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Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

reuters.com

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Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#151

Post by dmazzoni »

kalleboo wrote: post #55
ZaoLahma wrote: post #54

Earlier quoted context omitted.

And this is what I'm curious about. I can't imagine much of the original design would be left in the aircraft except for the overall shape of it. I'm guessing (remember now, basically zero aircraft development knowledge) that most tech has been updated to modern equivalents. Engines, controls, computers, ...? So what would be changed in a complete overhaul of the aircraft?

> overall shape of it That's the problem. It was designed for 60s-style boarding via air-stairs on the ground (rather than modern jetways from the terminal) so it's too low down. This requires doing funky things to fit modern, large, energy-efficient engines, starting with those weird flat-bottom cowlings and ending in moving the engines back and changing their angle, which changes the flight characteristics of the p…

It sounds to me like Boeing has been making incremental changes to the 737 over the years. Clearly now it's NOT the same plane. But was there a clear point in time where they crossed the line and it really should never have been certified as the same aircraft anymore?

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#152

Post by MilStdJunkie »

rob74 wrote: post #66
ZaoLahma wrote: post #43

Earlier quoted context omitted.

Why is it troublesome? As someone with very limited knowledge in aircraft development, I'm genuinely curious about what more modern designs would bring to the table compared to the modern 737s, which I assume are heavily updated versions of the original 1960s design?

The original 737 was the smallest aircraft in Boeing's passenger jet family, behind the four-engine 707 (which was already becoming obsolete at the time and was eventually replaced by the 747) and the three-engine 727. I mean, this was the original 737 model: https://en.wikipedia.org/wiki/Boeing_737#/media/File:Boeing_... - Lufthansa used it as a "CityJet", which is its regional brand! That's why the 737 sits so low…

False Equivalence is one of a big sawhorses I bring out for why things suck so much more now, in aerospace and defense generally. For the past 10-15 years, we've had mechanisms for quantitatively ballparking equivalence in pools of supportable assemblies and spared parts - but generally, no one wants to touch that. The purchasers of enterprise solutions (CAD, PDM, etc) want equivalence to be ultimately a financial decision, not a question solved by materials, interfaces, fluid dynamics, frickin' electricity, etc.

Your problem there is . . well, jeez, look around. You're treating completely different products like they're the same thing. Not exactly a new problem, either, but it sure is interesting how it's compounded since the great "financialization" experiment in American capitalism circa 1974, and with a whopper of a sequel post-2008. I am out of my sandbox here, but if I was a betting man, I would put the root cause of this nonsense in this bucket, i.e., lowering apparent risk (by making things look similar) so as to meet requirements of issuing larger financial instruments (bonds, etc).

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#153

Post by anticensor »

kranke155 wrote: post #105
mrjin wrote: post #99

Earlier quoted context omitted.

Solely being old isn't the problem. The early variants of 737s were solid. It became a problem with later versions with bigger engines etc: you can probably get away with some minor CHANGES without overhaul the design as long as it's still within the threshold of the original design, but those MAX variants crossed the line. Thus MACS was introduced. MACS, to some extent, was a feasible workaround if Boeing did not cu…

Its amazing you can´t prosecute some of these people for murder. 346 people are dead because of this.

Causation of vehicular murder, hmmm.

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#154

Post by wbsun »

lnxg33k1 wrote: post #2

I honestly don’t even know anymore if I’m living in a cracked / badly modded version of the sims, how can one wake up in the morning and seek for a safety exemption regarding I quote the article: She noted the exemption Boeing had sought "involves an anti-ice system that can overheat and cause the engine nacelle to break apart and fall off. This could generate fuselage-penetrating debris, which could endanger passeng…

As some comments mentioned that the culture in Boeing has been broken for a long time. How to fix it? I heard about a solution: set up a policy that every executive and board member must take their "safe" airplane once a week.

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#155

Post by Sohcahtoa82 »

hooby wrote: post #128
froh wrote: post #111

Earlier quoted context omitted.

ELI5! thanks so much! so the crashes were because the new software was confusing to the pilots and did something unintuitive? and now they want to do another change to how the airplane behaves (interacts with) the pilot?

Afaik, the crashes were caused by the software mistakenly believing the plane was in a stall due to a single faulty sensor and pulling down the nose - while the pilots had absolutely no clue what was going on (because they never were told the software could do this), and had no way to disable/counteract the software. I believe the updated software now uses both sensors and only acts if both sensors agree (which is ac…

> and had no way to disable/counteract the software.

Both pilots pulling up on their yokes couldn't override the system?

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#156

Post by jMyles »

filleduchaos wrote: post #146
jMyles wrote: post #136

Earlier quoted context omitted.

Sure they have - they very family under discussion. Just because they have attempted to foist a polite fiction that it is a 737 variant doesn't mean that it actually is. It's a new single-aisle transport with several serious problems.

It is a 737 variant, though. That's precisely where the several serious problems come from.

> It is a 737 variant

In name only, and by dint of software cludges to prime the vividness of our ability to imagine that pilots needn't be separately type-rated.

...but we all know that if it weren't for MCAS (and by extension, if it weren't for Boeing's special seat at the FAA table), this wouldn't pass muster.

(but yes, I think you and I are saying the same thing.)

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#157

Post by JohnFen »

vineyardmike wrote: post #94
leoh wrote: post #29

Earlier quoted context omitted.

Seriously. If I or any of my peers at Google back in the day ever talked like this we’d get PIP’d.

Clearly you're not familiar with Sundar.

I think that leoh was referring to "back in the day" before Google broke bad, well before Sundar.

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#158

Post by filleduchaos »

jMyles wrote: post #156
filleduchaos wrote: post #146

Earlier quoted context omitted.

It is a 737 variant, though. That's precisely where the several serious problems come from.

> It is a 737 variant In name only, and by dint of software cludges to prime the vividness of our ability to imagine that pilots needn't be separately type-rated. ...but we all know that if it weren't for MCAS (and by extension, if it weren't for Boeing's special seat at the FAA table), this wouldn't pass muster. (but yes, I think you and I are saying the same thing.)

"In name only" is an interesting way to say "literally re-engined 737s with minor tweaks to the airframe, in line with an incremental development".

Again, the whole reason the "software cludges" were implemented in the first place is precisely because it's more or less the same "hardware". The entire problem is that the 737 MAX family is in fact made up of 737s when they should have been redesigned from scratch. It's baffling to me how one could come to the conclusion that they aren't 737s.

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#159

Post by mjhay »

mjhay wrote: post #139
jsjohnst wrote: post #132

Earlier quoted context omitted.

> Cowlings are now composite (ie plastic) instead of aluminum. Um, no. Absolutely not “ie plastic”. Composite material in the case of aircraft means it’s made of two or more materials. In the case of modern aircraft, it often is carbon fiber, but can also mean fiberglass and Kevlar (aka aramid fibers).

A larger part is the epoxy, e.g., plastic. It being a composite would actually make it worse than just plastic under cyclic heating, because the epoxy and carbon fiber have different coefficients of thermal expansion.

e: should have said "large" not "larger". Ideally as much epoxy as possible is squeezed out.

Re: Boeing withdraws bid for safety exemption for Boeing 737 MAX 7

#160

Post by procflora »

Sohcahtoa82 wrote: post #155
hooby wrote: post #128

Earlier quoted context omitted.

Afaik, the crashes were caused by the software mistakenly believing the plane was in a stall due to a single faulty sensor and pulling down the nose - while the pilots had absolutely no clue what was going on (because they never were told the software could do this), and had no way to disable/counteract the software. I believe the updated software now uses both sensors and only acts if both sensors agree (which is ac…

> and had no way to disable/counteract the software. Both pilots pulling up on their yokes couldn't override the system?

Another armchair pilot here, also recommending Mentour Pilot's channel, but hopefully I can summarize it well enough.

In this case no, because the way the MCAS system operated was to actuate the stabilizer trim which changes the angle of the entire huge tail plane (the horizontal part of the tail). For the most part the yoke controls the elevator (a smaller flap on the trailing edge of the tail plane), so the pitch control authority available in the yoke movement is not enough to override the adjustment to the tail plane trim MCAS was making.

Once MCAS moved the trim far enough, you couldn't raise the nose with the yoke alone. To correct it, pilots needed to deactivate the trim adjustment motor ("stab trim cut-out" you might have heard about) and manually re-trim the tail plane by folding out a literal crank and spinning a wheel by their legs in the cockpit[1]. The concept of doing this was not new with the MAX (similar procedures around trim system malfunctions existed), but what was new was that MCAS existed in the first place, that it could repeatedly activate if the erroneous inputs were still present, and that it could move the trim quite far before pilots realized what was happening. As I understand it that is pretty different than a traditional runaway trim malfunction for which they'd had training for. I believe that looks more like a stuck switch making a constant movement of the trim until you hit the cut-out. If you cut it back in, either it immediately starts moving again and you know you have a problem or it doesn't and leaves you wondering.

[1](https://www.trbimg.com/img-5d0ba28b/turbine/ct-biz-wp-boeing...)

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