Nearly 200 Boeing 737 MAX 9 airplanes grounded after door plug flies off mid-flight On Saturday, the Federal Aviation Administration (FAA) ordered the temporary grounding of approximately 171 Boeing 737 MAX 9 airplanes one day after an emergency exit seal, known as a door plug, blew out of one operated by Alaska Airlines mid-air. An Emergency Airworthiness Directive now requires operators to conduct a four-to …
"Because of the pressurization of the aircraft and speed, if the pressure vessel fails in a scenario like this, it would fail catastrophically," one aerodynamicist told The Register.
-The pressure vessel did not fail.
A plug in the pressure vessel came out.
The edges around the plug were reinforced, and thus unlikely to fail. This is nothing like the 737 convertible incident https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243.
The fact that the plug did not hit and take out the left-hand horizontal stabilizer is more of a reason to rejoice.. As is the fact that no hapless passenger happened to sit in the adjacent seat without wearing a seatbelt.
No reason to make up scenarios when the actual event is sufficiently hair-raising in itself.
Every little bit helps. In this instance it helped that the aircraft had not reached cruicing altitude.
But yes, a person resting their head against the window / window frame (it is hard to find a comfortable resting position) will certainly have trouble keeping said head inside the cabin when the window pops.
Keep in mind that 0.5 bar of underpressure excerts 50 000 N force per square meter.
How exactly are you quantifying "failure of the pressure vessel" ? The door, in it's role of sealing in the atmosphere, popping out is certainly a failure.
Had someones been seated beside it, I am sure it would have been catastrophic for them.
So the door departing, what is that , 50% of the safety margin for "catastrophic failure" ? 95% ? I would not give Boeing the benefit of assuming they can engineer that margin, since they probably used MD engineering (IE cost engineering) on that door.
Brining up the spectre of catastrophic failure is certainly pertinent.
Although it's called a plug, it's really more of a hatch that can be opened (with a bit of messing around with the interior insulation, etc).
The seat count issue has been addressed else-post, but the point of this hole in the fuselage is that if you want more than 189 seats in the aircraft, you need an additional pair of emergency exits, and this is where they go. So Thai Lion Air currently operates three 737 Max-9's, but all theirs are configured for 221 seats, so the exit is installed and they aren't impacted by the emergency directive.
The Max-9 broadly exists as a 757-200 replacement, with similar capabilities but lower operating costs.
faulty-door-dooms-plane
FWIW, that was a failure of the internal floor of the DC10. The internal floor is not, and was not, designed to be a pressure vessel, so when the cargo hatch came off and the cargo hold depressurised, (without catastrophic failure of the pressure vessel), the floor failed. The floor failure took out the control systems, and the plane crashed. That was a control system catastrophe, not "if the pressure vessel fails in a scenario like this, it would fail catastrophically"
Failures can be prevented from propagating by the simple expedient of drilling a small hole. In this case the plug was surrounded by a large hole. And if the airframe was designed to depend on the presence of the plug for its structural integrity it was designed wrong. On the other hand this is a Boeing. . .
Because it's an opening engineered into the pressure vessel, with all the necessary reinforcement to make sure it doesn't become a stress concentration.
This is different than a failure that starts with a crack, where the tip of the crack becomes a stress concentration that continues the failure.
It's like pulling on a piece of paper with a round hole punched in it vs. pulling on a piece of paper with a tear in the edge. The torn piece will finish tearing quite easily.
Good, and Boeing deserves everything that's coming its way. There's been high demand for 737 Max aircraft and Boeing's been pumping them out without regard for other factors so it should come as no surprise that there's been shoddy workmanship and precious little checking.
In the good old days of the 707 and 747, Boeing was engineering-led and had a good safety culture. That all changed with the McDonnell Douglas merger resulting in the McDonnell Douglas bean counter managers effectively taking over Boeing and putting $$$ above everything else.
It is quite clear that things have not sufficiently changed since the two 737 Max crashes and I'd like to see a complete clear out of the Boeing executives and board members.
I may be wrong, but I have read posts indicating that this plug is not a new design. It may even go back to the 707.
One line of inquest seems to be whether the plug was inproperly installed during production or possible removed and inproperly re-installed as a part of service / maintenance work.
Too early for anything certain. For more info, see:
https://www.pprune.org/accidents-close-calls/656760-alaska-airlines-737-900-max-loses-door-flight-out-pdx-20.html
whether the plug was inproperly installed during production or possible removed and inproperly re-installed as a part of service / maintenance work.
Shouldn't such plugs be designed like the doors themselves, only removable from inside the plane and held in place against the frame by internal pressure? I'd hate to think that their integrity was dependent just on a few bolts.
Quite a few doors on airliners aren't plug type (777 and A340 IIRC ) the old "pull in and rotate" plug doors take up a lot of internal space, and of course almost all cargo doors are open outwards
The open-outwards doors are still held closed by air-pressure (and a metric shit-tonne of safeties) by having the pressure difference act on the latches in a rather clever arrangement.
https://www.youtube.com/live/kGWLBLb9Pm4?si=8QcWhcws_Q1nUWdE
NTSB found that the guides on the door plug were fractured.
The failure occurred because the door plug translated upwards, and the stop pins disengaged from the stop fittings.
They don't know whether the 4 bolts which exist to prevent the door plug from translating upwards were in place, they have not found the bolts.
https://www.bbc.com/news/world-us-canada-67919436
"Alaska Airlines says it has since found "some loose hardware" on some Max 9s.
United said: "Since we began preliminary inspections on Saturday, we have found instances that appear to relate to installation issues in the door plug - for example, bolts that needed additional tightening."
--Looks like the bolts may not have been installed at all, and that it is a production issue, not a maintenance issue. Looks bad for Boeing
I'd say it was a maintenance issue too, because you've got to remember how many people will have looked at that door plug and not noticed missing bolts or that they were badly installed, whilst the door plug would have been opened and closed many times to install interior fittings and other stuff, before the aircrafts was signed off ready for its first paying service.
That multiple instances of loose bolts are being discovered means even more eyes missed it.
You might think so, but the hole in the fuselage is specifically designed for an emergency exit, and those work better if they open outwards.
You can Google a 737 Max (-8) doing an evacuation at Stockholm last month; it's a "Ryanair Buzz" aircraft, which sounds like a low-cost version of Ryanair but may be something different!
it's a "Ryanair Buzz" aircraft, which sounds like a low-cost version of Ryanair but may be something different!
It's Ryanair's new cost-saving model. Instead of landing, they just skim past the terminal and passengers jump off. Saves on landing fees.
No the MAX is assembled in Renton, the components are not ALL built there.
B have also had issues with work adone at their spirit fab in i think it was wichita. Given the corporaate culture of slashing costs above all else, would it be a surprise that there are many other Charlestons one of which supplied parts of this plug ?
Well, the plug design may be same old, same old 707 one on paper.
But who's to say the undocumented MCAS was not just a part of a pattern of changing "minor" things all over the plane, and not documenting for example assembly process changes or reduction of quality checks during manufacturing, due to chasing tight schedules and bonus metrics? Now, that would really be the worst case scenario for Boeing.
"There's been high demand for 737 Max aircraft and Boeing's been pumping them out without regard for other factors so it should come as no surprise that there's been shoddy workmanship and precious little checking."
Boeing doesn't actually even manufacture the 737 fuselage themselves, the sold off the factory and outsource construction to Spirit AeroSystems.
"Boeing doesn't actually even manufacture the 737 fuselage themselves, the sold off the factory and outsource construction to Spirit AeroSystems".
^ That is an excellent example of why Boeing is in the state it is as of right now and that sell off should never have happened.
There is market payback now in the form of Boeing shares losing 9% of their values today with Spirit AeroSystems shares losing 12% of their value as well.
It wasn't just the McDonnell Douglas bean counter managers. It was *everybody* from MD. I was there. They came in like an infestation of rabid rodents, looking for places to build their little rats nests and steal everything they could get their paws on. They whacked the R&D budget first. Then proceeded to offshore manufacturing and engineering jobs, went to all-out war against the unions, moved headquarters to Chicago so the executives wouldn't have to suffer the wailing of the rabble, ran a ponzi scheme of buying back $20 billion in Boeing stock to fluff the lazy asses on mahogany-rows' compensation, farmed out every function they could think of that would do the most irritating damage, from finance, IT and HR to janitorial and cafeteria services to maintenance and facilities. Destroyed the pension plan and retiree benefits. Forced skilled white-collar professionals to train their replacements from Russia and India... I could go on, but, well, you name it, they fucked it up *intentionally*. To this day they are hell-bent on draining the life-blood of the heritage Boeing company. Then they will sell off the empty husk. The corruption and greed has infused itself so deeply that I don't think anything can fix it.
Am in Oregon (in January). Can confirm.
When my house was built, people said the guy was daft to build it here, it'd sink. But he built it anyway. It sank. He built a second one. That sank.
He built a third one. That caught fire, burned down, and sank. So he built a fourth one.
That one stayed up, and I'm living in it.
I this all the 737s that are of the same design or just a subset?
If not then why has not every single one been grounded?
If the design rolls back to earlier models why has not every 737 been grounded?
Just musing but this looks like corporate wellbeing is possibly a higher priority than passenger wellbeing........
The European Union Aviation Safety Agency (EASA) hasn't grounded any 737s because apparently these specific types aren't used in Europe. That suggests not all 737s use this design.
Correct. Most of them do, in fact. The door is only not installed (and replaced by the plug) if the amount of seating is below a certain threshold. Most European and Asian airlines load them up. United likes their fancy biz class up front, and so does Alaska, so the number of passengers drops to below the threshold.
How much money does it save, having a plug rather than an exit door? Wouldn't it still be a good idea to have *more* doors than the minimum required?
EDIT: maybe every exit door needs to have flight crew assigned to it? But I think I'd rather have an unmanned door than no door.
Boeing are having a company-wide conference call on safety - that's a new one I've not had on my bingo card before.
Strangely they also failed to use, "this has only affected a limited number of customers", given that notn everybody had the door plugs installed.
They do seem to have used the line with the BBC that the 737 Max is the most inspected plane in history. Which is true, but only because it was initially approved because Boeing lied to the FAA about the specificiations of MCAS to get it through certification - and nobody noticed what a pisspoor system it was until after two plane crashes and several hundred deaths.
^ Thank you for pointing out that other safety issue and Boeing should not still be relying on a kludge fix that icing issue which requires the pilots to remember to manually switch off the engine anti-ice system without any hazard warning reminder.
This matter will also be a test of the Federal Aviation Administration and its willingness to put public safety first. This time, they should stand up to Boeing and deny Boeing's request to allow a kludge fix while Boeing comes up with a proper remedy.
It is Congress that has granted the exemption. The FAA seems to have been put into a position of powerlessness on this matter.
I don't think that the US Congress quite realises what this means for Boeing's international market. Just because the US Congress has passed a law hamstringing the FAA, that has zero bearing on the UK's CAA, Europe's EASA, China's CAAC, etc. Worse, it puts overseas regulators in a real bind. They could simply roll with it and let the MAX7/10 fly. However, if anyone asks the awkward question "Please explain your thinking around the evidence that this aircraft is safe to operate over our heads", the only answer they've got is "the US Congress says Boeing don't have to do it".
That's not really fulfilling the role of a national / regional aviation safety assurance agency. Furthermore, if anything actually went wrong the persons involved could find themselves in some personal legal / career difficulty. Especially in China.
Properly speaking, overseas regulators should be reacting to this politically granted exemption, along the lines of determining that the USA is bullshitting everyone else on safety. That doesn't mean that US built aircraft shouldn't fly in, say, the UK. However, overseas regulators are perfecttly justified in requiring Boeing to put their new products through their full certification process instead of just taking the FAA's word for it. The danger for Boeing is that the -7 and -10 could very well become restricted to US operations only, or they're forced to do the work properly for aircraft sold overseas.
And SpaceX's attacks on the FAA have to be taken into account abroad, too. If the FAA is brow-beaten into permitting SpaceX operations, it's other countries that are in the line of fire and potentially suffer the consequences.
Whether or not an overseas regulator trusts the FAA or not is not for the US Congress or law courts to decide. If SpaceX's attacks on the FAA causes another regulator to decide that the FAA is toast, it could be Boeing that cops the consequences. This might be as a result of it becoming difficult for outsiders to be confident of where the political rot stops, whether it does or does not effect any one particular program. If that's what they decide, then any FAA certification becomes questionable.
Boeing, more than any other company in the USA, really really needs the FAA to be seen as healthy and effective, otherwise it's overseas sales are off. Rather than lobbying for an exemption for the -7 and -10, they should be lobbying for SpaceX to be put in their place.
SpaceX arent attacking the FAA that's pure media hyperbole, Musk has simply been highlighting the FAA dont have the background or experience in certification of space rockets, flights or rapid test programs and their approach to treating it like just another style of aviation, unless you're Boeing, causes unnecessary delay.
Does anyone really think the FAAs recommendation that SpaceX has education outreach projects as a launch licence consideration actually makes flying a rocket safer ?
The whole commercial space industry, so that includes Blue Origin and Virgin Galactic not just SpaceX have testified to a Senate committee the FAA have neither the resource or flexibility to cope or keep pace with the industry
Is it though?
They have had reports that the aircraft has had numerous pressurization issues. So to them the best thing to do is reset the alarm and fly it over land - instead of having a thorough investigation of the aircraft?
I know aircraft take to the skies every minute with a few things wrong with them that either can't be fixed or would be better suited to having the airline's own mechanics fix it. Of course, nothing that is of a safety concern would take to the skies normally. If a window is cracked or an engine doesn't work, it stays put until it's fixed.
But given this company's safety record in the past, it feels like it's top priority is money and not the safety of it's passengers. It'd be a completely different story today if some poor sod had been sucked out of that jet during the weekend. So while Boeing is getting a kicking (rightly so to be honest) do not let Alaska get away with not being scrutinized.
Thing is that the pilots didn't reset and carry on (and this is also a reason to check the CVR recordings along with the FDR). It went pop in climb. Previous flight notes given to maintenance after flight indicated there was a problem and that maintenance was meant to look at it. That hadn't happened (yet?), and someone in scheduling decided that a quick flight over land wouldn't be a problem (the authorisation for ETOPS was withdrawn). It wasn't a problem until, well, the cork popped and now 170+ pax and crew live with the trauma of nearly having been sucked out of a door-sized hole in the fuselage. That little kid who lost his short and whose mum was quick-thinking enough to grab and hold on to him will have mental scars for life, and I would *not* be surprised if that family is going to launch a lawsuit against the airline and more importantly Boeing.
On DEC 24th my wife and I went on a trip to Hawaii. Wife commented how nice and new the plane was... I replied we need to put a will together, who takes care of the dog is we dont come back? I never say stuff like that.
Super weird feeling. I checked and sure enough it was a 737- Max 9. Hard to believe I had a premonition that I was on a Boeing.
And yes it was the plane that lost the plug. Come to think of it, it did seem a bit drafty....
I hate flying, I've a strong fear of it. Nothing to do with the taking off or landing or turbulence. My fear is down to a trust of the people involved in getting and keeping that aircraft in the air. Everyone from the pilot flying to not have a bad day, through to the maintenance and ground crews doing their job.
This flight has properly triggered that fear, more for the fact the airline knew there was an issue (and now today they find a few of the planes had loose bolts). I don't know what I'd be like if I was you and had been on that flight just weeks before it popped, I don't think I could go on an aircraft again.
For now, thankfully, I don't have to go near a plane for the foreseeable. But when I have to I'm going to make damn sure it's not a 737 MAX-9. I didn't like the idea of the MAX anyway after the two crashes but this is the cherry to that particular cake.
> But of course you're putting a similar level of trust on everyone around you on the road, and with even less justification.
The other drivers are not maintaining your vehicle and they are also in the same boat in that they would probably rather not be in an accident as well.
The justification is that we all pretty much have the same self-interest in not dying which is why there are not more accidents on the road than there are (albeit that the accident rate is unacceptably high for other reasons).
I think it is high time we made all ground crew and management take the maiden flight on any aircraft that they have worked on. Might tend to focus them somewhat.
Yeah, having your passengers sucked out of the plane just like in every airplane catastrophe film is indeed a concern.
That is what Boeing is now, the groundwork for the scenarios of future flight accident films.
Thank God I don't need to take the plane anymore. TGV fills my travel needs nicely, thank you very much.
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This seems to be a bit of red herring.
It's not clear what the pilots could have been saying or doing to cause this.
If they were hoping for a "hey what does this 'door eject' button do" ? to absolve Boeing - I suspect they were likely to get a lot more "what the BLEEEP", followed by a lot of wind noise
Given reports say that P2's headset was ripped out of the socket and sucked into the cabin it probably goes something like:
P1: "white with no sugar please"
P2: "hey, that pressurization warning is on again"
P1: "ok, I will get the checklist out, you have con..."
<whoosh>
<crackle buzz> (as the headset gets ripped out of the scoket)
P1: I have control
P1: I can't hear you and I assume you can't hear me, I'm going to turn back and declare an emergency
<rest of communication done by pointing and gesturing>
More seriously they probably want to know if the pilots noticed a pressurization warning some period of time before the depressurization incident. They will know if the warning was made but knowing if the pilots noticed and understood it is important in preventing such incidents in future. The time between a warning being issued by the aircraft, the pilots noticing it and then the pilots working out what to do about it can often be a factor, and redesigning warnings, giving them earlier or having clearer checklists for what to do with a specific warning can often be outcomes of these types of investigations.
But if the full transcript was available you would have heard the pilot and copilot greeting each other at the start of the flight.
P1 : Good evening - I don't think we've met - I'm Clarence Oveur
P2: Pleased to meet you, my name is Michael Caine
Anon obviously - but thankful that the outcome was not a whole lot more tragic.
They don't want the CVR to establish the cause, but rather they're concerned because they suspect (based on testimony so far from the pilots and flight attendants) that severe in-plane communication breakdowns occurred due to the noise and chaos, that may have led to additional potentially dangerous situations if the incident was subtly different.
The tapes would allow them to analyse the nature of the comms, and develop recommendations for procedure changes in these scenarios, etc.
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Not just the door plug. It looks to me like the entire cabin door blew off. The door being unused and sealed to look like a window. The story about the flight-recorder data not being preserved because the pilot “forgot” to pull a circuit breaker being highly specious.
I find the CVR/FDR recorder thing very odd too. Standard procedure should have been to secure the data and why on earth do US planes only need to keep 2hrs? Everyone else on the planet stores much more and airlines like BA have secondary 'quick access' recorders that record more data channels and more frequently than the stock FDR.
Also from looking at all the pics this isn't a plug door. Its held in by the hinges at the bottom, the rails at the top and 6 'pads' down each side.
I think the 2 hours is left over from when the data recorder used a magnetic tape loop (of two hours) which just cycled round re-recording continuously. The recording stopped when the power was removed (either by catastrophic event or by being switched off). If I recall correctly, several years ago solid state data recorders were approved and now the recording time is effectively unlimited and therefore set to 25 hours for most of the world - enough time for the longest flight and to remember to turn it off afterwards. So, yes, the US really does need to catch up on this - it's not new technology and it's widely available.
In this case it's not clear what the "correct" thing to do would have been though - ignoring what the actual rules are and whether they followed them - given the two hour limit. Switch it off to retain the recordings of the initial incident but then lose all recording of any further incident while returning/landing/etc. ? Or leave it on so that you are capturing the riskier part of any flight, the landing (which is presumably a bit more risky in this case) but lose the data from the initial incident?
Tricky one.
I'd probably go for the latter on the basis that you survived the first incident and will be able to provide eye-witness accounts and the recorded radio traffic to ATC, and the recorder would then remain operational in case there was a catastrophic event later on during e.g. landing with an unexpected hole in the side...
(but I'm not a pilot nor do I have any relevant qualifications or experience on this!)
I thought I read that pilots unions werent happy with the idea of the CVR, the spy in the cockpit listening to all their chat, and so the 2hr limit might be born from original technical limitations, but isnt changing in the US anytime soon.
Arguably it doesnt need the 2hr extending, just needs a simple write protect flag linked to the on board systems that automatically preserves data in cases of emergency.
I think the relevant question is probably "what does the checklist tell them to do?" In an emergency that's what they're going to follow. No one is going to stop in the middle of limping a damaged aircraft back to the runway and think, "wait, should we pull the CVR breaker?" The CVR is mostly intended to cover incidents where the flight crew is no longer alive to be interviewed, so the last couple hours before the recorder loses power are usually plenty.
I'm also reminded of FedEx Express 705, where a dead-heading crew member attacked the flight crew with a hammer. He actually pulled the CVR breaker before takeoff hoping the cause of the crash wouldn't be determined, but the flight engineer noticed the breaker and turned it back on, thinking it had been forgotten in the pre-flight check.
No, that is a PLUG. A cabin door doesn't 'blow off', certainly not on a 737. A door is not 'unused and sealed to look like a window'. It's a PLUG. That's the point of a PLUG. It, as the name implies, PLUGS the door frame without the need for a door. JFC.
Ironically, assuming at least that this reddit post is to be believed, the plug door is actually a modified emergency door!
https://www.reddit.com/r/aviation/comments/191llbg/diagram_of_a_boeing_7379_midcabin_door_plug_and/?rdt=51226
And, potentially this is the cause of the incident - that, fundamentally, it _is_ designed to open but that this has been prevented to convert it to a plug and those prevention measures were insufficient...
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