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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

#691

Post by MilStdJunkie »

nolok wrote: post #356
jasode wrote: post #41

I found it interesting that Boeing did proactively tell airlines to inspect 737 MAXs for a possible loose bolt in a different part of the plane (rudder section) at least 8 days before the January 5th event. Example story: https://www.reuters.com/business/aerospace-defense/boeing-ur... Unfortunately, Boeing did not know they had other issues with the plug door bolts.

Imagine the quality of the manufacturing and QA / final inspection to have that kind of issue.

Given everything I've seen so far, I'd bet good money that what happened here was miscommunication between Spirit and Boeing. Spirit started out locking down the plug, then Boeing asked them to just loosely attach it[1] so Boeing could yank the plug for interior/wiring/AC/paint, then someone at Boeing forgot about the "loosely". So now, they get in a hurry (maybe the AC/interior didn't need any access to work on, which makes sense for this MAX variant, it wouldn't need as many hatches to pull wire) and it went down the Renton line as if the plug was fully installed. It's enough to pass high blow inspection and other inspections, but then over time that "shipment config" attachment vibrated out, and pop goes the plug.

Almost certainly systemic issue though, so that sucks. Sucks real bad.

They need to get a Tiger Team or whatever together to look at everything with a shipment config, and make sure those "ship kits" don't leak into the real actual airplane configuration. This is . . ok, this is really manufacturing 101 stuff, but well, things happen.

I'm in the industry, but haven't touched the MAX, so take this with a grain of salt.

[1] Basically a "shipping" or train configuration

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

#692

Post by guax »

nyokodo wrote: post #458
sp332 wrote: post #433

Earlier quoted context omitted.

The plane that lost a plug mid-flight was only two months old though. A design problem probably would have shown up in an older one.

> A design problem probably would have shown up in an older one. Maybe, unless it required really specific conditions that have only occurred for this one or also required some maintenance snafu that also had nothing to do with Boeing assembly QA. We don’t have enough data to establish anything as the most probable explanation yet.

According to the linked article: at least five aircraft. So, not unique to this one. Or the one that blew the door out.

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

#693

Post by mips_r4300i »

itronitron wrote: post #584
Syonyk wrote: post #20

Earlier quoted context omitted.

No, it's as insane as it reads. It means people were careless and sloppy during assembly. Think of it like seeing "one cockroach in your kitchen." It's not one cockroach. You just haven't opened up the rest of the walls.

From Alaska Airlines... >> "Initial reports from our technicians indicate some loose hardware was visible on some aircraft." Friendly reminder that 'some' can also mean most or all .

In the same way Apple's "a small number of affected devices" means anywhere from 1 to 99% of devices in the field

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

#694

Post by guax »

eterm wrote: post #268
chatmasta wrote: post #39

Earlier quoted context omitted.

It's "reassuring" in the sense that I'm reassured I've been making the right decision... but yeah, "vindicating" is probably a more appropriate choice of word :)

What you're describing is validation.

reassuring serving or intended to remove someone's doubts or fears.

can be reassuring if it removed the doubt that he was making a senseless decision. while still being the opposite about flying the thing.

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

#695

Post by deelowe »

paranoidrobot wrote: post #493
deelowe wrote: post #465

Earlier quoted context omitted.

Where did you see that? My understanding is that it's an optional plug door that's used to assist with interior installation. Once the interior is done, it's bolted shut and interior paneling is installed over top. From the inside, you can't tell it's there.

My source is [1], specifically at about 5:05. Alaskan airlines chose a 178 passenger configuration for their 737-9, and so are not required to have a mid-cabin exit door. Lion Air's chosen to go with a 221 passenger configuration, and so are required to have an operating door. Obviously changing up the number of seats isn't done on-demand, you'd need to go for a refit/maintenance cycles. But if Alaskan decided to cha…

Ahh. Well, in the case of the Alaska flight, it's a plug door and not used as an exit. It's pinned in place with large pin that has a bolt, a castle nut and cotter pin which lock the pin.

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

#696

Post by fzingle »

shiroiuma wrote: post #564
fzingle wrote: post #552

Earlier quoted context omitted.

> Does it make sense to degrade the performance of good software teams because bad software teams exist? Consider the classic statistic "most drivers think they are above average". I posit that the same is true of software teams, almost every team will self-assess as above average, i.e. good. Those teams will then imagine that, being good, they build quality into the process and very little verification QA is done. I…

I'm curious: in your many years of being a consultant to these bad teams, where the manager really thought they were top 20%, did you get a chance to talk to the rank-and-file team members, and did they paint a very different picture of the team health and software quality than their manager? Also, did you run across any orgs where they basically refused to use a process like Agile, and instead just did ad-hoc coding…

> I'm curious: in your many years of being a consultant to these bad teams, where the manager really thought they were top 20%, did you get a chance to talk to the rank-and-file team members, and did they paint a very different picture of the team health and software quality than their manager?

Yes, generally I join teams and work as an engineer or sometimes as a team lead, so I'm talking to all the team members.

Most start up teams are composed of junior developers, often pretty smart people. Usually 5 or fewer years of experience. Many times these are people who have already accomplished stuff they didn't think they could do. So that generally means that yes they think pretty highly of themselves. To a degree it is quite justifiable, they tend to be very accomplished but in a narrow domain. Unfortunately they don't realize that their technical accomplishments in a specific field does not mean that they are experts everywhere. Their managers understand that these are smart people and assume again that this is therefore a good team.

Non start ups that I join are usually just plain dysfunctional.

> Also, did you run across any orgs where they basically refused to use a process like Agile, and instead just did ad-hoc coding, insisting that this was the best way since it worked just fine for them back when they were a 5-person startup?

Usually more the opposite. In my experience I come across teams that are sure they must not need any help because they follow all the rules in Scrum and have great code coverage metrics.

It is really common to see this kind of thing. I call it "the proxy endpoint fallacy". It can crop up anywhere that there is something that can be measured. In that example, it would be confusing adherence to Scrum with having a working SDLC or perhaps confusing code coverage metrics with the objective of having bug-free releases.

This isn't a software only fallacy. In politics, GDP is often confused with societal well-being. Always be wary of your metrics and change them as required to keep you tracking your actual goals.

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

#697

Post by mc32 »

boringg wrote: post #688
mc32 wrote: post #466

Earlier quoted context omitted.

Yep, Chernobyl being a prime example. Or Komarov's failed re-entry after complaining about the design faults of the vehicle long before launch. Then there was the more uhhm run of the mill backyard blast furnace campaign which contributed to misallocation of workforce which then led to mass starvation.

There are many many more examples. I find it so tiresome to see young people just use capitalism as a catch all for the failure of something. It's such a lazy and uninformed argument. I'm not carte blanche defending capitalism - its a mixed bag but it sure outpaces the competing systems put forward to date. It does need some stronger safeguards against industry self regulation - that has a bad track record.

I think we're on the same page. Economic systems need failsafes so that they don't suffer from positive feedback loops.

What anti-capitalist sympathizers, in my view, don't realize is that this is due to people being in the loop. These economic systems are merely vehicles, some better than others, but the conductors are people, be they communists or capitalists. At least with capitalisms there is a delayed regulator (negative feedback) in communism it's up to the system to decide if it needs to modify itself.

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

#698

Post by local_crmdgeon »

jacquesm wrote: post #226
dralley wrote: post #181

Earlier quoted context omitted.

And you seem to be assuming that the problem is in the design and not the assembly... The latter seems more likely.

You are both missing the 'faulty process' and 'faulty communications' options.

And:

- "bad parts from vendor" - "bad programming on torque wrench from MRP" - "insufficient training on process" - "tooling was programmed correctly but bad sensors" - "lube mislabeled for 3 days"

This is absolutely not some simple thing. This is why people don't take us seriously as engineers.

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

#699

Post by yencabulator »

kakwa_ wrote: post #592
markdown wrote: post #589

Earlier quoted context omitted.

> The management imported from McDonnel-Douglas? I've heard this since they killed hundreds of people in the two crashes. Why are they being protected? They have names.

It's not necessarily a question of persons (and the CEO did a resigned after the Max crashes). It's more a question of culture (oversimplifying, sales vs engineering) and this is harder to change most of the time. Apparently, even the Max debacle was not enough.

With a 63 million golden handshake for job well done, on top of the all the money he previously made.

https://www.imdb.com/title/tt11893274/

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

#700

Post by pi-e-sigma »

MattPalmer1086 wrote: post #668
bb88 wrote: post #488

Earlier quoted context omitted.

> Good software teams build quality into projects by introducing continuous integration, unit testing, creating feedback, and tightening these feedback loops. No. Good software teams are led by competent, technical management. Managers who aren't afraid to get down into the dirty details. Managers who aren't afraid to roll up their sleeves and write code if they need to. The process doesn't matter. The management of…

Sigh... This myth that the only people who can competently manage developers are other developers has been floating round for decades. For some reason, developers seem remarkably blind to the skills other roles and disciplines require. Only a developer can do that, everyone else is basically useless fluff. Maybe it's a form of arrogance or just deep unself-awareness.

Let's apply your reasoning to medicine. I'm sure you would be completely fine with managers telling your surgeon what parts of the surgery can be 'optimized away'.
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