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aerolimani
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Fri Dec 06, 2019 11:23 pm

iamlucky13 wrote:
B777LRF wrote:
Not long ago, Björn postulated you'd have to pull 2Gs in order to stalll the aircraft. That was the exact same moment he lost all credibility.


You seem to be incorrectly recalling what he said. Please in the future verify statements you believe to be incorrect before citing them as a reason to doubt a person's credibility.

https://leehamnews.com/2019/11/08/bjorn ... sh-part-2/

In daily operation, a 737 MAX flies with an Angle of Attack below 7° to 8° and never passes 1.2 G in load factor (in fact it rarely passes 1.15 G, the load factor for a 30° bank turn).

MCAS is programmed to activate at almost double this AoA value and the pilot need to pull around 2G or more to get to where MCAS will be active.


He estimated it would take 2G's to cause MCAS to activate, not to stall. He does not explain how he arrived at that value, which is reasonable to question. I assume this is based on the speeds and AoA it activates at, but I'm unclear if he is stating that in reference to the design of MCAS as originally presented to the FAA, or based on changes that as I understand it were made to extend its operation to lower speeds.

It's been discussed several times in this thread. Yes, it seems that he is is essentially discussing MCAS before its functionality was extended to low-speed regimes. However, this was published on Nov 8, 2019, so we can't use the "old news" excuse. He pretty unambiguously puts it in the present tense, saying "MCAS is programmed to activate at almost double this AoA value and the pilot need to pull around 2G or more to get to where MCAS will be active." If it's an oversight, then it ought to be corrected. I do not find his language to be unclear.

We know that when MCAS was extended to the low speed regime, the G sensor was removed, because now the system also needed to activate when the plane wasn't puling high G forces.

So, if what Bjorn meant to say was "MCAS was initially programmed to activate…", then by now, surely the article should have been fixed.

To me, it's strange that Bjorn never does go on to mention MCAS's activation in the low speed regime. It's an important detail in the story that MCAS initially had sensor redundancy, requiring both high G forces and high AOA. It wasn't until Boeing extended its function to the low speed regime that the G sensor was removed from the loop, and redundancy was lost.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Fri Dec 06, 2019 11:48 pm

iamlucky13 wrote:
You seem to be incorrectly recalling what he said. Please in the future verify statements you believe to be incorrect before citing them as a reason to doubt a person's credibility.

He estimated it would take 2G's to cause MCAS to activate, not to stall


Activate, stall. Potato, potato. But if you will, Björn claimed MCAS would need 2G+ to activate, which is grade 1A BS as clearly demonstrated by both accidents. If you put that kind of misinformation out with your name on it, well, you're gambling with your professional reputation.

The fact the article is still up in a the original version, should tell us all a thing or two.
Signature. You just read one.
 
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aerolimani
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Fri Dec 06, 2019 11:56 pm

B777LRF wrote:
iamlucky13 wrote:
You seem to be incorrectly recalling what he said. Please in the future verify statements you believe to be incorrect before citing them as a reason to doubt a person's credibility.

He estimated it would take 2G's to cause MCAS to activate, not to stall


Activate, stall. Potato, potato. But if you will, Björn claimed MCAS would need 2G+ to activate, which is grade 1A BS as clearly demonstrated by both accidents. If you put that kind of misinformation out with your name on it, well, you're gambling with your professional reputation.

The fact the article is still up in a the original version, should tell us all a thing or two.

To be fair, Bjorn was writing about MCAS functioning as intended, not how it activated based on erroneous AOA data.

Nonetheless, that doesn’t change that he writes incorrectly about MCAS’s intended functionality.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 12:40 am

B777LRF wrote:
iamlucky13 wrote:
You seem to be incorrectly recalling what he said. Please in the future verify statements you believe to be incorrect before citing them as a reason to doubt a person's credibility.

He estimated it would take 2G's to cause MCAS to activate, not to stall


Activate, stall. Potato, potato. But if you will, Björn claimed MCAS would need 2G+ to activate, which is grade 1A BS as clearly demonstrated by both accidents. If you put that kind of misinformation out with your name on it, well, you're gambling with your professional reputation.

The fact the article is still up in a the original version, should tell us all a thing or two.


It's potato, tomato - related but still quite distinct. Actual stall can occur at a very wide range of speeds and g-loads. MCAS activates in a more limited range of speeds and g-loads, prior to reaching stall.

That said, I missed the prior references to the JTAR in the thread indicating the low speed case extended MCAS activations to 1G situations. I concede that necessitates more clarification in his statement.

The accidents do not provide direct input on the claim, because the claim was about the intended activation of MCAS, not about unintended activation due to the failure to account for bad data inputs.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 1:32 am

iamlucky13 wrote:
That said, I missed the prior references to the JTAR in the thread indicating the low speed case extended MCAS activations to 1G situations. I concede that necessitates more clarification in his statement.

Yes. His writing needs clarification in this regard. The fact it has sat for a month now, unchanged, is really quite bad, IMO. I expect inaccurate writing like this from certain general media sources, but from Leeham News, I expect better. The fact that the article hasn't been updated, and the fact that Bjorn never mentions MCAS in the low speed regime, leads me to believe he may not be as well-informed as his writing style purports.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 2:19 am

What about a case when a plane was in a shallow dive and pulled up abruptly, could it hit 2G? If a 30 degree bank at high speed yields 1.15 G, when they run turn test up to 2G, what bank angle are they at? Must be steep.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 3:53 am

DenverTed wrote:
What about a case when a plane was in a shallow dive and pulled up abruptly, could it hit 2G? If a 30 degree bank at high speed yields 1.15 G, when they run turn test up to 2G, what bank angle are they at? Must be steep.


60 degrees
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 4:17 am

kalvado wrote:
767333ER wrote:
estorilm wrote:
NONE of that sounds like the Boeing philosophy or tradition of exceptional flying machines that got them where they are today (well, a couple years ago I should say).

Rudder PCU hardovers, cargo doors opening in mid air, assembly using nonconforming parts, force fitting those parts, the DC-10... I’d say the 737 MAX is part of their tradition and philosophy. Minimize time and cost and hope it’s ok.

Show me ANY complex machine without problems. As margins are small and risks are high, any flying machinery is especially prone to small issues leading to big crashes.

Missing the point. Sure things are made with flaws, but the point is they denied or went so far as to try cover such things up; that’s what I’m getting at, and that has been the Boeing way.
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 4:30 am

CriticalPoint wrote:
DenverTed wrote:
What about a case when a plane was in a shallow dive and pulled up abruptly, could it hit 2G? If a 30 degree bank at high speed yields 1.15 G, when they run turn test up to 2G, what bank angle are they at? Must be steep.


60 degrees

Thanks, now it makes sense, 30, 60, 90 triangle. 2/square root 3 is 1.155g, 2/1 is 2g
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 1:09 pm

mjoelnir wrote:

This may be your opinion. Most of the regulators in the world look at the 737MAX as an unsafe frame that has to be fixed.


Unfounded and unsubstantiated allegations. The frame by itself is not a problem.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 1:15 pm

Saintor wrote:
The frame by itself is not a problem.


The World's aviation authorities (and Boeing for that matter) disagree with you.
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 1:22 pm

9Patch wrote:
Bjorn Fehrm at Leeham has his final installment analysing the Lion Air JT610 crash posted. Key highlights:

SNIP

The Boeing 737 has a good safety record. The aircraft has no special vices and is void of dangerous modes like a deep stall or aileron or rudder reversal. The larger MAX engines called for a pitch augmentation to give the pilot a linear pitch feel all the way to stall.

The introduced augmentation to fix this had an unusually sloppy implementation. The uproar over how this could pass into a certified air transport aircraft was called for. But now the corrected augmentation is there. The enormous amount of work which has gone into the update has made MCAS one of the most analyzed and tested flight control augmentations ever. The updated MCAS is now safe, measured with any standards.


https://leehamnews.com/2019/12/06/bjorn ... sh-part-6/

I don't think this is controversial.

MCAS was a "sloppy implementation" that relied too much on unreliable sensors.

Once the sloppy implementation (i.e. multiple activations, high amount of authority, poor ability to disable, etc) and reliance on single unreliable sensor issues are resolved, documented and tested, the updated MCAS will be safe. Going beyond this, MAX will have an active-active computer setup with all outputs being compared. It will be able to catch errors (i.e. five simultaneous bit flips, etc) that NG does not catch.

What we see on this thread is classic "shoot the messenger" behavior, IMO, finding one thing you have a problem with to discredit everything someone says, rather than evaluating things on their own merit.

I guess it's more fun than contacting the author ( https://leehamnews.com/contact/ has his email ) and seeing if he can't clarify the issue.

Here's another messenger we can have a go at:

Peter Lemme, a former Boeing flight-controls engineer and avionics expert who has been very critical of the original MCAS design, said Boeing has addressed all his concerns.

Once the FAA approves the fixes, said Lemme, he’ll fly on a MAX with “no misgivings.”

Ref: https://www.seattletimes.com/business/b ... -controls/

Once he's discredited a large slice of this thread will be null and void, let's see where we end up.
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 3:19 pm

Revelation wrote:
....Going beyond this, MAX will have an active-active computer setup with all outputs being compared. It will be able to catch errors (i.e. five simultaneous bit flips, etc)


undoubtedly a true quantum leap
they MAX helped boeing to push the technical level of the flight automation on the 737s from the 1960ies to the 1980ies

Chapeau!
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 3:53 pm

Revelation wrote:
Going beyond this, MAX will have an active-active computer setup with all outputs being compared. It will be able to catch errors (i.e. five simultaneous bit flips, etc) that NG does not catch.

Lost in all the noise in my opinion anyway is why is the bit flip issue so critical for the MAX RTS but not critical for the NG continued safe operation, including the trim wheels.
Is the problem with the MAX the reliance on one sensor or is it the sensor and the potential of the bit flip, so far we have not had any NG's go down due to bit flip.
Why do I ask this, well its because the fix for MCAS was delivered in June-2019 then the bit flip and other legacy items also on the NG were bought into the equation to essentially make the frame safer.
If the MCAS fix was resolved and the a/c RTS, the mandate would be there to have bit flip corrected on all 737's making the entire 737 fleet safer with as updated technology as possible, now because it has been constrained to the MAX, how are they going to push computer updates on the rest of the legacy 737 fleet, what will be their justification?
How will they get the NG fleet computers updated along with the other changes they are mandating for the MAX RTS all while the NG is happily flying along doing its business?
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 4:09 pm

par13del wrote:
Revelation wrote:
Going beyond this, MAX will have an active-active computer setup with all outputs being compared. It will be able to catch errors (i.e. five simultaneous bit flips, etc) that NG does not catch.

Lost in all the noise in my opinion anyway is why is the bit flip issue so critical for the MAX RTS but not critical for the NG continued safe operation, including the trim wheels.
Is the problem with the MAX the reliance on one sensor or is it the sensor and the potential of the bit flip, so far we have not had any NG's go down due to bit flip.
Why do I ask this, well its because the fix for MCAS was delivered in June-2019 then the bit flip and other legacy items also on the NG were bought into the equation to essentially make the frame safer.
If the MCAS fix was resolved and the a/c RTS, the mandate would be there to have bit flip corrected on all 737's making the entire 737 fleet safer with as updated technology as possible, now because it has been constrained to the MAX, how are they going to push computer updates on the rest of the legacy 737 fleet, what will be their justification?
How will they get the NG fleet computers updated along with the other changes they are mandating for the MAX RTS all while the NG is happily flying along doing its business?

My understanding is that MAX proved that control system has enough authority to run the plane into the ground, so reliability of control system must be high.
SInce control system authority is akin of FBW plane, system reliability is subjected to same requirements. Well, similar requirements.
NG.... I am not sure how autopilot disconnect is handled, and what that means for the actuators. If STS is active in manual flight, that means FCC still has enough authority - but you know, NG is a time-proven design, so take it easy...
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 4:12 pm

par13del wrote:
Revelation wrote:
Going beyond this, MAX will have an active-active computer setup with all outputs being compared. It will be able to catch errors (i.e. five simultaneous bit flips, etc) that NG does not catch.

Lost in all the noise in my opinion anyway is why is the bit flip issue so critical for the MAX RTS but not critical for the NG continued safe operation, including the trim wheels.
Is the problem with the MAX the reliance on one sensor or is it the sensor and the potential of the bit flip, so far we have not had any NG's go down due to bit flip.
Why do I ask this, well its because the fix for MCAS was delivered in June-2019 then the bit flip and other legacy items also on the NG were bought into the equation to essentially make the frame safer.
If the MCAS fix was resolved and the a/c RTS, the mandate would be there to have bit flip corrected on all 737's making the entire 737 fleet safer with as updated technology as possible, now because it has been constrained to the MAX, how are they going to push computer updates on the rest of the legacy 737 fleet, what will be their justification?
How will they get the NG fleet computers updated along with the other changes they are mandating for the MAX RTS all while the NG is happily flying along doing its business?

Bit Flip becomes an issue when Catastrophic failure modes are introduced (as with MCAS/MAX). It remains to be seen if the FCC X Check functions will also be applied to NG. It also remains to be seen if any potentially Catastrophic failure modes have been 'hidden' on NG through dodgy discounting and/or unsupported reliance on pilot reaction times either of which may require the FCC X Check to be retrospectively implemented.

Ray
 
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767333ER
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 4:16 pm

Saintor wrote:
mjoelnir wrote:

This may be your opinion. Most of the regulators in the world look at the 737MAX as an unsafe frame that has to be fixed.


Unfounded and unsubstantiated allegations. The frame by itself is not a problem.

Why is it not flying? Answer without being fallacious.
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 5:04 pm

kalvado wrote:
My understanding is that MAX proved that control system has enough authority to run the plane into the ground, so reliability of control system must be high.

Ok so is that different to MCAS or are you just using other words to define MCAS? I thought that MCAS is what drove the a/c because it relied on one sensor which was faulty?
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 5:10 pm

XRAYretired wrote:
Bit Flip becomes an issue when Catastrophic failure modes are introduced (as with MCAS/MAX). It remains to be seen if the FCC X Check functions will also be applied to NG. It also remains to be seen if any potentially Catastrophic failure modes have been 'hidden' on NG through dodgy discounting and/or unsupported reliance on pilot reaction times either of which may require the FCC X Check to be retrospectively implemented.
Ray

At present it is all about safety, but if the NG continues to fly with the legacy items that must be repaired to get the MAX RTS, it becomes more of a business case to the owners of NG's versus a safety issue, and at the end of the day, safety should be more important. How do they get the bulk of the 737 fleet updated, that is the issue, the MAX at the end of the day may end up with less a/c deployed versus the NG.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 5:45 pm

par13del wrote:
kalvado wrote:
My understanding is that MAX proved that control system has enough authority to run the plane into the ground, so reliability of control system must be high.

Ok so is that different to MCAS or are you just using other words to define MCAS? I thought that MCAS is what drove the a/c because it relied on one sensor which was faulty?

MCAS is not a physical component, it is just one of algorithms running on control system computer.
So I am describing change in hardware which is used by multiple logical systems, including mcas
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Dec 07, 2019 6:05 pm

par13del wrote:
Lost in all the noise in my opinion anyway is why is the bit flip issue so critical for the MAX RTS but not critical for the NG continued safe operation, including the trim wheels.


The opinions I heard privately from a flight controls engineer leads me to think the bit flip issue isn't critical at all, but in the context of the current situation, when it was identified, nobody was willing to apply the normal risk criteria to it and look like they were letting Boeing off easy.

I haven't heard any actual quantification of risk, but the impression I have is that probability of the 5 bits involved all being spuriously flipped at the same time is on the same order of magnitude as the risk of a meteor hitting an aircraft. Meteors are not a merely hypothetical risk, but they are an extremely remote risk, so we don't bother to address them.

767333ER wrote:
Why is it not flying? Answer without being fallacious.


Because of the flight controls. I read the prior poster's point as being that no agency has identified aerodynamic, structural, or mechanical changes as being necessary. We do, of course, know that the EASA submitted several questions about those to Boeing, but I'm not aware of any statements that if changes are made to the aerodynamics, for example, the aircraft could not be operated.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 08, 2019 5:23 am

Re but flip: Could it be that if one pulls back on the control wheel/column in an NG the trim cuts out? So it’s not as dangerous as MCAS that does not have the column cut out.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 08, 2019 5:47 am

ADent wrote:
Re but flip: Could it be that if one pulls back on the control wheel/column in an NG the trim cuts out? So it’s not as dangerous as MCAS that does not have the column cut out.


If true, there would be no need to for any retrospective changes to the 737NG as Ray suggested.
 
kalvado
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 08, 2019 12:48 pm

ADent wrote:
Re but flip: Could it be that if one pulls back on the control wheel/column in an NG the trim cuts out? So it’s not as dangerous as MCAS that does not have the column cut out.

A bit of a question is about actual implementation of trim hardware.
It is well known that primary controls, e.g yoke, are mechanical on all 737s; it is also known that MAX added some FBW elements.
What I don't understand is how electric trim is implementated. My possibly incorrect impression after these lengthy discussions is that yoke switches, including thumb switches and limit switches, went from direct acting relay controls to computer inputs, giving misbehaving computer significantly more power in terms of disabling pilot overrides. If that is the case, there are strong reasons to treat NG And MAX a bit differently
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 08, 2019 4:30 pm

iamlucky13 wrote:
Because of the flight controls. I read the prior poster's point as being that no agency has identified aerodynamic, structural, or mechanical changes as being necessary. We do, of course, know that the EASA submitted several questions about those to Boeing, but I'm not aware of any statements that if changes are made to the aerodynamics, for example, the aircraft could not be operated.

The word frame in its correct sense refers to those things but some use it to refer to the plane as a whole. As a whole the 737 MAX was grounded because it is unsafe. That’s what the first post in that argument meant and the Saintor took it out of context to strawman it.
9Patch wrote:
ADent wrote:
Re but flip: Could it be that if one pulls back on the control wheel/column in an NG the trim cuts out? So it’s not as dangerous as MCAS that does not have the column cut out.


If true, there would be no need to for any retrospective changes to the 737NG as Ray suggested.

If that’s the case on the NG the bit flip is basically just a nuisance more than anything I guess.
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 08, 2019 4:38 pm

iamlucky13 wrote:
par13del wrote:
Lost in all the noise in my opinion anyway is why is the bit flip issue so critical for the MAX RTS but not critical for the NG continued safe operation, including the trim wheels.


The opinions I heard privately from a flight controls engineer leads me to think the bit flip issue isn't critical at all, but in the context of the current situation, when it was identified, nobody was willing to apply the normal risk criteria to it and look like they were letting Boeing off easy.

I haven't heard any actual quantification of risk, but the impression I have is that probability of the 5 bits involved all being spuriously flipped at the same time is on the same order of magnitude as the risk of a meteor hitting an aircraft. Meteors are not a merely hypothetical risk, but they are an extremely remote risk, so we don't bother to address them.

767333ER wrote:
Why is it not flying? Answer without being fallacious.


Because of the flight controls. I read the prior poster's point as being that no agency has identified aerodynamic, structural, or mechanical changes as being necessary. We do, of course, know that the EASA submitted several questions about those to Boeing, but I'm not aware of any statements that if changes are made to the aerodynamics, for example, the aircraft could not be operated.


I agree that is why they made an issue out if the bit flip. With respect to a meteor strike I think the reason we live with the risk is that there is pretty much nothing you could do to mitigate it.
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 08, 2019 5:35 pm

planecane wrote:
iamlucky13 wrote:
par13del wrote:
Lost in all the noise in my opinion anyway is why is the bit flip issue so critical for the MAX RTS but not critical for the NG continued safe operation, including the trim wheels.


The opinions I heard privately from a flight controls engineer leads me to think the bit flip issue isn't critical at all, but in the context of the current situation, when it was identified, nobody was willing to apply the normal risk criteria to it and look like they were letting Boeing off easy.

I haven't heard any actual quantification of risk, but the impression I have is that probability of the 5 bits involved all being spuriously flipped at the same time is on the same order of magnitude as the risk of a meteor hitting an aircraft. Meteors are not a merely hypothetical risk, but they are an extremely remote risk, so we don't bother to address them.

767333ER wrote:
Why is it not flying? Answer without being fallacious.


Because of the flight controls. I read the prior poster's point as being that no agency has identified aerodynamic, structural, or mechanical changes as being necessary. We do, of course, know that the EASA submitted several questions about those to Boeing, but I'm not aware of any statements that if changes are made to the aerodynamics, for example, the aircraft could not be operated.


I agree that is why they made an issue out if the bit flip. With respect to a meteor strike I think the reason we live with the risk is that there is pretty much nothing you could do to mitigate it.

The measurement based science and requirements have been presented in these threads and are available for perusal elsewhere. All avionics are required to demonstrate compliance.

Why some to want believe some old wives tales and some conspiracy theory that Boeing are being hard done by in having to demonstrate the same compliance as every other manufacturer beats me.

Ray
 
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 08, 2019 6:28 pm

ADent wrote:
Re but flip: Could it be that if one pulls back on the control wheel/column in an NG the trim cuts out? So it’s not as dangerous as MCAS that does not have the column cut out.


I read recently they are reinserting the column stab cutout in the Max update (and removing the MCAS column electric trim cutout). So maybe this is one of the mitigating factors to address the flip-bit (easier to say) issue. Because comparing FCC outputs in a fail-safe design seems more difficult to me. And we have an indication (by a TC employee) that removing MCAS altogether might be an option.
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Oo-oo-ooh.
 
sgrow787
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 08, 2019 6:54 pm

Finally the media is getting it right this time:

https://www-washingtonpost-com.cdn.ampp ... story.html

The Max has been grounded since March, after a flawed flight control feature contributed to two crashes in five months, killing 346 people in Ethiopia and off the coast of Indonesia.


"Flawed" explicitly implies a design flaw, which is much more serious for Boeing than a software bug.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
9Patch
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 1:43 am

sgrow787 wrote:
Finally the media is getting it right this time:

https://www-washingtonpost-com.cdn.ampp ... story.html

The Max has been grounded since March, after a flawed flight control feature contributed to two crashes in five months, killing 346 people in Ethiopia and off the coast of Indonesia.


"Flawed" explicitly implies a design flaw, which is much more serious for Boeing than a software bug.

Well, the flawed flight control feature could be a bug in the software. Software is designed too.
 
sgrow787
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 2:55 am

9Patch wrote:
sgrow787 wrote:
"Flawed" explicitly implies a design flaw, which is much more serious for Boeing than a software bug.

Well, the flawed flight control feature could be a bug in the software. Software is designed too.


For real-time embedded systems, software is the implementation of the design. For a front-end application for a website, the layout of the forms for that front-end is the system design (software application design), and the software coding is the implementation of that design.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
DenverTed
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 3:12 am

sgrow787 wrote:
ADent wrote:
Re but flip: Could it be that if one pulls back on the control wheel/column in an NG the trim cuts out? So it’s not as dangerous as MCAS that does not have the column cut out.


I read recently they are reinserting the column stab cutout in the Max update (and removing the MCAS column electric trim cutout). So maybe this is one of the mitigating factors to address the flip-bit (easier to say) issue. Because comparing FCC outputs in a fail-safe design seems more difficult to me. And we have an indication (by a TC employee) that removing MCAS altogether might be an option.


If the column stab cutout shuts off MCAS, then how would MCAS work? Unless the cutout is at a force beyond what is needed to pull into a stall with MCAS. Because, pulling into a stall with MCAS generating more column force through the final degrees (or deceleration) are the mandated tests.
 
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aerolimani
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 3:24 am

sgrow787 wrote:
ADent wrote:
Re but flip: Could it be that if one pulls back on the control wheel/column in an NG the trim cuts out? So it’s not as dangerous as MCAS that does not have the column cut out.


I read recently they are reinserting the column stab cutout in the Max update (and removing the MCAS column electric trim cutout). So maybe this is one of the mitigating factors to address the flip-bit (easier to say) issue. Because comparing FCC outputs in a fail-safe design seems more difficult to me. And we have an indication (by a TC employee) that removing MCAS altogether might be an option.

Where did you read this? Such a change would be a significant event in this story. Please post a source.
 
SFOtoORD
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 3:27 am

sgrow787 wrote:
9Patch wrote:
sgrow787 wrote:
"Flawed" explicitly implies a design flaw, which is much more serious for Boeing than a software bug.

Well, the flawed flight control feature could be a bug in the software. Software is designed too.


For real-time embedded systems, software is the implementation of the design. For a front-end application for a website, the layout of the forms for that front-end is the system design (software application design), and the software coding is the implementation of that design.


Seems pretty pedantic in the bigger picture of what this thread is about.

Would be great if we had another thread that was news only on the MAX without the rehash of rehashed rehash that is this thread.
 
sgrow787
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 3:44 am

aerolimani wrote:
sgrow787 wrote:

I read recently they are reinserting the column stab cutout in the Max update (and removing the MCAS column electric trim cutout). So maybe this is one of the mitigating factors to address the flip-bit (easier to say) issue. Because comparing FCC outputs in a fail-safe design seems more difficult to me. And we have an indication (by a TC employee) that removing MCAS altogether might be an option.

Where did you read this? Such a change would be a significant event in this story. Please post a source.


Sorry, I don't recall the source.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
sgrow787
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 3:52 am

SFOtoORD wrote:
Seems pretty pedantic in the bigger picture of what this thread is about.

Would be great if we had another thread that was news only on the MAX without the rehash of rehashed rehash that is this thread.


This is the grounding thread, which includes what, when, where, why, and how of the grounding. It includes expert opinion on what went wrong at Boeing, the flawed design of this plane, and what they're doing to address it. For non-techies that just want to know when it'll be flying again, then maybe we need an ungrounding thread.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
SFOtoORD
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 4:07 am

sgrow787 wrote:
SFOtoORD wrote:
Seems pretty pedantic in the bigger picture of what this thread is about.

Would be great if we had another thread that was news only on the MAX without the rehash of rehashed rehash that is this thread.


This is the grounding thread, which includes what, when, where, why, and how of the grounding. It includes expert opinion on what went wrong at Boeing, the flawed design of this plane, and what they're doing to address it. For non-techies that just want to know when it'll be flying again, then maybe we need an ungrounding thread.


I’m not looking for non-techie info, but thanks for the condescension. I’m looking for a thread that isn’t full of pedantics about whether it’s a flawed design or a software bug (I’m an Electrical Engineer working in the software industry). And thread not full of the same repetitive posts and topics that have been litigated in this forum 100+ times over months.
 
sgrow787
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 4:29 am

SFOtoORD wrote:
sgrow787 wrote:
SFOtoORD wrote:
Seems pretty pedantic in the bigger picture of what this thread is about.

Would be great if we had another thread that was news only on the MAX without the rehash of rehashed rehash that is this thread.


This is the grounding thread, which includes what, when, where, why, and how of the grounding. It includes expert opinion on what went wrong at Boeing, the flawed design of this plane, and what they're doing to address it. For non-techies that just want to know when it'll be flying again, then maybe we need an ungrounding thread.


I’m not looking for non-techie info, but thanks for the condescension. I’m looking for a thread that isn’t full of pedantics about whether it’s a flawed design or a software bug (I’m an Electrical Engineer working in the software industry). And thread not full of the same repetitive posts and topics that have been litigated in this forum 100+ times over months.


No problem. So you're a techie, but maybe not aerospace or embedded systems techie even. I've followed this thread since day one and only today noticed a media report using the words "flawed" to describe MCAS. It struck me pretty hard that I hadn't thought of the same word myself, having noticed a trend in the media to call the one sensor design a software bug that was getting a fix or update. And constant stories that seem to imply airplane systems could constantly be updated with a software update like the smartphone industry does.

No apologies though. You were saying how my post was out of context. You could have done that privately with the moderators.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
oschkosch
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 6:48 am

https://www.cbsnews.com/news/boeing-tri ... sentation/

Boeing tries to restore confidence in 737 Max in stakeholders' presentation

The Boeing presentation, held on December 3 and 4, is also an effort to build confidence with analysts, airlines, pilots, flight attendants and unions.

The meetings came as Boeing officials are acknowledging the company will likely miss its target of resuming 737 Max deliveries by the end of the year. A return to service is possible in the first quarter of 2020 if the FAA completes its certification process for the plane.
:stirthepot: :airplane: "This airplane is designed by clowns, who in turn are supervised by monkeys" :airplane: :stirthepot:
 
JonesNL
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 7:36 am

We already knew it, but now even Boeing confirms it; We are having an new thread for Q1 2020 :champagne: :champagne: :champagne:
 
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Spiderguy252
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 7:47 am

Bottomline: don't believe any deadlines Boeing puts out. Actions speak louder than words and the timelines will become clear through surrounding sources if the MAX RTS is indeed on the horizon.

Overall, this saga has cannon-balled Boeing. If Airbus or any other manufacturer finds itself in a situation some 20 years from now where they have a choice between kicking off R&D for a new frame vs stretching say an A320 to the limit, we hope lessons from the MAX are learnt and said manufacturer doesn't shoot itself in the foot.

Not holding my breath though.
Vahroone
 
iamlucky13
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 9:02 am

Spiderguy252 wrote:
Bottomline: don't believe any deadlines Boeing puts out. Actions speak louder than words and the timelines will become clear through surrounding sources if the MAX RTS is indeed on the horizon.


I haven't seen any Boeing deadlines.

Rather, they keep talking about the time it will take them to finish the remaining tasks the regulators want completed.

The regulators, for their part, appear to be finding more questions they want answered as they review the information they receive from Boeing.
 
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seahawk
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 9:10 am

"A return to service is possible in the first quarter of 2020 if the FAA completes its certification process for the plane." This is a very soft wording.
 
P1aneMad
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 9:13 am

So even in the best case scenario the vast majority of airlines who have MAXes lying around won't be able to operate them commercially before a full year goes by since they were grounded.
Wow, just wow!
 
planecane
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 11:32 am

oschkosch wrote:
https://www.cbsnews.com/news/boeing-tries-to-restore-confidence-in-737-max-in-stakeholders-presentation/

Boeing tries to restore confidence in 737 Max in stakeholders' presentation

The Boeing presentation, held on December 3 and 4, is also an effort to build confidence with analysts, airlines, pilots, flight attendants and unions.

The meetings came as Boeing officials are acknowledging the company will likely miss its target of resuming 737 Max deliveries by the end of the year. A return to service is possible in the first quarter of 2020 if the FAA completes its certification process for the plane.


I enjoyed the graphics they used, especially the cartoon pilot which seems to be from a play set for three year olds.
 
9Patch
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 1:54 pm

sgrow787 wrote:
9Patch wrote:
sgrow787 wrote:

"Flawed" explicitly implies a design flaw, which is much more serious for Boeing than a software bug.

Well, the flawed flight control feature could be a bug in the software. Software is designed too.


For real-time embedded systems, software is the implementation of the design. For a front-end application for a website, the layout of the forms for that front-end is the system design (software application design), and the software coding is the implementation of that design.


How can something be explicitly implied?
Explicit means something is made clear and stated plainly.
Implicit means something is implied but not stated directly.

But if you see this as an epiphany by media, validating your pet theories, I'm happy for you!
 
sgrow787
Posts: 379
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 4:19 pm

9Patch wrote:

How can something be explicitly implied?
Explicit means something is made clear and stated plainly.
Implicit means something is implied but not stated directly.

But if you see this as an epiphany by media, validating your pet theories, I'm happy for you!


You're getting implicit and implied mixed up.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
phollingsworth
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 4:37 pm

DenverTed wrote:
sgrow787 wrote:
ADent wrote:
Re but flip: Could it be that if one pulls back on the control wheel/column in an NG the trim cuts out? So it’s not as dangerous as MCAS that does not have the column cut out.


I read recently they are reinserting the column stab cutout in the Max update (and removing the MCAS column electric trim cutout). So maybe this is one of the mitigating factors to address the flip-bit (easier to say) issue. Because comparing FCC outputs in a fail-safe design seems more difficult to me. And we have an indication (by a TC employee) that removing MCAS altogether might be an option.


If the column stab cutout shuts off MCAS, then how would MCAS work? Unless the cutout is at a force beyond what is needed to pull into a stall with MCAS. Because, pulling into a stall with MCAS generating more column force through the final degrees (or deceleration) are the mandated tests.


I have no idea if the aft column cutout is coming back. It exists for STS which is also a stall identification augmentation. So in theory it should be possible to define an aft column cutout for 1g MCAS. My understanding is that it was removed to allow it to work in the wind-up turn condition. It could be that it comes back in 1g, though that would increase the complexity of the software logic.
 
patrickjp93
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 4:46 pm

sgrow787 wrote:
SFOtoORD wrote:
sgrow787 wrote:

This is the grounding thread, which includes what, when, where, why, and how of the grounding. It includes expert opinion on what went wrong at Boeing, the flawed design of this plane, and what they're doing to address it. For non-techies that just want to know when it'll be flying again, then maybe we need an ungrounding thread.


I’m not looking for non-techie info, but thanks for the condescension. I’m looking for a thread that isn’t full of pedantics about whether it’s a flawed design or a software bug (I’m an Electrical Engineer working in the software industry). And thread not full of the same repetitive posts and topics that have been litigated in this forum 100+ times over months.


No problem. So you're a techie, but maybe not aerospace or embedded systems techie even. I've followed this thread since day one and only today noticed a media report using the words "flawed" to describe MCAS. It struck me pretty hard that I hadn't thought of the same word myself, having noticed a trend in the media to call the one sensor design a software bug that was getting a fix or update. And constant stories that seem to imply airplane systems could constantly be updated with a software update like the smartphone industry does.

No apologies though. You were saying how my post was out of context. You could have done that privately with the moderators.


All bugs are flaws, whether it's in an embedded system or not. If someone specifies it's architecturally or structurally flawed, that's significant.

For instance, a buffer overflow occurring on user input in a piece of software is a bug which causes errors, even to the point of exploitable security vulnerabilities. It's a pesky, annoying edge case that won't affect most people, it's a big security hole, and it's everything in between.

That said, it's not a structural problem requiring reimplementation of all functionality. The trendy example would be monoliths vs. microservices in the cloud. Monoliths generally are difficult to scale out and load balance, primarily for session management reasons. We have a workaround called sticky sessions on the load balancers, but this has nasty levels of networking overhead.

If you're developing an app for thousands of users to start but will eventually be serving millions within the same country/continent, then a monolith is architecturally flawed, even if it's bug-free. Microservices are, generally, a structurally flawed approach for small systems with user counts in the low tens of thousands and concurrent connection counts in the low hundreds. The amount of knowledge required to manage the infrastructure, deployment, and diagnostics is so high compared to the knowledge of your product's functionality and hardware costs that you'll be paying top dollar for IT talent up front before profits have started rolling in to cover those costs effectively.

So to me, saying soft/hardware is flawed is pretty meaningless. All software (and hardware) has bugs. You just haven't discovered them yet. Depending on the flaw, it's innocuous and can go by the wayside, or it could be monumental and require very serious rework of a system.

Though I'm sure a certain fanbase here will vehemently disagree, I'm fairly certain requiring the sensor disagree light and making MCAS disablement easy will satisfy the regulators on the MCAS issue specifically just fine. As for direct law control when a disablement is needed, there will have to be operational directives added to restrict the MAX to a tighter envelope to avoid the dangerous conditions when in direct law, but that's still fairly minor from a systems perspective.

There are plenty of areas of flight envelopes that 30 y/o (A320), 40 y/o (717/ERJ/CRJ/Turboprop), and 50 y/o (737) designs can't be certified to under current rules. The A320 NEO does not by any means adhere to every standard current when it was certified. The A330 NEO isn't completely current either. Neither is the 747-400 or 8I. But if we want to eliminate grandfathering completely, you're going to have to come to terms with innovation slowing down, planes getting much more expensive to produce, and ticket prices going up without any proven mathematical basis on safety improvement.

Frankly if Boeing were allowed to grandfather the 737 while raising the landing gear (and thus fitting the engines more classically), we wouldn't even be discussing this now. Airlines wouldn't care all that much over getting some more luggage ramps and vehicles. The simulator differential training is much more expensive to amortize.
 
IADCA
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 09, 2019 4:50 pm

sgrow787 wrote:
9Patch wrote:

How can something be explicitly implied?
Explicit means something is made clear and stated plainly.
Implicit means something is implied but not stated directly.

But if you see this as an epiphany by media, validating your pet theories, I'm happy for you!


You're getting implicit and implied mixed up.


Regardless of the definitional quarrel you present, he's still right. You you can't imply something explicitly. If something is explicit, it is openly stated. Something implied (or implicit, to the extent that the explicit statement has any implicit assumptions) is by definition not openly stated. While implicit and implied are different, explicit is mutually exclusive of both.

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