As I understand it, there are two versions of the "9", the one for one for budget airlines has more seats so needs an additional emergency exit.  The other airlines have fewer seats, so that the extra exit is replaced by a door shaped "plug" which has a window.  This is supposed to be permanently fixed in place and from the inside looks like an ordinary window.

The incident was lucky in two respects.  The seat by the window was unoccupied, and the blowout happened when it did.  Three or four minutes later the altitude would have been much higher so the outside pressure would have been much less and passengers may have had their seat belts unfastened.

Interfering with the planes structure just to satisfy some H&S emergency evacuation risk assessment.

is not a good idea if that is what happened. 

You would hope that as every passenger  plane has to be able to fly safely  with any one door open, it can also fly with the plug out as well - so the actual structure of the plane does not depend in any way on either being present. 

I suspect we we will eventually be told that the plug retaining bolts were the wrong ones or were not bolted in properly, as I'm sure the actual design would have been very thoroughly analyzed in both door and plug configurations, when correctly fitted, but presumably not as actually assembled  correctly- hence the checks.

Mike.

You would hope that as every passenger  plane has to be able to fly safely  with any one door open, it can also fly with the plug out as well - so the actual structure of the plane does not depend in any way on either being present. 

I suspect we we will eventually be told that the plug retaining bolts were the wrong ones or were not bolted in properly, as I'm sure the actual design would have been very thoroughly analyzed in both door and plug configurations, when correctly fitted, but presumably not as actually assembled  correctly- hence the checks.

Mike.

We are talking about the Boeing 737 Max here - a plane that was designed wrong from the start.  I wouldn't like to guess whether it was a rushed design without proper tests, or something built in a hurry to clear the backlog of outstanding orders.

Hmm. well this just now from Reuters...

Does rather look like someone at the factory forgot something -perhaps the  threadlock or a torque wrench.

Not exactly a confidence inspiring newsflash.

https://www.reuters.com/business/aerospace-defense/no-data-captured-alaska-airlines-737-cockpit-voice-recorder-ntsb-chair-2024-01-08/

"Jan 8 (Reuters) - United Airlines (UAL.O) has found loose bolts on multiple 737 MAX 9 aircraft, it said on Monday, referring to the Boeing model grounded after a cabin panel blew off an Alaska Airlines-operated (ALK.N) plane in mid-flight Friday.

United found issues related to the installation on several panels that were being inspected following the accident, it said in a statement."

Makes one wonder what else has been cocked up that has not yet come to light.

Mike

I wonder what kind of nut and bolt arrangement is used for the Plug?

Does it use

- Locktite (other brands are available)

- Second nut up tight against the first nut

- Split pin throught the nut and bolt arrangement

- Sping washer under nut

- Serrated washers either side of workpeice

- Lock nut with Nylon insert

People need to understand that vibration on a plane can do strange things to fixings as can the changes in pressure