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It's a hole in the side of the plane that is designed to have two functions.
If the aircraft is being used in a Ryanair-style, high density, pack 'em in like sardines configuration, the hole has to have a functional emergency exit door in it. As Tony notes, if it opened by rotating inwards (either on the horizontal or vertical axis), that would involve two major problems: you'd be fighting the psychological instinct of how people act under pressure (they'd be trying to push the thing out), and you would have to remove seats, luggage bins, etc. to free up interior space for the door.
If the aircraft is being used with a less sadistic seating density, that hole does not have to have a door in it, but it does need to have a pressure-resistant plug. That plug needs to (a) not open if it is not told to, but (b) be easily replaceable with an actual door, if the configuration of the aircraft is to be changed from low density seating to high density.
So the only way you can enable both functions is with an optional door or plug that is designed to open outwards, but designed and installed and maintained not to open at all unless a maintenance tech deliberately opens it. The latest news seems to be that fasteners either weren't installed at all, or weren't torqued correctly, depending on which account you believe. I suppose that's the lesser of two evils relative to a design flaw, but it's still not good.
For some reason I can't save that picture to post here, but that's the interior view of that opening with the interior panelling removed. Normally, with the panelling in place, that section of wall looks just like the sections in front of and behind it.
It's a wall. Not a door.
Other people have apparently noticed the same thing:
In the aftermath of last week’s Alaska Airlines in-flight emergency, some aviation experts are questioning the structural design of the section of the Boeing 737 Max 9 that blew off the plane.
On that January 5 flight, a “door plug” – a portion of the plane’s fuselage the manufacturer can put in place instead of an emergency exit door – detached from the plane and was later discovered in an Oregon backyard.
In interviews with CNN, some experts argued that if that door plug were designed to be larger than the opening it covers and installed inside the plane, the force of the pressurized air in the passenger cabin would force the plug against the plane’s interior frame and a situation such as the one on the Alaska Airlines flight could have been avoided. However, such a design could have added costs and practical disadvantages, some said.
“It doesn’t make sense to me why they would do it that way and not have it installed from the inside, where it literally cannot come out unless there is a structural failure in the airframe,” said David Soucie, a former FAA safety inspector and CNN analyst. “Historically, since we have had pressurized airplanes, emergency exits are designed to come inward… so why would they have not done the same thing with this plug?”
The point is, it's not an exit. It isn't even a door. It's an opening in the fuselage with a cover plate bolted over it.
From the point of view of the passengers in the plane, it's just another section of the interior wall of the plane.
Are you going to attempt to exit by pushing on a random spot on the wall or will you go to the place where there's a door and use that?
C'mon now Frank, you are just arguing for the sake of arguing. What part of the end purpose of said opening do you not get? Blanked off or not, as I mentioned in my previous post, it would be impractical, costly and cause too much downtime to engineer the plug to be secured in a manner opposite of the intended (future) use of the opening. Think about it in terms of your theatre's doors as well. Say you wanted to change out the Auditorium main entrances to open in the opposite direction, think of the demolition, reconstruction and down time to do so.
I had already agreed with you and your brother that from the standpoint of a pressurized cabin, it is opposite of the physics. But you can argue with me all you want, but it will NOT change the fact that an emergency exit MUST open outwards to the exterior. And airlines for decades have designed emergency exits that way. And they aren't going to change it (nor will it ever get approved due the factors in my last post) no matter how much you, your brother, or me insist that it should be changed.
Let's settle on this though: It IS stupid that they even designed this fuselage with the need for a plug if a door wasn't to be installed. That was simply to save costs, as an alternate airframe would have to go through the ENTIRE certification and testing processes. Having been around aircraft for many years, that cost is substantial. Boeing was trying to save money, and it bit them in the ass, big time.
I disagree, insofar as the purpose of the door in this case is concerned..there is so little space INSIDE the cabin and seat area that an emergency exit opening INWARD would be a serious obstacle to fast egress, which is the whole point of those emergency exits. If you read the card or decal you'll see that on many aircraft, when used as an emergency exit, it opens out and is actually discarded outside the aircraft. I understand that some of the closure designs use a series of pins (like in a bank vault) that when the lever is used, retracts those pins and you push OUT on the door to remove it. (Just like all standard emergency exits are required to push OUT, never PULL, to be opened.)
Now the physics of a pressurized cabin back up your position fully, which I agree with you and your brother on.
BUT the elephant in the room (or plane) is the reality of how people react in an emergency situation, and there are many who would, in the height of panic, be frantically PUSHING on that exit (since that's where they want to go, right?) and if the door required ANY kind of pulling to the inside.....lots of people get hurt or die. Think about it.
The final test? Which way do the emergency exits in your theatre open?
After two or three DC-10 accidents involving cargo bay doors blowing out in the 1970s and IIRC, some later airliner designs had the doors opening inwards for exactly this reason. The problem was that the door restricted what could go through the opening, making it impossible to pass a standard size cargo container through it, with the result that Boeing and Airbus went back to doors that swung outwards, but with beefed up latching and fastening mechanisms. Basically, they decided to accept an intrinsic risk for greater reward.
My brother (the engineer) pointed out that there's an obvious and simple design flaw where that door cover is on the outside of the frame. If it was on the inside the interior pressure would help hold it in place rather than pushing it off.
The reason it has to be on the outside is because that opening is intended to be readily retrofitted to an actual emergency exit door, which MUST open outwards, not in. To design it as your engineer brother pointed out would require actual modifications to the hinge and stop points on the airframe for the conversion, which opens up a LOT of other inspections and certifications to do that retrofit. They tried to KISS, but it bit them in the ass. Current reports are blaming QC issues at the Spirit plant that built it.
My brother (the engineer) pointed out that there's an obvious and simple design flaw where that door cover is on the outside of the frame. If it was on the inside the interior pressure would help hold it in place rather than pushing it off.
Yea, finding that part so fast will generate a proper repair procedure for it pretty quickly, and there are six of those "plug doors on that model... the higher capacity version has extra evacuation doors in those 6 places.
A second phone was also found, but they didn't say much about it.
Maybe its owner was watching porn on it when the thing got sucked out?
But yes, that's a pretty impressive ad, both for the iPhone, and whatever protective case/shell its owner had put on it.
As for the door, it came down in a suburban backyard. 20 feet in the other direction, and it could have gone through the roof of a house, onto a car ... yet another astonishingly lucky escape.
Yea, and that iPhone falling from 16k feet and not a scratch on it. But I'm still not buying one... A second phone was also found, but they didn't say much about it.
Good one Tony! I think Boeing's problems may well extend to all the planes of that model. I'd rather drive anyway, too much stuff to see and do along the way. Airports suck, and so do the airports. Some are so big now that one may need to take a copter from one side to get to a connecting flight at a gate on the other side.
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