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

theaircurrent.com

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

#331
post #290

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.

> Does wiring bolts actually help?

There's different kinds of bolts that get wired, with different kinds of goals and results.

My only experience is wiring bolts according to the rules for club racing motorcycles.

Some things, like oil sump drain bolts for example, wiring them will stop them backing out so far as to fall our, and while it will probably weep oil if it loosened enough to take ups the writing slack, it wouldn't dump all the oil out quickly.

Other things, like axle bolts, if it backs out enough to take up the wire slack, it'll have lost its clamping pressure and that's bad, but not immediately catastrophic. The major axle loads are all in shear so the wheel won't fall off, it'll just get more floppy than it's supposed to be. Long term it'd be bad and cause wear to the point that something would eventually fail, but it'd get you to the end of the race most likely, and hopefully the rider will have felt something odd and gone looking or a post race inspection would have caught it.

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

#332

Earlier quoted context omitted.

Working conditions in the USA have come to a point where many don't care because the company doesn't care about them. People are fired at will after working for 20+ years with zero shits given. There is zero loyalty and in return workers just don't care either. There are only so many checks and balances you can build in until this situation will catch up with you. Doesn't amazon have such a huge turn over that they a…

Sorry, but habe you ever worked in an aero assembly plant? You're making it sound like it's just like any other warehouse sweatshops job where you need to pee in a bottle while you work to meet your quotas when it's the furthest thing possible from that. You definitely have enough time to work at leisurely pace and assemble every part right. There's not much rushing going on there. If workers get away with doing dodg…

The report from Al Jazeera in 2014[1] about Boeing's assembly line for the 787 was pretty damning, workers were complaining exactly about quality control issues, Cynthia Cole was at Boeing for 32 years as an engineer and she mentions in the report she wouldn't fly on the 787.

So conditions at the plant in North Charleston haven't looked very good for almost 10 years...

[1] https://www.aljazeera.com/program/investigations/2014/7/20/t...

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

#333
post #131

Earlier quoted context omitted.

" Eschew flamebait. Avoid generic tangents. " " Please don't use Hacker News for political or ideological battle. It tramples curiosity. " https://news.ycombinator.com/newsguidelines.html

wouldn't dismissing discussion of hiring practices on product quality be trampling curiosity for political or ideological battle?

[deleted]

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

#334

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.

Just had all my connections cancelled. So extra day in San Fran for me which is less than ideal, but probably better than being on the flight if something happens.

It was total bedlam at the airport when I got in this morning however. With almost no flights available to replace the grounded ones.

Another red eye special for me tonight but at least no connections.

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

#335

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?

Deliberate or not, the NHTSA and automakers have found a symbiotic relationship where mandatory safety requirements become integral to a planned obsolescence sales cycle. Cars are more reliable and longer lasting than ever, but safety features mean many people feel compelled to buy a new car much sooner than they might have 30 or 40 years ago. Automakers negotiate with the NHTSA to set mandatory safety feature timelines so that features can work their way from luxury models down over the course of several years. By the time a features becomes mandatory, it's already been milked as a sales differentiator, and trickled down into most if not all car models.

I don't know if such a state of affairs is possible with the aircraft or airline industries. Those industries are too rational, whereas the expense of safety features in the consumer automobile market is in part quietly covered by arguably irrational consumer spending habits.

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

#336
post #223

Earlier quoted context omitted.

IIRC every bolt's torque value needs to be logged any time it's (re)fastened. At least that's true for aircraft engine maintenance, not sure if it applies to the assembly process of the airframe, I'd sure hope so!

> IIRC every bolt's torque value needs to be logged any time it's (re)fastened. So how did this happen if they we checked so recently?

Most likely they were either not installed properly in the first place, or there is some kind of design flaw.

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

#337
post #90

Given that these are plug-style doors even if these were bolts in the hinges it would not risk the integrity of the fuselage seal.

They're not plug-style doors. They open outward. That's the problem. Opening outward is mechanically riskier, but more likely to be useful in an emergency. The drill for plug-style over-wing exits: Remove cover from upper handle, grab upper and lower handle, yank upper handle, pull door inside, have 15Kg or more of door land on your lap, turn big clunky door sideways, pitch through hole so it's outside and out of the…

As an interesting comparison to your A320 video, it looks like the A320neo overwing exits are now outward-opening instead of plug-style: https://youtu.be/VhiYfyE3Vps?si=FuKeNfpd1pD4sgc_&t=47

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

#338

Earlier quoted context omitted.

They do disassemble the entire plane for heavy maintenance checks every 6-12 years. The MAX 9 has been in operation for just a few weeks though...

That’s pretty incredible. After a heavy maintenance breakdown, what percentage of the plane gets replaced? Or is everything already on a routine maintenance schedule so the intention is to visually identify unexpectedly failing parts?

Things like fasteners all get replaced, other things get replaced or refurbished on defined schedules.

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

#339
post #300

Earlier quoted context omitted.

I think the concern is more the attitude that allowed this to happen, despite all the issues Boeing has had.

Yes, this seems like a top to bottom culture rot problem at Boeing sacrificing quality control in exchange for reduced costs. A few years ago, I had read that certain airlines demanded planes manufacturered in Washington rather than South Carolina, and I wonder if that information actually ends up being a useful signal for better quality planes. https://www.postandcourier.com/business/airline-surveys-poin... https://…

I think the Max 9 are made in WA though, so it would be a much wider scale cultural problem than just SC's non-union vs. WA union factories.

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

#340
post #223

Earlier quoted context omitted.

IIRC every bolt's torque value needs to be logged any time it's (re)fastened. At least that's true for aircraft engine maintenance, not sure if it applies to the assembly process of the airframe, I'd sure hope so!

> IIRC every bolt's torque value needs to be logged any time it's (re)fastened. So how did this happen if they we checked so recently?

Process issues
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