Alaska Airlines Alaska Airlines Flight 1282 737 MAX 9 Update - Episode 202
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- เผยแพร่เมื่อ 11 ต.ค. 2024
- Latest on the Alaska Airlines Alaska Airlines Flight 1282. The 737 MAX 9 aircraft plug door separation and rapid decompression. Todd, Greg, and John discuss recent developments, including the recovery of the plug door.
They talk about the value of having the plug door for inspection. They share the sequence of events that led to the door separation based on factual evidence.
The spotlight is now turning to Boeing. Will the company's future actions keep the CEO's promise that Boeing will be transparent about what happened?
Hear their insider take on the challenges Boeing may face when it comes to earning confidence that company will correct problems with the 737 MAX. The approach that Boeing has taken in the past may not be adequate to address the quality issues of the 737 MAX.
Thank you this very informative site. Nice to see Greg again. These are my thoughts : The "plug" is, like Greg mentioned, made from the outer part of the full emergency door assembly. The handle on the inside of the emergency exit door unlocks the door so that it can be pushed upwards. Springs at the bottom helps to make the door lighter. Still needs a little push though. When mounted as a plug the handle locking assembly is no longer present, instead movement of the door is permanently blocked by four bolts, functioning as pins. IF those bolts are not installed the door is just resting on the springs, without a lock. As long as the stop fittings are aligned the cabin pressure will keep the door in place. As the aircraft is working the door will slowly grind upwards and after weeks or months the door will start to leak a little. When the door has raised itself 2 inches or so the upper guide roller disengages like it was originally built to do.
Finally one other person that has an understanding of how this plug actually works... these guys seem to speculate an awful lot even though they claim that they don't... they should at least understand what they're speculating against
That makes me wonder if it would have been noticeable in the preflight walk around. In the pre 911 days, a family member might have taken a useful picture during the pushback. I've also wondered if the door perimeter was masked off during painting or sprayed over.
Now we are at it. "We build an airframe with an extra hole in it, for saleability and ease of production. Then, if not needed, we plug it. Since we got the outer door on the shelves we'll use that". Which means that the door-plug has an "in-baked" quick release mechanism. That is "reverse-engineered" with four blocking bolts. Smells a little of jury- rigging.
@@idlewild-f6c- I wouldn’t call it “jury-rigging” [sic], I would call it engineering. But it is clearly a critical component which must be installed properly. It should never be closed up without a safety inspector signoff.
I don't know if that would have been noticeable from the ground or not. If the door had not been all the way down in its position, maybe you would have been able to notice the step out. But most likely, the conditions of the flight caused it to translate up in order to pop out. You have to realize that that door is 25 to 30 ft off the ground.
With loose bolts being found on multiple planes, I am worried about similar types of issues on other, unrelated parts of the plane. If something like this were to get past QC (if that is indeed what happened), then who's to say that proper QC was conducted on the rest of the plane?
Before the plug door, it was loose bolts on the rudder assembly. I would like Boeing to at least fully inspect 2-3% of the delivered aircrafts, to find out where issue are the most likely to be. The best would be complete inspection of all the planes, that would reassure everyone, but will never happen.
Due to the lack of QC at Boeing to save money on the front side, I refuse to fly in the MAX.
exactly, if you ever saw aeroplane production, you would see that every part and every action is documented and "approved" meaning if they have MORE THAN 1 (SINGLE) LOOSE BOLT - there has been a major breach of check up procedures and actions meaning EVERY BOEING PLANE is now jeopardized. Amazing what they allowed themselves to become. Thats what we get for not punishing them for MCAS emails and coverup.
@@rcajavus8141 Trained and seasoned in ISO, ASTM (I) GMP, SMS etc for manufacturing, engineering and administration, this is totally unacceptable by Boeing as it appears they have learned nothing from the past.
5:21 Just prior to the plug’s departure, the plane hit some turbulence. (Think twisting) and there were severe pressurization fluctuations at the same time. The delta P may have been very low.
As a member of the flying public THANK YOU for this show. I never miss an episode.
Greg Feith is the best!
Wasn't aware this show existed but sure glad I do now. Instant subscribe.😊
I grew up watching Greg and others on Mayday!! I'm glad you guys are still out there doing your thing. It was that show and the understanding of crew resource management that sparked my love for aviation and specifically, how and why it's such a safe industry. It sparked such an interest and drive in me, I wanted to work for the Canadian Transportation Safety Board when I grew up and would tell anyone who would listen from the 4th grade onwards.
Thank you for all your incredible information, time, guidance, and wisdom! So happy to see everyone is still doing well! Cheers from the Great White North 💕🇨🇦
I've been keeping tabs on the WPVI Helicopter crash & the NTSB is doing a 2-D reconstruction of the wreckage of Chopper 6 to figure out what went wrong.
At 6:18 the loose bolts are for the door to hinge arm guides attach points. They do not carry any air pressure load however if they are loose or missing the door can move vertically off the actual pressure stops/pads and bye-bye door if fuselage is pressurized. At 37:00+ of the video clarity is provided, good job gentlemen.
Also Mr. Goglia, I worked US Air Pittsburgh for 1987-2005. Heavy Mtc., Line Mtc., and Inspection/NDT JT-8 overhaul. Currently working in Memphis for my current employer.
This is true but only providing the upper retention bolts are missing as well
Castellated nuts and cotter pine do no goof if the assembly that holds these pins are loose and can vibrate off.
I'm 76 and can remember when management started to believe you can't inspect quality into a product but I'll tell you ignoring problems is MUCH more dangerous. Fire the bean counters and put the money into inspectors that have the authority to shut lines down till a problem is solved.
Right, in my place, a defense contractor, if anyone finds a systemic problem everything stops. Not just the station where the problem was found. It's a real pain sometimes when we are trying to get something done and they find a manufacturing issue with our prototypes. But it's for the best.
You guys have been posting videos back to back. I'm loving it.
Very interesting, but this analysis, it seems to me misses an important point. If the top pins are fully engaged in the channels, then the 12 pressure pads are also engaged and the door cannot escape. The door needs to move up 40mm to disengage the pressure pads. If that happens then the top pins disengage. That means that the top must have swung out first, and the slipstream and leverage are what ripped the lower hinges out. So the only explanation I can see is that all the locking bolts were only vestigially inserted and operational, and vibrated out in the few hours this aircraft was flying/cycling pressure.
I'm an ex-instrument fitter from the military. This door was not a plug design. Its a typical hinge door design that allows maintenance actions to happen. Why is this door any different to an outward opening cargo door? 100% agree these bolts should have been safety wired and should be a critical maintenance operation (needs 3 levels of signatures). When we used to change Cabin Pressure Controllers, we had to do an aircraft pressurizaton run to confirm serviceability. Keep up the great work guys.
Didn’t they have castleated nuts with cotter pins?
Vociferon,
There are multiple bolts in this door latching system. The bolts that pin the latches in the closed position ARE lock-wired(or cotter pinned) but the assembly bolts that hold the mechanism (these are the ones in the alleged United pictures) on the door are not
I had the same consideration.
@@floundericiouswa5694 Are those the bolts that are missing? The pics of the airframe and recovered plug seem to have the fittings attached on the Alaska plane.
They need to pay whatever is necessary to bring back the people of John’s generation, the experienced and retired folk, to mentor the current generation, even if on a part-time or contractor basis. For the want of a nail the shoe was lost. For the want of a shoe the horse was lost.
I just retired last year after 42 years working maintenance with 2 major airlines. I'm not going back! But I would love to if our time on earth was unlimited.
@@Part_121 I don’t blame you. But you are one of the guys I miss. Thank you for your service.
For want of a horse the War was lost
They won't listen thougu
The problem isn't generations, or else Airbus would be experiencing the same issues. The problem is in Boeing.
This YT channel is must-see in my household. Thank you for refreshingly straightforward reports.
As for the Max issue - once it is identified and resolved - and Boeing transparency, I realize that management is highly unlikely to demonstrate its confidence in its re-configured or repaired product by filling a Max with top brass and their families for a flight, but the idea occurs to me nevertheless.
I love listening to really smart men discuss things.
Yeah, they're very interesting.
I grew up watching Greg on Air Crash Investigation and loved seeing him again! Excellent video, I’m definitely a new subscriber to this awesome channel. Cheers guys!
Love Todd! Wish he would talk more on these episodes. He’s so knowledgable and practical. Great voice too.❤
I agree, and I am not a good-looking girl, and I am not light in the loafers.
Thanks for the compliment. I definitely have a lot to say in the shows that are closer to my area of expertise. Also, I'm responsible for many of the graphics and written explanations in the show, which helps to put everything we say into context.
Categorically more informative than any other source. Thank you for your diligence , expertise, and dedication.
My suggestion - Have all airlines using that specific plane create a list of ALL problems reported and fixed by their maintenance staff. Then, using that list, create a consolidated list of those issues and require technicians to go over every one of those planes to certify that that every one of those listed issues ether does not exist or did exist and was corrected.
The manufacturers and airlines do this and have been doing this since for decades.
That's what ADs are suppose to do.
Lookup "FAA Service Difficulty Report" I think that is what you're talking about.
I think the HQ split is a real problem because there's always concerns that you wouldn't want to email (and the Max emails were frankly dire) but you'd bring up at the water cooler.
@@Plutogalaxy kind of sometimes a quiet word can sort things out because Boeing has fired whistle-blowers.
The four bolts are carrying shear loads so torquing is not as important as long as the castle nut is making contact with the fitting and cotter pins installed. The two upper guide pins and two lower hinges remain on the airplane.
As a matter of installation constancy of the installers (GMP), all bolts, nuts etc absolutely should be torqued exactly to engineering specification.
@@icare7151 I agree, one picture on the internet seem to indicate the loose bolts are on the lower fitting in the plug and not the two that keep the plug from traveling up.
@icare
The normal install procedure to install a bolt with castle nut is to torque the assembly to "seat" everything, then back the nut off to allign the castle nut to the hole in the bolt to insert the cotter pin. Meaning their is no longitudinal preload on the bolt. Some free play. But the bolt is only operating is shear load. So this is ok.
If the washer being used is a spring washer, then it might be possible to seat the nut, then further tighten to allign the hole in the nut to bolt then insert cotter pin. But this is rarely done in most castle bolt/nut applications.
Kevin
@@catmando3250 Thank you for the clarification. As this is a spring loaded system that if understand correctly, during maintenance assists in pulling the plug door up and out to a 15° angle to perform maintenance.
If there is play anywhere in the system that allows the door to move up slightly as it is under spring upward tension, might allow the door to deflect slight upward and outward very slight into the jet steam which then rips the door completely out of the plane.
Your thoughts?
The door design relies on the that slide/slot hinge thingy constraining the door.
The castle nut/bolt clamping force is not relevant. But the body of the bolt prevents movement of the main door hinge/slide from movement up or down.
A bolt/ nut can serve two purposes.
A clamping force. To prevent two plates from pulling apart.
Or a shear force. Preventing two plates from sliding past each other.
The bolt is only operating in shear mode.
Kevin
@icare
The normal install procedure to install a bolt with castle nut is to tonque the assembly to "seat" everything, then back the nut off to allign the castle nut to the hole in the bolt to insert the cotter pin. Meaning their is no longitudinal preload on the bolt. Some free play. But the bolt is only operating is shear load. So this is ok.
If the washer being used is a spring washer, then it might be possible to seat the nut, then further tighten to allign the hole in the nut to bolt then insert cotter pin. But this is rarely done in most castle bolt/nut applications.
one thing for sure is the fact that it is not possible to "set" a specific torque on a castle nut/bolt assembly. what do you do if when a specific torque is set and the holes don't line up? your forced to either lossen the assembly to get hole alignment or over torque to get hole alignment.
Kevin
No one is addressing Alaska's role. That aircraft made 22 flights to Hawaii before it was deemed too unsafe to fly over the Pacific. Multiple depress alarms. Not seating anyone next to that plug. What did they know?
Exactly. Why was no one in that seat. Would love to hear from other passengers on this flight when booking and other flights.
Apparently they missed a connection or didn't show up.. pure luck
There are quite a few things that can be inoperative and the plane can still fly. The pressuration system has Automatic 1 Automatic 2 and if those two fail, manual control.
First off, the fact that nobody was sitting in the window seat nearest the plug was just happenstance not something purposeful- there were people sitting in the middle and aisle by the plug who would have absolutely been sucked out if they weren’t wearing their seatbelt. If anyone at Alaska had any suspicion the plug was unsafe, they would have grounded the plane, period. Not seating someone in the window seat but letting someone sit in the middle seat would be completely pointless. And secondly, Alaska maintenance was literally MORE proactive than was required by regulations. This wasn’t negligence on their part. Pressurization issues - ESPECIALLY intermittent and unusual ones - are EXTREMELY difficult to pinpoint and diagnose. That goes doubly so for an issue that has never occurred before in the history of the industry. The maintenance people would have been following the manual which would have pointed them towards the PSEU computer, the outflow valve, and related systems, not the plug. If you hear hoofbeats, you think horses not zebras. They would have checked and found all those were fine and drawn a blank, which would point to the problem being a smaller, non-catastrophic issue and would have concluded the plane safe to fly per the Boeing manual, yet since they didn’t have an answer, they decided to be MORE conservative than required by the FAA and pulled the plane off ETOPS routes while waiting for more information and guidance from Boeing just in case.
This had nothing whatsoever to do with Alaska or their maintenance people - they did an above average job given the circumstances. This is 110% on Boeing.
@@GlutenEruption they never tried to find the leak and should of grounded the plane. That's all on Alaska
Just discovered this channel and hope it grows as it certainly dispenses clear and understandable details that even the most pedestrian "information consumers" (me for example ...😉) can learn from. Thanks for all your hard work and expertise!
Excellent. Three brilliant men. Thank you!
It is my opinion that the plug door was removed in Renton for interior fitting. With regard to the plug door assembly from Wichita, I don't think they will have culpability in this mishap. The feds have announced an intense scrutiny of Boeing today. I didnt see them mention Spirit but that may be forthcoming. I firmly believe that we will begin to see other fallacies coming out of Boeing again. We simply have no idea the true extent of garbage happening in Washington State these days. Quantity over quality, mishaps and loss of life is all we have ever gotten from the post 1997 Boeing Company.
As a quality control expert with decades of quality control testing and forensic failure analysis engineering experience, finding the missing bolts are key.
The missing bolts must be checked and tested to validate if the bots were themselves within engineering specifications.
Meanwhile, they need to get samples of all missing parts from the same lot numbers that were used on this aircraft for the door plug assembly, checking them for engineered design specifications as well.
If a major redesign is needed, though more expensive, just install the actual emergency exit door vs the plug, assuming that doesn’t have a design deficiency as well.
Instead of installing actual emergency exit door in any case, why not have two fuselage types: One for dense seat configuration with emergency exit, another one without the hole and thus no need for the plug?
The answer to "Why not?" is always going to be cost effectiveness. How many great ideas, like yours, have never seen the light of day, because it would mean smaller dividend for the shareholders. Another lesson of the indictment of greed.@@user-yt198
That sounds incredibly optimistic
@@user-yt198 The cost of have two different types of fuselages is cost prohibitive and would likely require recertification.
Also, not having the option of having multiple passenger seat configurations would significantly devalue the aircraft especially in the secondary market.
@@icare7151 Airbus can reposition the emergency exits anywhere on the fuselage from A321 upward. So it is not a cost for them, but only for Boeing?
Why would Boeing care about the second hand value of the aircraft? And how many airlines may purchase a second hand low density 737-9 and turn into a high density configuration?
Liked, shared and subscribed. Very interesting and informative.
The door in the drawing has much more square corners than the real door which is why the stop fitting can be seen from the outside in the NTSB photo. As a former F-18 CDI, Me and a "maintainer" could easily install this in 30 minutes or so, bonding straps and all, just need to know the torque values and have fresh cotter keys. This of course would be a safety of flight item in the Navy, so 2 of us would sign the maintenance action form, and then go get a 3rd QA person to come and inspect our work. All 3 of us would have to sign it off.
That's the beauty of not having to report to shareholders 😂
The jet was climbing, so the horizontal stabilizer would've been lower in the air stream, I also read that the plane encountered turbulence just before the door exited. I'm thinking somebody did not put the bolts with the castlelated nuts keeping the door from raising allowed the door to raise and then leave the plane.
also, I read on another posting that the little boy who is sitting by the door, told his mom that he heard hissing coming from the door when it was climbing .
and that aircraft had repeat write ups for pressurization issues
makes you wonder how many other loose bolts are on that jet that nobody knows about yet.
Things just aren't that simple. When you are at climb power the engines are producing a lot of thrust below the aircraft, that tends to pitch the nose up, so nose down trim is required, and that is achieved by raising the front of the stabilizer. Most nose up trim is required, for a particular load balance, when descending at lowish level and high speed when the engines are at idle and their drag is pulling the nose down. I expect you have a good chance of being right about the bolts being absent though.
@@cageordie I wanted to work for the airlines or be a tech rep with GE for the J85 jet engine, I worked on the J 85 engines for something like 14 years. I got my A&P license back in 1986. After retiring from the Air Force, I went to a couple engine overhaul facilities and saw the way they were working on the engines I decided it's not for me, so I have not been around a jet engine since I retired from the Air Force back in 1999.
too many managers are telling the technicians to hurry up to meet scheduling and they take shortcuts .
The four locked points don't hold the pressurization load, they lock the door in place over the 12 pads that do hold the pressurization loads. If the bolts through the top and bottom guide fittings are in place the door can't move up to clear those pads, even if one lower hinge was completely missing.
Why can't they just wield it shut?
@@Dubinski2382 It is there for other seating configurations and is used during fitting out and maintenance. The way to eliminate this is to never make the opening, to replace it with normal ribs. But that would mean two different fuselages.
One question is, how far can the assist springs in the bottom lift the door up, when thr lock bolts are missing ?
The door plug has 4 bolts that need to be removed in order for the plug to come out. The two larger bolts at the top. And two smaller bolts in the hinged mechanism at the bottom that keeps the springs compressed and does not allow the plug to move up or down until they are removed. Per the AMM chapter 52.
The bolts are supposed to bolt into captive nuts that have an interference thread/fit. (I read elsewhere.) I presume the bolts have a flat washer, not a split washer, due to tightening up onto aluminum. It looks like torque ratings weren't met. Or the lower bolts are too small for application. And the lower washers barely cover the hole.
@@moyadapne968 I think he was talking about different bolts, not the bolts holding the brackets to the airframe.
@@ImperrfectStranger Thanks. On the inside illustration of the plug at 33:07, I do see 1 bolt each side for the lower hinges, and 2 upper guide fittings, one each side. Those fittings have four inner bolts, on each side (the ones I meant). Those top fittings roll into their fixture against spring pressure, and are bolted and split pinned to stop them rolling out. I wasn't aware the whole plug was held on with only 4 bolts, as I can't see them. I do see 12 stop pads.
@@moyadapne968 yes, all correct. What most people don't realise is how the stop pads operate. There are much clearer descriptions here: th-cam.com/video/kKSNdqtG3dY/w-d-xo.html
@@ImperrfectStranger OK, I read that. I see now, ta. So stop pads are not simply 'stop pads'. With all that going on, how did that door still manage to depart ! If only we could see the offending plug photos from the inside. It seems the photos taken in the back yard are only of the outside. Or is there a photo around..
The process of installing this door-plug might happen like this:
1. The plug is closed shut.This is probably done by just pushing it down and make the rollers go into the roller guide.
2. Preferably the same workers who shuts the plug then secure it with 4 bolts . Or it’s a new crew who has this responsibility.
3. The door plug assembly is inspected, with emphasis on those four bolts, and approved by a quality-inspector.
4. The inner panels are mounted, maybe by a new team, and then the whole thing is largely forgotten about, at least til the next larger inspection of the aircraft.
But the points 2 and 3 where obviously never done. If this refects the working culture and the general process of assembling the aircraft- of course there could be other hidden flaws.
The only thing negating this, might be that the bolting af the door-plug is not a typical production process, since it’s meant to block the door from moving, though it’s originally built to do exactly that. A sort of backwards engineering.
I wonder if the empty seats next to this panel were coincidental or the result of some observations by the crew/passengers on previous legs?
The door leaving the aircraft, reminds me of the issues that McDonnell Douglas had with the rear cargo door locking mechanism design in early DC-10-10.
Yes me too! When someone said the window blew out, I thought.. of alllll the Mayday videos I’ve seen, I never saw that, but did remember a few doors blowing out.. and then, sure enough, this was a door.
Seems to me from the schematic image that what keeps the door out of the slipstream is the 12 stop fittings against the 12 stop pads. If the guide fitting and guide roller are installed and bolted properly there is no way you could move the stop fittings off the stop pads. In that case it would seem to me you could even remove all 8 of the “loose” hinge fitting bolts on the fore and aft of the door and the door still wouldn’t raise, go off the stop pads and out into the slip stream. What am I missing here?
Exactly... as long as the Locking bolts are in place it does not matter whether the hinges are installed or not... the door still cannot lift off of the stops.
Agreed. I don't think you're missing anything here. So many people are criticizing the design (without actually understanding it), but the design appears to be robust IF it is assembled correctly. Same as with any other component of any aircraft. Pretty sure the final analysis will point to incorrect assembly.
Nothing. That is the only explanation I can see, which makes the bottom hinge analysis here wrong
@@RicktheRecorder I totally agree.... the hinge bolts being loose as long as the upper bolts are installed has no relevance.... they're just a separate matter altogether.
@bambazam3983 I believe you are absolutely correct that incorrect assembly is going to be the fault here. This is an old and proven design. all cargo aircraft such as FedEx UPS DHL all have these plugs installed in their aircraft and always have this is a one-off incident which they may find additional aircraft with faulty installations. Which I believe will lead to one or two employees not doing their job correctly in the manufacturing process and also not being caught by the QA process.
48:24 note the difference in door corners, compared to the diagram. At one point Todd identifies some hardware as being at a LOWER corner of door due it being rounded, as opposed to square like shown in the diagram. Are there different versions of doors? Or is the drawing not correct?
I'm not sure if that drawing, which was provided by Boeing soon after the incident, was specific to the Alaska Airlines installation. We will review the full NTSB report when it comes out and likely have a future episode that will address your issue.
I have a deep appreciation for John’s comments in regards to the Educational training for those that have an MBA degree.
It’s been my experience working with 2 corporations with global reach, have never been held accountable for their bean counting decisions destroying one company and crippling another.
Airflow over the outside surface of the door lowers the pressure even more than the ambient air pressure differential.
So you are saying the slipstream produces suction, on a fuselage surface? Maybe, but the air moving at 300 MPH is plenty of force to rip the plug off the airplane once the edge was lifted a bit.
that's what Bernoulli states. and can be demonstrated most easily by holding a piece of paper by the edges. and blowing on the upper surface. it will levitate the paper due to decrease in air pressure. also, the airplane was pressurized before the incident, at least partially. @@HaroldBrice
It’s not about the door, bolts, cotter pins etc. It’s about the lack of inspections and quality control. FOCUS, PEOPLE!
The three people in this video are not discussing the construction of the door. They ARE discussing the ineptitude of Boeing, and the carelessness of Boeing, and the cavalier attitude of Boeing toward safety.
FOCUS, PEOPLE. Listen to what these men are saying.
the pic @ 42:12 looks like the hinge bolts that appear loose do not have enough torque surface area. almost like the lock washer fit inside the cutout that it was engineered to hold torque against. if this is true a larger flat washer should be incorporated under the lock washer.
love watching your videos! great photos of the incident/door. scary stuff. hope you guys continue to contribute input. aviation safety needs you.
What load is required to overcome the pressurisation compressive load on the stops at 12 locations? Would stops not act as a failsafe if designed correctly!
Do you think it is OK to the cockpit to explosive open like it did?
Excellent show. I recommend that you avoid using the initials SMS and State the full name of the procedure for those of us who are not experts
Relying on torque only and not using castellated nuts and cotter pins on the whole plug unit? Have bean counters struck again?
Why didn`t the NTSB show a photograph of the other side of the plug?
What other bolts may be loose or missing? Did anyone check to see if the wings are secure?
A friend of mine rented a room to a kid who was working as a air and power plane mechanic at the airport here ,and ,going to school. This was about 30 yrs. ago. He had stories of planes that would come in with in his words “major issues” including one that actually had duct tape on the windshield! He talked about oil leaks he thought were bad enough to not fly the plane that the pilots would override and fly it anyway! The duct tape story though! That had to be seen before the plane took flight! Not sure why it was there but it sounded like an accident waiting to happen and I never felt he was making that story up! Why would he? I mean we were just visiting friends having normal convos watching a ball game whatever! It wasnt some party where everyone was drinking etc. Everyone there was a responsible adult albeit mostly college age! My friend had already gone thru pharmacy school etc. Just a crazy story I have and will always remember!
Following the swiss cheese theory, this time the holes didn't line up, but only by the skin of our teeth. It's amazing that this wasn't much, much worse.
Not sure you guys understand how the door works .. the door had to have slid up 1 inch for all the wedge lugs to let the door free … means your assessment of bottom going out in the slipstream is impossible .. the entire door must move up for all the lugs to clear then the door both bottom middle and top are released at the same time and it moves outward … There is only one possible fault that allows this and that’s the two cross bolts falling out or missing … I knew what happened the moment I heard about the accident .. Let me state this again .. the door must move strait up an inch to clear all the lugs top , middle and bottom at the same time to release this door … I’m shocked you guys don’t know this
Great point. If it doesn't move up first, it can't move out. Would it not actually be four cross bolts? Two upper + two lower?
Truly excellent discussion and analysis of probable cause of incident.
The hinges don't do anything to support the pressure load - the load is all supported by the 6 stops and pins along each side of the door. As long as the upper guide/pin combination are engaged to keep the pins and stops aligned, the pressure inside the fuselage will force the plug against the stops. It can only leave the aircraft if it lifts up ~1.5" first and clears the stops. This is what NTSB described - the door lifted, cleared the stops, and then the guides were fractured because they're longer than the stops are high. The door was found well north of the flight path.
At 39:12, John seems to be saying that the loose screws at the bottom, (not) attaching the hinge guide assembly to the door, alone could cause the door/plug to separate. Wouldn't the door/plug still have to move up to clear the stop fittings before it can open enough for the slipstream to rip the door/plug off ? For the door/plug to move up, it seems that the upper locking bolts have to be missing as well, no matter what problems may exist at the bottom.
Second, in the picture at 40:00, it looks as if the surface the lower screw attaches to was angled (by design). If this is the case, the washer would be titled when the screw is tightened. I'm not a mechanical engineer, but that looks undesirable as well.
From the UAL photo, it seems that even if the castellated nuts are in place, if you lose those other bolts ( that secure the bracket ), the door will fall out.
The door still has to move up sufficiently (4 bolts stop this) to clear the 12 stop fittings (which bear the pressurisation loads)
Im just glad diversity is our strength and has nothing to do with all the recent problems in the industry.
49:39 flew 154 hours. A time delay theory...
It's hard to see how it would have got through previous flights with all 4 locking bolts missing without catastrophic failure, especially as it would have gone to over 30,000 ft on those flights.
Some are saying the friction of the rubber door seals was enough to prevent it lifting for some time.
I'm wondering if just the rear hinge vertical movement arrestor bolt was fitted. For many flights this was enough to hold the door down until...
Each of the 2 hinge guide fittings is attached to the door by 4 screws. A photograph from the United airlines inspections showed an example where 2 of these 4 bracket attachment screws were found to be undone sufficiently that you can see a gap between the screw heads and their washers. Not only are those screws loose but the holes in the bracket look like they are slotted. The slots would be to allow for adjustment of the vertical position of the door when the 2 locking bolts are fitted through the hinge tubes such that the 12 door lugs are perfectly aligned with the 12 frame lugs when the locking bolts are in place.
The slots would allow adjustment as follows: With the door plug closed & all 4 locking bolts fitted, all 8 bracket screws (4 on each bracket) would be loosened while the door is moved up/down until the 12 door lugs are perfectly aligned with the 12 frame lugs. The 8 bracket screws would then be tightened to the specified torque, to fix the position of the 2 brackets on their slotted holes. (I'm surprised there's no locking wire on the screw heads but just perhaps there's something at the other end).
These 8 bracket mounting screws would only be adjusted once, when a particular door plug is first fitted to a particular door frame. Any other time the door plug is removed & refitted, nobody is looking at these screws. So although the 4 lock down bolts were no doubt in place during that "one time" adjustment of the hinge bracket height, they weren't fitted the last time the door plug was opened/closed.
Also, either someone is leaving the bracket height (lug alignment) adjustment process incomplete, or the specified torque (& possibly locking process if there is one) is inadequate.
The distant photo from outside the Alaska aircraft, showed the hinge tubes apparently undamaged, however it appears to me there is something attached to the rear (right hand in the photo) hinge tube. This could be the remains of the hinge guide fitting after the it has torn through the bottom of the door. (Or it could just be some random irrelevant debris or just a shadow).
If the rear hinge vertical movement arrestor bolt was the only one of the 4 locking bolts to be fitted. (May not have been tightened & had it's castle nut & split pin fitted - that's possibly not too relevant). That would probably be sufficient to prevent the door lifting enough for the 12 door lugs to be sufficiently out of alignment with the 12 frame lugs, so the door is OK for several flights.
If most or all of the 4 bracket mount screws are (or become) loose at the rear hinge, then the assist spring on the other hinge (that doesn't have a locking bolt fitted) can lift the door further, as the 4 loose bracket retaining screws are now able to rise up to the top of their slotted holes (in the bracket).
Once that movement has taken place, the door is not only restrained from moving up by only one of the 4 locking bolts (which was a pretty marginal situation already) but now the door height position adjustment has slipped to the highest extreme of its adjustment slots for that one locking bolt that is fitted.
If that movement of the bracket wasn't enough for the door to let go on the next flight, further flights will further loosen the bracket screws, producing even more play.
The rear hinge lift spring is disabled, so long as it's locking bolt remainins in place. The front hinge's lift assist spring is free to lift the door as far as it can. Initially for a few flights that might not be close to a critical amount but as the 4 bracket securing screws become loose enough, the door can rise an extra amount as the bracket retaining screws slip to the top of the adjustment slots in the slotted bracket adjustment holes. If that doesn't allow the door to move high enough (raised by the lift assist spring in the front hinge that doesn't have a locking bolt fitted), then a few more flight cycles loosening the 4 rear hinge bracket screws will eventually allow the door to raise high enough (even if the front hinge locking bolt is fitted) for the 12 doorframe/door lugs to be sufficiently misaligned at takeoff for the door to blow out at altitude.
(Incidentally the door blowing out in this way will damage the bottom ends of the roller guides).
To clarify what the bracket is: The lower locking bolt passes through the (black) hinge tube. It also pass through a (green) hinge guide fitting. This locks the hinge guide fitting in position on the hinge tube, so that it cannot rise up the upper portion of the (black) hinge tube, as it normally would when the door plug is being opened. Part of the hinge guide fitting extends sideways and ends with an approximately square plate which has a vertically slotted hole in each corner. This is what I'm referring to as the bracket and the screws that go through the slotted holes into a vertical web that is a structural part of the door, I am referring to as the bracket screws. These are the screws where United found 2 of the 4 screws so loose you can see the gap behind the screw heads. There is a separate hinge guide fitting/bracket for each of the 2 hinge tubes.
Finally! I have it in my mind that NTSB said they were still looking for a spring (not for 2 springs). Just a thought, is one still on the rear hinge tube? Can anyone verify what they said? They appear to take their videos off TH-cam.
There seems to be some confusion with the bolts you discuss and the bolts United claim were loose on inspection. The loose bolts are those that hold the hinge mechanism, seems these do not have nuts involved, and the longer bolts with castellated nuts and cotter pins.
John, gentleman, please DO NOT refer to this panel as a door. It is a PLUG used to fill an opening in the fuselage which an optional door assembly may be installed on planes with other seating configurations. The flight aircraft here did not have a door installed in this location. Referencing it as a PLUG DOOR rather than a DOOR PLUG confuses the public in this conversation. They are clearly two very different components that serve two very different functions. One intended to access the interior for assembly and maintenance, the other intended for evacuation in the event of an emergency.
The DOOR option is required in this location for egress capacity when seat configuration exceeds a specific potential passenger count.
Also I'm certain that the stop bolts that keep the door from traveling up on the hinge assembly and also moving the Upper Door Plug Guide up & off the frame mounted pin which engage when the Door Plug is being closed and secured after inspection ARE REQUIRED in all 4 locations.
The Plug, when the all 4 Stop Bolts are removed or fall out as may be the case here would allow the Door Plug to lift up on the hinge still flush with the Fuselage then off the Guide Pin and allowing 15 degrees of opening at the top edge of the Plug from the Frame & Fuselage. In the slip stream the straps that hold the PLUG DOOR at that 15 degree position would not hold the force of decompression and the Plug would have departed the plane in a very violent manner.
In a video, I saw the door warning lights were INOP. Do you think that maybe if they were operative, that pressurization faults may have led to that plug door being checked by pressurizing the aircraft.?
As a retired. aviation technician(structures) Im glad You Tube has. led me to your channel I. look forward to following in the. future!!!! FtThank you for your thorough explanation of this plug door issue!! Unfortunately the cultutre of our sciety is that nobody is held accountable ffor their actions i.e. (lack offquality aasurance) which has no. place in aviation in my upinion. And. for the head pf Boeing to call it a '''wuality escape' which is a lame statement in and uf itself dors nott instill confifeence that anything will change at Boeing.Thsnk. you for this. channel!!!!
The pictures ou showed for this video show that the loose bolts have nothing to do with the castellated nuts but are on the right side of the plug attaching the hinge to the frame. These bolts clearly have no cotter pins. It is not clear whether these bolts have even been mentioned by the NTSB in their briefings. I think there is clearly a poor understanding of exactly how this plug was designed and thus a poor understanding of how it should be inspected and maintained.
Agree. The best description of how this works is by the 737 guy in the UK. The loose bolts mentioned here hold the bracket that holds the hinge pivot mechanism which is bolted to the sill structure. If this side bracket came loose the door would not start to go out into the slipstream. The door would not move vertically either up or down if the top guide fitting castellated bolt and nut were in place.
I'm going to start with I agree with you on the point that there is a poor understanding of how this plug works. The hinges are a minor part of the retention mechanics. In order for this plug to depart the airframe the door must move upward to dissingage from the 12 retention stops. If the bottom of the door had popped out as the gentleman had speculated the lower retention stop would have been damaged, which does not seem to be the case as the NTSB stated the plug did translate up in order to depart the aircraft leading one to believe that the 4 locking bolts where either sheered somehow or non existent.
Why did the cabin door blow open? Wouldn't the emergency panels blow have blown out first? I don't understand why it would affect the entire door. Gald I found your channel!!
1. At about 3:24 the speaker refers to the image as an emergency exit door. It is labelled "mid cabin exit door plug," not 'emergency exit door'.
2. Regarding the safety of travel: The statistics still favor airlines, as you implied. But it is disturbing to see the quality deficiencies at Boeing persist for so long, with new issues appearing almost annually. What else are they failing to do that will result in a future incident caused by a different design/construction/maintenance item?
so at around 5:45 / 5:50 we have tons of cabin pressure on the door and then when it gets loose about 7:00 and it gets out into the slipstream it has only a ton of force (not pressure I suggest, rather force)???
Loose bolts in this application does not matter. Look at the pictures! When a castle-nut is securing it's bolt, that castle-nut is "LOCKED" into place with it's "Cotter Pin." My humble opinion is the 4 bolts were never installed.
If the bolts were missing from day 1 would the door have taken two or three months to finally "pop" free? If the bolts were in place, but the Cotter pins were not install, would that delay the fast exit of the door plug for a few month?
Poor quality of management leads to poor quality of product. I used to live down the street from the plant in Renton and walked by it every day. It’s actually a fairly small facility. I’ve always wondered how did they get so many planes out of such a small place?
Another thought. What keeps the doors from moving sideways enough for the stop tabs to slide off the stop pads on the side? Doesn't look from the schematic like they have to go that far to slip off. As has been pointed out this is not a plug door bigger than the opening that will seal with pressure on the periphery. It uses the tabs. The door is smaller than the opening a bit and it would seem to me that you could have sideways motion. I would say that the hinge guide fitting on the door normally is the is the mechanism that stops any sideways motion. However, as we are seeing these loose bolts holding the hinge guide fitting to the door perhaps there is now some freedom to move sideways? Move sideways a little and the tabs pop off on one side and then that side is open to the slipstream? And from there the slipstream forces tear off the door? What am I missing here?
the upper two plug attachments and the two lower hinges prevent lateral movement
I think pictures should be taken a part of the final inspection process. Just like police cam documentation so there is no question of what happened. Then there would be no question if something was installed or not. Just the thought of it could prevent pencil whipping through an inspection where someone thinks is not important.
Easily done, with Vuzix like glasses. Camera on the frame and small HUD on the lens to help you frame your picture with AI, after that you can train a neural network so if something is a little bit out of normal you have a caution, and if a recognized bad installation is detected, a warning. It would work on along the human, not replacing their current checks
wow great episode - so much explained clearly
That guy is exactly like perfect "engineer" from Central Casting 😂
You gentlemen are truly brilliant 👍👍👍👍👍👍👍👍👍👍👍👍👍
The picture with loose bolts was not the bolt with the castle nut and cotter pine. It was the bolts holding the hinge to the frame of the plane. Not the hinge to the door.
A bad torque wrench or a person that didn't know how set the torque wrench.
Why not have inspectors photograph each assembly for documentation and responsibility?
Is a door or plug, or nothing, already installed when the fuselage arrives at Boeing from Wichita ??? If a plug, is it rigged AND locked in place with the 4 bolts??
Has Airbus had the same history of manufacturing / inspection defects like Boeing? Seems like the 737 hard-over rudder issue to the Max to now this.. I don’t recall hearing similar problems from Airbus. Thoughts?
Will the door plug flex? Do i see a crack near tbe window in the recovery photo? Think of the failure mode tnat would present!
"We don't speculate"... except for when we're speculating.
Greg you still look as young as you did on air crash investigation over 20 years ago! Keep up the great work gentlemen 👍 between you 3 there isn't anyone more qualified on the internet to talk about aviation.
Aviation is a big subject. When we get in trouble we always "aviate, navigate, and then communicate" so just talking about poor management plans and some missing bolts may not be the top in aviation.
No, no, fail information. It's not a DOOR. It's a PLUG/PANEL in a door frame. A panel equipped with a window. This panel/plug is not a emergency exit door on this configuration of the MAX 9 airplane. It is a replacement for a possible emergency exit door on other configurations of the MAX 9. Please stop giving wrong information.
My guess is that the plug door was left open to allow easy access for cabin trim and seat fit. Mechanic doing the close up may not have been familiar with the locking process.
Door is held upwards in upper latch cams by springs at lower hinge. As aircraft passed through turbulence at 14000ft the door would bounce on the springs allowing the stop pad and pins to misalign. The door would be held by the upper latches but lower double hinge arrangement would allow the bottom of the door to blow out with pressurisation loads. Lower hinge quickly fractures followed by upper latches as door swings upwards.
A bad design in my opinion as no fail safe in place to allow for a simple engineering error.
This is a prime example of what happens when Account’s are put in charge of the organization. Their job is to count Penney’s, they typically have no clue of what happens in the field. Mistakes happen, that’s why we have to have independent inspectors going over the work. A CEO having a meeting accomplishes nothing. It’s the people on the floor who are in control.
I have a problem with that to! Self inspection is BS they started that when I retired!!
I agree that Boeing should fire the MBA’s and focus more on quality control-I worked for a corporation that let the MBA’s take over-with this said- focus shifted from the customer to profit-in Boeing’s case- cutting corners in aircraft manufacturing is a terrible mistake- like firing the former CEO and giving him a golden parachute-160 million dollars-sounds like BS to me-mahogany row always covers each others ass.
I have managed several small business and have always maintained that the people at the bottom make things work.T he people at the top, who think they run things, are just there to keep score.
"Accounts" does not have an apostrophe in it!!" "Penney's is James Cash Penney's business, pennies is the plural of penny" It is clear you do not possess the attention to detail required to work on airplanes.
@ 48:38 keep in mind, this particular craft, reportedly had pressurization instability issues prior to this incident.
Seeing Todd in the intro suggests that he is a gamer. Are you a gamer, Todd? If so, what's your poison?
OK, here is my Door Plug design. The key is knowing if all the screws or bolts holding the door on are attached. Remember those Christmas tree lights where when one is removed they all go out? Keep that thought. Imagine each panel screw hole contains two discs that are separated until a screw is tightened and the two discs make electrical contact. Think of the two discs as washers that are separated and built into the door with an electrical wire attached to both discs and wired like Christmas tree lights. If one set of discs aren't touching each other, that means a screw is either loose or missing and in turn sets off an alarm. This is my KISS solution of Keeping It Simple Stupid.
Or perhaps just build a fuelselage for a billion dollar plane without extra holes?
All of the information obtained about this airframe is Alaskan Airlines accepted it back in October 2023. So, how many flights have this airframe had before this incident? Not one person has addressed this issue. If, this airframe had had previous flights, why no issues with this "Plug Door"?
Excellent podcast. I subscribed right away.
at 5:50 several tons of pressure ? Do you guys all reside in the same care facility ?
6:35 So you're saying that the dynamic pressure of, say, 350 knots at 16,000 feet altitude on the edge of the door is more than the pressurisation forces on the full interior surface of the door? Not sure about the NG, but our 747-400s already have 5 or 6 psi differential pressure on the door at 16,000 feet. Dynamic pressure at 16,000' at 350 kts is 1.75psi according to online calculators. Maybe you could check my numbers.
Thank you John G for pointing out that these issues didn't start unit MD took over.
Hope Boeing listens more to their engineers and customers and less to their share holders. Great video very analytic and critical but fair.
The shareholders should not be in disagreement with the safety engineers. Crashes are bad for investors.
You guys are great . Also like the Mayday series !
Could the design be made more redundant? Could the design to the door be updated to make the door attachment be more robust? Will just an inspection satisfy the flying public?
First off it was a very good ex ation of what could’ve possibly happened. The one question I have is that the photograph that was shown that showed the bolt that secures the door in its track that appeared to be loose. I also noticed that the washer on that bolt seemed like the diameter was too small For the size of the slot or the hole that it is going to secure i.e. when you tighten that nut it didn’t look like the washer in front of it was big enough to properly cover that hole that that bolt is in. I’m just curious about this I was always under the understanding that a washer is a very important piece of a bolt and nut when it’s securing a device to something , and from the picture that I saw that washer looks too small that when you tighten that nut down to its specifications that that washer is barely going to cover the slot or the hole it almost look like a slot to me. Just curious thanks for your show. Have a good day .
I saw in one discussion that Boeing ship out the fuselage with the plug installed, but then it is removed again for the interior trim fit at a different location, (by a different company?). Could this mean the issue is not a Boeing QC issue, but a logistics / maintenance issue?
Sorry I can't be more specific. (I'm just an interested member of the public who enjoys flying and used to work for BAES in the UK; I'm not a journalist or interested party in any other way, so am not taking notes).
Would appreciate your insight in this matter.
Thanks.
Everyone knows that you’re always on your toes when the boss CEO could drop in at anytime. Yet that can’t occur if the CEO is 2500 miles away.
I thought, wrongly, (?) cabin pressure kept the door in place against the seal.??.....can someone clarify please?
Cabin pressure keeps the door in place against the stops, of which there are six on each side. The stops hold the door against the seal.
Perhaps this might force Boeing to install a Emergency Door, and remove the Plug Door. This would allow easy inspection without the 8 hour inspection to remove the interior panels. This is a result of not having a true Plug Door that is held in place by the exterior fuselage under pressurization.
You clearly dont have an understanding of what a plug door is. Have you ever been on an aircraft where the doors open in? Every commercial aircraft that I'm aware of all doors open outward.. a true plug door as you put it could only open inward.
Those 4 bolts that hold hinge to airframe are most likely threaded into nutplates riveted to frame should have torque paint on them & they don't appear to have any. The paint will Crack or become misaligned if bolts loosen after torqued, clearly those bolts are loose in that pic you can see space between bolt head & washer, the castle nut/bolt/cotter pin assy most likely not loose it looks like the problem was with the 4 bolts in each lower hinge mount. The RII inspector should have questioned that fact & had the worker put a torque wrench on them in front of them to prove they were installed properly then torque paint put on in front of them. Clearly looks like human error & not an engineering/ design problem.
As a now retired quality auditor, I noticed over the past 10-15 years that safety programs and policies are only documented in procedures to enable a company to comply with government and international standards legislations (cover your a**). Management and executive Boards believe it is the responsibility of the factory floor to meet these standard while all the time reducing resources and staff training. I have no hope for the corporate world - nothing changes, it's all $$$$. Love watching you guys!
Now that I understand how the "Stop Pads" are meant to work, if the upper bolts were correctly fitted to the guides even if the lower hinges were not fastened the door still could not move up and therefore would remain secured by the " Stop Pads" and could not move out.
Correct
Great video thanks for sharing the information.
If it's Boeing, I ain't going. Subscribed.