Alaska Airlines 737-900 MAX loses a door in-flight out of PDX
I have no knowledge of the terminology used in Ireland but FAA AC 41.13-1b has 9 different references to setscrews all of which are fully thread headless fasteners. In my native UK these were known as grub screws, in US as set screws. Clearly these door hinge fasteners have heads.
Last edited by EXDAC; 12th Jan 2024 at 00:00.
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I’ll first answer question #2: the previously logged cabin pressure controller faults have been mentioned several times in the thread, and they were reported to be not linked to cabin air leakage.
Still, I think I’ve read that hissing noises had been reported nevertheless. Investigators will still have an open ear for this detail!
Still, I think I’ve read that hissing noises had been reported nevertheless. Investigators will still have an open ear for this detail!
The NTSB Chair stated at least 2 times "we don't know." If you have a more current and credible source than NTSB as late as 8-Jan, please provide a source.
From Avweb, backs up what I said in post #35, "Maybe Spirit (Boeing) is suffering the same pitfalls, get the aircraft out the door and focus being lost on the process"
Weeks before a catastrophic incident involving a Boeing 737 MAX 9, workers had raised warnings about defective production procedures. Reporters at Jacobin.com posted a story yesterday (Jan. 9) citing documents filed in federal court from workers at Spirit AeroSystems, the Boeing subcontractor that reportedly manufactured the door plug that departed a Boeing 737 MAX 9 on Jan. 5 over Portland, Oregon.As part of the federal securities lawsuit, a Spirit employee allegedly told higher-ups about an “excessive amount of defects,” later telling a colleague he “believed it was just a matter of time until a major defect escaped to a customer.” According to the court filing, the company ignored the warnings.
Broadly, the lawsuit alleges that Spirit deliberately covered up systemic quality-control deficiencies, encouraged employees to underplay defects and retaliated against workers who spoke out about their safety concerns.
The complaints speak to Boeing’s allegedly insufficient oversight of subcontractors such as Spirit and the FAA’s inability to effectively regulate quality control. According to the Jacobin report, William McGee, former panel member advising the U.S. Department of Transportation (DOT) and now a senior fellow for aviation and travel at the American Economics Liberty Project, said, “The FAA’s chronic, systemic, and longtime funding gap is a key problem in having the staffing, resources, and travel budgets to provide proper oversight. Ultimately, the FAA has failed to provide adequate policing of outsourced work, both at aircraft manufacturing facilities and at airline maintenance facilities.”
According to Jacobin reporters, Spirit received a $75 million public subsidy from the U.S. DOT in 2021 and reported greater than $5 billion in revenues in 2022. A class action lawsuit launched in May 2023 and amended in December claimed that Spirit management “concealed from investors that Spirit suffered from widespread and sustained quality failures. These failures included defects such as the routine presence of foreign object debris [FOD] in Spirit products, missing fasteners, peeling paint, and poor skin quality. Such constant quality failures resulted, in part, from Spirit’s culture, which prioritized production numbers and short-term financial outcomes over product quality.”
One quality control inspector reported in the court filings that management at Spirit was putting inspectors in “a very uncomfortable situation” by asking them to inaccurately record the number of defects. In an ethics complaint, the inspector wrote, “We are being asked to purposely record inaccurate information.” The inspector conveyed his concerns in a direct email to Spirit CEO, Tom Gentile, according to the complaint.
Broadly, the lawsuit alleges that Spirit deliberately covered up systemic quality-control deficiencies, encouraged employees to underplay defects and retaliated against workers who spoke out about their safety concerns.
The complaints speak to Boeing’s allegedly insufficient oversight of subcontractors such as Spirit and the FAA’s inability to effectively regulate quality control. According to the Jacobin report, William McGee, former panel member advising the U.S. Department of Transportation (DOT) and now a senior fellow for aviation and travel at the American Economics Liberty Project, said, “The FAA’s chronic, systemic, and longtime funding gap is a key problem in having the staffing, resources, and travel budgets to provide proper oversight. Ultimately, the FAA has failed to provide adequate policing of outsourced work, both at aircraft manufacturing facilities and at airline maintenance facilities.”
According to Jacobin reporters, Spirit received a $75 million public subsidy from the U.S. DOT in 2021 and reported greater than $5 billion in revenues in 2022. A class action lawsuit launched in May 2023 and amended in December claimed that Spirit management “concealed from investors that Spirit suffered from widespread and sustained quality failures. These failures included defects such as the routine presence of foreign object debris [FOD] in Spirit products, missing fasteners, peeling paint, and poor skin quality. Such constant quality failures resulted, in part, from Spirit’s culture, which prioritized production numbers and short-term financial outcomes over product quality.”
One quality control inspector reported in the court filings that management at Spirit was putting inspectors in “a very uncomfortable situation” by asking them to inaccurately record the number of defects. In an ethics complaint, the inspector wrote, “We are being asked to purposely record inaccurate information.” The inspector conveyed his concerns in a direct email to Spirit CEO, Tom Gentile, according to the complaint.
Assembly crews (such as the folks putting in the interior panels) would be used to seeing those bolt holes in your picture empty on the emergency exit door equipped models. I wonder if this particular airframe was the first after a run of a few airframes equipped with emergency exit doors. Perhaps complacency or rushing though the task of checking all the doors/plugs: then signing off a whole page of sign offs could be a factor.
They are interleaved in production with the 737-MAX8, the shorter aircraft, which does not have or need any door at this position at all, and never has any plugs or provision for them..
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It is very clear at 3:58 that the springs bear the entire weight of the plug, holding the stop pins above the stop fittings. Clearly the plug must be pushed down, after being pulled into the frame, in order to place the 4 stop bolts.
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Discussion. In FAR 25.365, the size of the rupture in the pressure shell that you are required to assume, in square feet, is given via a formula. This is fixed for a given model of aircraft. It's the same no matter where the rupture occurrs.
If the rupture occurrs in a large compartment, like the cabin, the time to vent all the air out of that compartment is longer than the time to vent a smaller compartment like the cockpit. That's because the same size hole must be assumed for both compartments.
So if the rupture occurrs in the cabin, the general gaps around the cockpit bulkhead may allow sufficiently fast venting of the cockpit into the cabin to prevent exessive delta-p on the cockpit bulkhead. If the rupture occurs in the cockpit, the decompression is much faster, and the natural venting around the cockpit bulkhead may not be fast enough to prevent high dp's on the bulkhead.
That explains why blowout panels into the cockpit exist, but there are none the other way.
The 25.365 formula gives a size of the required rupture on the MAX 9 of about 4 square feet (caveat: I calculated that myself, so, not an offical value). the Alaska 1282 blowout was much bigger than what the aircraft is required to be designed for.
What I feel this might mean is that the cockpit door is not supposed to open in a decompression that conforms to certification. But this was a much larger decompression opening than Boeing was required to consider. Through either luck, or just good ethical design practice, the door latch was made weaker than the bulkhead, and blew open, thus possibly saving the bulkhead.
It's not that surprising that Boeing didn't put something in the AMM that covers an eventuality not considered in certification.
Last edited by incompleteness; 11th Jan 2024 at 23:59. Reason: grammar
Probably too expensive to plug the doorway from inside the fuselage with the plug being larger than the opening, sealing tighter as the cabin pressure differential increases. Also, plugging an exit to fit in a couple of additional seats is like shortening a runway. Safety is compromised again by the accountants!
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I have not seen the maintenance manual but I would expect that the stop fittings are adjusted so the door plug skin is flush with the fuselage skin and all stop fittings are in contact. Photos of the incident aircraft seem to show that the seal is fixed to inside of the fuselage and the door plug would be pulled into it when it was closed. I very much doubt that the fit of the seal is of any consideration in the adjustment of the stop fittings.
What I feel this might mean is that the cockpit door is not supposed to open in a decompression that conforms to certification. But this was a much larger decompression opening than Boeing was required to consider. Through either luck, or just good ethical design practice, the door latch was made weaker than the bulkhead, and blew open, thus possibly saving the bulkhead.
It's not that surprising that Boeing didn't put something in the AMM that covers an eventuality not considered in certification.
It's not that surprising that Boeing didn't put something in the AMM that covers an eventuality not considered in certification.
Fly safe,
B-757
Psychophysiological entity
I'm looking at the castellated nut
EXDAC
but I would expect that the stop fittings are adjusted so the door plug skin is flush with the fuselage skin and all stop fittings are in contact.
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I'm still convinced that someone removed all the stop bolts and never reinstalled them. Somehow they got the door closed and it stayed in place.
Until it didn't.
They built it like a mouse trap.
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What am I missing here?
How does the door plug seal itself if it is on the external side of the pressurized cabin? It is like looking at a tapered drain plug from the bottom. There must be some seals involved, but the interior air pressure is forcing the door outward away from the seals. What am I missing here?
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Unknown is how much upward force they exert on the plug when its in the closed position. Also unknown is how much of an interference fit there is between the stop pads and the adjustable pins in the stop fittings. It could be that it takes a bit of force to dislodge the door from the stop pads, but when free the springs push the hinge slide fittings up against the washers in the end of the hinge and hold the plug it at its upward limit on the hinges. Conversely, I imagine it would take downward pressure on the plug to overcome the spring and shift it down. Then a little extra force to overcome the interference between the stop pads and stop pins to get it fully closed.
I'm still convinced that someone removed all the stop bolts and never reinstalled them. Somehow they got the door closed and it stayed in place.
Until it didn't.
They built it like a mouse trap.
I'm still convinced that someone removed all the stop bolts and never reinstalled them. Somehow they got the door closed and it stayed in place.
Until it didn't.
They built it like a mouse trap.
2) There should be zero interference between the stop pads and stop pins on the ground at zero differential pressure
3) IMO there is no way the plug was sealed behind the interior plastic trim without at least one "placed" bolt. Whether that bolt also had a castellated nut with or without a split pin is another question.
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In an earlier post someone stated that the NTSB described the "Altn" light coming on during the pressurization events, this means the primary controller detected a a parameter that tripped a fault with the primary controller and the alternate system did not detect the same fault. Actual pressurization events (cabin altitude climb of over 2000fpm, excessive cabin diff pressure <8.75 psi or cabin alt over 15,800 feet) would trip an "Auto Fail" light without the "Altn" light as both controllers would detect those faults if they were real. A pressure leak or failure to pressurize would not trip anything that would cause an "Altn" fault, so it would be easy to deduce that the pressurization controller events were unrelated to a leaky plug door if indeed the "Altn" light was part of the events. That may be where this is coming from.
However, would a transient event that causes the AUTO FAIL indication cause the ALTN system to also indicate if that transient event was no longer present?
Isn't it possible that the condition was no longer present when ALTN was active?
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What I feel this might mean is that the cockpit door is not supposed to open in a decompression that conforms to certification. But this was a much larger decompression opening than Boeing was required to consider. Through either luck, or just good ethical design practice, the door latch was made weaker than the bulkhead, and blew open, thus possibly saving the bulkhead.
It's not that surprising that Boeing didn't put something in the AMM that covers an eventuality not considered in certification.
..My manual (not 737) clearly states that the whole door may open in case of a rapid cabin decompression..Do not know about Max..
Fly safe,
B-757
It's not that surprising that Boeing didn't put something in the AMM that covers an eventuality not considered in certification.
..My manual (not 737) clearly states that the whole door may open in case of a rapid cabin decompression..Do not know about Max..
Fly safe,
B-757
Follow-up question would be whether those aircraft with a masked inactive door still have the active sensors and annunciators that an active door would have.
Last edited by lateott; 12th Jan 2024 at 01:37. Reason: format