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Amiga500
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 2:00 pm

Amiga500 wrote:
AvFanNJ wrote:
New from Aviation Week. You may need to be a paid subscriber to access full article: https://aviationweek.com/commercial-avi ... -grounding

I found this paragraph interesting: "The briefings continue to emphasize that the MCAS, which was added to the speed-trim system to standardize handling qualities with those of the 737 Next Generation, is “not a stall-protection function and not a stall-prevention function,” says Mike Sinnett, Boeing Commercial Airplanes vice president of product development and future airplane development. “It is a handling-qualities function. There’s a misconception it is something other than that."


You want to know why that is a load of bull?

Boeing have turned around 2 weeks ago and said; "OK, MCAS makes things worse. We're gonna pull it off the aircraft permanently and have a new type rating for MAX."

The cost if Boeing paid for every pilot to be trained on the new type would be noise compared to how much they are going to have to pay out with the continued grounding.


Hence - its quite obvious MCAS does more than "standardize handling qualities". Furthermore, to "standardize handling qualities", it is relatively straightforward to add dampers and even servos to the main elevator controls that blend in at higher AoAs.


Hmm, can't edit this for some reason.

Line 2 should have read:

Boeing could have turned around 2 weeks ago and said; "OK, MCAS makes things worse. We're gonna pull it off the aircraft permanently and have a new type rating for MAX."
 
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keesje
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 2:20 pm

MD80Ttail wrote:

The public has an amazingly short attention span. It doesn’t really matter long term or Boeing or the Max. The public will forget out this in literally eight seconds. A recent study found the average attention span has dropped from 12 seconds to a mere eight seconds. The same study found goldfish have an attention span of nine seconds.

Very sorry for the crashes and people involved, their friends and families. However, this just isn’t a bid deal for the industry, Boeing or the Max long term. Five years from now no one will remember and all will be well with Boeing, Max and industry. Please understand the prior comment is only related to the program. Crashes are horrible and life is precious.


This is one of the many hope mails I've seen. Remember the "software fix in 4 weeks" news. Just 2 weeks ago.
I guess many people with stock trying to soften the storm & encourage each other.
"Never mistake motion for action." Ernest Hemingway
 
XRAYretired
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 2:22 pm

Elementalism wrote:
ArgentoSystems wrote:
AvFanNJ wrote:
New from Aviation Week. You may need to be a paid subscriber to access full article: https://aviationweek.com/commercial-avi ... -grounding

I found this paragraph interesting: "The briefings continue to emphasize that the MCAS, which was added to the speed-trim system to standardize handling qualities with those of the 737 Next Generation, is “not a stall-protection function and not a stall-prevention function,” says Mike Sinnett, Boeing Commercial Airplanes vice president of product development and future airplane development. “It is a handling-qualities function. There’s a misconception it is something other than that."


I find this not making much sense. If that is indeed the case, we can just remove MCAS and train pilot to get used to the new handling.

Also, the implementation of the said goal ("It is a handling-qualities function") is really retarded. It is like implementing speed limit on a car my applying brakes, instead of limiting engine power.


I think the issue becomes commonality loss between NG and MAX. If the handling characteristics are different. A pilot has to be type certified in the MAX. afaik in the US, a pilot can only hold one type rating at any given time.


if so, should the headline read?:-

DID US ARLINE PILOT ROSTERING DRIVE A/C DESIGN AND CERTIFICATION NON-COMPLIANCE CRASH HORROR!?


Ray
 
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AirlineCritic
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 2:38 pm

If those statements are true, that is pretty shocking. You can't improve if you're not recognising the situation you are in. If those public statements are also the internal mindset, they haven't come close to even starting the work. People will call their aviation regulators and demand that while such an attitude persists, they shall not certify the aircraft.

I think what's needed is a comprehensive recognition that the system consisting of:

- sensors & mcas
- stick shaker
- manual trim and the efficacy of the trim motors under different flight conditions
- procedures, pilot training & simulators

has at failure modes that were not understood. The problem needs to be understood, communicated and addressed. If it takes a hardware modification, so be it. But At this point, Boeing cannot afford to fail. All these weasel words and attempts to explain things in the best like are now hurting them. I think I predicted already long time ago a 6-9month grounding. I think that is now looking to be the best case, and a total failure of the MAX program is the worst case. I'm not a shareholder, but if I was, I'd be very scared.
 
planecane
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 2:52 pm

ArgentoSystems wrote:
More from the article:

Sinnett says: “Mechanically, on the NG there is a column cutoff switch that stops any automatic trim when the column is back to a certain spot. On the MAX, we still needed automatic trim when you got to that spot. "

I understand this as on NG if you pull the yoke (or what it is called) it disables automatic trim, immediately putting the pilot back in control. But on Max it does not. That is a hell of a difference. Omitting this from the manual, and saying pilots don't need additional training is... well I can't wrap my head around it.

Also, this begs a question: why do they "still needed automatic trim when you got to that spot."?


The column switches are still there. Without MCAS operating they still disable automatic trim if the column is moved opposite of the automatic trim.

The switches can't disable MCAS because at the point MCAS is supposed to kick in, the pilot would be putting back pressure on the column for a coordinated turn. The pilot is intentionally pitching up. The nacelles on the MAX start to add even more pitch up and reduce the force on the column necessary to pitch up even more. MCAS is intended to counteract that. If the switches disabled MCAS it would never activate because the situation it is designed for guarantees control column input opposite to the automatic trim.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 3:11 pm

Amiga500 wrote:
AvFanNJ wrote:
New from Aviation Week. You may need to be a paid subscriber to access full article: https://aviationweek.com/commercial-avi ... -grounding

I found this paragraph interesting: "The briefings continue to emphasize that the MCAS, which was added to the speed-trim system to standardize handling qualities with those of the 737 Next Generation, is “not a stall-protection function and not a stall-prevention function,” says Mike Sinnett, Boeing Commercial Airplanes vice president of product development and future airplane development. “It is a handling-qualities function. There’s a misconception it is something other than that."


You want to know why that is a load of bull?

Boeing have turned around 2 weeks ago and said; "OK, MCAS makes things worse. We're gonna pull it off the aircraft permanently and have a new type rating for MAX."

The cost if Boeing paid for every pilot to be trained on the new type would be noise compared to how much they are going to have to pay out with the continued grounding.

Hence - its quite obvious MCAS does more than "standardize handling qualities". Furthermore, to "standardize handling qualities", it is relatively straightforward to add dampers and even servos to the main elevator controls that blend in at higher AoAs.


If your stick response is non linear, you can not certify the plane. And without MCAS the additional lift from the engines creates a momentum that will push the nose higher while keeping the same force on the stick. On a FBW plane it would be a few lines of code and it would be done, on the 737 this is a problem.
 
uta999
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 3:37 pm

If the MAX is to remain grounded for 6-9 months, that’s another 378 new builds in addition to the already 450 built.

All will need modifying, both hardware and software. The entire program could collapse if they persist in getting it wrong.
Your computer just got better
 
LDRA
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 3:46 pm

seahawk wrote:
Amiga500 wrote:
AvFanNJ wrote:
New from Aviation Week. You may need to be a paid subscriber to access full article: https://aviationweek.com/commercial-avi ... -grounding

I found this paragraph interesting: "The briefings continue to emphasize that the MCAS, which was added to the speed-trim system to standardize handling qualities with those of the 737 Next Generation, is “not a stall-protection function and not a stall-prevention function,” says Mike Sinnett, Boeing Commercial Airplanes vice president of product development and future airplane development. “It is a handling-qualities function. There’s a misconception it is something other than that."


You want to know why that is a load of bull?

Boeing have turned around 2 weeks ago and said; "OK, MCAS makes things worse. We're gonna pull it off the aircraft permanently and have a new type rating for MAX."

The cost if Boeing paid for every pilot to be trained on the new type would be noise compared to how much they are going to have to pay out with the continued grounding.

Hence - its quite obvious MCAS does more than "standardize handling qualities". Furthermore, to "standardize handling qualities", it is relatively straightforward to add dampers and even servos to the main elevator controls that blend in at higher AoAs.


If your stick response is non linear, you can not certify the plane. And without MCAS the additional lift from the engines creates a momentum that will push the nose higher while keeping the same force on the stick. On a FBW plane it would be a few lines of code and it would be done, on the 737 this is a problem.


The actual regulation only says "no abnormal pitch up". It is only the current FAA interpretation of the regulation that AoA response to control column force has to be monotonic.

FAA can simply change its interpretation of the FAR regulation so that MCAS is not required

Quite frankly, using a slow, fixed rate trim actuator(0.27deg/sec) to correct control column feel characteristics in dynamic situation(time constant of seconds) is goofy as hell in the first place.
 
MD80Ttail
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 3:50 pm

keesje wrote:
MD80Ttail wrote:

The public has an amazingly short attention span. It doesn’t really matter long term or Boeing or the Max. The public will forget out this in literally eight seconds. A recent study found the average attention span has dropped from 12 seconds to a mere eight seconds. The same study found goldfish have an attention span of nine seconds.

Very sorry for the crashes and people involved, their friends and families. However, this just isn’t a bid deal for the industry, Boeing or the Max long term. Five years from now no one will remember and all will be well with Boeing, Max and industry. Please understand the prior comment is only related to the program. Crashes are horrible and life is precious.


This is one of the many hope mails I've seen. Remember the "software fix in 4 weeks" news. Just 2 weeks ago.
I guess many people with stock trying to soften the storm & encourage each other.


It’s going to take a lot longer than four weeks. My crystal ball told me that four weeks ago. Unfortunately, that’s the only accurate thing my crystal ball has provided me with. This will take an extended amount of time. I have no basis for what I’m about to opine, no rumors heard and no inside info from a cousin of a cousins friend’s dad.....except being in the industry a bazillion years...wouldn’t surprise me if the Max doesn’t re-enter commercial service until 1st quarter of 2020. Hope I’m wrong, but if I am it certainly will be the later part of 2019. I think that’s just a reality. Again. this is based on nothing more than my own banter.

I do believe long term this won’t affect Boeing, the Max or the industry. People forget. Rather fast. No one remembers the Tylonal scare, people are buying Exxon fuel and the DC10 had a long and glorious successful career that’s actually still going into it’s twilight. The MD80 survived a well shown on TV crash landing during intital testing where the whole tail broke off, Airbus crashed a test A320 in rather spectacular fashion way back before it was even introduced, the 737 lived through its rudder issue, the 787 is a gem, people still fly Malaysian and on and on.

This seems like a huge deal now and it is—but only in this moment. Again very sad for the deaths and family’s that will always be affected. However, I don’t see any long term impact other than a plane that’s safe becoming much safer and lessons for the next generation of airplanes. That’s about it.
Last edited by MD80Ttail on Tue Apr 09, 2019 3:51 pm, edited 1 time in total.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 3:50 pm

LDRA wrote:
seahawk wrote:
Amiga500 wrote:

You want to know why that is a load of bull?

Boeing have turned around 2 weeks ago and said; "OK, MCAS makes things worse. We're gonna pull it off the aircraft permanently and have a new type rating for MAX."

The cost if Boeing paid for every pilot to be trained on the new type would be noise compared to how much they are going to have to pay out with the continued grounding.

Hence - its quite obvious MCAS does more than "standardize handling qualities". Furthermore, to "standardize handling qualities", it is relatively straightforward to add dampers and even servos to the main elevator controls that blend in at higher AoAs.


If your stick response is non linear, you can not certify the plane. And without MCAS the additional lift from the engines creates a momentum that will push the nose higher while keeping the same force on the stick. On a FBW plane it would be a few lines of code and it would be done, on the 737 this is a problem.


The actual regulation only says "no abnormal pitch up". It is only the current FAA interpretation of the regulation that AoA response to control column force has to be monotonic.

FAA can simply change its interpretation of the FAR regulation so that MCAS is not required

Quite frankly, using a slow, fixed rate trim actuator(0.27deg/sec) to correct control column feel characteristics in dynamic situation(time constant of seconds) is goofy as hell in the first place.


It is an unnormal pitch-up if the plane pitches up without the stick being moved.
 
hivue
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 3:52 pm

uta999 wrote:
All will need modifying, both hardware and software.


A software mod should be no big deal (once it's been certified, anyway). What hardware mod are you talking about? I haven't heard anything about that.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
MD80Ttail
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 3:56 pm

seahawk wrote:
LDRA wrote:
seahawk wrote:

If your stick response is non linear, you can not certify the plane. And without MCAS the additional lift from the engines creates a momentum that will push the nose higher while keeping the same force on the stick. On a FBW plane it would be a few lines of code and it would be done, on the 737 this is a problem.


The actual regulation only says "no abnormal pitch up". It is only the current FAA interpretation of the regulation that AoA response to control column force has to be monotonic.

FAA can simply change its interpretation of the FAR regulation so that MCAS is not required

Quite frankly, using a slow, fixed rate trim actuator(0.27deg/sec) to correct control column feel characteristics in dynamic situation(time constant of seconds) is goofy as hell in the first place.


It is an unnormal pitch-up if the plane pitches up without the stick being moved.


Define “abnormal”. (Rhetorical) All aircraft pitch up when adding power unless you are flying a pusher prop like an amphib...then you get the opposite with power. So I don’t see anything abnormal about pitching up w power. The million dollar question and I don’t think we really know is how bad is the pitch-up s system had to be designed for it. Every pilot knows add power, all things equal, probably going to pitch up. Basic physics of flight. So really curious how nasty things can get MCAS was needed. I have friends flying the 737 and the NGs I am told can be a huge handful w Togo power on the go. So have to imagine things are pretty wild for an MCAS system. Again, I’ve never flown a 737 or Max. I did jumpseat in a Max a couple of times. Nice plane but really nothing stood out as different than a NG.
Last edited by MD80Ttail on Tue Apr 09, 2019 3:57 pm, edited 1 time in total.
 
hivue
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 3:56 pm

LDRA wrote:
Quite frankly, using a slow, fixed rate trim actuator(0.27deg/sec) to correct control column feel characteristics in dynamic situation(time constant of seconds) is goofy as hell in the first place.


Oh what a tangled web we weave when first we practice to make a 21st century generation of a 50-year-old design be type common with the previous generation of the 50-year-old design.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
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seahawk
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:01 pm

MD80Ttail wrote:
seahawk wrote:
LDRA wrote:

The actual regulation only says "no abnormal pitch up". It is only the current FAA interpretation of the regulation that AoA response to control column force has to be monotonic.

FAA can simply change its interpretation of the FAR regulation so that MCAS is not required

Quite frankly, using a slow, fixed rate trim actuator(0.27deg/sec) to correct control column feel characteristics in dynamic situation(time constant of seconds) is goofy as hell in the first place.


It is an unnormal pitch-up if the plane pitches up without the stick being moved.


Define “abnormal”. (Rhetorical) All aircraft pitch up when adding power unless you are flying a pusher prop like an amphib...then you get the opposite with power. So I don’t see anything abnormal about pitching up w power. The million dollar question and I don’t think we really know is how bad is the pitch-up s system had to be designed for it. Every pilot knows add power, all things equal, probably going to pitch up. Basic physics of flight. So really curious how nasty things can get MCAS was needed. I have friends flying the 737 and the NGs I am told can be a huge handful w Togo power on the go. So have to imagine things are pretty wild for an MCAS system. Again, I’ve never flown a 737 or Max. I did jumpseat in a Max a couple of times. Nice plane but really nothing stood out as different than a NG.


It does not pitch up with power, it pitches up when reaching a certain AoA, as the engine nacelle and wing then work like some kind of slotted flap.
 
hivue
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:01 pm

seahawk wrote:
It is an unnormal pitch-up if the plane pitches up without the stick being moved.


Say what? Pitch trim is concept almost as old as powered flight.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
wingman
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:04 pm

MD80Ttail wrote:
This seems like a huge deal now and it is—but only in this moment. Again very sad for the deaths and family’s that will always be affected. However, I don’t see any long term impact other than a plane that’s safe becoming much safer and lessons for the next generation of airplanes. That’s about it.


I agree with your general thrust but would point out that the MAX wasn't and isn't safe. It will become so, I believe that. And one major change I hope it causes worldwide is the complete separation of the FAA and like agencies from the manufacturers. They need more expertise and more thorough vetting procedures in certification. The FAA didn't understand the coding in the 777 and I seriously doubt they or any other regulator truly understands any modern aircraft completely. As to Boeing, by this time next year they'll have a new line up in management and be out at least $10B..it's the only way for them and everyone in the business to learn from these 300+ deaths.
 
Amiga500
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:05 pm

seahawk wrote:
If your stick response is non linear, you can not certify the plane. And without MCAS the additional lift from the engines creates a momentum that will push the nose higher while keeping the same force on the stick.


In other words it is unstable at high AoA.

An aircraft that is loaded at the fwd c.g. operating envelope limit but would be within conventional trim ranges at nominal cruise state (i.e. largest nose-up operational trim limit - which is not largest H-stab limit which MCAS can go to) could be unstable at high AoA.

That is why MCAS exists.


I'm pointing out the holes in Boeing's story about what MCAS is. It is not something to make the MAX "feel like the NG". It is something much more serious. Otherwise they'd have whacked it off the plane the instant these problems hit and took the financial penalties in any sales contracts for a new pilot type rating.
 
MD80Ttail
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:08 pm

hivue wrote:
LDRA wrote:
Quite frankly, using a slow, fixed rate trim actuator(0.27deg/sec) to correct control column feel characteristics in dynamic situation(time constant of seconds) is goofy as hell in the first place.


Oh what a tangled web we weave when first we practice to make a 21st century generation of a 50-year-old design be type common with the previous generation of the 50-year-old design.



Everyone needs to get off this 50 year old design thing. The Max is an advanced cutting edge design competitive in performance and costs. In some sectors and mission profiles it leads the industry. I see the fact it’s not a clean sheet as a pro not a con. The fact a plane designed 50 years ago before much in the way of modern computers has been able to evolve..and early build models still fly in harsh conditions reliability and safely—its a huge testament to the intelligence and skill of the orginal design. My hats off to everyone that worked on the 737. Many other planes have come and gone, some with a couple of gens or so but nothing really compares to the 737 in terms of flexibility the original design has provided.

No other aircraft and no other manufacturer has achieved what the 737 and Boeing has. Even if the Max was a clean sheet design doesn’t mean we couldn’t have the same problems now and even a grounding. Planes are complex. The DC10 and 787 were clean sheet designs and both grounded. So to beat a bandwagon if the Max had been a clean sheet somehow none of this would have happened is very bogus. The issue might not be called “MCAS” but there could very well be an issue with a new design. Very possible. Eveloution sif design verses clean sheet, problems verses no problems are not mutually exclusive.

I prefer evolutions of tried, tested and proven designs updated with cutting edge technologies as they become available. Clean sheet can be great but a solid argument can be made for evolutionary improvements.

The 737 truly is a marvel of engineering.

How old is the A320 platform now? 35ish? Another excellent design standing the test of time.
 
kalvado
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:16 pm

wingman wrote:
MD80Ttail wrote:
This seems like a huge deal now and it is—but only in this moment. Again very sad for the deaths and family’s that will always be affected. However, I don’t see any long term impact other than a plane that’s safe becoming much safer and lessons for the next generation of airplanes. That’s about it.


I agree with your general thrust but would point out that the MAX wasn't and isn't safe. It will become so, I believe that. And one major change I hope it causes worldwide is the complete separation of the FAA and like agencies from the manufacturers. They need more expertise and more thorough vetting procedures in certification. The FAA didn't understand the coding in the 777 and I seriously doubt they or any other regulator truly understands any modern aircraft completely. As to Boeing, by this time next year they'll have a new line up in management and be out at least $10B..it's the only way for them and everyone in the business to learn from these 300+ deaths.

Moreover... How often you need to certify airplanes? How much difference in the expertise is required to certify next generation plane?
What those engineers and regulatory specialists will be doing between major projects? How much debugging of actual software code is required to truly understand what is going on?

My impression is that serious certification, beyond basic "Please show the documents proving compliance to 1234.567 (8) (i) (9)? OK, check. 1234.567 (8) (i) (10)? OK, check." cannot really happen, especially for software. Especially for software, which is the issue.
Maybe a shift from certifying actual airplane to certifying development process, especially for software, is what would happen next. And maybe third party experts being paid for that, as opposed to government employers.
 
FlyBitcoin
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:16 pm

uta999 wrote:
Is there not a way of removing MCAS altogether then? By simply adding ballast and moving the CoG to where it should be, so it behaves like an NG.

MCAS is now known publicly as a stall-protection system, that does not work. No amount of PR spin from Boeing will ever change that. Remove it completely and make the MAX fly like an NG without it. Time for Plan B.


Agree 100%. This whole fiasco is eroding the Boeing brand, the MAX brand, and the concept of the MCAS system.
Which of the three is easiest to offload all of the blame onto?.... That evil MCAS.

If Boeing adds redundancy of sensor input but keeps MCAS, then it is still admitting the plane cannot fly without MCAS, which makes Boeing look like it was involved in a cover-up by making a plane that does not share the weight/balance/handling characteristics of the NG and passing it off as the same type. Not to mention greed for not making the disagree light and sensor redundancy standard in the first place.

Need to think about the flying public here. If they won't fly on this plane, then it hurts the brand of the airlines as well. When I was very young, I remember my dad calling to find flights not on a DC-10 because my mom refused to fly them. Perception matters.

Offload the blame on the MCAS system. Ditch it. Then the plane is still a 737 like the NG and they have a chance to save the "MAX" line. They may even need to rename the aircraft the 737-E (for efficiency) or something like that to break the connection to the MCAS-enabled 737's.

The longer this takes, and the more stubborn Boeing is about making a fix that not only fixes the engineering, but the public perception as well, then the deeper the scars on their brand.
 
planecane
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:19 pm

wingman wrote:
MD80Ttail wrote:
This seems like a huge deal now and it is—but only in this moment. Again very sad for the deaths and family’s that will always be affected. However, I don’t see any long term impact other than a plane that’s safe becoming much safer and lessons for the next generation of airplanes. That’s about it.


I agree with your general thrust but would point out that the MAX wasn't and isn't safe. It will become so, I believe that. And one major change I hope it causes worldwide is the complete separation of the FAA and like agencies from the manufacturers. They need more expertise and more thorough vetting procedures in certification. The FAA didn't understand the coding in the 777 and I seriously doubt they or any other regulator truly understands any modern aircraft completely. As to Boeing, by this time next year they'll have a new line up in management and be out at least $10B..it's the only way for them and everyone in the business to learn from these 300+ deaths.

No agency will have the budget and talent to understand modern aircraft down to the source code. The agency needs to design tests that put the code through all forseeable situations to ensure the aircraft reacts properly. This includes failed sensor tests.
 
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PW100
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:20 pm

kalvado wrote:
morrisond wrote:
Before everyone goes Hyperbolic - here is the best description I've seen on MCAS from 737.org.uk

"MCAS is a longitudinal stability enhancement. It is not for stall prevention (although indirectly it helps) or to make the MAX handle like the NG (although it does); it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as required by regulation.

The LEAP engine nacelles are larger and had to be mounted slightly higher and further forward from the previous NG CFM56-7 engines to give the necessary ground clearance. This new location and larger size of nacelle cause the vortex flow off the nacelle body to produce lift at high AoA. As the nacelle is ahead of the C of G, this lift causes a slight pitch-up effect (ie a reducing stick force) which could lead the pilot to inadvertently pull the yoke further aft than intended bringing the aircraft closer towards the stall. This abnormal nose-up pitching is not allowable under 14CFR §25.203(a) "Stall characteristics". Several aerodynamic solutions were introduced such as revising the leading edge stall strip and modifying the leading edge vortilons but they were insufficient to pass regulation. MCAS was therefore introduced to give an automatic nose down stabilizer input during elevated AoA when flaps are up."

Please note that it is a slight pitch up effect - the controls get light.. If you hold the controls steady the Nacelles will not generate enough lift to pull it into a stall - it just becomes easier to pull it into a stall if the pilot ignores the AOA indicator - the stick shaker - the stall horn - the frame buffeting , etc..etc...

The control response is non-linear which is not allowed by the FAR's.

BTW - Air is not a constant medium - you can fly through pockets which totally unload the controls as well.

And honestly speaking it is extremely difficult to buy such an explanation. Trying to correct a feel by a single-step addition of extra load should be very confusing. I suspect in actual use - and MCAS is supposed to operate in a small corner pilots should be avoiding anyway - it would be a short dash into a banned territory, where column suddenly gets a bunch of extra force, then that force is gone - all on top of a non-standard flight. Warnings turned off at extreme AoA for AF447 seem like a much weaker attempt to confuse.
So I am still not convinced this is a good solution for the feel correction, until the goal is to make sure pilot feels totally lost (and that is something MCAS is already good at!)


And on top of that, as mentioned by Zeke, if this is a stick force thing, why not use the existing Elevator Feel Computer, and adjust its logic to compensate for dissimilar stick force?
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seahawk
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:22 pm

Amiga500 wrote:
seahawk wrote:
If your stick response is non linear, you can not certify the plane. And without MCAS the additional lift from the engines creates a momentum that will push the nose higher while keeping the same force on the stick.


In other words it is unstable at high AoA.

An aircraft that is loaded at the fwd c.g. operating envelope limit but would be within conventional trim ranges at nominal cruise state (i.e. largest nose-up operational trim limit - which is not largest H-stab limit which MCAS can go to) could be unstable at high AoA.

That is why MCAS exists.

I'm pointing out the holes in Boeing's story about what MCAS is. It is not something to make the MAX "feel like the NG". It is something much more serious. Otherwise they'd have whacked it off the plane the instant these problems hit and took the financial penalties in any sales contracts for a new pilot type rating.


A new type rating won´t help, as with the characteristic it can not be certified at all.
 
planecane
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:24 pm

FlyBitcoin wrote:
uta999 wrote:
Is there not a way of removing MCAS altogether then? By simply adding ballast and moving the CoG to where it should be, so it behaves like an NG.

MCAS is now known publicly as a stall-protection system, that does not work. No amount of PR spin from Boeing will ever change that. Remove it completely and make the MAX fly like an NG without it. Time for Plan B.


Agree 100%. This whole fiasco is eroding the Boeing brand, the MAX brand, and the concept of the MCAS system.
Which of the three is easiest to offload all of the blame onto?.... That evil MCAS.

If Boeing adds redundancy of sensor input but keeps MCAS, then it is still admitting the plane cannot fly without MCAS, which makes Boeing look like it was involved in a cover-up by making a plane that does not share the weight/balance/handling characteristics of the NG and passing it off as the same type. Not to mention greed for not making the disagree light and sensor redundancy standard in the first place.

Need to think about the flying public here. If they won't fly on this plane, then it hurts the brand of the airlines as well. When I was very young, I remember my dad calling to find flights not on a DC-10 because my mom refused to fly them. Perception matters.

Offload the blame on the MCAS system. Ditch it. Then the plane is still a 737 like the NG and they have a chance to save the "MAX" line. They may even need to rename the aircraft the 737-E (for efficiency) or something like that to break the connection to the MCAS-enabled 737's.

The longer this takes, and the more stubborn Boeing is about making a fix that not only fixes the engineering, but the public perception as well, then the deeper the scars on their brand.


It would be interesting to know, between the ET crash and FAA grounding, how many people refused to fly on a MAX. This number will give insight into how big of an issue perception is going forward. That period had the MAX in the news and other countries grounding it.
 
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PW100
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:28 pm

Revelation wrote:
AvFanNJ wrote:
New from Aviation Week. You may need to be a paid subscriber to access full article: https://aviationweek.com/commercial-avi ... -grounding

Technically correct, but not very relevant, IMHO.

After reading the same article, seems the lawyers have been all over what he can and cannot say.

For instance:

In these sessions, pilots and regulators were able to interact via intercom and a big screen with Boeing pilots in the 737 MAX engineering cab. Following the sessions, “we went back to the classroom and said, ‘Here are the things that concern us most when we look at the scenario of the two accidents we just experienced,’” Sinnett says. “Upon reflection on what has occurred, it appeared the system could present a high-workload environment—and that’s not our intention. So we looked at changing the design to compare values from multiple AOA indicators to essentially eliminate the unintended trigger condition that causes MCAS to activate."

It reads as another form of the "we did all we were required to do so don't blame us" strategy.

In essence he's saying Boeing changed the system to use multiple AOA sensors not because it was stupid if not patently negligent to rely on one AOA sensor with evidently no bounds checking or other form of data sanitization, but because we wanted to reduce the workload on the pilots who just can't seem to calmly step through the checklist as the airplane turns itself in to a bucking bronco.
?

Perhaps he is using work load environment in a very descriptive way: work-out load. Load, as in brute stick force.
Yes, it would be smart to reduce that . . .

Not sure if that interpretation would stand though, as English is not my first language.
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tw747
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:29 pm

This is not the first time software or the AOA sensor on an airplane caused a dive. Qantas 72 (A330) had similar issues that required AB to make modifications to their software. Fortunately, there were no A330 crashes due to this issue. Boeing will correct the software issues, and the 737M will be fine.

https://en.wikipedia.org/wiki/Qantas_Flight_72
 
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PW100
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:36 pm

seahawk wrote:
If your stick response is non linear, you can not certify the plane. And without MCAS the additional lift from the engines creates a momentum that will push the nose higher while keeping the same force on the stick. On a FBW plane it would be a few lines of code and it would be done, on the 737 this is a problem.


The 737 does have a stick force system. Why not add some logic to the Elevator Feel Computer that manipulates the stick force as intended. Why use the trim system for that?
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
Amiga500
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:37 pm

seahawk wrote:
A new type rating won´t help, as with the characteristic it can not be certified at all.


Exactly my point.

MCAS is so much more than just what is alluded to here:

"The briefings continue to emphasize that the MCAS, which was added to the speed-trim system to standardize handling qualities with those of the 737 Next Generation, is “not a stall-protection function and not a stall-prevention function,” says Mike Sinnett, Boeing Commercial Airplanes vice president of product development and future airplane development. “It is a handling-qualities function. There’s a misconception it is something other than that."


It is both a handling qualities function (as per what you are saying about non-linearity approaching stall) and also stall protection.

Boeing are being disingenuous saying the former is not (in this case) the same as the latter (it can be, but not here).


Furthermore, by the definition of handling qualities (as per the "feel of the NG") can be adjusted by adjusting servo-ing on pitch.
That leaves the aerodynamic platform alone. But that obviously isn't enough.

Therefore Boeing are having to not just add something that changes handling qualities as per what the pilot experiences (control), but also stability changes due to the H-stab move.
Last edited by Amiga500 on Tue Apr 09, 2019 4:40 pm, edited 1 time in total.
 
marcelh
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:37 pm

MD80Ttail wrote:
The 737 truly is a marvel of engineering. .

The MAX is a restomod what went wrong.
 
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PW100
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:42 pm

hivue wrote:
uta999 wrote:
All will need modifying, both hardware and software.


A software mod should be no big deal (once it's been certified, anyway). What hardware mod are you talking about? I haven't heard anything about that.

How about a bigger elevator, so that at high AoA the elevator can actually do that work (for which is there in the first place), instead of misusing the trimming system?

I would expect/hope that Boeing have an engineering team working in parallel on this.
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
XRAYretired
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:42 pm

kalvado wrote:
wingman wrote:
MD80Ttail wrote:
This seems like a huge deal now and it is—but only in this moment. Again very sad for the deaths and family’s that will always be affected. However, I don’t see any long term impact other than a plane that’s safe becoming much safer and lessons for the next generation of airplanes. That’s about it.


I agree with your general thrust but would point out that the MAX wasn't and isn't safe. It will become so, I believe that. And one major change I hope it causes worldwide is the complete separation of the FAA and like agencies from the manufacturers. They need more expertise and more thorough vetting procedures in certification. The FAA didn't understand the coding in the 777 and I seriously doubt they or any other regulator truly understands any modern aircraft completely. As to Boeing, by this time next year they'll have a new line up in management and be out at least $10B..it's the only way for them and everyone in the business to learn from these 300+ deaths.

Moreover... How often you need to certify airplanes? How much difference in the expertise is required to certify next generation plane?
What those engineers and regulatory specialists will be doing between major projects? How much debugging of actual software code is required to truly understand what is going on?

My impression is that serious certification, beyond basic "Please show the documents proving compliance to 1234.567 (8) (i) (9)? OK, check. 1234.567 (8) (i) (10)? OK, check." cannot really happen, especially for software. Especially for software, which is the issue.
Maybe a shift from certifying actual airplane to certifying development process, especially for software, is what would happen next. And maybe third party experts being paid for that, as opposed to government employers.


MCAS probelm is a system design and certification failure Sir. The software, I'm sure fully met the requirements placed upon it by the system design and will have been fully validated as doing so with one to one traceability from design requirement through software requirement, software design, code implementation and verification back up the chain. You clearly do not understand software design and validation processes in safety related systems. You may wish to read DO-178.
 
D L X
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:47 pm

WIederling wrote:
AvFanNJ wrote:
So there is no pitch up moment at high speeds that can create stall and needs to be prevented by MCAS? IMO Boeing should prevent using strawman's and playing with words.


Lawyers must have sweated through several nights to bake this into a campaign that seems to work on Jedi "hand waving"
"this is not a stall protection or flight envelope sanitation but just there for easement of the pilots".

(Corporate) Lawyers invariably are an abomination.

We really aren't. This kind of talk is silly. You know who's working against every lawyer you hate? A lawyer.
 
kalvado
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:53 pm

XRAYretired wrote:
kalvado wrote:
wingman wrote:

I agree with your general thrust but would point out that the MAX wasn't and isn't safe. It will become so, I believe that. And one major change I hope it causes worldwide is the complete separation of the FAA and like agencies from the manufacturers. They need more expertise and more thorough vetting procedures in certification. The FAA didn't understand the coding in the 777 and I seriously doubt they or any other regulator truly understands any modern aircraft completely. As to Boeing, by this time next year they'll have a new line up in management and be out at least $10B..it's the only way for them and everyone in the business to learn from these 300+ deaths.

Moreover... How often you need to certify airplanes? How much difference in the expertise is required to certify next generation plane?
What those engineers and regulatory specialists will be doing between major projects? How much debugging of actual software code is required to truly understand what is going on?

My impression is that serious certification, beyond basic "Please show the documents proving compliance to 1234.567 (8) (i) (9)? OK, check. 1234.567 (8) (i) (10)? OK, check." cannot really happen, especially for software. Especially for software, which is the issue.
Maybe a shift from certifying actual airplane to certifying development process, especially for software, is what would happen next. And maybe third party experts being paid for that, as opposed to government employers.


MCAS probelm is a system design and certification failure Sir. The software, I'm sure fully met the requirements placed upon it by the system design and will have been fully validated as doing so with one to one traceability from design requirement through software requirement, software design, code implementation and verification back up the chain. You clearly do not understand software design and validation processes in safety related systems. You may wish to read DO-178.

Somehow following standard procedures is assumed, but Boeing's software design procedures were never spelled out, at least I didn't see that. And there is a precedent: Toyota unintended acceleration fiasco - a major reputable company created a shit of a code; "unmaintainable" , "undebuggable" and "violating basic development procedures" being the terms used to describe it.
It is still to be seen if Boeing would let anyone to see their code, and how good that code would be.
 
Olddog
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:55 pm

planecane wrote:
]
No agency will have the budget and talent to understand modern aircraft down to the source code. The agency needs to design tests that put the code through all forseeable situations to ensure the aircraft reacts properly. This includes failed sensor tests.


And you won't solve that problem by trying to kill the regulators with manufacturers lobbying to cut their budget....
 
planecane
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 4:55 pm

PW100 wrote:
hivue wrote:
uta999 wrote:
All will need modifying, both hardware and software.


A software mod should be no big deal (once it's been certified, anyway). What hardware mod are you talking about? I haven't heard anything about that.

How about a bigger elevator, so that at high AoA the elevator can actually do that work (for which is there in the first place), instead of misusing the trimming system?

I would expect/hope that Boeing have an engineering team working in parallel on this.


A bigger elevator would not solve the problem. The issue isn't that the elevator doesn't have enough authority. The issue is that at high speed and high AoA it takes LESS force on the control column to pitch up more.

The only control surface change that I could see helping would be a crazy split elevator design so only part of it moves at high speed, high AoA. Good luck engineering that onto the existing 737 and maintaining the same type certificate!
 
MD80Ttail
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 5:04 pm

marcelh wrote:
MD80Ttail wrote:
The 737 truly is a marvel of engineering. .

The MAX is a restomod what went wrong.


A clean sheet could have had similar or even worse issues. Evolution vs clean sheet vs accidents or not. Not mutually exclusive. More clean sheet designs have been grounded and killed more people in the history of aviation than evolutionary designs. Think about that one. Really to many to list but the A320 would make the list for sure as would many others.
 
XRAYretired
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 5:05 pm

kalvado wrote:
XRAYretired wrote:
kalvado wrote:
Moreover... How often you need to certify airplanes? How much difference in the expertise is required to certify next generation plane?
What those engineers and regulatory specialists will be doing between major projects? How much debugging of actual software code is required to truly understand what is going on?

My impression is that serious certification, beyond basic "Please show the documents proving compliance to 1234.567 (8) (i) (9)? OK, check. 1234.567 (8) (i) (10)? OK, check." cannot really happen, especially for software. Especially for software, which is the issue.
Maybe a shift from certifying actual airplane to certifying development process, especially for software, is what would happen next. And maybe third party experts being paid for that, as opposed to government employers.


MCAS probelm is a system design and certification failure Sir. The software, I'm sure fully met the requirements placed upon it by the system design and will have been fully validated as doing so with one to one traceability from design requirement through software requirement, software design, code implementation and verification back up the chain. You clearly do not understand software design and validation processes in safety related systems. You may wish to read DO-178.

Somehow following standard procedures is assumed, but Boeing's software design procedures were never spelled out, at least I didn't see that. And there is a precedent: Toyota unintended acceleration fiasco - a major reputable company created a shit of a code; "unmaintainable" , "undebuggable" and "violating basic development procedures" being the terms used to describe it.
It is still to be seen if Boeing would let anyone to see their code, and how good that code would be.



If Toyota had applied DO-178 or even UK SMMT guidelines equivalent for automotive industry i.e. they didn't violate basic development procedures, than they may not have erred so comprehensively.
 
L1049L1011
Posts: 18
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 5:13 pm

Just for reference, here is the FAA view of MCAS as a "pitch stability augmentation" function of STS (from the March 26, 2019 FSBR_B737_Rev17_Draft.pdf, which was online at faa.gov till yesterday, but has now been removed):

B-737-MAX Maneuvering Characteristics Augmentation System (MCAS). The Speed Trim System (STS) provides speed and pitch augmentation. Speed stability augmentation is provided by the Speed Trim function of STS. Pitch stability augmentation is provided by the MCAS function of STS. MCAS ground training must address system description, functionality, associated failure conditions, and flight crew alerting. These items must be included in initial, upgrade, transition, differences, and recurrent training.
 
MD80Ttail
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 5:14 pm

“”Need to think about the flying public here. If they won't fly on this plane, then it hurts the brand of the airlines as well. When I was very young, I remember my dad calling to find flights not on a DC-10 because my mom refused to fly them. Perception matters.””

Your dada was an outlier. No matter how “dangerous” the plane the reality is more people die in a single day in car crashes than ever will on any type of airplane. Facts. I think even more people have died falling out of bed than statistically with flying. My neighbor cracks me up. Guy won’t fly. Thinks I’m a nut. Says he expects a day to come I die in a crash. Then he revs up his Harley Davidson and rides off without a helmet. True story. (Don’t worry. He’s in total control he assures me. Doesn’t need a helmet bc he won’t crash). Figure that out. Smart guy too.

Point is people have irrational fears fed by fake news and over hyped mediat saturation. There will be some folks that will never fly on a Max moving forward. There are some that won’t ever fly “xyz” airlines. Some that won’t fly an Airbus. Ect ect. They are outliers and statistically insignificant.

The DC10 had a great career and made s lot of money and carries millions and millions of people over a long career. Still flying making money. Safe and sound.

Your assertions during a short time period after two media hyped accidents with 24/7 news outlets spinning facts we should see how many people had jitters and refused to fly the Max is really absurd. All it will tell us is how many irrational people there are. None of that will matter a year or two and 10 down the road. People that are not in the aviation biz and are not enthusiastists have no idea what kind of plane they are on and they don’t care. They just care how much the ticket costs and what time they get there.

That’s a fact.

Once the Max starts flying and media moves on to somthing else all will be forgotten except by a small number of outliers that are irrational. Period. I’m right. I just popped two Tylonal for a headache.
 
kalvado
Posts: 2971
Joined: Wed Mar 01, 2006 4:29 am

Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 5:19 pm

XRAYretired wrote:

If Toyota had applied DO-178 or even UK SMMT guidelines equivalent for automotive industry i.e. they didn't violate basic development procedures, than they may not have erred so comprehensively.

At some point Toyota claimed adherence to Motor Industry Software Reliability Association standards, then they said they have their own standards.
Do you have any link that explicitly says that such and such standard was applied to MAX code development? For one, I am pretty sure repeated activations, especially after pilot counteraction, should be considered as part of proper algorithmic review.
 
Andy33
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 5:24 pm

planecane wrote:
It would be interesting to know, between the ET crash and FAA grounding, how many people refused to fly on a MAX. This number will give insight into how big of an issue perception is going forward. That period had the MAX in the news and other countries grounding it.


I'm not sure how relevant the information would be, because as we all know, the grounding by the FAA only affected the USA, the rest of the world had already grounded the MAX by the time President Trump kicked them into action. In the case of China, grounding came less than a day after the ET crash. So the time available for the public to reach the conclusion "this aircraft might be unsafe, I'll not book flights using it" before they no longer had the opportunity to book any, varies significantly from airline to airline.
A very significant majority of MAX deliveries so far, and an even greater one of outstanding orders, are for airlines outside the USA. You'd need to measure perception in each world region, the MAX simply isn't viable as a US-only model. If, for example, Chinese customers continue to mistrust the plane when it is finally cleared to fly by CAAC (which may well not be the same time as the FAA clears it), Chinese airlines are in big trouble, and so is Boeing.
 
morrisond
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:06 pm

PW100 wrote:
seahawk wrote:
If your stick response is non linear, you can not certify the plane. And without MCAS the additional lift from the engines creates a momentum that will push the nose higher while keeping the same force on the stick. On a FBW plane it would be a few lines of code and it would be done, on the 737 this is a problem.


The 737 does have a stick force system. Why not add some logic to the Elevator Feel Computer that manipulates the stick force as intended. Why use the trim system for that?



That is a good question. Maybe it is not Dynamic and can't deal with non-linear forces and just adds or subtracts effort on an linear scale?

Here is the best description I could find in this document - it sounds like that it is purely a function of Airspeed and Stablilizer Position - It doesn't mention anything about AOA.

This is for the NG .

http://www.737ng.co.uk/B_NG-Flight_Controls.pdf
 
morrisond
Posts: 2943
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:10 pm

MD80Ttail wrote:
“”Need to think about the flying public here. If they won't fly on this plane, then it hurts the brand of the airlines as well. When I was very young, I remember my dad calling to find flights not on a DC-10 because my mom refused to fly them. Perception matters.””

Your dada was an outlier. No matter how “dangerous” the plane the reality is more people die in a single day in car crashes than ever will on any type of airplane. Facts. I think even more people have died falling out of bed than statistically with flying. My neighbor cracks me up. Guy won’t fly. Thinks I’m a nut. Says he expects a day to come I die in a crash. Then he revs up his Harley Davidson and rides off without a helmet. True story. (Don’t worry. He’s in total control he assures me. Doesn’t need a helmet bc he won’t crash). Figure that out. Smart guy too.

Point is people have irrational fears fed by fake news and over hyped mediat saturation. There will be some folks that will never fly on a Max moving forward. There are some that won’t ever fly “xyz” airlines. Some that won’t fly an Airbus. Ect ect. They are outliers and statistically insignificant.

The DC10 had a great career and made s lot of money and carries millions and millions of people over a long career. Still flying making money. Safe and sound.

Your assertions during a short time period after two media hyped accidents with 24/7 news outlets spinning facts we should see how many people had jitters and refused to fly the Max is really absurd. All it will tell us is how many irrational people there are. None of that will matter a year or two and 10 down the road. People that are not in the aviation biz and are not enthusiastists have no idea what kind of plane they are on and they don’t care. They just care how much the ticket costs and what time they get there.

That’s a fact.

Once the Max starts flying and media moves on to somthing else all will be forgotten except by a small number of outliers that are irrational. Period. I’m right. I just popped two Tylonal for a headache.


Good point.

From Association for Safe International Road Travel "Nearly 1.25 million people die in road crashes each year, on average 3,287 deaths a day. An additional 20-50 million are injured or disabled. More than half of all road traffic deaths occur among young adults ages 15-44."
 
oschkosch
Posts: 610
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:15 pm

morrisond wrote:
MD80Ttail wrote:
“”Need to think about the flying public here. If they won't fly on this plane, then it hurts the brand of the airlines as well. When I was very young, I remember my dad calling to find flights not on a DC-10 because my mom refused to fly them. Perception matters.””

Your dada was an outlier. No matter how “dangerous” the plane the reality is more people die in a single day in car crashes than ever will on any type of airplane. Facts. I think even more people have died falling out of bed than statistically with flying. My neighbor cracks me up. Guy won’t fly. Thinks I’m a nut. Says he expects a day to come I die in a crash. Then he revs up his Harley Davidson and rides off without a helmet. True story. (Don’t worry. He’s in total control he assures me. Doesn’t need a helmet bc he won’t crash). Figure that out. Smart guy too.

Point is people have irrational fears fed by fake news and over hyped mediat saturation. There will be some folks that will never fly on a Max moving forward. There are some that won’t ever fly “xyz” airlines. Some that won’t fly an Airbus. Ect ect. They are outliers and statistically insignificant.

The DC10 had a great career and made s lot of money and carries millions and millions of people over a long career. Still flying making money. Safe and sound.

Your assertions during a short time period after two media hyped accidents with 24/7 news outlets spinning facts we should see how many people had jitters and refused to fly the Max is really absurd. All it will tell us is how many irrational people there are. None of that will matter a year or two and 10 down the road. People that are not in the aviation biz and are not enthusiastists have no idea what kind of plane they are on and they don’t care. They just care how much the ticket costs and what time they get there.

That’s a fact.

Once the Max starts flying and media moves on to somthing else all will be forgotten except by a small number of outliers that are irrational. Period. I’m right. I just popped two Tylonal for a headache.


Good point.

From Association for Safe International Road Travel "Nearly 1.25 million people die in road crashes each year, on average 3,287 deaths a day. An additional 20-50 million are injured or disabled. More than half of all road traffic deaths occur among young adults ages 15-44."
MD80Ttail: you might be mistaken. In today's media bad news travels fast and the internet nevers forgets.

Another example: popular flight price app Kayak has announced you will be able to filter put aircraft types such as the 737 Max in case you want to avoide flying on one of those in the future.

Gesendet von meinem SM-G950F mit Tapatalk
:stirthepot: :airplane: "This airplane is designed by clowns, who in turn are supervised by monkeys" :airplane: :stirthepot:
 
kalvado
Posts: 2971
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Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:16 pm

MD80Ttail wrote:
Once the Max starts flying and media moves on to somthing else all will be forgotten except by a small number of outliers that are irrational. Period. I’m right. I just popped two Tylonal for a headache.

There is another aspect of it. MAX will be on probation for a few years. Boeing better work out all the kinks now.
Another airframe related crash within next 2-3 years, and MAX is toast for good.
 
XRAYretired
Posts: 870
Joined: Fri Mar 15, 2019 11:21 am

Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:18 pm

kalvado wrote:
XRAYretired wrote:

If Toyota had applied DO-178 or even UK SMMT guidelines equivalent for automotive industry i.e. they didn't violate basic development procedures, than they may not have erred so comprehensively.

At some point Toyota claimed adherence to Motor Industry Software Reliability Association standards, then they said they have their own standards.
Do you have any link that explicitly says that such and such standard was applied to MAX code development? For one, I am pretty sure repeated activations, especially after pilot counteraction, should be considered as part of proper algorithmic review.


DO-178 is the default standard for CFR14. Any deviation has to be demonstarted to meet the objectives of DO-178.

The system design patently failed to require dual sensor input nor action therefore upon AOA disagree.
 
marcelh
Posts: 1136
Joined: Wed Jun 19, 2013 12:43 pm

Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:19 pm

MD80Ttail wrote:
marcelh wrote:
MD80Ttail wrote:
The 737 truly is a marvel of engineering. .

The MAX is a restomod what went wrong.


A clean sheet could have had similar or even worse issues. Evolution vs clean sheet vs accidents or not. Not mutually exclusive. More clean sheet designs have been grounded and killed more people in the history of aviation than evolutionary designs. Think about that one. Really to many to list but the A320 would make the list for sure as would many others.

Indeed... COULD. And going back into history isn’t relevant, because we are talking about 2019. Fact is that the MAX - a state of the art evolution of the 737 - became a lawn dart twice, because the latest upgrade went partially wrong. You can slap on new wings, engines, electronics, etc., but Boeing wanted it to “feel” like an NG. It’s like upgrading a sixties Corvette with a modern engine, electronics, powersteering, but let the brakes feel like the original car.
But unfortunately Boeing had 280 million reasons not to upgrade the 737NG into the MAX the way it should have been.
 
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aerolimani
Posts: 1329
Joined: Tue Jun 18, 2013 5:46 pm

Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:36 pm

Let's imagine a "normal" MCAS activation; as in, one that occurs when MCAS receives high AOA values from a functioning sensor. After the AOA returns to a "normal" value, does the MCAS software then trim back to a normal trim? Or, is that something which is left up to the pilots (if flying manually), or the STS (if on autopilot)?

I ask, because if the system does not revert, once the aircraft has come back from the situation which caused MCAS activation, would that not also be considered a poor system design?

And yes, I understand that this would not have mattered in the crashes, where the MCAS system was receiving faulty AOA data.
 
kalvado
Posts: 2971
Joined: Wed Mar 01, 2006 4:29 am

Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:38 pm

XRAYretired wrote:
kalvado wrote:
XRAYretired wrote:

If Toyota had applied DO-178 or even UK SMMT guidelines equivalent for automotive industry i.e. they didn't violate basic development procedures, than they may not have erred so comprehensively.

At some point Toyota claimed adherence to Motor Industry Software Reliability Association standards, then they said they have their own standards.
Do you have any link that explicitly says that such and such standard was applied to MAX code development? For one, I am pretty sure repeated activations, especially after pilot counteraction, should be considered as part of proper algorithmic review.


DO-178 is the default standard for CFR14. Any deviation has to be demonstarted to meet the objectives of DO-178.

The system design patently failed to require dual sensor input nor action therefore upon AOA disagree.

I still fail to see how algorithmic review failed to bring up AoA disagree situation - when switching sensors was implemented. So I suspect required protocol may not be equal to actually implemented one.
 
transswede
Posts: 1008
Joined: Fri Sep 21, 2001 9:30 am

Re: B737MAX Grounded Worldwide

Tue Apr 09, 2019 6:40 pm

MD80Ttail wrote:
The DC10 had a great career and made s lot of money and carries millions and millions of people over a long career. Still flying making money. Safe and sound.


Yes, it was safe and sound - AFTER some rather serious design issues were corrected. Before? Not a death trap per se or anywhere close, but concerns were valid in comparison to other airliners.

(And I have had several pleasant flights on DC-10s, so I am not a concern troll, but serious design issues should NOT be rolled under the carpet)

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