FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes • Hacker News Board

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#151

Post by adenozine » Sat, Jul 25, 2020, 12:05 AM UTC

LittlePeter wrote: post #106

adenozine wrote: post #49

Earlier quoted context omitted.

Your post seems to imply that a bad product negates the respect earned by leading an industry, nay, multiple industries, for several decades. Do you really truly think that just because the MAX is a POS, that everything that comes out of Boeing can be evaluated under that same lens? Surely you aren't so blind to the reality that engineers do occasionally produce quality work. To your credit, I wouldn't fly myself or…

> Do you really truly think that just because the MAX is a POS, that everything that comes out of Boeing can be evaluated under that same lens? No I do not. I still wouldn't ever refer to Boeing as well-respected nowadays. Granted, it may be irrational quirk of mine. To clarify, do I respect Boeing? Yes. But I would not make a post on the Internet and write out "well-respected". I understand Boeing's cultural shift f…

I can understand why it may have sparked those feelings because of the way I wrote it.

I'm a pretty forgiving person, I've spent some time in and around rehab and I've learned personally the value there is in giving people a chance they don't deserve. I know how hard some of the engineers at any big industro-* corp are working, and I choose to have hope that those hard-working folks' ideas and values are represented in the product line that they serve on.

I didn't mean to say that recent events should be scrutinized any less critically, and I disagree with that, especially in the case of passenger aircraft, the utmost care should be taken.

I've read a little bit about 737 MAX, and it strikes me as one of those things where too many boardroom cowboys got to run off and make deals, and the brains and engineers and designers were left with the scraps of an impossible task.

I don't know. I just have a soft spot because I can imagine what it's like for a lot of those guys, going to work and doing their best, and the project is so large that there's just not much any single person can do when it all begins to fall apart at the seams and catch fire. I feel bad that all those people have this terrible mark on them because of the product being a huge, public, terrible failure.

Boeing has done incredible things for the field of aviation, aerospace, maritime, rescue, you name it, they've made a flying vehicle to do it. That can't be washed away because a bunch of guys fucked it up, because it wasn't the people that worked the hardest. So, while I perceive that critically, I respect the name Boeing for what it's given the world in the past.

Anyhow, I wasn't trying to start anything by writing that, I guess it was just part of my thought process that didn't get edited into words very well.

Thanks for your perspective.

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#152

Post by aunty_helen » Sat, Jul 25, 2020, 12:26 AM UTC

t0mas88 wrote: post #33

matt-attack wrote: post #30

Earlier quoted context omitted.

And this may be obvious to some, but why does use inhibit rust?

In normal use these valves take air out of the turbine stage, so they see very very hot air with almost zero moisture in it in normal use. If you park them long enough I can imagine they get wet from rain or even just condensation.

According to the AD this is the 5th stage bleed air valve, so on the compressor side and cold air.

>Bleed air is tapped at the 5th and 9th stages of the HP compressor and from the fan.

https://hursts.org.uk/airbus-technical/html/ar01s19.html#idm...

(Airbus doc but the engines are CFM56 on the 737 models listed) Also according to this page the CFM56 doesn't have a turbine bleed air takeoff.

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#153

Post by bfuclusion » Sat, Jul 25, 2020, 1:12 AM UTC

matt-attack wrote: post #30

JanSolo wrote: post #18

Interesting that the vast majority of 737s were flying so frequently that this was not found earlier. For their entire 20-ish year service life, those planes are never left idle long enough for this part to rust! Amazing. Goes to show how popular and successful the 737 line is.

And this may be obvious to some, but why does use inhibit rust?

Not specific to this part, but most mechanical items that move get oiled as part of their operation. When they don't move for a long time that oil evaporates, and now the moisture in the air can attack the surfaces. This is a common situation in general aviation if they're not flown regularly and can lead to early replacement of the engine.

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#154

Post by quarterdime » Sat, Jul 25, 2020, 1:14 AM UTC

TallGuyShort wrote: post #45

LittlePeter wrote: post #28

Earlier quoted context omitted.

I really struggle to understand how you could have used the term "well-respected" here. It ain't muscle memory, this was done deliberately. Could you explain how you can refer to Boeing being well-respected after the 737 MAX fiasco? Maybe I am missing something. [edit] remove a word

They've had some big screw-ups that were well covered on HN. But from 2014 to 2018 they were consistently the biggest and most profitable aerospace company in the world[1]. You don't get there by being disrespected and all-around shitty. [1] https://en.wikipedia.org/wiki/Aerospace_manufacturer#Largest...

As a long time lurker I finally had to create an account to reply to you. Boeing was indeed extremely large and profitable. Building such a successful enterprise came from lifetimes of work with dedication to excellence in engineering, manufacturing, safety, etc. Unfortunately we are seeing that a decade or so of attacking these values is enough to destroy even a giant. I do not believe that we are seeing just a streak of bad luck. Off the top of my head, let's review a few of Boeing's recent big projects.

787 - Historically over budget and delayed. Failed static wing deflection test, showing how much we can trust the FEA work. In cockpit battery fires led to a historic worldwide grounding of Boeing commercial aircraft. A NTSB report blamed (in part) Boeing engineers for not considering worst case scenario for a lithium battery in a cockpit compartment that contained no fire suppression system. A grounding like the one OP linked is not unprecedented, it is of the 'the plane is grounded until it passes an inspection' type. The battery fire issue led to a 'all planes are grounded until Boeing has a fix.' I believe that this is the first time that Boeing had an aircraft grounded in this way. I believe it was 3 months for Boeing to have an FAA approved fix. Incidentally the 'fix' was a heavy duty sheet metal box around the battery, with a vent to outside the aircraft. I suppose time will tell how reliable a fix this is. Finally there have been issues with debris being left in fuel tanks, metal shavings in wire bundles, etc. Allegedly in aircraft delivered to customers.

737 MAX - A half-baked software bodge has left hundreds dead and all these aircraft grounded worldwide. This is the second time Boeing had a commercial aircraft grounded worldwide with no end in sight. As with the 787 there are issues with debris being found in "complete" aircraft, with foreign object material being found in fuel tanks AFTER the aircraft has left assembly and passed inspection.

KC-46A (Air Force Refueling Tanker) - Years late, over a $1B over budget. Egg on face issues like not having the (required) FAA approval for fuel pods and drogue system. Repeated issues where Air Force refused delivery because of... debris in fuel tanks.

Starliner Crew Capsule - multiple critical software errors that meant the capsule never docked with the ISS and was nearly lost.

There are some common threads here. Bad software for 737 MAX and Dreamliner. Foreign object material ending up in wings and fuel tanks over and over.

Finally there is good reading to be had about quality issues in assembly, parts being rejected as defective and then "disappearing." Whistleblowers are reporting that the "disappeared" defective parts such as tail assemblies are ending up on aircraft and being delivered to customers. It seems there is pressure from management to sacrifice safety for profit, pressure to approve designs (thanks to some really good lobbying, Boeing essentially gets to approve its own designs with minimal FAA oversight), pressure to keep you mouth shut about safety concerns (and retaliation if you don't).

These are not signs of a healthy company. By now I think that Boeing has slid into "all-around shitty." The above is my best recollection of news stories from years of watching Boeing, if I have made a mistake then I am happy for any corrections. Let me know if you would like links to any of the particular stories or believe that a [citation needed] is in order.

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#155

Post by [deleted] » Sat, Jul 25, 2020, 1:22 AM UTC

adenozine wrote: post #16

wwv25 wrote: post #7

One of the inspection checklist items: Measure the clearance between the flapper bushings at both locations on each engine bleed air 5th stage check valve. If the clearance between the flapper bushings is a minimum of 0.004 inch (0.102 mm) at both locations, the engine bleed air 5th stage check valve at that location has passed this inspection. I knew that aviation engineering dealt with tight tolerances, but boy, it…

They've had calipers for literally thousands of years. I used to be involved in some intermediate gunsmithing work, and we had these tools called 'dial calipers' which have a little gauge you read and you can measure extremely precise things. We used it for getting cylinder diameters or clearances that needed that degree of precision. I can only imagine that in aviation, there are even more advanced tools, especially…

[deleted]

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#156

Post by WalterBright » Sat, Jul 25, 2020, 1:36 AM UTC

Your car will also start exhibiting random failures if you leave it parked long enough. Parts will corrode, stick, develop flat spots, cold weld themselves together, water gets in, bugs and mice set up shop, chew on the wires, etc.

Especially if you leave it out in the weather.

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#157

Post by int_19h » Sat, Jul 25, 2020, 1:48 AM UTC

linuxftw wrote: post #149

noir_lord wrote: post #144

Earlier quoted context omitted.

Somewhat sadly a lot of the drive for that tolerance was weapons, until we could accurately make very high tolerance (for the day) parts you couldn't use parts from one rifle on another without a smith, it certainly wasn't field serviceable - this imposed a lot of maintenance overhead until they solved it properly. It seems like we really like to push the limits when it comes to shooting each other.

> Somewhat sadly Weapons can be used for defensive purposes. There's nothing inherently wrong with them, only how people use them. > parts you couldn't use parts from one rifle on another without a smith You cannot swap bolts in the field on most rifles. At minimum, you require a go/no go gauge. The tolerances on modern firearms are very precise.

That the tolerances are so precise is exactly why you can do that on most modern rifles. It depends on the design - specifically, how they achieve headspace. On an AR-15, or almost any firearm with a similar bolt locking arrangement, bolts - indeed, entire BCGs - are swappable in practice, and people do that routinely without bothering with gauges regardless of what the manual says. On AK and similar designs, yeah, that's a really bad idea.

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#158

Post by int_19h » Sat, Jul 25, 2020, 1:51 AM UTC

lisper wrote: post #53

bewaretheirs wrote: post #44

Earlier quoted context omitted.

Yep. To check tolerances, you'd need a go/no-go pair -- one that should fit, and a slightly bigger one which shouldn't.

This is a thing that non-aviators often don't realize about aviation in general: the hard part is designing the artifacts and processes so that by the time you get around to operations, everything is routine and nothing is hard. Flying, building and maintaining airplanes seems hard, but that's mainly because of the volume of stuff you need to know, not because any single item is particularly difficult. All aircraft a…

It's not just aviation. Our entire industrial civilization works like that, and this is the only reason why it can work. We are surrounded by high-precision machinery even in daily life, and are completely oblivious to just how much technomagic it is - and how much historical effort went into building the industry up to the point where it can produce such things so easily and cheaply.

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#159

Post by perl4ever » Sat, Jul 25, 2020, 3:50 AM UTC

esaym wrote: post #121

wwv25 wrote: post #7

One of the inspection checklist items: Measure the clearance between the flapper bushings at both locations on each engine bleed air 5th stage check valve. If the clearance between the flapper bushings is a minimum of 0.004 inch (0.102 mm) at both locations, the engine bleed air 5th stage check valve at that location has passed this inspection. I knew that aviation engineering dealt with tight tolerances, but boy, it…

>Do field technicians have dependable tools and methods of measuring with such high degrees of precision? Yes, it is basic stuff in most mechanics. For instance, the valve clearance on most car engines is going to be .002-.005. I worked aviation maintenance for years. Most larger planes are held together with 'hiloks' [0] They are an "interference" fit. For a quarter inch hilok, you'd first pilot drill a hole around…

Tolerances and path dependence are the fundamental reasons why I've always gravitated towards software and programming rather than building/repairing physical stuff.

It's interesting to me how getting the right physical configuration of something so it's reliable kind of encodes the complex procedure that gets it there.

It's so much harder than a program where you can identify all the parts and modify them in any order. And whenever you make a mistake, you can generally just reach in an fix it, rather than redoing a long disassembly or something.

Re: FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes

#160

Post by sgnelson » Sat, Jul 25, 2020, 4:48 AM UTC

cartoonfoxes wrote: post #80

nabilhat wrote: post #70

Earlier quoted context omitted.

Who even uses calipers for critical precision? Calipers are for dimensions machinists append with -ish, as in four thousandths-ish. Important dimensions deserve a micrometer, especially the feeler guage that just said you need to tell your boss to scrap a 737. Decent machine shops even have different classes of micrometer; there's the one you carry in your pocket, and then there's the fancy set locked up in your boss…

I see this in my own shop. Digital displays instill people with greater confidence in the measurement than is warranted. This is something of a UI fail, as the tool manufacturer (Mitutoyo) has very clearly defined measurement precision for all their metrology equipment (+- 0.001" and 0.0015" for the calipers).

That is a very interesting observation, thank you. I've never thought about the digital vs analog in terms of actual "oh, it's digital, it's better." measurement variation.

In my experience, I think you're probably right, it does seem like people may take them as "more accurate."