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United finds loose bolts on plug doors during 737 Max 9 inspections

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Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#301

Post by bastardoperator »

AnthonyMouse wrote: post #285
epicureanideal wrote: post #229

Earlier quoted context omitted.

Maybe Apple, or Elon Musk, or some other person or company with a spare hundred billion could spin up a decent aircraft company?

Elon Musk doesn't have a spare hundred billion. Apple is one of the only entities that does, but it's not really their kind of market. Institutional customers that are going to expect gradual iteration and thorough specifications that allow independent third party repairs etc. That's more like Microsoft's kind of market, but uh... don't give them any ideas.

I can't even fathom what it would cost to ride an Apple airplane, coach.

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#302

Post by alistairSH »

bobsomers wrote: post #284
Aqueous wrote: post #247

Literally just flew on a United Airlines 737 MAX 9 one week ago. It seems like the craft I flew on has probably been grounded in the week since. I noticed that we were flying on a MAX before boarding and nearly asked to switch flights, but consoled myself that I was being irrational and that the planes were almost certainly fine now. Guess my confidence was misplaced.

FWIW, it's only the Max 9s which have this issue. The Max 7s and 8s don't have an exit in that location (too few seats) and the Max 10s require an exit door to be installed in that location, not the door plug. It's only the Max 9s that have the option of the door plug, if the installed seat count is below the threshold where an additional exit is required.

7s and 10s aren’t out in the wild yet. Only 8s and 9s.

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#304

Post by RandallBrown »

heads wrote: post #290
gnopgnip wrote: post #257

Earlier quoted context omitted.

Shouldn't the bolts be safety wired after being torqued?

Does wiring bolts actually help? I feel like if a bolt is going to come loose enough such that the wire is all that is holding it in then you have a big problem already. The wire is just delaying the inevitable. A bolt is either fastened or it isn’t. If the wire is all that’s left to hold it, then it isn’t fastened and your parts are being held together with a very weak piece of wire.

The wire is supposed to prevent the bolt from becoming loose.

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#305

Post by gruez »

phkahler wrote: post #222
gruez wrote: post #121

Earlier quoted context omitted.

Statistically speaking it's not worth worrying about. In 2021 there were less than 0.001 deaths per 100M passenger miles. Assuming these aircraft are 10x more dangerous than the alternative, that works out to 0.01 deaths per 100M passenger miles, or 0.00000026 deaths NY to SF flight. For an average american aged 38.9 years[2] with 40 years of life left[3], that works out to a loss of life of 5.4 minutes. I don't thin…

A better metric IMHO is "crashes involving at least one fatality" per flight. For large aircraft the fatalities are often everyone on board or nearly so. So people care about "what is the probability that the flight I'm getting on has a fatal accident?" This is largely independent of number of passengers or miles flown.

I don't get it, is your point that the "deaths per 100M passenger miles" is underestimating the likelihood of death? Doesn't the metric already normalize for number of passengers on a plane?

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#306

Post by Syonyk »

Rapzid wrote: post #293
stefan_ wrote: post #221

Earlier quoted context omitted.

To be fair it seems there is an image of some of the loose bolts: https://nitter.net/ByERussell/status/1744460136855294106 I think this should stick out to an assembly person as not quite right.

That lock nut may not have lined up correctly for some reason and was backed off a bit to get the pin in? That could make it torqued under spec. But also, it doesn't look like that bolt clamps anything so it may not matter if it was a little "loose"..

Are you looking at the center nut in the photo that's cotter pinned in place, or the two over on the right side that appear to be "loosely threaded on at best, washer rattling along the shaft"?

The center one doesn't concern me. The two that aren't even finger tight do.

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#307

Post by heads »

Bolts and machine screws are very interesting. One mistake I, an amateur bike mechanic, made for years was not greasing bolts properly before assembly.

It sounds counterintuitive but without grease a bolt (or machine screw) will bind early with a high torque well before it is correctly tensioned lengthways. The torque is just a proxy for the tension and it is this tension which is needed to fasten your components together as intended.

The grease means that when the torque to turn the bolt reaches the correct value then the bolt is also under the correct tension instead of being because it got stuck in the thread half way.

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#308

Post by RandallBrown »

Scoundreller wrote: post #294
KptMarchewa wrote: post #186

Earlier quoted context omitted.

Force it to develop actually new airplane, not rely on grandfathered type license from 60 years ago.

I wonder what automotive designs would look like if we allowed that kind of grandfathering. Or maybe we do but people keep wanting new car designs?

We don't really get many new car designs do we? Aren't most cars just built on top of old platforms that only see iterative updates?

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#309

Post by consumer451 »

plagiarist wrote: post #297
consumer451 wrote: post #164

Earlier quoted context omitted.

Please refresh and look at my edit. If a missing some major required component aside from finetuning and frames per sec, which will require a few years for everything to be fast enough... please let me know what it is. Wait, oh it will be understanding of time... the sequencing of the frames. That is missing for now, right?

I think you're giving it too much credit for solving examples that are obviously wrong. Not only a non-expert but even most children know those pairings don't go together. Given that the discussion in this post is around torquing to the right specifications, I don't know if just fine tuning is enough. It might need more serious training on videos of assembly. Even then, can it distinguish between the right torque or…

Oh definitely, I was giving it some softballs. Maybe I am also giving too much credit to what fine tuning can achieve.

But in a manufacturing environment, if one labelled wrench sizes with different colors, then things like noticing wrench size would be easier. Also, I imagined that the camera would of known (same) geometry during training and inference in a Boeing implementation.

I also wonder if multimodal LLMs are blowing my mind unnecessarily. It really feels like a huge leap to me though.

Re: United finds loose bolts on plug doors during 737 Max 9 inspections

#310

Post by gruez »

tw04 wrote: post #144
gruez wrote: post #121

Earlier quoted context omitted.

Statistically speaking it's not worth worrying about. In 2021 there were less than 0.001 deaths per 100M passenger miles. Assuming these aircraft are 10x more dangerous than the alternative, that works out to 0.01 deaths per 100M passenger miles, or 0.00000026 deaths NY to SF flight. For an average american aged 38.9 years[2] with 40 years of life left[3], that works out to a loss of life of 5.4 minutes. I don't thin…

>Statistically speaking it's not worth worrying about. Those statistics don't really work out at all. They take number of miles and deaths, and nothing else. Let's say flown miles and driven miles are exactly the same for arguments sake. If the number of miles flown on planes were traveled by 4 million people, whereas the number of miles traveled by car were from 4 billion people, your likelihood of dying in a plane…

> They take number of miles and deaths, and nothing else. Let's say flown miles and driven miles are exactly the same for arguments sake. If the number of miles flown on planes were traveled by 4 million people, whereas the number of miles traveled by car were from 4 billion people, your likelihood of dying in a plane crash is FAR higher than by car if you're one of the 4 million who fly on a plane.

It's passenger miles, so the number of passengers is already factored in.

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