Very interesting video. The maintenance manual says door/panel opens down when it opens up. Manual says it’s a plug which is debatable. Flight deck door opened at time of event, opening not specified in manual.
What a mess.
Earl
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I’ve never cared much about the type of aircraft when booking a flight but it might be wise to start checking.
Pressurization alarms are fairly common: No plane has ZERO leaks, it’s just a question of what threshold of replacement-air requirement will set that trouble warning condition, and pilots tell me that except for finding huge and dangerous openings they assume the trigger threshold is just set a little too low for whatever poor condition that particular leaky ol’ jet is in. Not unusual for things to seal up when they get a little higher (more pressure differential), warmer, colder, etc. too. The FAA’s reg re:overland only when one of these trouble alerts comes & goes is good practice given the incredible rarity of reportable events, let alone catastrophic ones like this, imho and so said my pilot friends… until this… 
This, yes! NO question a ‘plug’ of any sort should be larger on the high-pressure side. And maybe welded. C’mon, at least spring for some loc-tite, people…!!!
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Yes, plugging what’s an additional emergency exit in some configurations lets them add a row of seats by it and save a few pounds. Fine if done properly, not so fine the way they did it.
Even the money guys are dumping on Boeing management:
As an employee of Honeywell Aerospace I worked with both McDonnell and Boeing in the early 70’s through the early 80’s and his characterization of the two company cultures (as is Peter Robison’s) is bang on.
Earl
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A prime example of regulatory and political capture. It will continue until CEO’s go to jail which means it will continue forever.
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Here’s what the “plug” looks like in place. (Scraped off FB):
I’d love to learn the design rationale for that thing.
Cheers,
Earl
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It looks like it’s intended to be made functional with a minimum of fuss.
Here’s a Seattle Times diagram that claims to show where the missing bolts were supposed to go:
Edit: It looks like that one out of the four bolts would have been enough to secure the “plug.” It appears the most likely cause was that the nuts/bolts were not put in at all. NTSB should be able to determine that. If the bolts had been put in but the nuts omitted or not secured with the wire, they would have had to vibrate off and the bolts vibrate out of position completely. Seems unlikely, but if so there should be witness marks on the door from the vibration.
So both the bolt installer and the inspector were AWOL?
Earl
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Door plugs have been used in airliner designs for many decades. It is not something new to the 737-9 or even to Boeing. The airplanes can be customized to suit the customer’s requirements.
If the bolts were installed and correctly torques the threads in the bolt holes should be stretched.
In this case the FAA lets Boeing perform and sign off their inspections in house. The FAA has said that ends and henceforth FAA personnel will conduct and sigh off, or not, all inspections.
The locking bolts use a castellated (castle) nut and cotter pin.
https://www.nytimes.com/2024/01/15/business/boeing-737-max9.html
Summary of the Boeing response: we’re adding more inspectors. Ah, the attitude that quality is the responsibility of the QA department. How very 1950s of them.
Oh, well, the Boeing board and management have demonstrated that they are up to speed on all the latest techniques for cooking the books. Designing and building stuff, not so much.
Earl
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From the NYT article:
United Airlines, the largest operator of Max 9 planes, said it had found some loose bolts during early inspections last week, and Alaska Airlines, the second-largest Max 9 operator, also said it had found loose hardware in the area of the door plug.
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More Boeing trouble:
Sorry Charley, that has sweet FA to do with Boeing. It was a failure of some sort in a GE engine that just happened to be bolted to a Boeing instead of an Airbus.
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Earl
Diversity and inclusions policies to blame?
https://www.barrons.com/articles/boeing-elon-musk-dei-diversity-c102c788