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PW100
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Mon Jun 10, 2019 9:46 pm

Interested wrote:
PW100 wrote:
Interested wrote:

And isn't that exactly what Boeing were hoping they could get away with?


It has nothing to do with getting away with, as every change Boeing initiates is validated through FAA. This is just part of every day life and continous improvements.

While Boeing has lots of xplainings to do on so many levels, this one is fairly low at their list. But I guess some see a bear behind every tree . . .


I didn't think FAA or the airlines were aware of the faulty sensor?

Boeing chose not to tell them!!

That's how bad this all is

Not exactly a bear behind a tree

Shocking stuff really


Faulty sensor? Boeing not telling anybody? Any bird strike can take out an AoA sensor.

In the grand scheme of things, the (missing) AoA sensor alert is really minor. If you don't believe me, that's fine. I recommend you to read some of the AD's on Boeing and Airbus commercial models. You'll find many items much more shocking to you . . .


PS. Why is it more and more people think that each sentence's full stop (if they actually use them . . . ), needs to be followed by a double hard enter (ie. blank line). Do people feel their words won't get attention? Perhaps the message isn't strong enough and need artificial beefing up?
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Mon Jun 10, 2019 9:49 pm

Interested wrote:
PW100 wrote:
Interested wrote:

And isn't that exactly what Boeing were hoping they could get away with?


It has nothing to do with getting away with, as every change Boeing initiates is validated through FAA. This is just part of every day life and continous improvements.

While Boeing has lots of xplainings to do on so many levels, this one is fairly low at their list. But I guess some see a bear behind every tree . . .


https://www.rt.com/usa/461371-boeing-alert-fix-2020/

Would you like to re-consider your point of view now?


I don't see any new information in there that hasn't been discussed for at least a week on here.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Mon Jun 10, 2019 9:49 pm

aerolimani wrote:
It’s interesting that this idea is found only in forums, and has never been reported in any media I can find. Why is that, do you suppose?


Because the media can't realize any advertising dollars off such non-sensational information.

aerolimani wrote:
The most damning article I have ever found is this one: https://www.forbes.com/sites/jeremyboga ... rocedures/


That's the trouble with what this thread has become: everyone is constantly looking for the most damning thing they can find: damning to the crews, damning to Boeing, damning to the certificating authorities.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Mon Jun 10, 2019 9:52 pm

mjoelnir wrote:
morrisond wrote:
Interested wrote:

https://www.rt.com/usa/461371-boeing-alert-fix-2020/

Would you like to re-consider your point of view now?


I might be wrong but I don't think Lionair or ET paid for the optional sensors so it would never had worked anyways.

From the RT article

"Pilots were supposed to be alerted about possible problems with the sensors by an AoA Disagree alert, which should light up when data coming from two AoA sensors does not match. But the alert required an optional set of indicators to be installed to actually work, and only 20 percent of the aircraft sold had them."


The AoA disagree should have worked according to the information and manual for the MAX. Boeing was hiding the fact, that it was not working in the standard configuration. So it could well be pilots were expecting the warning to come in case there problems with the AoA sensors.

So was the standard version of the MAX even certified with the AoA disagree not active? Because according to certification it should have been active.


Does the 737 (MAX) have an AOA DISAGREE NNC?
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sillystrings
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Mon Jun 10, 2019 9:56 pm

PW100 wrote:
Interested wrote:
PW100 wrote:

It has nothing to do with getting away with, as every change Boeing initiates is validated through FAA. This is just part of every day life and continous improvements.

While Boeing has lots of xplainings to do on so many levels, this one is fairly low at their list. But I guess some see a bear behind every tree . . .


I didn't think FAA or the airlines were aware of the faulty sensor?

Boeing chose not to tell them!!

That's how bad this all is

Not exactly a bear behind a tree

Shocking stuff really


Faulty sensor? Boeing not telling anybody? Any bird strike can take out an AoA sensor.

In the grand scheme of things, the (missing) AoA sensor alert is really minor. If you don't believe me, that's fine. I recommend you to read some of the AD's on Boeing and Airbus commercial models. You'll find many items much more shocking to you . . .


PS. Why is it more and more people think that each sentence's full stop (if they actually use them . . . ), needs to be followed by a double hard enter (ie. blank line). Do people feel their words won't get attention? Perhaps the message isn't strong enough and need artificial beefing up?


I would agree that the AOA DISAGREE is not that important in the NG and previous models. They do not have any automation relying solely on AOA data. The MAX however had MCAS which had unlimited authority over the stab trim based only on AOA data. This is a completely different situation.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 12:07 am

keesje wrote:
If the goal of putting everything MAX into one mega thread, where nobody can find back anything & 10 sub topics come & come back, to suppress usefull exchange of information, that seems successful. It has become a useless monsterthread. Pitty..

Having been here as long as I have, I know that we've tried what you're suggesting before, and it doesn't work.

If we had ten sub topic threads the same group of hardcore zealots would be cross posting the same things across ten threads rather than just one (with perhaps a few things changed to appear to be on topic) so they could sleep well knowing as many people as possible have the benefit of their very important opinions, in turn creating ten times the bickering about off-topic posts and ten times the bickering about duplicate threads and thus one hundred times the policing burden for the mods.

You can keep pushing on the rope if you want, but I doubt this will change.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 12:44 am

PW100 wrote:
mjoelnir wrote:
morrisond wrote:

I might be wrong but I don't think Lionair or ET paid for the optional sensors so it would never had worked anyways.

From the RT article

"Pilots were supposed to be alerted about possible problems with the sensors by an AoA Disagree alert, which should light up when data coming from two AoA sensors does not match. But the alert required an optional set of indicators to be installed to actually work, and only 20 percent of the aircraft sold had them."


The AoA disagree should have worked according to the information and manual for the MAX. Boeing was hiding the fact, that it was not working in the standard configuration. So it could well be pilots were expecting the warning to come in case there problems with the AoA sensors.

So was the standard version of the MAX even certified with the AoA disagree not active? Because according to certification it should have been active.


Does the 737 (MAX) have an AOA DISAGREE NNC?


Yes, the MAX has an AOA DISAGREE NNC. It’s exactly the same as the procedure for the NG.
 
RickNRoll
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:01 am

OldAeroGuy wrote:
RickNRoll wrote:
I have wondered by Boeing didn't put it in the EAD.


It is in the EAD, along with a list of other symptoms.

Here's a portion of the EAD along with indications that would have been present shortly after liftoff for ET302 are shown in BOLD.
AOA DISAGREE is shown in italic.

737 MAX EAD 2018-23-51 lists these symptoms for potential erroneous MCAS operation:

Continuous or intermittent stick shaker on the affected side only
Minimum speed bar (red and black) on the affected side only
Increasing nose down control forces
IAS DISAGREE alert
ALT DISAGREE alert

AOA DISAGREE alert (if the option is installed)
FEEL DIFF PRESS light
Auto pilot may disengage
Inability to engage the autopilot

In terms of criticality, stick shaker and IAS DISAGREE would have had a higher pilot action priority than AOA DISAGREE.

There has been no evidence that NNC's were performed for either condition.

Sure, but it doesn't say anything about the root cause, the AoA failure which would present an AoA disagree alert, because Boeing knows that it's not working for most customers. It also says this can cause the pitch down problem, which should be more clear. It will most probably cause a pitch down problem that is dangerous. It doesn't say you can prevent the pitch down ever occurring if you never raise the flaps, or follow the UAS NNC, rather than waiting for the pitch to change significantly at a dangerously low height.

The document is a masterpiece of passive voice legalese that could have explained to pilots the root cause much more clearly so that they knew exactly what they were dealing with and how to prevent the most dangerous consequences ever happening.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 5:44 am

PW100 wrote:
Interested wrote:
PW100 wrote:

It has nothing to do with getting away with, as every change Boeing initiates is validated through FAA. This is just part of every day life and continous improvements.

While Boeing has lots of xplainings to do on so many levels, this one is fairly low at their list. But I guess some see a bear behind every tree . . .


https://www.rt.com/usa/461371-boeing-alert-fix-2020/

Would you like to re-consider your point of view now?


I don't see any new information in there that hasn't been discussed for at least a week on here.


"It has nothing to do with getting away with, as every change Boeing initiates is validated through FAA. This is just part of every day life and continous improvements"

That's what you told us only yesterday.

Boeings plan to rectify the defective sensor 3 years after they discovered it - was initiated by Boeing alone and was not given to FAA to even consider or validate?

How was that possibly continuous improvement in any shape or form? And what has FAA got to do with that decision? Other than it being hidden from them?

I was quite simply giving you the opportunity to correct what you told us.

Don't you want to take that opportunity?
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 6:08 am

PW100 wrote:
Interested wrote:
PW100 wrote:

It has nothing to do with getting away with, as every change Boeing initiates is validated through FAA. This is just part of every day life and continous improvements.

While Boeing has lots of xplainings to do on so many levels, this one is fairly low at their list. But I guess some see a bear behind every tree . . .


I didn't think FAA or the airlines were aware of the faulty sensor?

Boeing chose not to tell them!!

That's how bad this all is

Not exactly a bear behind a tree

Shocking stuff really


I recommend you to read some of the AD's on Boeing and Airbus commercial models. You'll find many items much more shocking to you . . .



My shock is that Boeing chose not to tell the FAA and/or airlines about this fault immediately they found it.

You told us everything Boeing do is validated by FAA??

I'm confused now?? Please educate me some more?

How can such a basic error like this happen in the first place?

Why didn't Boeing tell anybody about this mistake they had made until AFTER the first crash?

If there is moe shocking stuff I've not read about yet then Boeing must be even worse than I could ever imagine possible?
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 10:05 am

sillystrings wrote:
I would agree that the AOA DISAGREE is not that important in the NG and previous models. They do not have any automation relying solely on AOA data. The MAX however had MCAS which had unlimited authority over the stab trim based only on AOA data. This is a completely different situation.


Agree completely that that is a different situation.
However that is not a function/result of AoA, but of MCAS. And it's poor implementation. Once MCAS issue has been corrected, the AoA disagree becomes a moot issue.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 10:06 am

AABusDrvr wrote:
PW100 wrote:
[
Does the 737 (MAX) have an AOA DISAGREE NNC?

Yes, the MAX has an AOA DISAGREE NNC. It’s exactly the same as the procedure for the NG.

OK Thanks.
Is that also a memory item?
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 10:30 am

Interested wrote:
I'm confused now?? Please educate me some more?
You told us everything Boeing do is validated by FAA??

Correct. When Boeing implements this change, it needs to be validated by FAA (or delegated authority). Every change, from the most "simple" bolt/washer/nut, to any piece of software, even seat fabric change, must be validated and approved by the relevant authorities (FAA for Boeing, EASA for Airbus).


Interested wrote:
How can such a basic error like this happen in the first place?

Good question. Perhaps it was a function of insufficient oversight, too much delegated authority combined with poor reporting channels. I'm sure the FAA will have a good look at this. Because, while I remain convinced the issue itself is overblown, FAA definitely will want to know how this was not caught in the various levels of oversight.


Interested wrote:
Why didn't Boeing tell anybody about this mistake they had made until AFTER the first crash?

Perhaps because of the interaction with MCAS, and MCAS being in the centre focus of the investigation.
Safety critical findings must be reported immediately to the authorities. Non-safety critical issues are usually not reported immediately, but will find their way to the authorities when the changes is proposed for certification.
Apparently Boeing found this non-safety critical. Which in itself is not strange. MCAS 1.0 on the other hand . . .



Interested wrote:
If there is moe shocking stuff I've not read about yet then Boeing must be even worse than I could ever imagine possible?

And it is my believe that this question is the reason why the un-grounding is taking so long. If the piss poor MCAS was not caught by the certification checks and balances, what else might have escaped?
Can other authorities (EASA, TCCA, CAAC, etc) trust FAA certification process when it wasn't able to detect something so fundamentally wrong as MCAS?
And to a lesser extent, I'll happily give you that, the AoA issue. If at all, the AoA issue increases the doubts these agencies have grown against FAA and Boeing. As an old Dutch saying goes: Trust arrives by foot, leaves by horse. I guess the meaning of that is rather obvious.
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 11:00 am

PW100 wrote:
sillystrings wrote:
I would agree that the AOA DISAGREE is not that important in the NG and previous models. They do not have any automation relying solely on AOA data. The MAX however had MCAS which had unlimited authority over the stab trim based only on AOA data. This is a completely different situation.


Agree completely that that is a different situation.
However that is not a function/result of AoA, but of MCAS. And it's poor implementation. Once MCAS issue has been corrected, the AoA disagree becomes a moot issue.

If MCAS relies on AOA data, then it most definitely has an impact on the system. The issue isn't whether the new MCAS will be better implemented. The issue (among others) is that the AOA DISAGREE NNC was carried over from NG without an update. It's likely the reason for not updating the NNC is because this would require Boeing to disclose the existence of MCAS, and also probably require additional training.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 11:21 am

PW100 wrote:
Interested wrote:
I'm confused now?? Please educate me some more?
You told us everything Boeing do is validated by FAA??

Correct. When Boeing implements this change, it needs to be validated by FAA (or delegated authority). Every change, from the most "simple" bolt/washer/nut, to any piece of software, even seat fabric change, must be validated and approved by the relevant authorities (FAA for Boeing, EASA for Airbus).


It was not declared for 13 month to the FAA by Boeing, that the certified warning AoA disagree was not working, because of how it was implemented.

Rather than presenting this change to the FAA for validation, Boeing seems to have completely ignored the fact that the FAA needs to validate changes.

So clearly Boeing does not present changes to the FAA, if it is to much of a bother.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 11:27 am

sillystrings wrote:
PW100 wrote:
sillystrings wrote:
I would agree that the AOA DISAGREE is not that important in the NG and previous models. They do not have any automation relying solely on AOA data. The MAX however had MCAS which had unlimited authority over the stab trim based only on AOA data. This is a completely different situation.


Agree completely that that is a different situation.
However that is not a function/result of AoA, but of MCAS. And it's poor implementation. Once MCAS issue has been corrected, the AoA disagree becomes a moot issue.

If MCAS relies on AOA data, then it most definitely has an impact on the system. The issue isn't whether the new MCAS will be better implemented. The issue (among others) is that the AOA DISAGREE NNC was carried over from NG without an update. It's likely the reason for not updating the NNC is because this would require Boeing to disclose the existence of MCAS, and also probably require additional training.

Yes, there are strong indications that push this scenario. Normally a pilot procedure is created for a situation when a failure mode can't be handled by the design (mainly using redundancy). It look like there used this normal flow in the revers order: there identified a pilot procedure (stab runaway) that could (hardly) handle the failure mode and decided that it allow a add a new hidden failure mode without notice. It's so against the normal safety practice that it will inevitably raise questions whenever it was intentionally or incompetency.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 12:19 pm

Ralph Nader Says Boeing 737 Max Is Flawed and Should Never Fly Again

Consumer advocate Ralph Nader said the larger engines mounted to the Boeing 737 Max represented a design flaw and called for the plane to be permanently grounded.


https://www.bloomberg.com/news/articles/2019-06-04/nader-says-boeing-737-max-is-flawed-and-should-never-fly-again
 
planecane
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 12:57 pm

MrBren wrote:
Ralph Nader Says Boeing 737 Max Is Flawed and Should Never Fly Again

Consumer advocate Ralph Nader said the larger engines mounted to the Boeing 737 Max represented a design flaw and called for the plane to be permanently grounded.


https://www.bloomberg.com/news/articles/2019-06-04/nader-says-boeing-737-max-is-flawed-and-should-never-fly-again

This was posted a week ago and Ralph Nader is not an expert on aircraft design. He's an attorney with no engineering education in his background. I'm sure all that lost family members in either MAX crash would have the same opinion.

While the max shouldn't have ever flown with MCAS 1.0, as long as the fix is properly thought out and implemented, there is no reason the MAX won't be as safe as the NG going forward.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 1:08 pm

planecane wrote:
MrBren wrote:
Ralph Nader Says Boeing 737 Max Is Flawed and Should Never Fly Again

Consumer advocate Ralph Nader said the larger engines mounted to the Boeing 737 Max represented a design flaw and called for the plane to be permanently grounded.


https://www.bloomberg.com/news/articles/2019-06-04/nader-says-boeing-737-max-is-flawed-and-should-never-fly-again

This was posted a week ago and Ralph Nader is not an expert on aircraft design. He's an attorney with no engineering education in his background. I'm sure all that lost family members in either MAX crash would have the same opinion.

While the max shouldn't have ever flown with MCAS 1.0, as long as the fix is properly thought out and implemented, there is no reason the MAX won't be as safe as the NG going forward.

I do wonder if Nader might be the hold out and take it all the way to court rather than settle like all the others are likely to do.

Ray
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 1:11 pm

planecane wrote:
MrBren wrote:
Ralph Nader Says Boeing 737 Max Is Flawed and Should Never Fly Again

Consumer advocate Ralph Nader said the larger engines mounted to the Boeing 737 Max represented a design flaw and called for the plane to be permanently grounded.


https://www.bloomberg.com/news/articles/2019-06-04/nader-says-boeing-737-max-is-flawed-and-should-never-fly-again

This was posted a week ago and Ralph Nader is not an expert on aircraft design. He's an attorney with no engineering education in his background. I'm sure all that lost family members in either MAX crash would have the same opinion.

While the max shouldn't have ever flown with MCAS 1.0, as long as the fix is properly thought out and implemented, there is no reason the MAX won't be as safe as the NG going forward.

Weeell, while most reasonable people aren't hardline regulatory advocates like Nader it's obviously not true that the MAX has 'no reason' to be less safe than the NG even with a safer software - the plane itself is a compromise and a plane with a smaller engine on essentially the same frame is obviously going to be inherently and logically safer. No?
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 1:15 pm

planecane wrote:
MrBren wrote:
Ralph Nader Says Boeing 737 Max Is Flawed and Should Never Fly Again

Consumer advocate Ralph Nader said the larger engines mounted to the Boeing 737 Max represented a design flaw and called for the plane to be permanently grounded.


https://www.bloomberg.com/news/articles/2019-06-04/nader-says-boeing-737-max-is-flawed-and-should-never-fly-again

This was posted a week ago and Ralph Nader is not an expert on aircraft design. He's an attorney with no engineering education in his background. I'm sure all that lost family members in either MAX crash would have the same opinion.

While the max shouldn't have ever flown with MCAS 1.0, as long as the fix is properly thought out and implemented, there is no reason the MAX won't be as safe as the NG going forward.


Can you explain how a plane with engines too big for the fuselage that needs software to fix issues with stability etc

Can be as safe as the same plane with the right sized engines for the fuselage that doesnt need software to fix stability issues etc

There's more things can go wrong or need correcting?

Maybe you could say it can nearly be as safe as the NG

Regardless - isn't it a sorry state of affairs when a new plane as important as this one is introduced and the best we can hope for is it will eventually be as safe as the older plane it replaced

Shame that's all we can aim for now
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 1:42 pm

planecane wrote:
MrBren wrote:
Ralph Nader Says Boeing 737 Max Is Flawed and Should Never Fly Again

Consumer advocate Ralph Nader said the larger engines mounted to the Boeing 737 Max represented a design flaw and called for the plane to be permanently grounded.


https://www.bloomberg.com/news/articles/2019-06-04/nader-says-boeing-737-max-is-flawed-and-should-never-fly-again

This was posted a week ago and Ralph Nader is not an expert on aircraft design. ....


Do one - at this stage - really need to be an expert on aircraft design to know that this can not be "making safe things even safer"?

Why don't they publish the MCAS certification Flighttest results? If they changed the MCAS action up to a such high value, one could suspect that the tests results with the previously planned low values must have been a desaster in stabilty of flight
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:02 pm

Interested wrote:
Can you explain how a plane with engines too big for the fuselage that needs software to fix issues with stability etc

Can be as safe as the same plane with the right sized engines for the fuselage that doesnt need software to fix stability issues etc

Somehow 737NG, with engines so big that nacelle had to be flattened on the bottom - apparently, due to engine too big for the fuselage - happened to be statistically safer than 737 jurassic, which had right sized engine.
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:09 pm

kalvado wrote:
Interested wrote:
Can you explain how a plane with engines too big for the fuselage that needs software to fix issues with stability etc

Can be as safe as the same plane with the right sized engines for the fuselage that doesnt need software to fix stability issues etc

Somehow 737NG, with engines so big that nacelle had to be flattened on the bottom - apparently, due to engine too big for the fuselage - happened to be statistically safer than 737 jurassic, which had right sized engine.

NG did not need MCAS, so maybe the engines were not too large for the fuselage? It was a bit large for the ground clearance, but not in way that required compromising aerodynamics.
 
planecane
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:24 pm

Interested wrote:
planecane wrote:
MrBren wrote:

This was posted a week ago and Ralph Nader is not an expert on aircraft design. He's an attorney with no engineering education in his background. I'm sure all that lost family members in either MAX crash would have the same opinion.

While the max shouldn't have ever flown with MCAS 1.0, as long as the fix is properly thought out and implemented, there is no reason the MAX won't be as safe as the NG going forward.


Can you explain how a plane with engines too big for the fuselage that needs software to fix issues with stability etc

Can be as safe as the same plane with the right sized engines for the fuselage that doesnt need software to fix stability issues etc

There's more things can go wrong or need correcting?

Maybe you could say it can nearly be as safe as the NG

Regardless - isn't it a sorry state of affairs when a new plane as important as this one is introduced and the best we can hope for is it will eventually be as safe as the older plane it replaced

Shame that's all we can aim for now


Based on hull loss accident statistics and fatal hull loss accident statistics, the 737NG is the 4th safest aircraft with over a million departures ever produced. The 717, 787 and CRJ700/900/1000 are all ahead of it at a 0 accident rate. However, all of those models have far less in service and far less flights. I don't believe any NG hull losses are root caused to a design issue. Therefore, it is probably not possible to make a safer plane than the 737NG without making it prohibitavely expensive or inefficient.

With a properly designed and implemented MCAS, there is no reason for the MAX to be less safet than the NG. I don't think requiring software for edge of envelope stability/stall prevention is inherently less safe. Are all aircraft that require yaw dampers unacceptable?
 
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:25 pm

It's about the lift the MAX's nacelles generate at high angle of attack due to complex airflow between nacelle, pylon and wing, rather than "engine too big".
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:31 pm

asdf wrote:
planecane wrote:
MrBren wrote:

This was posted a week ago and Ralph Nader is not an expert on aircraft design. ....


Do one - at this stage - really need to be an expert on aircraft design to know that this can not be "making safe things even safer"?

Why don't they publish the MCAS certification Flighttest results? If they changed the MCAS action up to a such high value, one could suspect that the tests results with the previously planned low values must have been a desaster in stabilty of flight


No. If you read the reporting, they determined MCAS was needed for some situations at low speed flight where they originally only thought it was needed in high speed flight. The reason the additional authority was needed was because the stabilizer (or any control surface) has less physical authority at low speed. It is not because the lower authority would have been a "disaster in stability of flight."

Spoliers are used for roll control in low speed flight for more control authority. It's the same concept where more control surface force is needed when the airflow is slower over the wings and control surfaces.
 
FluidFlow
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:48 pm

Revelation wrote:
It's about the lift the MAX's nacelles generate at high angle of attack due to complex airflow between nacelle, pylon and wing, rather than "engine too big".



In my opinion it is mostly the position not so the size of it.

Edit: Sorry that was a lot of crap i wrote here MCAS is not active when flaps are down.
Last edited by FluidFlow on Tue Jun 11, 2019 2:56 pm, edited 1 time in total.
 
frmrCapCadet
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:49 pm

Nader can claim some credit for Florida going to Bush and several hundred thousand people dying in Iraq. I think he would do well to shut up, crawl back into his burrow, and disappear.
Buffet: the airline business...has eaten up capital...like..no other (business)
 
kalvado
Posts: 1887
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:52 pm

ArgentoSystems wrote:
kalvado wrote:
Interested wrote:
Can you explain how a plane with engines too big for the fuselage that needs software to fix issues with stability etc

Can be as safe as the same plane with the right sized engines for the fuselage that doesnt need software to fix stability issues etc

Somehow 737NG, with engines so big that nacelle had to be flattened on the bottom - apparently, due to engine too big for the fuselage - happened to be statistically safer than 737 jurassic, which had right sized engine.

NG did not need MCAS, so maybe the engines were not too large for the fuselage? It was a bit large for the ground clearance, but not in way that required compromising aerodynamics.

So too large for fuselage or overall layout suffered?
I believe A320 fuselage is about same size and handles same size engines as MAX without extra issues.
So starting statement
Interested wrote:
plane with engines too big for the fuselage

becomes questionable. Which doesn't bring extra credibility to the rest of it.
If people want to blame BOeing for wrongdoing, they need to understanding the essence of a problem beyond basic statements which quickly become meaningless and even incorrect after a few iterations.
 
sillystrings
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 2:56 pm

planecane wrote:
asdf wrote:
planecane wrote:
This was posted a week ago and Ralph Nader is not an expert on aircraft design. ....


Do one - at this stage - really need to be an expert on aircraft design to know that this can not be "making safe things even safer"?

Why don't they publish the MCAS certification Flighttest results? If they changed the MCAS action up to a such high value, one could suspect that the tests results with the previously planned low values must have been a desaster in stabilty of flight


No. If you read the reporting, they determined MCAS was needed for some situations at low speed flight where they originally only thought it was needed in high speed flight. The reason the additional authority was needed was because the stabilizer (or any control surface) has less physical authority at low speed. It is not because the lower authority would have been a "disaster in stability of flight."

Spoliers are used for roll control in low speed flight for more control authority. It's the same concept where more control surface force is needed when the airflow is slower over the wings and control surfaces.

Wouldn't it make sense to limit MCAS authority based (at least) on speed? To me it's inconceivable that Boeing would expand MCAS authority in this fashion without examining what are the consequences to the original design requirement. It just doesn't add up. I find it extremely unlikely that no one was asking these questions, so the issue is how were these questions addressed.
 
ArgentoSystems
Posts: 313
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:03 pm

kalvado wrote:
I believe A320 fuselage is about same size and handles same size engines as MAX without extra issues.

I think you are nitpicking. You know what the problems is. Nader talks to masses and he needs to simplify the problem to the level of general folk.
 
ArgentoSystems
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:04 pm

sillystrings wrote:
Wouldn't it make sense to limit MCAS authority based (at least) on speed?

It is, even in MCAS 1.0. For high speeds the authority is less than for low speeds.
 
XRAYretired
Posts: 554
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:10 pm

mjoelnir wrote:
PW100 wrote:
Interested wrote:
I'm confused now?? Please educate me some more?
You told us everything Boeing do is validated by FAA??

Correct. When Boeing implements this change, it needs to be validated by FAA (or delegated authority). Every change, from the most "simple" bolt/washer/nut, to any piece of software, even seat fabric change, must be validated and approved by the relevant authorities (FAA for Boeing, EASA for Airbus).


It was not declared for 13 month to the FAA by Boeing, that the certified warning AoA disagree was not working, because of how it was implemented.

Rather than presenting this change to the FAA for validation, Boeing seems to have completely ignored the fact that the FAA needs to validate changes.

So clearly Boeing does not present changes to the FAA, if it is to much of a bother.

You missed the target I believe. The 'change' had not been proposed and therefore not yet submitted for approval by FAA (delegated ODA) although relevant ODAs may have been aware of the problem. In fact? as reported, it was not intended to be submitted until 10 MAX was approved ~2020. In this light, I suspect that no actual 'change' to the PFD fitted to 8 MAX would be proposed other than retro-fitting 10 MAX PFD (already correctly configured with AOA DISAGREE alert as standard) to 8 MAX as an upgrade -at cost- to the 8 MAX operators. I.e. the development and validation costs would be borne by the 10 MAX project budget already sanctioned, and retro-fit costs by the operators. (It may also suggest that they were intending to retro-fit 8 MAX with 10 MAX PFDs anyway for some other reasons before this problem was known?).

Personally, I would have thought that the problem should have been notified to the operators (and FAA) via a Notice or Service Information Letter or similar since it was a clear non-conformance to what had been sold and was at the pilot interface. (NB. a prima-facia case for failure under Strict Liability not to do so in my opinion). But, should it have been so, I suspect that this would then have Boeing in the position of having to bear the costs having admitted fault, and since it would be unlikely that anyone would have accepted a three year delay, this would include costs of development, validation and certification of the change in addition to the 10 MAX project costs, and a retrofit on the fleet existing at the time. In support of the argument, they may have been paying for say 350 aircraft retro-fits or being paid for maybe 1500 aircraft retro-fits with 10 MAX PFDs (make money out of it!).

It is argued that notification or fix of the alert problem was/is not of any import because the alert is pointless/unnecessary anyway. If so why is it fitted? Why was it fitted to NG when the PFD was developed? It is also offered, in answer, that it is an aid to maintenance as a potential reason for it to be fitted.

The missing alert became of import in the aftermath of JT610 and, suddenly, it is to be corrected and change is to be retro-fitted in concert with the MCAS fix. I would suspect this is because the investigation team asked the question of why AOA DISAGREE was not reported post flight JT043, as it should have been, and potentially could have resulted in AOA high being fixed before JT610. The JT043 pilot was probably in the dock for this at first. It is a question I wondered as soon as became aware that AOA DISAGREE alert on PFD existed.

Some red herring. Pushing AOA DISAGREE alert not available quickly and quietly under the carpet as inconsequential may be the red herring here.

Ray
 
DenverTed
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:24 pm

ArgentoSystems wrote:
sillystrings wrote:
Wouldn't it make sense to limit MCAS authority based (at least) on speed?

It is, even in MCAS 1.0. For high speeds the authority is less than for low speeds.

How so?
 
FluidFlow
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:33 pm

DenverTed wrote:
ArgentoSystems wrote:
sillystrings wrote:
Wouldn't it make sense to limit MCAS authority based (at least) on speed?

It is, even in MCAS 1.0. For high speeds the authority is less than for low speeds.

How so?


It seems tho it had full authority on ET even tho the aircraft was way over the intended speed limits.

As i understood it was also first dependent on gforce and AoA and not speed.
 
mjoelnir
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:35 pm

frmrCapCadet wrote:
Nader can claim some credit for Florida going to Bush and several hundred thousand people dying in Iraq. I think he would do well to shut up, crawl back into his burrow, and disappear.


Ralph Nader lost his grand niece in the Ethiopian crash. I think he as the right to vent about the 737 MAX and Boeing.
 
snowkarl
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:38 pm

Revelation wrote:
It's about the lift the MAX's nacelles generate at high angle of attack due to complex airflow between nacelle, pylon and wing, rather than "engine too big".

Obviously. But this is pedantry. The only reason the MAX has a tendancy to pitch town due to the high aoa is because they wanted to mount more efficient engines in a frame that was in fact too small.

It's an irrelevant point to make to switch focus from what actually caused the poor design to be implemented. There's a very simple reason this same issue is not present in the NG.
 
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par13del
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:39 pm

kalvado wrote:
So too large for fuselage or overall layout suffered?
I believe A320 fuselage is about same size and handles same size engines as MAX without extra issues.
So starting statement

So to be clear, in every other thread discussing the 737 and the A320 we are constantly told how much wider and more comfortable the A320 is over the 737, every 737 fan who says they do not notice the difference are ridiculed, but here we are now being told that there is little to no difference in size between the two, say it ain't so, blasphemy of the highest order.

Hmmmm.... the things that come out when trying to make a point.
 
OldAeroGuy
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 3:48 pm

kalvado wrote:
So too large for fuselage or overall layout suffered?
I believe A320 fuselage is about same size and handles same size engines as MAX without extra issues.
So starting statement
Interested wrote:
plane with engines too big for the fuselage

becomes questionable. Which doesn't bring extra credibility to the rest of it.
If people want to blame BOeing for wrongdoing, they need to understanding the essence of a problem beyond basic statements which quickly become meaningless and even incorrect after a few iterations.


Actually, the A320neo engines have a larger diameter than the 737 MAX engines.

A320neo fan diameters.
LEAP 1A: 78.0"
PW1000G: 81.0"

737 MAX fan diameter.
LEAP 1B: 69.4"

If you look at fan diameter vs fuselage width, the results are:
A320neo (156" fuselage width)

LEAP 1A Fan/Fuselage Width: 50.0%
PW1000G Fan/Fuselage Width: 51.9%

737 MAX (148" fuselage width)

LEAP 1B Fan/Fuselage Width: 46.7%

Some much for simple minded comments on complex aerodynamic situations.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
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Revelation
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:00 pm

snowkarl wrote:
Revelation wrote:
It's about the lift the MAX's nacelles generate at high angle of attack due to complex airflow between nacelle, pylon and wing, rather than "engine too big".

Obviously. But this is pedantry. The only reason the MAX has a tendancy to pitch town due to the high aoa is because they wanted to mount more efficient engines in a frame that was in fact too small.

Complexity is the opposite of pedantry.

You are presuming facts not in evidence, such as there could have been a way to mount the LEAP onto 737 and not need MCAS, such as a different nacelle or pylon design, yet they reached for MCAS rather than try other nacelle or pylon designs when they encountered the pitch up (not down) issue because it appeared to be the quickest way forward.

Engineering is all about trade offs. You don't get to build an all new plane just because integrating a new engine is complicated, because building an all new airplane comes with side effects like losing much of your market share and customer base due to the time needed to develop an all new airplane. Of course another thing you don't get to do is undersell the complexity of the engine integration and botch the implementation.
Wake up to find out that you are the eyes of the world
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Wake now, discover that you are the song that the morning brings
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kalvado
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:05 pm

ArgentoSystems wrote:
kalvado wrote:
I believe A320 fuselage is about same size and handles same size engines as MAX without extra issues.

I think you are nitpicking. You know what the problems is. Nader talks to masses and he needs to simplify the problem to the level of general folk.

Problem is with meaningless use of word, which commonly happens when complex statement are used by big crowds. Happened quite often, never ends good.
 
Interested
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:10 pm

Revelation wrote:
snowkarl wrote:
Revelation wrote:
It's about the lift the MAX's nacelles generate at high angle of attack due to complex airflow between nacelle, pylon and wing, rather than "engine too big".

Obviously. But this is pedantry. The only reason the MAX has a tendancy to pitch town due to the high aoa is because they wanted to mount more efficient engines in a frame that was in fact too small.

Complexity is the opposite of pedantry.

You are presuming facts not in evidence, such as there could have been a way to mount the LEAP onto 737 and not need MCAS, such as a different nacelle or pylon design, yet they reached for MCAS rather than try other nacelle or pylon designs when they encountered the pitch up (not down) issue because it appeared to be the quickest way forward.

Engineering is all about trade offs. You don't get to build an all new plane just because integrating a new engine is complicated, because building an all new airplane comes with side effects like losing much of your market share and customer base due to the time needed to develop an all new airplane. Of course another thing you don't get to do is undersell the complexity of the engine integration and botch the implementation.


In an industry where Airbus and Boeing pretty much have things sewn up. Do we really need trade offs that reduce safety and end up killing people.

Surely every plane should be a chance to improve not compromise

It's all about money. It shouldn't be allowed to happen like it's happened. These big guys have too much power to do what they want.
 
seb76
Posts: 51
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:21 pm

OldAeroGuy wrote:
kalvado wrote:
So too large for fuselage or overall layout suffered?
I believe A320 fuselage is about same size and handles same size engines as MAX without extra issues.
So starting statement
Interested wrote:
plane with engines too big for the fuselage

becomes questionable. Which doesn't bring extra credibility to the rest of it.
If people want to blame BOeing for wrongdoing, they need to understanding the essence of a problem beyond basic statements which quickly become meaningless and even incorrect after a few iterations.


Actually, the A320neo engines have a larger diameter than the 737 MAX engines.

A320neo fan diameters.
LEAP 1A: 78.0"
PW1000G: 81.0"

737 MAX fan diameter.
LEAP 1B: 69.4"

If you look at fan diameter vs fuselage width, the results are:
A320neo (156" fuselage width)

LEAP 1A Fan/Fuselage Width: 50.0%
PW1000G Fan/Fuselage Width: 51.9%

737 MAX (148" fuselage width)

LEAP 1B Fan/Fuselage Width: 46.7%

Some much for simple minded comments on complex aerodynamic situations.


What is (conveniently?) missing in this comparison is the initial size of the JT8D had when the fuselage was designed compared to the LEAP 1B of today...
it was 48" and the same fuselage

LEAP 1B Fan/Fuselage Width: 46.7%
JT8D Fan/Fuselage Width: 32,5%

Still convinced that it has a neglectible influence on the aerodynamics of the airframe?
And we talk about a properly working engine with power output under control. Now imagine how much rudder authorithy you need to counter the drag of a stopped engine after an engine failure. Will it be the same for a tiny engine or a large one? Of course Boeing had this tested and demonstrated before launching the max, but this is just to explain that putting a big engine in a place that was supposed to fit a large has many side effects.
 
DenverTed
Posts: 247
Joined: Wed Mar 27, 2019 11:12 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:27 pm

seb76 wrote:
OldAeroGuy wrote:
kalvado wrote:
So too large for fuselage or overall layout suffered?
I believe A320 fuselage is about same size and handles same size engines as MAX without extra issues.
So starting statement

becomes questionable. Which doesn't bring extra credibility to the rest of it.
If people want to blame BOeing for wrongdoing, they need to understanding the essence of a problem beyond basic statements which quickly become meaningless and even incorrect after a few iterations.


Actually, the A320neo engines have a larger diameter than the 737 MAX engines.

A320neo fan diameters.
LEAP 1A: 78.0"
PW1000G: 81.0"

737 MAX fan diameter.
LEAP 1B: 69.4"

If you look at fan diameter vs fuselage width, the results are:
A320neo (156" fuselage width)

LEAP 1A Fan/Fuselage Width: 50.0%
PW1000G Fan/Fuselage Width: 51.9%

737 MAX (148" fuselage width)

LEAP 1B Fan/Fuselage Width: 46.7%

Some much for simple minded comments on complex aerodynamic situations.


What is (conveniently?) missing in this comparison is the initial size of the JT8D had when the fuselage was designed compared to the LEAP 1B of today...
it was 48" and the same fuselage

LEAP 1B Fan/Fuselage Width: 46.7%
JT8D Fan/Fuselage Width: 32,5%

Still convinced that it has a neglectible influence on the aerodynamics of the airframe?
And we talk about a properly working engine with power output under control. Now imagine how much rudder authorithy you need to counter the drag of a stopped engine after an engine failure. Will it be the same for a tiny engine or a large one? Of course Boeing had this tested and demonstrated before launching the max, but this is just to explain that putting a big engine in a place that was supposed to fit a large has many side effects.

Like an 81" GTF on an A319? I'm not sure it is the configuration, just that Boeing botched the control system.
 
IADFCO
Posts: 127
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:30 pm

FluidFlow wrote:
Revelation wrote:
It's about the lift the MAX's nacelles generate at high angle of attack due to complex airflow between nacelle, pylon and wing, rather than "engine too big".



In my opinion it is mostly the position not so the size of it.

[...]

It's quite likely that's a wing airflow issue at high AoA, besides the extra nacelle lift, but nobody really knows that for a fact. It could be a minor change compared with the NG, or a catastrophically worse post stall pattern, or anything in between.

Ralph Nader doesn't make the list of my 1000 most favorite politicians, but I do hope that he manages to extract technical facts about the MAX aerodynamics from Boeing and the FAA. Otherwise I'm afraid it would be out of court settlements and NDAs as far as the eye can see. He doesn't need to know anything about aerodynamics or piloting. He can work with people who do.
 
DenverTed
Posts: 247
Joined: Wed Mar 27, 2019 11:12 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:31 pm

What's the new MCAS input, just AOA based on two sensors instead of one? Or is speed or something else now an input?
 
snowkarl
Posts: 19
Joined: Fri May 24, 2019 7:48 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:34 pm

Revelation wrote:
snowkarl wrote:
Revelation wrote:
It's about the lift the MAX's nacelles generate at high angle of attack due to complex airflow between nacelle, pylon and wing, rather than "engine too big".

Obviously. But this is pedantry. The only reason the MAX has a tendancy to pitch town due to the high aoa is because they wanted to mount more efficient engines in a frame that was in fact too small.

Complexity is the opposite of pedantry.

You are presuming facts not in evidence, such as there could have been a way to mount the LEAP onto 737 and not need MCAS, such as a different nacelle or pylon design, yet they reached for MCAS rather than try other nacelle or pylon designs when they encountered the pitch up (not down) issue because it appeared to be the quickest way forward.

Engineering is all about trade offs. You don't get to build an all new plane just because integrating a new engine is complicated, because building an all new airplane comes with side effects like losing much of your market share and customer base due to the time needed to develop an all new airplane. Of course another thing you don't get to do is undersell the complexity of the engine integration and botch the implementation.


Not only are you misrepresenting what was implied because I never argued against any of this, only the fact that the larger engines directly caused the plane's structural imbalance and the fatal flaw MCAS was supposed to counteract.

It's like being delivered a burned piece of bread and when you complained it's burned the seller says - no actually, the erroneous readings on the oven caused the temperature to be too high! It's the same thing buddy.

Also, to say that engineering is about trade-offs and describing "losing a market share" as a trade off is really quite brilliant. Yes, they knowingly engineered a subpar plane which has already killed over 300 people becaues their lack of initiative and foresight caused a panic to rush out a competitor to Airbus. This has NOTHING to do with "engineering trade offs" and simply a very poor and catastrophic decision that they should not only be made to paid heavily for but also receive full blame for - rather than having their mistakes pushed onto pilots who were not even briefed on how their plane worked.

Have anyone watched the new Chernobyl show from HBO? Watch it and just imagine that the Vladimir I Lenin reactor number 4 is replaced by Boeing's MAX and you'll struggle to find any difference. It's really quite disturbing how poorly they've not only acted throughout these past years but also the revisionist messaging being put out about the pilots.

It's never going to happen but it would be better for everyone if China or someone actually started competing with the duopoly and forced AB/B to actually innovate and improve rather than just protecting the status quo, because standards are quite obviously slipping.
 
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Revelation
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Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:41 pm

Interested wrote:
Do we really need trade offs that reduce safety and end up killing people.

If somebody intended to reduce safety and intended to kill people you might have a point.

They didn't, so you don't.

Now, back on to my ignore list you go.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
Interested
Posts: 647
Joined: Thu May 19, 2016 12:19 pm

Re: Boeing 737MAX Grounded Worldwide Q2 2019

Tue Jun 11, 2019 4:50 pm

Revelation wrote:
Interested wrote:
Do we really need trade offs that reduce safety and end up killing people.

If somebody intended to reduce safety and intended to kill people you might have a point.

They didn't, so you don't.

Now, back on to my ignore list you go.


Interesting reply?

Have you got any evidence that anything they did with Max was done to improve safety over NG?

I can't see anything. It's about improving efficiency and money. And needing extra software to be stable it brings in more things that can go wrong. And have gone wrong.

So your answer doesn't do you any credit.

Safety was reduced. There's certainly no decision to put safety ahead of efficiency. And yes that has ended up killing people.

Doesn't need to be intentional for people to die for the trade offs to be unacceptable . So my point stands.

It's airline safety gone backwards. Unacceptable in the modern age IMO. Should never have been allowed to happen.
Last edited by Interested on Tue Jun 11, 2019 4:52 pm, edited 1 time in total.

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