NTSB confirms door plug bolts were missing on Boeing 737-9 MAX

By the Leeham News Team

Feb. 7, 2024, © Leeham News: The National Transportation Safety Board (NTSB) yesterday issued its preliminary report on the Alaska Airlines Flight 1282 structural failure on Jan. 5 this year. (A link to the report is below.)

The emergency exit door plug separated from the two-month-old Boeing 737-9 MAX due to faulty installation, the National Transportation Safety Board confirmed.

A door plug on an emergency exit on a two-month-old Boeing 737-9 MAX blew off the airplane as it passed more than 16,000 ft shortly after takeoff from Portland (OR). Nobody was killed and only a few injuries occurred. The flight crew made an emergency landing in Portland a few minutes later.

Within days, the focus for the incident landed on Spirit AeroSystems, which makes the fuselages and installed the door plug, and on Boeing, which completed final assembly at its Renton (WA) 737 plant. Quality assurance, or “quality escape” in aviation jargon, was suggested to be issues at Spirit and Boeing.

LNA’s Bjorn Fehrm quickly concluded that four bolts meant to hold the door plug in position after installation were missing. The bolts are designed to prevent the plug from moving upward off flanges that hold the plug in place in the fuselage opening.

The NTSB’s investigation confirmed that these four bolts were missing after Boeing removed and reinstalled the plug to fix a quality escape from Spirit affecting the plug. Boeing employees failed to reinstall the plug.

Removing the plug is not a standard final assembly procedure. It’s called an “unplanned removal.” There is a specified procedure to reinstall an unplanned removal. It appears that Boeing failed to follow its own procedures.

LNA on Jan. 15 detailed the procedures for unplanned removals and reinstallation.

Related articles

NTSB report

The NTSB report (available here: AS 1282 DCA24MA063 Preliminary report) examines the history of the airplane, work performed by Spirit that was flawed, and work by Boeing to address these flaws. After the airplane, N704AL, was delivered to Alaska, no further work on done involving the plug.

Investigators also examined records from the third-party company AAR, which installed satellite equipment after the aircraft had been delivered to Alaska, but before it was put into service by the airline. AAR’s work was performed correctly.

The investigation continues.


154 Comments on “NTSB confirms door plug bolts were missing on Boeing 737-9 MAX

  1. So defects are not detectable upon delivery QC and on pre-flight checks?? Looks like Boeing and some of its suppliers are not worthy of the AS9100 certification status.

    • These bolts are hidden from normal view behind cabin fixtures. No way they can be checked during a pre-flight check.

      This failure is 100% on Boeing. They removed the door and failed to reinstall it correctly.

      • It cannot be emphasized enough that the bolts do not do the work of holding the Exit Blank against pressure.

        That is the job of 12 pads (6 on both the exit blank and the door frame.) When Pressure is applied inside, it pushes the exit door against those pads and those are what hold the door against pressure.

        The Bolts are in two tracks (left and right) at the top and across the springs at the bottom (again two – its a more nuanced that that at the bottom but all 4 keep the door from moving upwards)

        Upwards and then out moves the door off the pads and flimsy brackets hold it onto the hull of the aircraft. Those are simply to hold the door in place so the Exit Blank can be inspected or maint done. They serve no purpose for holding against pressure nor letting the door be moved into its maint position.

        Once in the maint position the exit blank can stay there until returned to its normal position or removed if more in depth maint is needed on the exit blank (this also is a position a seal can be put around the plug/exist blanks)

        Its is very possible that the 15,500 foot event could only occur in a band at lower attitudes (below 20k for instance). The more pressure on the pads the more friction and the exit blank may not move above say 20k.

        But below X altitude with no bolts it can move and it did.

        It was always clear there were not bolts in place as there was not tearing damage (though one bolt might have kept it form moving, no telling)

        It ejected so cleanly it was clear there was nothing there.

        It was possible they had “rattled” loose but that gets into impossible if the washers, nuts and cotter key wee installed at all on any one of them (and if one bolt was installed correctly its a certainty that all of them would have been as the mechanic would have been aware and the lack would catch his eye or not having 4 in hand would send red flags up)

    • No it was not designed by clowns.

      Management is clearly complicit but the design is solid and valid.

      • The concept of “design” applies not only to the airframe, but also to manufacturing and QC processes.

        And the airframe design is a shambles: it crashed twice, still doesn’t satisfy EASA requirements as regards MCAS sensor inputs, and has a problem with nacelle overheating (to name but a few shortcomings).

        • Design applies to all that goes into the Airframe.

          MCAS was a design failure. The Inlet Anti-ice would also be a design failure or problem.

          But the build is not design. The term is industrialization and it has nothing to do with design.

          Build is a process and each and every step in that process has QC layers and the materials are supposed to meet spec and be assembled to spec.

          You can argue that MCAS does not have the 3rd ref, I will argue that the fatal flaws are corrected. There are multiple layers of cutout and safety in it now and that includes the reduced travel.

          If it should trigger, pilots know about it.

          Mentour Pilot has a video on the pilots of an A320 pushing it into insanity and none of the computer backup systems worked and they wound up in mechanical control (and crashed – fortunately sliding down the runway and the 8 people on board survived)

          I agree the FAA should have not allowed production with the anti ice system. It clearly is a hazard.

          But the structure of the aircraft is not a design flaw, its a failure to execute the build per certification and safety standard for building an aircraft.

        • @Bondi

          And to your point – both Spirit and Boeing seemed to have absolutely no problem manufacturing the 737NG. I think you may be on to something, here

          • Designing processes is just as important as designing products.
            BA can no longer do either, it seems.

        • What is the basis for your claim that the model crashed twice due to the airframe design being in shambles? What exactly was wrong with it? What are EASA’s requirements for MCAS sensor inputs that are still not being met and what are the aviation regulation number(s) that are the basis for those requirements? How did EASA certify the design for entry into service if it wasn’t compliant with the regulations, and re-certify the design and return the airplane to service even though—as you claim—it is STILL non-conpliant?

          What are some of those other shortcomings in the design that you didn’t list?

          • Don’t you keep up with the aviation press?
            Even if you don’t, a few minutes on Google would answer your questions.

          • The reality is that you are wrong.

            The Anti ice is the only design issue. I have seen other serious issues that they allowed to not be fixed for years.

            EASA that allowed two bad RR engines on the 787 out of Rome is another example. India refused to allow even one and one, they had to be good engines on both spots.

            The 787 engine that let go was the one with fewer hours and cycles on it. Full load on another iffy engine, again lucky.

            MCAS is a design issue that was corrected and there have been a number of failures of the Airbus 3 x sensors.

            The fix for the MAX is a synthetic air speed setup that in fact is vastly superior to the pitot / static port system.

            You are trying to lump design into build process failures and that is plane wrong.

          • @TW
            I see you are walloping in half truth … again!
            it’s a sport for you?

          • @TW

            Another case of cognitive dissonance and temoer tantrum?

            Appear there’re many cases of small changes (in design) not fully vetted before but handled by experienced work force that morphed into “nonconformances” and “quality escapes”. See my post below.

          • You guys are truly a hoot.

            There is no connect between making a process and a design.

            The reality is the process was in place at one point, it clearly no longer was.

            As people a lot more in depth than me in Aviation have stated, its not a design failure, its a process failure.

            When you discuss technical issues words and definition matter.

            Throwing spaghetti at a teflon wall and hoping something sticks is not it.

          • “Throwing spaghetti at a teflon wall and hoping something sticks is not it.”

            Couple or ten posters here would applaud you heeding that insight. 🙂

        • When dealing with tech issues, words and their definitions matter.

          Design issues are not build issues.

          • Designing an insufficient build system is a design issue.

            The actual airframe and the build system for it are conjoined twins.

          • Nope.

            They are two totally different aspects.

            You can’t have a safe build unless the design is good.

            You can fail to ensure your processes are in place to ensure that a good build occurs.

            Boeing has had design failures (MCAS and agreed on the Anti Ice failure and I believe that is Boieng as I think they are making those nacelles (previous it was others)

            But you do not make a process failure into a design failure as the fix for either one is totally different.

            They can have the same underlying cause (management failures)

      • Everyone is saying that the doors are not normally removed by Boeing. The doors are clearly unpainted in photos of the fuselages on the train.Either Boeing does remove the doors for painting or Spirit paints the edges and Boeing paints them in situ

          • Yes I know, but where is the door plug painted?Obviously it’s painted at Renton too, so how do they do that without removing it?

          • Why would they have to remove it?

            You tape over the windows and spray paint the whole thing.

          • This is not Caterpillar or some agricultural refurbishing place.
            ( tape off some rubber parts and douse in paint.)

            Look at automotive initial painting lines.
            Doors and such are slightly open to also have a final paint coat
            on less accessible areas.

          • Okay,I’ll start again.Who painted the sides of the structure behind the outside facing panel of the door plug?
            Who painted the inside of the door frame?

          • @Grubbie – From various photos it appears the inside of the door plug and frame recess are already painted white when the fuselage is shipped (trained) to Renton. External painting can then be achieved by simply masking as required – it should not be necessary to even open the door plug for painting.

            I have also read this explanation of the painting process on another site.

  2. CEO pay has skyrocketed over the years. Dennis Muillenburg has a nice retirement package. During his time, he cut hundreds of QA inspectors at Boeing. He ‘saved’ Boeing money by doing this in the short term. But, in the longer term, it’s cost Boeing Billions. Big Pharma is under the same profit over safety mantra. They own the Federal oversight agencies as Boeing owns the FAA and Congress.
    Until the economic incentives for profit over safety are changed, I don’t see the problem of safety being dealt with properly. You can see this in the Morton Thiokol Space Shuttle disaster. Until CEO pay is tied to safety in some manner, the system is rigged to kill people for profit.

    • You are spot on, because people are very sensitive to financial incentives they can influence. But the question is what “metrics” does one use?

      1. The safety record during the CEO’s tenure? Necessary, but also not sufficient. Perhaps an idea is for performance pay to vest over a multi-year period, subject to the safety KPIs being met
      2. The existence of the right SOPs? Also necessary, but also not sufficient (Boeing already has an SOP for unplanned removals)
      3. The actual application of these SOPs? Strikes me as essential, but more difficult to measure (unannounced 3rd party audits?) and also more difficult to enforce (this is where the culture change comes in, but that is harder to influence for a CEO).

      Seeing as #3 is more difficult to influence, one can already imagine CEOs negotiating with boards to put far more emphasis on #1 and #2 in the pay packages. We could then have companies boasting about their new focus on safety whilst, in the day-to-day practice, little changes.

      Implementing safety in pay packages such that it actually makes a difference really isn’t trivial.

      • What is needed is performance based.

        You 787 is grounded due to Shim issues? You pay gets cut by 3/4. Your MAX has a failure, you pay gets cut. Your MAX line is halted, you pay gets cut.

        Said pay is not formed with stocks, that leads to corruption.

        Stock buy backs are not allowed.

        Golden Parachutes are not allowed.

        You take back the 5 million Calhoun should never have been paid in the first place (supposedly for getting the MAX in the air, so if he got the MAX in the air he is also responsible for it being held up and repeated quality failures)

        • Yes, there is zero accountability at the top. Bonuses are like water flowing through a check valve….only goes one way.

    • Would
      “safety escapes” and downright “break down of quality assurance”
      void all bonuses ( even retractive ?)

      be a workable solution?

      We see the bonus issues here with “Deutsche Bahn” management.
      Only 70% of trains are on time, connections are dropped or turned around before they reach their destination ( both measures don’t count as delayed 🙂 but mangement got full boni for some achieved funnies .

    • Friction and good luck.

      The plane was out of service for several weeks having satcomms installed.

      • Even more good luck that this aircraft had already been pulled from over-water flights. Hate to think about being on that plane halfway to Hawaii with a blowout.

        • That was an Alaska Airlines decision, it turns out it has nothing to do with flying that route (ETOPS)

          Its a case of where you have a safety feature that then is allowed to be ignored because in theory, you can still get to Hawaii or back to the Mainland (point of no return but its time based)

          However, that safety feature (going to 10k and idling along) that you have sufficient fuel to do does not account for a big hole in the hull, be it an exit blank or a fuselage panel blowing out.

          So in theory a perfectly working aircrtaft leaves the factory and then airlines can fly them with known defects in equipment because it meets a Minimum Equipment List (MEL) matrix.

          So its designed and in theory delivered with many layers of safety and then they can fly them with fewer, legally even though Boeing or Airbus cannot deliver them in that state.

          That is truly absurd.

          • Alaska had to pull it off ETOPS routes because of the pressurisation issues on previous flights.

          • No they did not.

            You did not read the so called allowance. There are multiple systems for pressurization.

            But you can dispatch ETOPs with a bad one as well as iffy ops.

            The reasoning is that at the worst possible point between Hawaii and the Mainland, you can decedent to 10k and get to one or the other.

            Note it was ALASKA that pulled it not regs.

            What the MEL bust does not take into account is a hole in the fuselage. That makes for a wide gap that you are going to ditch.

          • Did they ever tie the pressurization indicator back to the fact that the plug was not locked in? Or was that something entirely unrelated?

          • Casey:

            While it makes a logical link, right now you can’t make a direct link.

            The pressurization alarms could have been from other causes.

            The Plan is not flying until NTSB releases it as evidence.

            So at a guess its 99.9% but not 100% and may not be.

            Its not like anyone is ever going to test that again.

            This does go back to the basic fact that pressure tests are not intended to check for missing bolts (or loose ones)

            Equally the sudden pressure increase on a test is guarantee to hold the exit blank in place (it got through pre delivery, delivery and then a number of flights)

            It may have taken bumps on landing to start it moving.

    • There are flanges (12 IIRC) that hold the plug in place. To open/remove the plug, four bolts that secure the plug down have to be remove in order for the plug to move upward and open the plug.

      The bolts are designed to prevent the plug from moving upward off flanges that hold the plug in place in the fuselage opening.

    • Look closely at the figure 16 pic in the NTSB preliminary report. Notice the zip tie secured around the stop fitting & pin, second up from bottom on forward set of stops? That pic was taken last September during rivet rework. Suggestions have been the zip tie was the only thing holding plug downward for 250 flights.

  3. Bolts not reinstalled by Boeing: airline questions:
    Does Boeing perform a ground pressurisation test before transfert to flight department?
    Does not Boeing test flight or customer’s acceptance flight protocol make it possible to demonstrate this fault during a voluntary depressurisation with the passenger masks down?
    What would be an event (airframe shock on the ground, in-flight turbulence, etc.) that lifted the door after more than a month of operation, and what flight parameter or pilot input would have allowed maintenance to suspect this hidden default ?

    • RE 737 HIgh Blow pressure test
      Try http://www.b737.org.uk/production.htm

      ” Near the beginning of the moving line, an overhead crane lifts the 23-foot-high (7-meter) tailfin into place so it can be attached. Next, floor panels and serving galleys are installed and functional testing begins.

      In a test called the “high blow,” mechanics pressurize the plane to trick it into thinking it is flying 92,847 feet (28,300 meters) in the air (more than twice as high as it will fly in service). Then, inspectors make sure there are no air leaks. In another test, large yellow jacks lift the 154,983-pound (70,300-kilogram) airplane into the air so employees can try out the landing gear retraction system. “

      • Yes, but we have no idea at what stage of the build process this test is conducted. I would expect it’s done with an empty cabin, before all the interior is installed.

        Given the damning photo clearly shows the seats installed, I suspect this pressure test was conducted before the plug was removed and reinstalled.

        • You are understanding the setup wrong.

          There are pads that the exit blank pushes against.

          Put a high pressure in the hull and it pushes against those pads.

          The Bolts keep the exit blank from moving up (and then out) to the maint position.

          The flying and rattling around of landing let the exit blank move.

          Pressure does not let it move at all as there is incredible friction on those pads.

          The ground test is not intended to check the bolts are in, it is intended to check if the seal is working right.

          Also the aircraft is flown on delivery checkouts, so it got a full test or tests doing that.

          None of those tests are intended to check bolts in place.

          The Processes in place with multiple checks are intended to do that.

          Once the interior is installed, you have not a clue if the bolts are there or not.

          • I’m not misunderstanding anything. You’re reading too much into my reply.

          • I do not think I am.

            You are ignoring that there are pre delivery flights where the client checks the aircraft out as well.

            It also was flown for a time and the alarms were intermittent.

            Somewhere in the details will be what the final pressure check is or was and frankly it makes no difference.

            The check is not going to reveal missing bolts. The Pads will hold it and it will seal (hard to argue that it did for a time)

            A pressure check does not ensure the wiring is right. All the final tests as well as pre delivery do that.

            You might as well expect the pressure test to ensure the vertical fin its installed correctly.

            What ensures the fin is installed correctly is someone doing the work, it being inspected and signed off (and more than a simple two step process)

          • @transworld

            There you go again, telling people what they’re thinking. Please don’t feel the need to reply again.

          • Unless Scott policy has changed then people can comment and your verbiage shows that you are trying to create dust in the air when there really is no point to the comment.

            Its purely a process failure if a plug is moved and a test is not done.

            Clearly there are pressure events before the aircraft is delivered.

            And none of those have anything to do with no bolts.

            No bolts is not a test failure, its a process failure. When they did or do the test is irrelevant.

            Seals fail all the time post major test.

            You are not looking for missing bolts. If they are not there its a process failure not a where in the sequence this test was run.

    • One would assume a pressure test with helium as a small atom gas and multiple sensors around the aircraft after a cabin pressure warning.

  4. Any information on the Gates reporting that BA has not given all documentation to the NTSB as requested?

    Does our internal source know if it is the SAT/CMES communication stuff that they are after?

    • You gotta wait as the devil is in the details.

      Boeing may not have supplied the documentation because they don’t have it.

      Now why that process step was dropped on that side and not the other side nor have there been reports of missing bolts though reports are out there of loose ones?

      Missing bolts is an entirely separate aspect of loose.

      Both would be process failures

    • I wonder what is the target market. Lower part of it is handled by quite modern A220. And A220-500 could take over for A320 and free more slots for A321. Upper part of single aisle market? A321XLR is selling like hot cakes and is actually still in certification, so hard to imagine Airbus creating a successor too quickly.

      Airbus has biggest problems on smaller widebody segment where A330neo is simply uncompetitive against 787 and on freighter market.

      • Airbus knows, that commercial air traffic will can only grow on long term, when they switch to climate neutral propulsion. If the size of the market gets limited due to environmental regulations, the grow potential of Airbus is limited too.
        This is why Airbus public announced the intend, that the want to introduce a clean sheet liquid hydrogen powered aircraft. They just did not decide which segment this will be. They showed drawings of an ATR72 sized fuell-cell powered propeller plane and of an A320 sized plane with hydrogen burning jet engines.

  5. The replies tend to blame everyone except the ‘poor’ folks whose job it was to flag an ‘unplanned removal”. The Boeing supplied photo in the NTSB of the MED installed after the rivet rework is WITHOUT the 4 locking bolts is disheartening.

  6. Airplane passenger shocked by ‘gaffer tape’ all over Boeing 787 wing: ‘What the hell!?’ (you need to see the pictures)

    “However, Boeing has since assured the public that the airplane adhesive is “speed tape,” which is perfectly safe for use on airplanes.

    “Speed tape is a Federal Aviation Administration (FAA) approved material for some temporary fixes,” a company spokesperson clarified to SWNS.”


    • It’s purely cosmetic.

      I agree it’s not a good look for Boeing’s most technically advanced plane, but we’ve seen lots of images of it and it’s zero threat to flight safety.

      • Its the airline flying the planes choice.
        Maintenance isnt perfect as manufacture either .

        But of course the self appointed experts who would have trouble changing a bike tyre know all about manufacturing .
        yes , I have run my own manufacturing business

        • Duke:

          I will disagree on self appointed experts.

          Its people interested in Aviation.

          I disagree with them when I think they are wrong. Mostly I believe I have my facts accurate but I am not anywhere near perfect.

          Anyone can comment. Scott has kept this open to everyone. We can disagree but they have every right to post.

          I may have technical insight into things like fasteners, but I am not an expert on aircraft mfg let alone the various stages of inspection and quality control.

          I do know failure modes and it was clear that there were not bolts in the Exit Blank. Not everyone knows how that mechanism works (I did not) but once I saw it, it was clear bolts were completely missing.

          The bolts could have rattled loose in theory, but if they were in at all most if not all would have been installed and with the cotter key and nut, could not have moved.

          So, my take was the bolts were never installed and they had not come loose – you have to understand (and I am sure you do) that if one bolt was in, they all were in. No ripping or tearing meant they were all out and 99.99999% possibility that they never were installed.

          It does not mean I can explain why the door moved on the flight it did and not another one. I doubt we will ever know.

          And frankly it does not matter. If the bolts were in place, maybe as few as 2, it never would have ejected.

          But again, if two were in, 4 would have been in.

          An area we do not know is what is meant by LOOSE.

          Its an interesting application of castellated nut as that application would not require a torque (there might be a lite one).

          Typical for a castellated nut and cotter key is down to snug and back off until holes line up, or you can have a torque down to XX lbs and back off 1/4 Turn.

          But most people don’t work with fasteners and while ignorant, does not mean they are now allowed to comment.

          Frank P does a whiz bang job of laying out Financial Reports. Not my thing though I do know how to manage an operation and its most annoying to him when I simplify it.

          But this is a very techy failure and the financial of cut at all cost played into it but in and of itself its not financial, its a process failure (acualy a bunch of them)

  7. A tiny LNA correction: NTSB says door departed passing 14,850 feet, climb was then stopped at 16,320 feet.

    • Yes, aircraft was on auto pilot and the emergency procedure is to leave it there while the pilots get oxygen masks on.

      That assumes the aircraft is behaving normally and despite the blow out. it was.

      As they were in a climb mode the aircraft kept climbing until one of the pilots had their oxygen mask on and then began the what do we do now process.

  8. “Quality assurance, or “quality escape” in aviation jargon…..”

    Wait a minute. When did this obnoxious term become aviation jargon ? I only see it as a Boeing spin doctor contrivance.

    • A lot like Moon Shot to try to cover up the management failures on the 787.

    • I don’t currently work in the Aviation industry but in a mostly unrelated high-consequence-of-failure industry (think Macondo). We started using the term Quality Escapes instead of Defects years ago partly to de stigmatize reporting of Defects and get more of them officially recorded but it just became bs jargon instead. It always makes me think of El Chapo when I hear it.

      Regardless of industry or quality system, falling back on Risk Management any deviation, which by itself or in combination with any other defect can result in unacceptable consequences needs to be eliminated or by default the consequences are accepted.

      No bolts in the door plug seems like an obvious critical defect that management either deliberately or much more likely blindly tolerated. It costs money and brainpower to drive critical defects to zero.

      Personally, I don’t believe in relying on a procedure (document that you installed the bolts) and I’d try to design it out somehow. Visual indicators or some kind of latching interlock come to mind, those may not work but you get the idea.

      • The Maconda blowout is one of my all time tops for violating the many layers of safety. Its stunning to see how it progressed into the disaster it was.

        But in the end a process is people and you do have to trust people to not just do their job, but when they sign it off its been done and the inspections should confirm that.

        There are a lot of fasteners in an aircraft. Each one has a process linked to it (some cover many of the same fastener doing a job like the door pads are secured)

        In this case it was a failure to have a process in place, how it got to be a blank has to be part of the investigation and reports. But it was like it simply did not exist for a door plug activity.

        It literally is not something you design around with indicators, its impossible to build anything that way.

        This is kind of 3 different Swiss Cheeses all with a hole through them and that should be impossible. Obviously is isn’t.

        FAA failed, Spirit has failed in other aspects and Boeing failed. That is what is stunning. None of the layers of safety caught this.

        And worse, quality failures from Spirit were a way of life that they then forced Spirit to fix them at Renton when they should have been stopped after the first quality failure was found in the doors/plugs or any other aspect.

        This is not just a single failure, its years of failures to do it right by all parties involved.

  9. Scott and team, good work, thank you.

    Things worth noting:

    First, praise to the Alaska flight crew for cool heads and grace under pressure. Aviate, navigate and communicate.
    Praise also to the flight attendants, people they are there for your SAFETY!
    As usual, a very good comprehensive investigation and report from the NTSB.
    Boeing? Well what can we say, really just pathetic and disgusting.

    I noted in the NTSB report about AAR SMS (Safety Management System) technically they are better than Boeing. Boeing has a so called FAA approved SMS but how do you think that’s working for them folks? Spirit, still working on an SMS, good grief!
    SMS is all about risk mitigation and the workforce to report anything without impunity….

    I was stunned the NTSB has a Boeing factory photo of the Alaska jet with the plug door installed with no safety bolts installed! Talk about damning.
    One last thing, This is all on Boeing, but the NTSB report didn’t address Alaska mx on what actions they took when the psi problems started occurring for approximately a month? I keep saying that door had to be making one hell of a noise as it was moving up and the door seal gap increasing.

    I just don’t know what to think anymore about Boeing. They said everything would change after the first two devastating accidents, but nothing has changed.

    • Agreed with most of it.

      The picture needs context, it could have been taken to confirm the door was back in place and that to be followed up by bolt install.

      As bolts got back in on the right side, its a serious question why the left side got dropped.

      There is also the question that is covered per above, how come so many loose bolts were found on in service -9?

      Loose vs missing.

      • I wonder when we will find out if the other aircraft with loose bolts also had the plug removed at Boeing or were there own escape from Spirit. I still have not heard a definitive answer on the blowout aircraft whether the bolts were ever installed by spirit

        • Casey:

          It seems clear it was delivered with bolts there by Spirit.

          Loose bolts is a whole different aspect and that may well be Spirit and a process flaw at Boeing as the Renton inspection before the interior is put in should show that.

          But this also is amidst other failures by Spirit as well as Boeing in not getting to root causes and Spirit just fixing stuff at Renton.

          The reality may be that you have some of that but it should not be the same spot over and over again and even higher up, once one flaw is logged, it is supposed to be back tracked to where it occurred and stopped.

          Ultimate Spirit and or Boeing should have dealt with Malaysia supplier.
          Per the report that this has gone on at least a year, they did not.

          That cascades into an FAA failure as well as that is the things that should be flagged and if not followed up, then strop production until it is corrected.

    • And Spirit is on a number of hooks for taking bad exit blanks and doors, brackets atched wrong, holes in a pressure bullhead drilled wrong and more rivet holes drilled wrong around windows.

      And those are just the ones we know about so far.

      The missing bolts are only technically a Boeing failure.

      The whole thing is many layers of failure by FAA, Boeing and Spirit.

      There is a long history of those Exit blanks and doors with failed quality control (let alone the rest of it).

      Nothing was done, ignored or missed and it should never be missed with the many layers of safety.

      • Depends. Last year, BA has to engineer a financial bailout close to half a trillion for SPR, even after giving out a $180 million advance.

        At the end of the day, BA would have a mess on its lap in case SPR implodes. IMO Calhoun and West would try to avoid that (almost) at all costs.

        Yeah it’s FAA’s fault.😉 Time for FAA to shut down SPR/BCA production to ensure everything is proper!!

    • Maybe. When they bump the list of aircraft with loose bolts against the list of aircraft Boeing pulled the plug on, we will tell if Spirit is guilty at their assembly of undertorqueing the bolts

      • Casey:

        That gets into fastener process and a castellated nut (for the cotter key) and the bolt which has a hole in it line up.

        Usually with that setup, you don;t have a torque spec, they are tightened until no play then back off until the first hole lines up.

        This is a different application of calculated nut and cotter key, at most is going to have a pretty minimal torque spec.

        It even could be none, turn into its snug, then advance it until a hole lines up or loosen it until a hole lines up.

        Either way, its not torque that retains the bolt its the cotter key.

  10. Congrats to Bjorn Fehrm and the Leeham News Team for delivering very solid reporting!

      • And then what do they do about it if a MAX is the only way to get there or that MAX Airlines is less costly than an Airbus airline?

        Like the vast majority they will fly it. Some will not.

        I was on an aircraft that returned to the airport with some kind of equipment failure. That was into a wind storm verging on a Cat I hurricane. Why they did not fly onto the calm airport up North not a clue.

        They said it was fixed and all of us got back on, one lady I knew did not.

        I figured no matter what it was if it could land in a low level hurricane it was not serious.

  11. Transworld : Agree about main purpose of ground test for proper seal works but how can the door “GRADUALLY” move upwards? ( to be consistent with the damage found on the stop pads and stop fittings ) . Then with the breakage of the lower hinge fittings, linked to the last pressurization cycle, the plug door would move upwards, aided by the vertical component of the pressurization. Is this realistic without any suspicious noise having been identified by the commercial crew for many flights?

    • mieul:

      That gets deep into weeds of trying to determine exactly what the failure movement of the door was.

      The only aspect the crew would know about is if the pressurization fails and they get an alarm.

      If the alarms were related to the Door Blank then it was a clue and an exterior sound test might have detected that.

      So its not a simple answer, we may not get an answer as to a major degree the door had to have stayed in position for the seal to work at all in the flights.

      The pilots follow the airlines process for dealing with a pressure alarm and in this case it was very intermittent.

      The indicators are that the door suddenly moved but that also depends on how resilient the seal is to the door moving and possibly flexing with the door to a degree.

      I don’t believe the crew had any indicator and AK Airlines does not have a process in place to check intermittent pressurization alarms.

      In fairness, parts of the aircraft don’t just leave and a brand new aircraft should not have a pressure hull loss (SW did for a newer one).

      The door is hidden behind interior and you have a seal possibly to stop any rattle.

      Why the exit blank moved and departed on the flight it did, phew, huge amount of modeling but it won’t be done as I suspect if even one bolt was in it would not have done that.

      I know its a lot of verbiage but its that odd situation that the simple answer to is put the bolts in.

      Yea a seal can then fail but that is obvious and it does not erupt like this one did.

      • There are reports of passengers hearing a whistling on previous flight.

        Unfortunately its coming from a lawyer.

        Supposedly pointed out (eared out?) to cabin crew but it seems they did not hear it.

        Due to the nature of how it failed, it seems to have been intermittent assuming the alarms were related.

        A brief of Senators (but not us?) said they saw indicators the exit blank had moved before.

        That likely would be markings on the pads though its possible the track could show wear.

        It seems the FAA is being obtuse with the public as all that information is public right to know.

  12. Hopefully, Market forces will eventually wake up the Board of Directors of Boeing. If it doesn’t, then Boeing will be a footnote in the history of aviation.
    Until real change happens, by putting Pilots and Engineers back in the C-Level ranks, and the Board of Directors, replacing the Financial and Political types, the passengers and eventually airlines will shun Boeing. It will be interesting to see how fast or slow this happens, but, it will happen. Ford Automotive, when faced with horrible financial results, pulled the plug on family management and brought in outside help. It usually takes a massive shock that pushes the Board against the wall, to induce the changes necessary.

      • Five consecutive years of losing $$$ … proof it’s “winning” and “successfully” ran!?! 😂

        Old habits die hard. 🙈 🙉 🙊

        • And the entire recovery of the program assumes that they can run the Max line until 2035. There is a massive write-down waiting to happen if market forces compels Boeing to move on earlier than they hope.

          • Casey:

            Spot on.

            Do they have to give up program accounting then?

            I will defer to Frank P

          • Market pays attention to if the management is going to keep its promise of $10b FCF by 2025-2026-ish.

          • With Boeing planning (sometime this year) to replace the 1960 vintage 737 wing riveters with new ones (BOD 2026-27), this $100 million investment indicates the Max will run past 2035. This procurement was scheduled for late 2023, still not placed. My bet, its poker chip for the upcoming IAM contract negotiations. You want a 40% pay increase then the Everett Second 737 FAL and Renton 737 new riveter can to go to South Carolina

          • David P:

            They would have to move the whole wing assembly operation and they do not have the room in South Carolina to do so. Ramp up to 10 x 787 means no space nor is that space setup for a 737 wing build.

            They would be foolish to threaten because they can’t do it.

            No money and it cost them even more as you have to get the Wings to Renton regardless.

            Labor always has a company at risk, they just have to hold out long enough. That was their failure to not just keep striking as Boeing would have had to cave.

            Now its easy to say when you have a mortgage to pay and your other bills, but if you arrange ahead in less than 3 months its over.

            Boeing has its bills it has to pay and even stiffing suppliers you built that up in arrears and then you got no money coming in and now 53 billion in debt to pay off.

          • David P:

            It makes no sense as it then adds a huge cost to the MAX and NG builds (P-8 and E-7)

            And it gets you what?

            Charleston was never intended to be an mfg (assembly) point and only some odd things came to be that it turned into that.

            Lots of better places to build other than a swamp.

            Or let alone the money that it costs and adds to the overhead for no return.

    • No doubt Airbus is revisiting Southwest with an offering for a modern certified 737-7 alternative, the A220-300.

      – To be customized for Southwest specifications and operations.
      – Build in Mobile, Alabama with tonnes of US content.
      – A quieter and more comfortable ride for Southwest passengers.
      – 6-8% cheaper to operate than a 737-7.
      – It’s proven, has EICAS, works well for Jetblue & Delta.

      • Delivery horizon! 2030?

        Getting your purchase earlier was probably Boeing’s only valid advantage in recent years. And that is going down the drain too.

      • Don’t ignore the Chinese Comac C717. In 5 or 10 years, they will be competing head to head with Airbus, and Boeing, if it still is making a B737 then. Or maybe Boeing will just sell them the Renton facility to make the C717?

        • Not sure what the C-717 is.

          They do have a C-919 and the never to be made C-929.

          The C-919 is based on increasingly dated tech as well.

          Its not even certified by a recognized AHJ

          • “Its not even certified by a recognized AHJ”

            Neither are the MAX7, MAX 10 and 777X…and, yet, we’re supposed to believe that those planes are top notch.

          • Don’t forget we’re told repeatedly BA/BCA has multiple successful programs e.g. the 737 MAX, 787 and the 777X. It’s hard when there’re parallel universes/alternate reality.

  13. Why not call a spade a spade?

    The accident was a colossal “safety lapse” not a “quality escape.”

    There is no reason to embrace the spin of Boeing public relations and Dave Calhoun.

    • Hear, hear- euphemistic, obscurative speech is part of the problem.
      “Move to the right” (a *delay*, we used to call that) is
      another example. Say what you mean!

      A Rectification of Names is badly needed, amongst many
      other things.

    • It was not an accident.

      It was negligence.

      The quality escape is Calhoun’s brain

    • Yea I mentioned that above.

      Just because someone says it does not make it true, its all based on a lawyer and law suits.

      And the lawyer is trying to rope in Alaska Airlines. Alaska had a legitimate claim that they took action and did not dispatch to Hawaii when they did not have to and the had every right to believe the MAX was built right, not have 4 missing bolts.

      Seal leaks happen all the time, its not a huge issue, unless the door plug ejects because it was not built right.

      Alaska has no obligation nor should they do a D check on a newly delivered Aircraft.

  14. “Boeing strikes conciliatory tone with suppliers amid 737 MAX crisis”

    “The aerospace giant’s shift in tone was underlined by a speech on Wednesday by Ihssane Mounir, Boeing’s vice president of supply chain and fabrication, at an aerospace conference outside Seattle. “We build the airplane together. There’s no you and us. It’s just us,” he said.”


    I suspect the suppliers may want to see more money and less attitude…as opposed to empty words. But Boeing can’t cough up more money, so nothing will actually change.

      • It’s just MBA-speak.
        An example of talking without actually saying anything.

    • Bondi:

      Boeing negotiated with Spirit getting them more money and a loan I believe.

      So yea, they can dig up the money if they want to.

      Calhoun needs to throw in his 5 million as he failed on the MAX that he got the bonus for.

    • “There’s no you and us. It’s just us”
      Hopefully BA/BCA is willing to share its $3b FCF from the latest quarter with its suppliers. Actions speak louder than words.
      But I know there are words and there’re empty words.

  15. Folding wingtips, open rotor, TTBW;

    The FAA, with egg all over it’s face again, is going to slow roll the cert process now. The Max 7 probably won’t be flying in service in 2024.

    If Boeing can’t be trusted to get it’s production in order on it’s 737 Max line, a product it has been making since the 60’s – how on earth are you going to let it go ahead and produce an aircraft with folding wingtips that has never been done on a commercial jet?

    There was supposed to be a reset after the Max grounding, where it was the most scrutinized aircraft now being produced in the most careful manner. Obviously, it hasn’t worked out that way and Boeing has shown they can’t be trusted.

    How can you even consider letting them roll out a new product?

    • TTBW / Open Rotor™ is pie-in-the sky coming from that
      dismal outfit. What are they presently called: Boing, or something? That’s before the buyout/takeover..

      More failing PR.. if it were Airbus I might
      take it seriously. But there’s something bigger going on.

    • Well the 777X is coming to an airport near you sooner or latter (unless Boeing craters)

      And yea that is the FAA job, to evaluate all that design work.

      The point is that its a TTBW with folding wings that resolves the slot problem at an airport (single aisle gates)

      I don’t claim any of it works but Boeing has also stated that they could go with a non open rotor engine to start. That makes sense as its not waiting for pie in the sky.

      TTBW and open rotor are not linked by other than possibles.

      The wing length has been a cited problem and that solves it assuming they can design a system that makes it work (the US Navy has had folding wings for something around 90-100 years so its not new)

      In the meantime Boeing is still being allowed to make 787s (a much more techy design) and mfg MAX and NG aircraft.

      The door blank failure is not going to stop that though the FAA may stop things on and off until its resolved or Boeing goes belly up.

      • “US Navy has had folding wings for something around 90-100 years”

        and the last thing they work on is monetary efficiency.
        ( same “duhh, simple but” thing as with “Navy nuclear propulsion” as procedures template )

        • Uwe – if they just add in Martin Baker seats for all the pax, along with parachutes, it’ll be exactly like Navy flying.

      • Folding wings are not costless, they add weight (adverse to fuel efficiency and range) and increase complexity to design and operation.

        • Pedro, I just can’t wait to hear of the first trip back to the gate, because some bag or other piece of FOD got blown into the mechanism and the wings aren’t able to fold down and lock into position.

          I wonder how it’s going to handle snow/cold conditions? I’d like to see what happens when freezing rain get’s into the mechanism. How about when dust and sand get’s blown in there, out in the ME?

          Not to say that it isn’t an innovative and unique solution to get longer wings onto an aircraft, but the commercial aircraft business isn’t flying off a carrier – where you have a dozen guys all around your aircraft, checking on things, as you taxi into launch position, with access to the plane a lot easier, as it’s closer to the ground.

          I guess airlines might have to get used to having a ladder close at hand, along with a leaf blower – to get up there and clean out anything stuck in the mechanism.

    • From your link:

      The employee shared with KIRO 7 a photo of the plant where a sign hangs that reads, “Just ship it.”

      “Everybody that walks through the main aisle sees that,” he said. “If by chance something is caught it’s caught by chance not by design like those inserts, that was by chance it was caught and not by design.”

    • The information in that link is sufficient ground for the DOJ to rescind the sweatheart DPA deal with BA.

      It inticates flagrant disregard for customers, passengers and the law.

    • Before posting/reposting, please take the time to actually look at the source material. In the video on Kiro7, there is a bulletin board with pix, one being an internal group photo with the “Just ship it” caption. Is this a photo of the transportation team responsible for shipping parts throughout the factory/sites? Without context as to when or why this photo was displayed, concluding the photo implies that quality is ignored in the interest of expediency is not supported.
      Without evidence by part# of defective product that the “whistleblower” has issue with being passed to production, this was not worthy of being put on the air.

  16. https://aviationweek.com/air-transport/safety-ops-regulation/faas-boeing-crackdown-offers-preview-broader-changes

    “Sweeping FAA certification reforms in a 2020 law were supposed to be the second tranche of fundamental steps to address years of regulatory missteps within Boeing’s Commercial Airplanes business. The initial tranche—prompted by production-related noncompliances across six programs dating back to 2011—was spelled out in a 2015 settlement agreement with the FAA targeting, among other things, Boeing’s weak quality assurance process.

    But the fallout from the Jan. 5 inflight loss of a door plug on a 737-9 during Alaska Airlines Flight 1282—almost surely caused by mistakes made within Boeing’s walls—is underlining what several years of post-settlement production dysfunction spelled out. Boeing is chronically unable to build and deliver aircraft consistently that comply with FAA regulations, let alone meet its exacting design specifications.

    • “[…] Another example is how a relatively minor design or production alteration in the past might have been manageable by the wider supply chain.

      By comparison, a present-day failure often can be traced back to a *small change that was not fully vetted* with new conditions in mind.”

    • When you have $600M in loan interest hanging over your head every quarter, one can see the temptation to put quantity before quality.
      However, BA seems to have forgotten that short cuts inevitably lead to loonngg delays.

      The blind leading the lame.

  17. If Southwest were to go even dual-source, it would be the industry equivalent of Nixon going to China.

    The Gang that Can’t Shoot Straight based in WDC seem to be making that inevitable. “Uh, maybe 2026, or 2027, or.. something.”

    Maybe there’s something bigger going on, though.

  18. I’ve never worked a shop floor making a 737. Some of you seem to have some experience in the inner workings of putting together a big airplane. When I receive a kit to put together, and I have 4 bolts left over, I ask myself, I wonder where these should go? Is there any electronic parallel in Boeing’s computerized inventory system? That for airplane number 12345, we have 4 bolts left unallocated for use? Are there 4 bolts, sitting in some bin, that are allocated to airplane number 12345, still not used? I have worked on an assembly line many years ago, during summer break in school. We were making soda machines. Inner doors matched up with outer doors matched up with chiller units etc. With so much repetition and each person doing one very specific job all day long, I can’t remember any missing parts.
    I remember certain quirks we had to work around. When the “458” model doors came down, I had to drill an extra hole, because of some defect up the line, didn’t punch out a hole. That would cause me grief, as it was a few extra seconds I didn’t have per door to do. The line would eventually stop and all hell would break loose. The Boeing door plug issue sounds like a non-standard work around that demanded more attention, as it was a break in the standard flow. I’ve learned that if something interrupts the checklist flow in a cockpit, you back up a few steps and restart the flow. Otherwise, you may not remember where your thumb was when the interruption happened and forget a critical item on the checklist. And you’ll find out about that missing critical item at precisely the wrong time.

    • Thanks for this pertinent comment.

      I still find it amazing (almost beyond belief!) that *four utterly critical door-plug bolts* could somehow be “forgotten” on one of these serially ill-fated Boeing 737 MAXes: “oops!”

      It’s a funny ol’ world.

    • While removing the door, the hardware should be stored in a controlled way & environment, making it clear when the (not so small) 4 bolts would be left over.

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