Boeing 737 Max again, it would be nice if the windows stayed in!

[pickle9000]

Plane was new Oct 21 2033

[SiliconWizard]

Must have been pretty chilly.

[Ranayna]

Best description of the event.

Oh, so far i only have seen the inside picure also shown in the video thumbnail. The outside picture looks different from what i expected when i read people saying that a whole wall panel was ripped out. That - in my non expert opinion - really looks like just the door "dummy" (or whatever it should be called) was ripped out, taking the inside paneling with it.

[amyk]

Since they would have zero reason to actually open that non-door, it's odd that whoever was responsible for its design didn't make it physically impossible to remove like a normal door, e.g. by bolting it in place all around.

[nctnico]

'My God, it's full of stars'

Alaska Airlines has grounded its fleet of 737 Max 9s after a cabin window and part of the fuselage blew out at a mere 16000ft!

More precisely: an unused emergency exit got blown out. If a part of the fuselage blew out, the plane likely would have lost structural integrity. Maybe somebody tampered with it.

[PartialDischarge]

Most probably a couple of fitting bolts were forgotten during manufacture. Which is actually not that a simple problem to solve, except one expects Boeing to have the resources to do it right

[SeanB]

Given the issues at Boeing currently, mostly relating to a lot of strife between workers and management, and also with a lot of issues, regarding QC from subcontractors amongst others, having been found in recent times, not unlikely that the door was installed, and the person responsible for checking was meant to come next shift to verify, but never actually did, probably either because they were sitting with 500 tasks to sign off on, and 8 hours to do them, or was off the next day, and the next shift put the interior panels over the loose bolts. Either way there are multiple issues related to new aircraft on delivery on occasion. not good for Boeing, though the other major competitors also has reported issues with poor quality work on sub assemblies supplied from other sites, often needing to be scrapped entirely, and redone again. there are a lot of fake parts, or parts of dubious parentage, that also are in the spares lines as well, which has led to a few flights needing to divert due to in flight failures.

[tom66]

If bolts were missing, one would expect the numerous QC processes to notice it, right?

Some guy has to fit the door frame and door, someone has to inspect that, and someone has to fit the trim afterwards.  There are probably other in-between steps but this seems like a good minimum.

So presumably at least three sets of eyes missed this. 

Not good at all Boeing.

[Gyro]

Scary to think how many times that door would have been up to cruising altitude since the end of October and how many people have sat in that empty window seat (in fact a fair number of surrounding seats it it had blown out at full altitude)!

It's still puzzling that it let go at only 16000ft when it would have presumably been up to cruising altitude on the immediately preceding flight, that's not where you would expect missing bolts to show up, unless they suddenly vibrated out. A lot of passengers got really lucky!

[tom66]

The other odd thing is that the pilots reported some pressurisation warnings on a few prior flights, which suggested the door may have been 'loose' before it failed.  I don't know how well-sealed a plane has to be to guarantee pressurisation, but it suggests a possible progressive failure.  Perhaps if only bolts were fitted on one side the door could become somewhat ajar before it failed completely.  The repeated cycles from the last few flights could have exacerbated the fault.

Another extremely fortunate aspect was that the door didn't then hit the horizontal stabiliser as it flew off, which could have led to 177 fatalities if the plane became uncontrollable afterwards. 

[Gyro]

The other odd thing is that the pilots reported some pressurisation warnings on a few prior flights...

That ought to be a huge red flag - 'The cabin is losing integrity, find out why!'

[fourtytwo42]

I wonder if this extra-door was another of the "doesn't need testing/same aircraft" infamous modifications carried out to produce the MAX series from the basic 737 ?

[PartialDischarge]

This video explains how the panel is locked.

https://youtu.be/maLBGFYl9_o?

[johnk0gcj@gmail.com]

Maybe, 2023?

[pickle9000]

I wonder if this extra-door was another of the "doesn't need testing/same aircraft" infamous modifications carried out to produce the MAX series from the basic 737 ?

I'd vote for it being installed incorrectly. The fact that the area is not torn up is crazy.

[SeanB]

The other odd thing is that the pilots reported some pressurisation warnings on a few prior flights, which suggested the door may have been 'loose' before it failed.  I don't know how well-sealed a plane has to be to guarantee pressurisation, but it suggests a possible progressive failure.  Perhaps if only bolts were fitted on one side the door could become somewhat ajar before it failed completely.  The repeated cycles from the last few flights could have exacerbated the fault.

Another extremely fortunate aspect was that the door didn't then hit the horizontal stabiliser as it flew off, which could have led to 177 fatalities if the plane became uncontrollable afterwards. 

Pressurisation could have been attributed to either leaking or sticky outflow valves, which probably was noted as a thing for maintenance to look up when it was due for the first check. Or as an imbalance with a poorly adjusted AC pack that is not regulating inlet flow correctly.

[Gyro]

This video explains how the panel is locked.

https://youtu.be/maLBGFYl9_o?

At 9:50 there are two more locking bolts, at the bottom of the door, that are supposed to prevent the door from lifting and unlatching. How many bolts can you miss / not tighten / break?

Edit: That's four in total.

[floobydust]

It seems the doors are removed when the fuselage comes in from Spirit AeroSystems, to allow easier (interior) assembly at Boeing, and then they're put back in.
Might be where the ball got dropped, the locking bolts never were installed.

[Gyro]

... with a couple of strong springs on the hinge pins at the bottom to helpfully support the weight of the door when it's lifted!

[pickle9000]

I wanna see a video of a mechanic opening one.

[tom66]

This video explains how the panel is locked.

https://youtu.be/maLBGFYl9_o?

What's most interesting about that video is the hinge should have held the "plug" in place even if bolts failed - you would still have a depressurisation event but the door would not become detached and risk damaging the rest of the aircraft.

It's possible that failing under pressure broke the hinges too, but it seems like those would should been designed to carry significant forces.  There are two issues for Boeing here;

- Either someone forgot all four bolts and this wasn't caught in QC - easy fix, but embarrassing and further damages the reputation of newer Boeing aircraft.
- And/or the hinge mechanism is defective - potentially an expensive fix with aircraft grounded for some time until the hinge can be replaced with an improved design.

[Gyro]

Looking at the outside view in the video in Reply #27, those appear to be the two hinge pins sticking out horizontally. The front one is clean - minus the big guide retaining (travel limiting) washer and locknuts. The rear one appears to still have something still attached to it - the remains of the hinge guide ripped from the door?

[pickle9000]

This video explains how the panel is locked.

https://youtu.be/maLBGFYl9_o?

What's most interesting about that video is the hinge should have held the "plug" in place even if bolts failed - you would still have a depressurisation event but the door would not become detached and risk damaging the rest of the aircraft.

It's possible that failing under pressure broke the hinges too, but it seems like those would should been designed to carry significant forces.  There are two issues for Boeing here;

- Either someone forgot all four bolts and this wasn't caught in QC - easy fix, but embarrassing and further damages the reputation of newer Boeing aircraft.
- And/or the hinge mechanism is defective - potentially an expensive fix with aircraft grounded for some time until the hinge can be replaced with an improved design.

Correct me if I'm wrong. To open you remove 4 locking wires, 4 nuts and then the 4 retaining bolts. Next the door is tilted
out at the top and a large spring at near the hinge helps lift the door and de-latch it. So the top retaining points seem to
be the most vulnerable.

[pickle9000]

Looking at the outside view in the video in Reply #27, those appear to be the two hinge pins sticking out horizontally. The front one is clean - minus the big guide retaining (travel limiting) washer and locknuts. The rear one appears to still have something still attached to it - the remains of the hinge guide ripped from the door?

One of long bits at the bottom is probably the spring that carries the weight of the door so it can be delatched..

[AndyBeez]

@PartialDischarge thanks for posting the door plug photo. My theory, the bolts were overnight and the threads stripped. It is one thing to use a torque wrench or bolt driver, another to set it correctly. Outside of Boeing Field, the door may have been off for access when the cabin was fitted out?  Temperature and pressure cycling found the weakness. The bottom hinge threw the door downwards and away.

Where is the door? https://www.oregonlive.com/portland/2024/01/door-in-alaska-airlines-accident-believed-to-have-fallen-over-beaverton-publics-help-sought-in-finding-the-key-evidence.html