Boeing 737-9 Max - two months old plane loses cabin window and panel

[Not_Karl]

Imagine how many fewer worries we would have if aeroplanies didn't have windows or doors.

New quality glitch to delay some Boeing 737 MAX deliveries
Feb 4 (Reuters) - Boeing Co (BA.N) said on Sunday it will have to do more work on about 50 undelivered 737 MAX airplanes, potentially delaying some near-term deliveries, after its supplier Spirit AeroSystems (SPR.N) discovered two mis-drilled holes on some fuselages.
Boeing confirmed the findings in response to a Reuters query after industry sources said an "edge margin", or spacing problem, had been found in holes drilled on a window frame on some jets.

https://www.reuters.com/business/aerospace-defense/boeing-delays-some-737-max-deliveries-after-new-quality-defect-2024-02-05/

[Evan]

From the NY Times today:

A photo indicates that bolts in a fuselage panel were removed at a Boeing factory and not replaced, the National Transportation Safety Board said.

Preliminary Report is out. It includes this disconcerting bit of information:

Photo documentation obtained from Boeing shows evidence of the left-hand MED plug closed with no retention hardware (bolts) in the three visible locations (the aft upper guide track is covered with insulation and cannot be seen in the photo).

The door plug was originally removed to gain access in order to repair five damaged rivets in the fuselage. So this was not an error in the initial build process, but occurred during a non-standard maintenance procedure.

That's good news because it doesn't point to a concern affecting all aircraft having the door plug. It seems to have been a one-off performance.

In my gearhead days, I recall how bolts left over meant a teardown. I can only imagine what these screwballs did when they noticed the bolts laying around.

"Eh, probably nothing..."

Other big question this report brings up: How does an armored cockpit door, designed to withstand a determined forced entry, get 'blown open' during a mid-altitude decompression event? Seems a bit flimsy, init?

[Gabriel]

The door plug was originally removed to gain access in order to repair five damaged rivets in the fuselage. So this was not an error in the initial build process, but occurred during a non-standard maintenance procedure.

At this stage I would call it rework rather than maintenance.

That's good news because it doesn't point to a concern affecting all aircraft having the door plug. It seems to have been a one-off performance.

Mmmmm.... Maybe not all aircraft but certainly not a one-off either. It seems that opening or removing these plugs at Boeing, while not part of the standard process, is relatively frequent as part of reworks. In this same airframe the right-hand plug was also opened at Boeing (I think it was to repair or adjust the seal).

But this is still good news




for Spirit

In my gearhead days, I recall how bolts left over meant a teardown. I can only imagine what these screwballs did when they noticed the bolts laying around.

Exactly. Someone MUST have found these screws laying around at some point, one would think.

Other big question this report brings up: How does an armored cockpit door, designed to withstand a determined forced entry, get 'blown open' during a mid-altitude decompression event? Seems a bit flimsy, init?

Assuming that at 15000 ft they had a cabin altitude of 4000 ft that would make for a differential pressure of some 4.4 PSI or 0.3 kg/cm2. If the cockpit door is 50 x 180 cm that's 9000 cm2 or some 2700kg. I think we can assume that even a heavy person running straight into the door will not do that much force. Plus, the 737 cockpit door opens (and blew) outwards, while a charging impact would go inwards and against the frame.

[Evan]

Exactly. Someone MUST have found these screws laying around at some point, one would think.

These days, I'm having to operate on my electronic devices. New battery in the iPhone. Fan replacement in the laptop. Inviolable Rule: keep the workspace clean and all the parts and screws organized. Bins for everything. If there's a screw I forgot to reinstall, I will plainly see it. Is that too much to ask of Boeing (or their ex-Boeing contractor)?

Assuming that at 15000 ft they had a cabin altitude of 4000 ft that would make for a differential pressure of some 4.4 PSI or 0.3 kg/cm2. If the cockpit door is 50 x 180 cm that's 9000 cm2 or some 2700kg. I think we can assume that even a heavy person running straight into the door will not do that much force. Plus, the 737 cockpit door opens (and blew) outwards, while a charging impact would go inwards and against the frame.

Ok, but then why not the seats, the floor panels, the passengers, the emotional support lemurs?

You have to expect that these armored cockpit doors should be more secure than any of these things. All that was lost were one seatback cushion and one headrest.

[Gabriel]

Ok, but then why not the seats, the passengers, the emotional support lemurs?

Because seats, passengers and lemurs don't divide semi-airtight compartments that are normally kept at the same pressure but suddenly one of them lost all the pressure.

the floor panels,

This one is more interesting because the floor panels kind of do divide 2 semi-airtight compartments (pax cabin and cargo hold).

After a couple of accidents where the floor did not withstand the pressure difference between the pax cabin and cargo hold, impacting some important things like elevator control cables, requirements were put in place where the floor must withstand that differential pressure with a combination of reinforcing the floor and increasing the vents between the 2 compartments so the differential pressure is not so big to begin with.

All that said, I expect this issue to be addressed. If not the next terrorist just need to blow out a window to gain access to the cockpit. And I expect this to come in the form of increased vent through or around at least one of the doors (now that the FAA will require double doors, one of which may be a bars grid so pretty "permeable" to air.

[Evan]

Because seats, passengers and lemurs don't divide semi-airtight compartments that are normally kept at the same pressure but suddenly one of them lost all the pressure.

Aha

This one is more interesting because the floor panels kind of do divide 2 semi-airtight compartments (pax cabin and cargo hold).

After a couple of accidents where the floor did not withstand the pressure difference between the pax cabin and cargo hold, impacting some important things like elevator control cables, requirements were put in place where the floor must withstand that differential pressure with a combination of reinforcing the floor and increasing the vents between the 2 compartments so the differential pressure is not so big to begin with.

I'm aware of that. I think one was the 767 that lost a cargo door. Which would be a differential to the opposite.

All that said, I expect this issue to be addressed. If not the next terrorist just need to blow out a window to gain access to the cockpit. And I expect this to come in the form of increased vent through or around at least one of the doors (now that the FAA will require double doors, one of which may be a bars grid so pretty "permeable" to air.

I think, if the floor panels can be designed to handle the differential, an armored door supposedly capable of holding off multiple intruders for 30 minutes should be as well. A security theatre door, maybe not...

[Gabriel]

If my speculation (because that is what it is) is correct, I expect some plastic deformation and scratches on the top edge of the fuselage stops and bottom edge of the door stops.

Contact damage was noted on the lower sides of the 12 stop pins and fittings on the MED plug. Corresponding contact damage was noted on the 12 stop pads and fittings attached to the fuselage. Overall, the damage was consistent with the MED plug translating upward, outboard, and aft during the separation. Figure 9 shows damage features at the upper forward stop location and is representative of the other stop locations.

https://avherald.com/files/Report_DCA24MA063_193617_2_6_2024%202_22_52%20PM.pdf

[Evan]

At this stage I would call it rework rather than maintenance.


Mmmmm.... Maybe not all aircraft but certainly not a one-off either. It seems that opening or removing these plugs at Boeing, while not part of the standard process, is relatively frequent as part of reworks.

What is your source for that? Do you mean there are reworks at Boeing after receiving the fuselage from AeroSystems? And that this is common procedure?

[Gabriel]

What is your source for that? Do you mean there are reworks at Boeing after receiving the fuselage from AeroSystems? And that this is common procedure?

The source is everywhere. I don't remember the specific outlet but it was citing Boeing directly. Boeing of course has its quality control (flawed or not) and there are procedures (flawed or not) for what to do when there are findings. It was already known since a few days after the accident that this very airframe had the plug opened at Boeing for a rework done on the right side.

[Evan]

The source is everywhere. I don't remember the specific outlet but it was citing Boeing directly. Boeing of course has its quality control (flawed or not) and there are procedures (flawed or not) for what to do when there are findings. It was already known since a few days after the accident that this very airframe had the plug opened at Boeing for a rework done on the right side.

Up until the release of the preliminary report, I was reading that the blame rested with Spirit AeroSystems, who initially assembled the fuselage. Boeing was accepting that they were ultimately responsible but not admitting direct responsibility. Now it seems Spirit had nothing to do with it (aside perhaps from whatever damaged those five rivets).

[Gabriel]

Up until the release of the preliminary report, I was reading that the blame rested with Spirit AeroSystems, who initially assembled the fuselage. Boeing was accepting that they were ultimately responsible but not admitting direct responsibility. Now it seems Spirit had nothing to do with it (aside perhaps from whatever damaged those five rivets).

Actually it seems that there is an army of Spirit employees at Boeing dedicated to rework Spirit-generated defects, and that this was a rework performed by Spirit and because the system that Spirit uses doesn't play along well with Boeing's system a task for Boeing to check this rework was not generated. Or something like that. Sketchy info by now.

[Evan]

Sketchy info by now.

Indeed.

[Evan]

“Our people on the factory floor know what we must do to improve better than anyone,” Boeing’s chief executive, David Calhoun, said in a message to employees on Jan. 31. “We should all seek their feedback, understand how to help and always encourage any team member who raises issues that need to be addressed.

Great. So the people on the factory floor will 'feedback' that they need better wages and health and pension benefits and a less stressful work environment to attract more experienced colleagues, and less outsourcing to companies that refuse to do this. Providing these things will conflict with short-term quarterly stock performance and absurd executive compensation, so we're back to nothing being fixed.

[TRTPUwU]

Imagine how many fewer worries we would have if aeroplanies didn't have windows or doors.


https://www.reuters.com/business/aer...ct-2024-02-05/

Well, planes without windows would make planes cheaper to produce, so, it would increase safety on boeing planes and make them cheaper. I am still wondering why so many windows on planes anyway, arent people afraid of heights?

[Evan]

The NY Times reporting on FAA findings from an audit of Boeing production facilities:

the F.A.A. conducted 89 product audits, a type of review that looks at aspects of the production process. The plane maker passed 56 of the audits and failed 33 of them, with a total of 97 instances of alleged noncompliance,

Apparently, there was a lot of improvisation going on. I’d like to remind these shops that it is a 100M passenger jet they are dealing with, not a 69 Camaro.