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FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

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Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#291

Post by cmurf »

tremon wrote: post #199
cmurf wrote: post #122

Earlier quoted context omitted.

What's the problem with the airframe? What's the problem with the larger engine nacelle causing a different pitching moment? I've yet to read either of those violate any portion of FAR 25. There is still an open question whether the MAX should have or will have a separate type certificate from other 737's, thereby requiring pilots of a type rating to fly the MAX, thereby requiring full disclosure and training on all…

What's the problem with the airframe? The #1 problem with the airframe is that it is not identical to the original 737 airframe. Therefore it shouldn't have been certified as a 737, and it should have required pilot training. Boeing has been using software to emulate a 737 airframe to avoid the pilot training costs. This approach itself is fraught with problems, and I hope the FAA puts a hard stop to these non-soluti…

The 757 and 767 do not have identical airframes, they share a type certificate. The Airbus 320 and 340 do not have identical airframes, they share a type certificate. I think you do not understand type certification.

The 737 MAX airframe is substantially more like a 737 NG airframe, than a 757 is to a 767. Etc. It sounds like you have a problem with how airplanes are type certified, not a problem with the airframe.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#292

Post by salawat »

bjourne wrote: post #133

Since this thread is already full of armchair airplane engineers opinions about the root cause, I'll add mine too: Never ever write new software under the condition that it must work EXACTLY as old software. It can't be done and you'll always miss something. Case in point: Wine. They've been at it for years and the emulation layer is still far from perfect. It works 99% of the time which is good enough for games, but…

GNU Octave would like to disagree.

In fact, divergence from MATLAB is considered a bug. Admittedly, the entire point there is a free and open source replication of MATLAB, and is only really necessitated by licensing.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#293

Post by count »

LMYahooTFY wrote: post #287
hwestiii wrote: post #234

This all points up the glaring conflicts of interest in the corporate business environment. Most of us think that Boeing is the business of building airplanes, but as a publicly traded company, its real business is making money for its shareholders, and aerospace is just a vehicle toward that end. The Boeing CEO's steadfast refusal to take responsibility for these two crashes are nothing more than CYA designed to lim…

This is only the beginning of a question. It's not obvious how the responsibility for those deaths should be allocated. What's the tolerance threshold for airline fatalities?

Zero. Aviation is a zero tolerance activity on safety issues.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#294

Post by dandare »

petascale wrote: post #258
dandare wrote: post #175

As a web/game developer, one thing I never understood is the alleged complexity of these control systems. There is no image/voice recognition, no graphics engine, no rocket science. What are they even doing? Or is it all a big lie? Lines of code, from the internet[1]: Pacemaker: 100k Boeing 787: 5M Chevy Volt: 10M Modern car: 100M [1] https://www.visualcapitalist.com/millions-lines-of-code/

As a web/game developer, you forgot to include the OS and the drivers in the lines of code involved in executing the stuff you are writing. The Linux kernel was 15M lines in 2013 [1], more than half of that was drivers. Windows XP was apparently 45M lines, the 2009 Debian distribution 300M lines [2]. So you're into millions of lines just to execute "Hello world" on a PC. Simple control systems generally don't use an…

Are you suggesting a passenger car runs its own Linux distro? What would be the reason, other than Not Built Here syndrome? (Or the goal to deceive regulators.)

How many I/O devices/drivers does a pacemaker talk to? How many of those are written by/customized by the pacemaker's developers?

If you include the underlying stack, then also my Hello world runs on tens of millions of lines of code (Browser+OS).

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#295

Post by JorgeGT »

skykooler wrote: post #289
TazeTSchnitzel wrote: post #174

Earlier quoted context omitted.

Wine is not a good example. They don't have access to the source code of the original system, and they haven't had the resources to cover the entire footprint of the Windows APIs.

That's a good point. It'd be like comparing Boeing building a new plane to, say, Tupolev trying to build an identical copy without any blueprints.

> Tupolev trying to build an identical copy without any blueprints.

They actually did. It's called Tu-4: https://en.wikipedia.org/wiki/Tupolev_Tu-4

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#296

Post by rossdavidh »

hwestiii wrote: post #234

This all points up the glaring conflicts of interest in the corporate business environment. Most of us think that Boeing is the business of building airplanes, but as a publicly traded company, its real business is making money for its shareholders, and aerospace is just a vehicle toward that end. The Boeing CEO's steadfast refusal to take responsibility for these two crashes are nothing more than CYA designed to lim…

Actually, I think it's worse than that. If it were all about making money for shareholders, they would have made sure this PR nightmare (which will likely result in many lost sales) didn't happen. The long term monetary incentive is to avoid crashes.

The more fundamental problem is that corporations are run by people who, mostly, care more about themselves than the company they are running, and more about this year than the future. Boeing needed to suck it up and accept a couple years' poor sales, in order to get an effective competitor to Airbus' latest. In the long run, or even the medium run, this would give the best monetary results, as well as save lives.

But, it would mean bad financial results this year and next year, and the corporate business environment is biased against that. If the CEO makes decisions which give worse results this year and next, but better results later, he will not be around in his job to enjoy those better results. So, he optimizes for the near term, and rolls the dice (with other people's lives).

The biggest exception to this would be companies where the CEO is the founder, who usually has the ability to retain his job through a bad year or two.

Of course, the CEO should have made the right decision anyway, and accepted the consequences, because people's lives are at stake and anyway it's not like he would starve if he got fired next year. But, if we're talking about incentives and conflicts of interest, that's the real issue, not money vs. lives (because both point in the same direction, of making the plane safe), but short term vs. long term and CEO vs. the company as a whole.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#298

Post by cmurf »

salawat wrote: post #237
cmurf wrote: post #122

Earlier quoted context omitted.

What's the problem with the airframe? What's the problem with the larger engine nacelle causing a different pitching moment? I've yet to read either of those violate any portion of FAR 25. There is still an open question whether the MAX should have or will have a separate type certificate from other 737's, thereby requiring pilots of a type rating to fly the MAX, thereby requiring full disclosure and training on all…

The problem with the airframe is that the shape of the nacelles, and their forward position create extra lifting surface in front of the center of gravity at high AoA. What this results in, is a non-compliant stick force response curve at high AoA. This violates FAA regulations which state that the stick force required to bring a plane to a stall must consistently increase all the way to the stall. No sickening or de…

I appreciate the response but it does not help at all one bit, it's a rehash of everything I've already read. In all of these 737 MAX discussions I'm one of the first to have brought up FAR 25.173(c) (although that whole section is relevant).

I do not see how software augmentation can be permitted to compensate for a deviation from FAR 26.173. That section is titled: Static longitudinal stability. Software augmentation cannot cause an airplane that lacks positive static stability to have positive static stability.

You have to understand that what you're proposing represents such a magnificent perversion of FARs, if true, that it is not conceivable to me that this is not a big f'n deal in the aviation community. It would be the elephant in the room, that somehow Boeing and the FAA permitted an airplane that in fact does not have certifiable positive static stability in one or more axis, to have been certified because of a software routine; let alone a software routine with no redundancy and is easily disabled in flight with no documentation on the consequences.

Let me put another fine point on it: I do not care if there are 50 AoA sensors and 100 independent computers on this airplane to compensate for a FAR 25.173 deficiency (or pick any of the other axis for that matter). You cannot use a goddamn computer to make an airplane statically stable when aerodynamically it is not statically stable. At least not without changing the FARs. As they are written, transport category airplanes must comply with FAR 25, and I see nothing in FAR 25 that permits computers papering over aerodynamic requirements.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#299

Post by VBprogrammer »

magduf wrote: post #270
avar wrote: post #201

Earlier quoted context omitted.

The alternative isn't a repeat of 9/11. You're assuming that passengers aren't a whole lot more motivated to overpower hijackers after 9/11 than before. One reason 9/11 could happen is that passengers generally assumed a hijacking was mostly a scary inconvenience, not a life-or-death situation.

Exactly; another 9/11 situation is impossible now. They just need to keep doing screenings of passengers and their carry-ons to make sure no one can bring obvious weapons on board; anything else is unnecessary and possibly counterproductive. If someone tries to hijack the plane using razor blades or whatever, the passengers will literally murder them.

I'm not sure if you were being sarcastic or not.

If not you have a lot of faith in people's willingness to sacrifice themselves to save others.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#300

Post by tremon »

cmurf wrote: post #291
tremon wrote: post #199

Earlier quoted context omitted.

What's the problem with the airframe? The #1 problem with the airframe is that it is not identical to the original 737 airframe. Therefore it shouldn't have been certified as a 737, and it should have required pilot training. Boeing has been using software to emulate a 737 airframe to avoid the pilot training costs. This approach itself is fraught with problems, and I hope the FAA puts a hard stop to these non-soluti…

The 757 and 767 do not have identical airframes, they share a type certificate. The Airbus 320 and 340 do not have identical airframes, they share a type certificate. I think you do not understand type certification. The 737 MAX airframe is substantially more like a 737 NG airframe, than a 757 is to a 767. Etc. It sounds like you have a problem with how airplanes are type certified, not a problem with the airframe.

Rather, I have a problem with airplanes falling out of the sky because pilots don't understand what they're flying, and airplane manufacturers trying to obfuscate their machinery. The details of how and why are secondary to that.
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