

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1468x787/screenshot_2024_01_29_at_16_37_18_aa56108b2cbbb0c76675e14926 8c4348fec16465.png
https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1066x784/screenshot_2024_01_29_at_17_43_43_1e468187c9d88d810249c9fa67 27304c82d896e8.png
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1517x801/screenshot_2024_01_29_at_16_44_06_317fe815d58b98b87eff38aa55 e18851e0b09336.png
https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/1514x798/screenshot_2024_01_29_at_16_55_32_1d2d7e08634dc0707f552d7d1e a57417c2afa2d5.png

All photos credited to @CA350

[incompleteness]

Something I've come across in various process/engineering situations is the whole mainstream Method Statement and QA checklist is thoroughly documented and watertight. However, this may not extend to the handling of QA failures, which may just rely at best on inspectors then using their ability for the process now needed to retest everything that needs retesting, down to the repairer just reporting back "fixed", without documenting what they did, or how.

I suspect few of us anticipate that someone formally reported "painted over it".

The RNC process (report of non-conformance, maybe called something else at Boeing) is really human-dependent. Quality writes up the issue and it can be as little as "chipped paint around rivet location xyz". But no matter how minimal it is, quality and mfg are supposed to work together to plan a rework which can range from "use as is" to "remove and replace". Sometimes an mrb engineer (works in quality, mrb = material review board) can be called in to analyze the issue if its outside standard repairs. The point is, its not supposed to be just a mfg tech deciding how to rework it.

I this case I suspect it was Spirit quality, not the tech, who decided to try painting it over. Yikes, right?

[geo10]

From the Wall Street Journal: Alaska Airlines Plane Appears to Have Left Boeing Factory Without Critical Bolts
It's behind a paywall
https://www.wsj.com/business/airlines/signs-suggest-alaska-airlines-plane-lacked-bolts-when-it-left-boeing-factory-f0246654?mod=hp_lead_pos3

Piece intro:

"Bolts needed to secure part of an Alaska Airlines jet that blew off in midair appear to have been missing when the plane left Boeing’s factory.
Boeing and other industry officials increasingly believe the plane maker’s employees failed to put back the bolts when they reinstalled a 737 MAX 9 plug door after opening or removing it during production, according to people familiar with the matter.
The increasingly likely scenario, according to some of these people, is based partly on an apparent absence of markings on the Alaska door plug itself that would suggest bolts were in place when it blew off the jet around 16,000 feet over Oregon on Jan. 5.
They also pointed to paperwork and process lapses at Boeing’s Renton, Wash., factory related to the company’s work on the plug door."

[A0283]

I don't think there is any doubt or ambiguity over what it does, even if the terminology used is somewhat confusing.

The 737-9 (and the -900ER) are built with two additional large holes behind the wing, one each side, and obviously before flight, something has occupy those holes to stop passengers falling out ...

Customers take their pick as to what the "something" is: an active E/E (if the number of seats requires it), a deactivated E/E, or the stopper-upper© (technical term) that most airlines have chosen.

It’s not about confusion but about risk. Words are very important here (believe it or not). Potential confusion also spreads out over the 5 phases that I sketched earlier. It would not surprise me if it turns out to be a core or contributing factor in this ‘lucky escape‘ event. Don’t know if you are familiar with interchangeability and what it means.

You don’t build something. Depending on what you build means a whole lot of different requirements, processes, and products. There is also a big difference in price, accuracy, post delivery, etcetera.

Customers don’t ask OEM’s to put ‘something’ in (not a technical term, as you well know). The cost difference between the options above could be say 100:10:1, while the pricing to customers might differ for commercial reasons.

[D Bru]

It’s not about confusion but about risk. Words are very important here (believe it or not). Potential confusion also spreads out over the 5 phases that I sketched earlier. It would not surprise me if it turns out to be a core or contributing factor in this ‘lucky escape‘ event. Don’t know if you are familiar with interchangeability and what it means.

You don’t build something. Depending on what you build means a whole lot of different requirements, processes, and products. There is also a big difference in price, accuracy, post delivery, etcetera.

Customers don’t ask OEM’s to put ‘something’ in (not a technical term, as you well know). The cost difference between the options above could be say 100:10:1, while the pricing to customers might differ for commercial reasons.

I agree on the risk issue. And how many of the well over 400 plugged 900ER's out of a just over 500 overall 900ER's (delivered between 2007 to 2019) have since been converted into having an active E/E? I believe that number could well be close to zero. And given that most Max flying airlines apparently prefer the door plug option over a an active E/E door, what is wisdom? How to create a risk problem for nothing could be the question here. Could it have been better to stick to an all active E/E in the given spot, which could be deactivated if airlines would wish so. In stead of having a plug door, no door that is? That the "no door" didn't pose a risk until very recently is of course another matter. But as obviously times are changing, so should perhaps the options....

[lateott]

I agree on the risk issue. And how many of the well over 400 plugged 900ER's out of a just over 500 overall 900ER's (delivered between 2007 to 2019) have since been converted into having an active E/E? I believe that number could well be close to zero. And given that most Max flying airlines apparently prefer the door plug option over a an active E/E door, what is wisdom? How to create a risk problem for nothing could be the question here. Could it have been better to stick to an all active E/E in the given spot, which could be deactivated if airlines would wish so. In stead of having a plug door, no door that is? That the "no door" didn't pose a risk until very recently is of course another matter. But as obviously times are changing, so should perhaps the options....Or instead maybe they could just install 4 bolts properly...

[D Bru]

Or instead maybe they could just install 4 bolts properly...

Nice one, but the jury is still out on this. There may be more.

[GlobalNav]

Following on from United's comments about the MAX9 grounding, Ryanair : "If United cancel any MAX10 slots, we will have them ..."

Ryanair tells Boeing it would buy any MAX 10 orders dropped by US airlines (msn.com) (https://www.msn.com/en-gb/travel/news/ryanair-tells-boeing-it-would-buy-any-max-10-orders-dropped-by-us-airlines/ar-BB1hpkMj?ocid=entnewsntp&pc=U531&cvid=24796338d08843668e7a33b6877909b9&ei=61)

I'm sure "at a price".
Bolts included?

[D Bru]

So now, because of this suspected "escape" or "mis-engineering" of "the four plugs" and the public response (followed by websites that allow for filtering out certain 737 seatings), there finally could be a belated and unprecedented industry run on replacing the "door plug" with a non-functional E/E door. This still could fit all well within the readapted parameters of Boeing following the recent incident with N704AL. Of course this was not intended to be, but I'm not hiding a certain amount of irony

[1southernman]

My attention span sux...Is there a common location/facility for last hands-on all these "doors" with issues?...Surely that's been researched early on and known...Cue "Airplane!" dialogue...

My post of 12 Jan...Based on the info at the time I felt the bolts were not installed, hence my question...

[chrisl137]

So now, because of this suspected "escape" or "mis-engineering" of "the four plugs" and the public response (followed by websites that allow for filtering out certain 737 seatings), there finally could be a belated and unprecedented industry run on replacing the "door plug" with a non-functional E/E door. This still could fit all well within the readapted parameters of Boeing following the recent incident with N704AL. Of course this was not intended to be, but I'm not hiding a certain amount of irony

It's not obvious that replacing the plug with a door (active or inactivated) is lower risk than the plug.

An openable door assembly mounts in much the same way as the plug - it still uses the same stop fittings to hold the force from inside the aircraft and must have a similar motion to move the door stops past the fuselage stops. But now it has a latch that's intended to be releasable (and a slide if it's an active door). So instead of four fixed bolts, any one of which should be able to hold the plug in place, now there's a single latch mechanism that's more complicated and has an active release capability. It does at least have sensors and alarms, but those are also things that can fail and have to be maintained.

If it's turned into an inactivated door you end up with a releasable latch whose existence is completely hidden behind interior trim. So that hidden latch has to have some equivalent of the four bolts to keep it positively closed, leaving us with a similar risk of leaving the retaining/locking fasteners out, but with the addition of a complex mechanism that's actually intended to open.

[Roger_Murdock]

I don't see the point of a non-functional E/E door. Just seems like a potential catastrophe when people try to use it in an emergency and it's inop. Safer to just panel over a plug (assuming you can install the plug correctly...)

[Old Ag]

The point of the door-style plug is it can be reconfigured to become an emergency exit for future use. So the aircraft is more flexible if the next operator should intend to max out the possible max seat count.

This is not correct. Boeing recommends the standard deactivated exit for customers who anticipate conversion to a configuration requiring an additional exit. In fact, as pointed out in Chris Brady’s video on mid cabin doors, Boeing warns that there is significant rework necessary for reconfiguring a plug to a door. The purpose of the plug was to allow for an extra full sized window for customers who would never need the additional exit door.

[Condor99]

Today, with everything we know, is there still a single unresolved question about this accident?
And if yes, which one ?

[DType]

C99
Where are the bolts?

[Condor99]

C99
Where are the bolts?
In the trash bin ! Where else ? :ugh:

[joe_bloggs]

Former Boeing employees warn production defects ignored by company and US aviation regulator put passengers at risk.

Nothing we don’t already know. But interesting that MSM here in Australia are looking deeper into the background/history of these events.

https://www.abc.net.au/news/2024-01-30/boeing-737-max-production-defects-ignored-aviation-regulator/103400468?utm_campaign=abc_news_web&utm_content=link&utm_medium=content_shared&utm_source=abc_news_web

[A0283]

Or instead maybe they could just install 4 bolts properly...

Just one viewpoint…

Investigation is about “what” happened, and even more importantly “why” it happened, the first often being easier than the second.
Solving “what” can provide closure, solving “why” increases safety even more,

Information made public since the first crash till today, shows a loss of safety culture, this increases the risk of things going wrong.

From that viewpoint not (properly) installing locking bolts …
(or other scenarios - while waiting for NTSB published facts - being for example not properly installing spring-bracket bolts, as front bracket is missing and aft bracket hanging by a thread …or…or ) …
is just a symptom.

The “why” still carries many questions … throwaway and TAC have lifted a tip of the veil here.

The Preliminary NTSB report will by definition cover part of the “what”, the Final report more of the “what”, but only a limited part of the “why” … a fuller report on the “why” is not being investigated yet, for that the NTSB would have to do a special Safety Study (which includes looking at how the FAA fits into this)…

[DaveReidUK]

This is not correct. Boeing recommends the standard deactivated exit for customers who anticipate conversion to a configuration requiring an additional exit.

No, the statement that the aircraft can be reconfigured (at cost) is perfectly correct.

Boeing might well recommend fitting the deactivated E/E instead - the bean-counters will certainly be happier than with a cheapskate customer who just wants the plug.

[DaveReidUK]

I don't see the point of a non-functional E/E door. Just seems like a potential catastrophe when people try to use it in an emergency and it's inop. Safer to just panel over a plug (assuming you can install the plug correctly...)

The deactivated E/E door is invisible from within the cabin, so no scope for catastrophic confusion

[Old Ag]

The point of the door-style plug is it can be reconfigured to become an emergency exit for future use. So the aircraft is more flexible if the next operator should intend to max out the possible max seat count.

This is not correct. Boeing recommends the standard deactivated exit for customers who anticipate conversion to a configuration requiring an additional exit. In fact, as pointed out in Chris Brady’s video on mid cabin doors, Boeing warns that there is significant rework necessary for reconfiguring a plug to a door. The purpose of the plug was to allow for an extra full sized window for customers who would never need the additional exit door.

No, the statement that the aircraft can be reconfigured (at cost) is perfectly correct.

Boeing might well recommend fitting the deactivated E/E instead - the bean-counters will certainly be happier than with a cheapskate customer who just wants the plug.


I don't recall stating that the plug could not be replaced with a door. I kind of remember stating that it is incorrect to state that the purpose of the plug was to allow for reconfiguration for use as an emergency exit in the future.

And yes it is for cheapskate customers who want lighter weight, less maintenance and just perhaps a row that is easier to sell than one without a window.

It works brilliantly, until you start leaving bolts out.

[Loose rivets]

I've been guilty of obsessing about the minutia. I call it lateral thinking, though really, what's nagging me in this case is the big picture. I don't think, in fact I'm sure, that in the last 50 years I've looked at a chunk of an aircraft and not been able to understand what the designers were thinking. It's the most klutzy, comity-designed piece of confusion I've ever seen. The engineering is plain ugly.

I'll concede that if I were to spend and hour with the real aircraft, I'd probably accept more of the thinking, but it's hard to imagine. Right from the get-go, the need for it to be there in the first place is really questionable, but given that decision is made, how in B-B-Blazes, and in the name of Boeing, did anyone come up with this? I'm looking past the hinge and at the tell-tale pressure marks of the shape that allows them to use the word, Plug. The angle changes at the sides - oh, that's okay, it's got an inward-facing ridge that must be pressing into a seal. The top's the same, a design I'd begrudgingly accept if the pressure on it were in the other direction. It's a total miss-use of aviation terminology, but I'll have to get used to calling this thing, a plug. I'd call it a misshapen mess. I'm supposed to be looking at the big picture, but is that pad, half painted? The Pins. Why have they used slotting of a threaded shaft in a part so totally and utterly vital? The hole in the middle, plus the slots, how much meat did they want to lose?

I'm obsessing again. My solution would be a total redesign of the 'plug' and the orifice it goes in. I have a bad, bad feeling this issue isn't going to stop with remembering to fit four frighteningly needed backup bolts.


https://cimg9.ibsrv.net/gimg/pprune.org-vbulletin/901x957/compression_adjusters_and_bottom_hinge_069c405bcfcfd269cccee aa3708f1c75ccbe318b.jpg

[hunbet]

"The Pins. Why have they used slotting of a threaded shaft in a part so totally and utterly vital? The hole in the middle, plus the slots, how much meat did they want to lose?"

The slot is for the locking clip that prevents the pins from turning. The end of the pin that you can't see is solid. The pads are not painted on any of the doors.

Boeing has used this same configuration on every Boeing that I have worked on starting 57 years ago and most other manufacturers have used the same.

[bc216]

Today, with everything we know, is there still a single unresolved question about this accident?
And if yes, which one ?As Europa01 noted (post #1373, permalink #post11583393), there are some pending questions about what happened on the specific flight and this specific moment to result in the door plug blowout: “what was different about the condition of the door on the event flight.”

Someone may know the exact numbers, but this plane flew without incident for 100+ commercial flights with hundreds (or thousands?) of hours of flight time. If there were no bolts installed (or if they were there but not properly secured), why did the incident happen on flight #100+ instead of flight #1 (or some other flight #n)? Did something unique happen only on the flight of January 5? Or did one or more subsequent events (or other defects) happen/accumulate over the course of 100+ flights? If so, were those subsequent issues directly or indirectly related to the missing (or mis-installed) bolts?

To put it another way, how on earth did the door plug NOT come out before January 5th?

I’m not a pilot or an engineer. My background is in epidemiology and genetics. When we think about causation, we sometimes frame this as proximal vs. distant/ultimate causes. In this case, the most distal/ultimate cause is a capitalist work culture that incentivized productivity/profit over safety. The next cause, which is slightly more proximal but still relatively distal, is the improper removal, reinstallation, and lack of QA/QC of the 4 locking bolts that prevent vertical movement. The most proximal cause(s), to my understanding, has not yet been determined.

[MechEngr]

Anyone have a part number for the stop screw?

[tsumini]

As Europa01 noted (post #1373, permalink #post11583393), there are some pending questions about what happened on the specific flight and this specific moment to result in the door plug blowout: “what was different about the condition of the door on the event flight.”

Someone may know the exact numbers, but this plane flew without incident for 100+ commercial flights with hundreds (or thousands?) of hours of flight time. If there were no bolts installed (or if they were there but not properly secured), why did the incident happen on flight #100+ instead of flight #1 (or some other flight #n)? Did something unique happen only on the flight of January 5? Or did one or more subsequent events (or other defects) happen/accumulate over the course of 100+ flights? If so, were those subsequent issues directly or indirectly related to the missing (or mis-installed) bolts?

To put it another way, how on earth did the door plug NOT come out before January 5th?

.
Will be the $64 question. NTSB will probably have to give their best guess. Personally I believe the plug stayed in place from taxi out until flights completed on the 100+ flights until the last flight when the plug worked itself up until tabs disengaged on the PDX flight. I believe the weight of the plug was enough to keep it down and stop pins in place with cabin differential pressure equal.. I understand that cabin pressure is scheduled so that cabin pressure is maintained at field elevation until after TO. Note that the airspeed increases significantly thru TO and climb. I suggest that the speed will result in a dynamic pressure less than cabin pressure on the plug and seat the plug on its pins and pin stop. I believe some where in this thread someone calculated the dynamic pressure at 160 knots ? Unless the cabin pressure is increased beyond schedule, the plug it will remain seated throughout flight.

[DaveReidUK]

I'll concede that if I were to spend and hour with the real aircraft, I'd probably accept more of the thinking, but it's hard to imagine. Right from the get-go, the need for it to be there in the first place is really questionable, but given that decision is made, how in B-B-Blazes, and in the name of Boeing, did anyone come up with this? I'm looking past the hinge and at the tell-tale pressure marks of the shape that allows them to use the word, Plug. The angle changes at the sides - oh, that's okay, it's got an inward-facing ridge that must be pressing into a seal. The top's the same, a design I'd begrudgingly accept if the pressure on it were in the other direction. It's a total miss-use of aviation terminology, but I'll have to get used to calling this thing, a plug. I'd call it a misshapen mess. I'm supposed to be looking at the big picture, but is that pad, half painted? The Pins. Why have they used slotting of a threaded shaft in a part so totally and utterly vital? The hole in the middle, plus the slots, how much meat did they want to lose?

I'm obsessing again. My solution would be a total redesign of the 'plug' and the orifice it goes in. I have a bad, bad feeling this issue isn't going to stop with remembering to fit four frighteningly needed backup bolts.

While your comments are undoubtedly valid, bear in mind that they could equally have been made about 11,000 or so narrow-body Airbuses which also have a "thing called a plug" at each corner, and a number of types prior to that.

[CAEBr]

Boeing might well recommend fitting the deactivated E/E instead - the bean-counters will certainly be happier than with a cheapskate customer who just wants the plug.

It's a bit unfair to call Alaska Airlines a cheapskate customer. They bought a plane to use a combination of range/payload to suit their network. Boeing were only able to meet that using a fuselage barrel that was manufactured to be capable of being configured to meet a greater variety of combinations. Boeing seem then to be incapable of safely completing the fuselage to remove the impact of those superfluous production options. If Alaska aren't concerned about maintaining the greater capacity option for future owners of the aircraft they should not be expected to be forced to take a standard they don't need to maintain a 'safe' aircraft.

[procede]

If Alaska aren't concerned about maintaining the greater capacity option for future owners of the aircraft they should not be expected to be forced to take a standard they don't need to maintain a 'safe' aircraft.

And the plug is probably also lighter than the disabled door, which then increases payload and decreases fuel consumption.

Not having the hole at all would off course be an even lighter option, but this undoubtedly complicates the production process and might require additional certification, and we know how much Boeing likes to avoid that...

[DaveReidUK]

Someone may know the exact numbers, but this plane flew without incident for 100+ commercial flights with hundreds (or thousands?) of hours of flight time.

The plug door blew out on the aircraft's 151st flight. TT would have been a bit over 500 hours.

[hec7or]

Surely the "unrelated" problems with the pressure controllers had something to do with the unsecured door plug.

[MarineEngineer]

Even if the plug door seal had started to leak, this would not have affected the cabin pressure. The cabin pressure controller identified an internal fault and switched to the alternate controller. The two are unrelated, as pointed out by the NTSB.

[hec7or]

Even if the plug door seal had started to leak, this would not have affected the cabin pressure. The cabin pressure controller identified an internal fault and switched to the alternate controller. The two are unrelated, as pointed out by the NTSB.
Not too sure about that, 1. The NTSB report isn't out yet, 2. Alaska restricted the aircraft to non ETOPs, so clearly cause of the pressurisation fault had not been fully rectified.
PS it's a door plug, not a plug door

[WHBM]

This is not correct. Boeing recommends the standard deactivated exit for customers who anticipate conversion to a configuration requiring an additional exit. In fact, as pointed out in Chris Brady’s video on mid cabin doors, Boeing warns that there is significant rework necessary for reconfiguring a plug to a door. The purpose of the plug was to allow for an extra full sized window for customers who would never need the additional exit door.
Boeing can recommend what they like but it was the leasing companies who led to this solution, by various steps along the way. In the beginning was the 737NG-800, up to 189 seats (if you are Ryanair) and emergency exit provision to suit. The mainstream US carriers typically put in about 150 seats, with F, galleys, their typical pitch, etc, and sought better, so Boeing came up with the 737NG-900, same exits so same limits, but longer fuselage, the US mainstream operators could get in about 180 seats now.

But the leasers and financiers didn't like it because there was no aftermarket opportunity for anyone with a less mainstream cabin fitout, and they didn't want to get stuck with them mid-life if [whatever] happened - Handed back, got a better deal elsewhere, Chapter 11, anything unplanned. Few would be interested. So it hardly sold. Boeing and the carriers/leasers looked, came up with the 737NG-900ER, various enhancements which included an extra aperture. Boeing fine, leasers fine, but now the carriers didn't like it, that door takes away one seat row, six seats, rather invalidating the expense of the stretch. Further design, insert a plug there, nobody inside the cabin will ever know, fully seated.

Yes, Boeing would rather sell the more complex MAX9 proper door. But you can now have it afterwards - if necessary. Airframe value preserved. That is not so difficult. Longtime UK observers will recall Dan-Air taking mainstream-seated ex-Japan Airlines 727s and actually cutting and inserting additional exits to allow high density seating. Doing that is far more complex than plug out, new door in.

[Yogi62]

If I was working at the factory in Renton and it was my job to close up the door and install the 4 locking bolts, where would I get new split pins? Do I turn in the old ones in the process?

Is there some level of parts where items are tracked and smaller items are just too common and are grab and go?