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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

#711

Post by burnerthrow008 »

x86x87 wrote: post #690
storf45 wrote: post #671

Earlier quoted context omitted.

From when I worked as an engineer on the assembly line for smaller jets, know that there would be a record trail of exactly who completed the work, who signed off on it and what the work order steps were for anything related to these assemblies and components. This would include the work done at Boeing and their suppliers. Will be interesting to ultimately hear the root cause here.

Let me ask this: assuming they did not tighten the bolts correctly and qa didn't check it, what are the odds they keep an accurate paper trail?

Close to zero, but that doesn’t help them. If the paperwork was falsified to say that everything was tightened and verified, and Boeing stands behind that, now Boeing has to investigate and come up with a plan to prevent these bolts from “mysteriously loosening” (because everything was fine when it left the factory)… which will be an even bigger pain in the ass than just fixing the QA process.

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

#712

Post by stickfigure »

_gabe_ wrote: post #565
cogwheel wrote: post #560

Earlier quoted context omitted.

This is beside the point. The code specifies what the product _is_, not what it "should" be. If you ask for a word processor and I deliver a perfectly bug-free and feature-complete calculator would you really believe it lived up to spec?

This is also beside the point. I think both of you are trying to warn against the dangers that lie on both sides of this coin: people can invest too heavily in a specification and waste an enormous amount of time, and people can immediately jump into coding and code something that does not do what it was intended to do. Like with all things in life, there’s a balance between these two extremes that’s correct. You nee…

A (human language) specification is simply _enough_ information about a system that a human can figure out the intention of the author. The smarter and more context-rich the human, the simpler the specification can be. The dumber and less context-rich the human, the closer the specification needs to be to code.

It's asymptotic. By the time you reach a human who is as dumb as an actual computer, the specification _is_ the code.

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

#714

Post by lobsterthief »

MarkMarine wrote: post #684
aredox wrote: post #622

Earlier quoted context omitted.

There are washers, or thread lock glue, but it is still a question of correct execution: has the glue been applied? Was the glue batch used before its shelf life? Were the parts degreased before glue application? Or did anyone decided to cut corners by using an old batch/skipping degreasing/not putting glue because they were late on delivery?

safety wire and cotter pins are preferred methods on aircraft.

Yes. For mission-critical bolts and nuts, absolutely safety wire and cotter pins should be used.

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

#715

Post by bb88 »

MattPalmer1086 wrote: post #705
pi-e-sigma wrote: post #700

Earlier quoted context omitted.

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'.

Haha, funny strawman. My reasoning is that non developers are capable of managing developers, notably people who have good management skills. Your contention is that the surgeon should be running the hospital.

The head of surgery should be a surgeon, not an accounting manager.

The head of accounting should be an accountant, not a surgeon.

And even at the executive level of a hospital, you would want people who have spent their careers in healthcare, rather than, say, architecture.

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

#716

Post by roelschroeven »

SoftTalker wrote: post #548
unyttigfjelltol wrote: post #453

Earlier quoted context omitted.

The problem was software that prioritized input from a fauly external sensor, over pilot control, and literally crashed planes directly into the ground. At a certain step in the sequence it was not physically possible for a pilot to pull hard enough on the control element to counteract the software. Could they have disabled the system? Only if they could figure out the specific software trying to crash the plane. Is…

Pilots should (are supposed to) disable the auto-trim if it's doing something uncommanded/unexpected. Runaway trim can happen for reasons other than faulty software. MCAS was a new factor and they should have been told about it, I don't dispute that at all.

Here we are again, this misconception just won't die.

In the 737 MAX, the only way to disable auto-trim also disables powered trim (the thumb buttons). As grand parent says, at a certain step in the sequence it was not physically possible for a pilot to trim the plain back to stability manually. It simply can't be done.

In the 737 ng, there was a button to do just that. That would have been useful.

And that's even ignoring the fact that all symptoms were very different from those present in a runaway trim situation as described in the manual and learned by the pilots.

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

#717

Post by caycep »

rob74 wrote: post #599
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.

Because the shareholders like the management? Cutting corners to increase (short-term) profits is more popular with them than focusing on quality. And now that the company has been in the red consistently since 2019 ( https://www.statista.com/chart/20660/boeing-earnings-loss/ ), of course the answer has to be to lower costs even more wherever possible in order to return to profitability...

So should something as mission critical as an aircraft manufacturing co have some ownership/oversight that's not public shareholders? Give the NTSB a few seats on the board

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

#718

Post by thsksbd »

chx wrote: post #648
thsksbd wrote: post #522

Earlier quoted context omitted.

Ya but your sample size is way too small to measure the death rate. Aircraft deaths are rare, but flying is too. The two MAX 8s that fell from the sky were 100% Boeing's fault and could have happened in the US. If 5% of airline traffic is in the US you can renormalize those hundreds of dead and you get dozens dead.

We know US pilots have been warning about the same issues that led to the deathly crashes later but were ignored. The thing is, one part of US commercial aviation being so safe is a lot of pilots responsible for the jet airliners are ex-military. Someone mentioned Southwest Airlines Flight 1380, yup, captain Tammie Jo Shults was one of the first Navy female fighter pilots. Miracle on the Hudson? Sully Sullenberger wa…

Let's assume American pilots are gods. They were shouting that their crafts were unsafe.

No matter how good they are and how prescient, that doesn't help them if the aircraft computer decides it's stalling, forces a nose down and they cant fight the controls.

But, even if we assume omnipotence from these American pilot gods, and assume they can fly outside the bird and Superman-style catch it, they are still only 30% of American pilots. Just another population to normalize out.

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

#719

Post by samstave »

jacquesm wrote: post #242
samstave wrote: post #11

Earlier quoted context omitted.

My money is on the window. It was compromised and then the plug/bolts/flanges structure was ripped out of the body.

You'd lose your money. The plug is inserted from the outside and retained with fasteners against cabin pressure.

https://en.wikipedia.org/wiki/Uncontrolled_decompression

Look at causes of explosive decompression - look at the mass increase to add windows' struct infra to weight and mass to a plane, look at explosive bolts for emergencies

* Explosive decompression is the most dangerous, and can cause severe injuries or death. It is caused by a sudden and catastrophic failure of the pressure vessel, such as a window blowing out or a structural failure.

* Rapid decompression is less dangerous than explosive decompression, but can still cause serious injuries. It is caused by a more gradual loss of pressure, such as a door being left open or a seal failing.he cowling on the window failed. It was due to poor quality control for the extra mass around the window housings on plugs - the extra mass due to the pull and (IN ADDITION) the patsy ois on bolts.

They dont use explosive bolts in aircraft plugs, apparently, but yeah - this wasnt just bolts. Its a procedural impact, installation impact AND faulty materials QA in componentry.

My bet is on faulty adhesives or faulty QA on bolts.

I am pretty sure BOLTS in a plug door are a ruse UNLESS one can prove that window assembly procedures are either by the same company, the same process, or the same QA from multi-vendors.

Rule that out first.

An explosive decompression will not happen unless a single core seal will break....

Look T THE PASSENGER MANIFEST FOR THIS FLIGHT... look at MH370...

And if you want a mind F - look at Facebooks Husband who died in that flight to mexico....

If you look at the similarities, large numbers of high-tech company execs were taken out when those two crashed....

Who was on this manifest?

AI execs? Who lived.... So just give a list of professions of the passenger manifest. (Yes, aware no deaths - who could have? Who were to folks that missed that flight?)

If a singular bolt was faulty - it wouldnt have been an explosive decomp

It would have been a leak.

Explosive at 10K feet is FF attack level "first priority"

(PS they already ruled IN that they use differing contractors to produce certain parts such as plug doors.

How secure are those?

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

#720

Post by samstave »

tavavex wrote: post #146
samstave wrote: post #35

Earlier quoted context omitted.

My assumption is the decompression event would have put the velocity of that decompression on the door/bolts and they are going to be weaker - and the addition of a window into a plug/door like this adds structural mass to add to that which is being sucked out via the decompression putting them over spec load for that area - but since it was a plug, the surrounding structure was still sound - just that thing couldnt…

I don't think there were any modern cases of airliner windows just being removed like that. They're fairly strong and consist of multiple layers of acrylic that are sandwiched between other components, so the entire window assembly would need to get torn out. Even then, it doesn't seem realistic that the difference in pressure would be big enough to instantly rip a properly-attached door clean off. Of course, only th…

See my other post. Not in agreement.
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