Really good MentourPilot video on the October “jumpseat pilot on shrooms pulls fire handles” incident. (As always, ignore the clickbait “title”.)
Among other things, it’s a serious essay on mental health stigmas. All in half and hour — and must have been created quickly, but it sure doesn’t feel like it! Also interesting for its use of comic-strip imagery (okay, that did help them develop it relatively fast — but it’s actually quite effective).
There’s no concern for the gapping around the door/plug, at least not in a general sense. It’s the structural gapping all doors have, there’s almost certainly a flexible weather seal all around it.
From a design perspective, it appears that Boeing did what I’d have done; designed and certified a fully functional door, then modify the door structure to make a “plug”. Externally this would mean removing the external handle and markings, internally the goal would have been to prevent access and use of an interior handle and cover it up with aesthetic sidewall.
Based on the photo it looks like this was done by removing the interior handle, which is reasonable and a weight saving advantage. I’m unsure (because I don’t know the Door design and actuation) whether additional actuation parts have been removed but it looks like they may have been. It would make a certain level of design sense to “decouple” the physical door from the mechanisms to move the locks and latches into place, so that the mechanisms are now a manufacturing jig and are no longer installed on the plane. Then, since the latches and locks are already certified for a functional closed door, it would make sense to say this is the same as it’s permanently closed. Any typical visual markings to verify the door has been closed or cockpit annunciation are ikely also removed (weight savings and no need to have a cockpit light warning the door is open, as it no longer can open). So, in many ways, the Plug is still a Door and relies on that certification but is not, itself, analyzed as a Door.
To be clear, this is all speculation on my part, I’m not making any claims of what actually happened or how we got to this point, I just see a possible design and certification decision process and therefore possible errors.
I can imagine a scenario- again, speculatively - that removing the actuation parts could have inadvertently diminished the function of the latches and locks. Perhaps reduced the strength of a backstop, thereby allowing the latches and locks to gradually vibrate over time and move out of position until they can no longer resist the loads and the Plug departed from the airframe.
It’s very possible that this scenario was obscure, or the failure mode was identified but not at an appropriate criticality, or other analytical errors or unfortunate omissions were done either due to lack of experience, lack of recognition of aircraft level safety effects (looking beyond the specific part changes), management and company pressure, etc. This field of engineering is incredibly difficult and under a lot of scrutiny (especially since the last Max groundings) as these types of dormant failures take real skill to identify and mitigate.
I’m really looking forward to the facts and investigation publications from the NTSB and the subsequent fallout in terms of regulatory actions for certification processes.
The tabs sticking out in the pictures have nothing to do with the hatch being held in place. They are used with threaded adjusters on the hatch to adjust the hatch to flush with the exterior skin panels. The hatches are held in place with 2 heavy duty hinge points at the bottom and 4 dogs, 2 on each side. On planes like this one, the dogs are permanently bolted in place. On planes where this hatch is used as an emergency exit, the 4 dogs are controlled by a handle on the aft side of the hatch. Pulling the handle releases the hatch which will fall open and activate an inflatable escape slide. These hatches are also locked along with the 4 overwing hatches. 3 things have to happen to lock these hatches, breakers closed, engine handles in the run position and landing gear lever in the up position. Did the functional test on the hatches at least a few thousand times in my years at Boeing.
Nice picture. Good find.
There are 6 bolted mounts on each side. The plug frame overlapping them on the inside. In pictures of the missing plug you can see three on one side and two on the other. No deformation of them. How the hell can that frame go outward and not bend or break them? Did the unit shift up or down, shearing 12 bolts, now being unaligned with the mounts, getting sucked out? Only some scrapes on paint of the mounts is visible.
The hatch use on this airplane is designed without any of the above features. It is strictly a plug. If a customer did want to convert this to an opening hatch, it would require the removal of the plug and a function hatch to be installed. Before I retired, Ryanair was the only airline that used this as an emergency hatch. If you look at the picture here, the hatch on this plane is much different than those used on other 737-9 airplanes. The biggest difference from the outside is the full size window and no exterior handle provisions. The Ryanair plane has orange tape on the doors, hatches and other access points, this is what they look like when place in storage.
Thanks. Can’t get any better information than from someone who did functional testing on the door.
In the picture in post 5041 I’m not seeing 2 sets of dogs. I might be looking in the wrong place. There’s something on the upper right side between the 2 threaded adjusters that might be one of them.
Also, are these door and frame combination pretty standard between plane types or specific to the 737-Max 9?
Outside photo of the failure here:
I also don’t understand how the door could have made it past the tabs without seriously damaging them. They’re fairly beefy on their own. The only thing I can imagine is that there was a structural failure of the door itself, so that it folded out, with the crease being a centered vertical line. That could, I suppose, shear off the adjustment bolts in a way that would leave them otherwise intact.
I think it lifts up and over the tabs in normal operation so the failure only has to allow that to happen, it doesn’t need to be a structural failure.
Ahh, ok. Perhaps I misunderstood racer72’s comment about threaded adjusters. Maybe there’s a ball joint or the like for the door and frame tabs to mate? That could be threaded for adjustment as well. Can’t quite tell from the photos.
MentourPilot puts out some good videos.
It’s a difficult situation for aviation by it’s nature. Mental issues are different from other medical problems in that they can’t be physically certified as functionally restored in the way a broken bone can. Success is based on the opinion of a doctor and there’s no way to substantiate it.
I’m not sure “stigma” applies here. The nature of the job is one that affects the safety of a large number of people so there needs to be a protocol in place with a high degree of certainty.
. I wish there were some high resolution pictures of the door frame because i can’t see where the door latches into it. in order for it to draw up against the adjustment stops. I would expect some kind of cam-lock set up
.I’m wondering if the door and frame is unique to the Max-9 or if it is used in other models. It’s a surprisingly early failure
No cite, but I believe it is common with earlier B737-900 models (ie non-MAX).
Some good (somewhat dry) technical info here: https://www.youtube.com/watch?v=maLBGFYl9_o&ab_channel=TheBoeing737TechnicalChannel
Interesting. The door is designed to slide up slightly, and then hinge outward (hinges at the bottom). There are springs at the bottom to help the door lift up and over the tabs (called stop fittings on the door, and stop pads on the frame). Some straps keep it from opening all the way, but obviously those would be totally inadequate to prevent the door from separating in flight once it popped open.
Given the lack of damage everywhere else, it almost has to be that the locking bolts either failed or weren’t installed at all. Then, the springs could have served to push the door up and past the tabs. Maybe helped with a bump from some turbulence or the like.
The door shouldn’t see significant up and down forces in normal flight–I’d think even a single bolt would serve to keep it in place. Could be they all failed the same way, they weren’t installed, or maybe they wiggled free one at a time due to improper installation.
Thanks for the link Richard Pearce. That explains the door and door frame in great detail. The adjustment tabs I misidentified were set as I described. The door tabs are on the inside and the frame tabs are on the outside so the door has to move in high to clear them and then slide down so they can mate up. The upper guide post in the door frame rides up into a channel in the door as it move down into position. The bottom latches are spring loaded to assist in the operation of inserting the door and sliding it down.
The 4 attaching points are bolted in position to prevent movement and the nuts for these are pinned into place.
If there is no structural failure the door has to move up before it can move out. One of the ways this could happen is if the 4 attaching points aren’t pinned in place. The other way would be for the upper post to pull straight out of the guide . For this to happen the door would have to buckle or the the frame flexed enough for it to pop out. If that happened the door would be torn out in the slip stream and there would be evidence of the bottom hinges ripped sideways.
If the 4 connecting points weren’t pinned into place then eventually the door would have worked its way out cleanly. Since the plane had pressurization issues that may have been what happened. The spring loaded door slowly slid up from vibration and was released relatively cleanly.
This is a wag on my part but they should have a good idea under what conditions the door departed.
And I see Dr Strangelove beat me to the same observations…
True. Surprised they don’t try and make it more flush.
The dogs are part of the hatch. Haven’t seen any pictures of that yet, if they can find it. That hatch is a 737-9 item only.
A woman on another website said her husband was on that flight, 2 rows ahead of the blowout! After things settled down a bit, he texted her a panicked “I love you” and then things got calmer as they got closer to the ground. The story about a boy having the shirt sucked right off his body? True.
The missing window, etc. was just located within the past couple hours.
What about the B737-900ER? Or is that a different plug?
Some more info has come out about the Alaska Airlines 737 Max 9 that lost part of its fuselage in flight. It seems Alaska had barred the specific plane in question from flying long routes over water because of pressurization warnings on recent flights. But they didn’t share that info with passengers, of course. I predict some “hi-jinks” will likely ensue.
The Alaska Airlines plane that lost a piece of its fuselage in midair on Friday was not being used in long flights over water because a pressurization warning light had gone off during three recent flights, the National Transportation Safety Board said on Sunday.
Jennifer Homendy, the board’s chairwoman, said it was too soon to say whether the issue had played a role in the Friday incident, which led to the grounding of 171 Boeing 737 Max 9 planes in the United States. “It is certainly a concern and it’s one that we want to dig into,” Ms. Homendy said at a news conference in Portland, Ore.
From the link below which I hope is a gift link.
And just for yuks I’ll let y’all in on a fun fact: I’ve got a ticket to fly on a 737 Max 9 jet in 8 days. On Alaska Airlines.