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gia777
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 5:51 am

Flight simulator all u want, I am not stepping into any B737max. The only thing that can make me confident in flying 737max is if they did 1 full year real live flight test 365 days 5 flight per day without any crash.
Cheers,

GIA777 :coffee:
 
questions
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 6:44 am

Will Boeing and/or the airlines do any sort of marketing to build the public's confidence in the aircraft? If so, what could it look like?

Will this aircraft be forever maligned in the media for any incident moving forward, e.g., blown tire, wing clip on the ground?

What impact would a third, equally serious incident, regardless of cause, have on the 737 program and Boeing’s viability?
 
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keesje
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:45 am

Interesting. Boeing still hopes to certifiy by December. Breaking news, stcocks jumped.

https://www.barrons.com/articles/boeing-stock-737-max-timeline-slip-faa-flight-control-software-51573512041

A short break from reality?
"Never mistake motion for action." Ernest Hemingway
 
jollo
Posts: 397
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 11:08 am

planecane wrote:
shmerik wrote:
Slide deck from a Boeing presentation to the FAA back in December 2018:

https://assets.documentcloud.org/docume ... 8-MCAS.pdf

Interesting that the dev and cert timeline slide is completely redacted

From this presentation and the Lion Air final report, it seems like the single sensor design wasn't the major mistake. It looks to me like the major mistake was allowing more than one MCAS cycle per high AoA event.

This document states that at the 2.5 unit maximum nose down trim authority, control using the elevator would still be possible in an erroneous activation.

If the original MCAS logic only reset MCAS after the AoA had gone below the trigger AoA neither crash would have occurred.

The single sensor design was not a good design but it wasn't the root cause mistake.


IMO the debate about finding the "root" mistake is misleading. It's as simple as: single input channel + unlimited authority + no "disable" switch = lethal controller. Take away one hole and the design might not show its flaws. But a culture of "let's find another quick workaround", "let's get another exemption" and "it's been working fine till now, let's not review the risk assessment" is almost guaranteed to line up the holes, sooner or later. Especially when tinkering on aging designs having accrued decades of compromises to start with.

(P.S. please don't bring up the "but pilots should only have run the runaway stabilizer NNC" argument again: I'm discussing the automation design, not the survivability of the accident flights. Suggested reading: difference between disabling the controller and disabling the actuator).
 
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PITingres
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 11:15 am

9w748capt wrote:
So will these fixes solve the underlying problem that the MAX is an unstable airplane at baseline?


The classic "when did you stop beating your wife" approach rears its ugly head.

Or, to be less snarky, your premise is false.
Fly, you fools! Fly!
 
chiki
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 11:37 am

I will fly the max anytime as I have confidence it's now safe, Boeing will not let it fly unless they are sure its safe.

Sent from my SM-J415F using Tapatalk
 
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MrBren
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 11:48 am

chiki wrote:
Boeing will not let it fly unless they are sure its safe.


So you mean they let it fly before its grounding knowing it was unsafe? So scary.
 
art
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 12:04 pm

keesje wrote:
Interesting. Boeing still hopes to certifiy by December. Breaking news, stcocks jumped.

https://www.barrons.com/articles/boeing-stock-737-max-timeline-slip-faa-flight-control-software-51573512041

A short break from reality?


According to flightglobal steps towards RTS are:

a "simulator session with airline pilots to assess human factors and crew workload under various test conditions"
then
an FAA certification flight test, according to the airframer
then
Boeing would have to submit its final Max aircraft software modifications to the FAA
then
a Joint Operational Evaluation Board representing several regulatory agencies would conduct another multi-day simulator session with pilots to determine training requirements
then
the FAA Flight Standardization Board would publish a report on the proposed training, review any public comments about it, and determine whether to approve the pilot training for Max aircraft

https://www.flightglobal.com/news/artic ... er-462143/

And Boeing say they are going to resume deliveries in December? :lol:
 
dtw2hyd
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 12:17 pm

9w748capt wrote:
So will these fixes solve the underlying problem that the MAX is an unstable airplane at baseline? So it'll still have a tendency to stall more often than comparable airplanes, right? So what's the software going to actually fix?


It gives the authority back to the crew. In layman terms, Creepy McCassey still on board but gets a off switch.

In the long run, BCA can pull a 788 trick on the MAX family. Introduce MAX10 landing gear to others, introduce bigger fin making it relatively more inherently stable. Swap orders to updated models. No one will ever notice. Everyone prises 789 improvements and no one misses 788.
All posts are just opinions.
 
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Revelation
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 12:44 pm

jollo wrote:
IMO the debate about finding the "root" mistake is misleading. It's as simple as: single input channel + unlimited authority + no "disable" switch = lethal controller. Take away one hole and the design might not show its flaws. But a culture of "let's find another quick workaround", "let's get another exemption" and "it's been working fine till now, let's not review the risk assessment" is almost guaranteed to line up the holes, sooner or later. Especially when tinkering on aging designs having accrued decades of compromises to start with.

(P.S. please don't bring up the "but pilots should only have run the runaway stabilizer NNC" argument again: I'm discussing the automation design, not the survivability of the accident flights. Suggested reading: difference between disabling the controller and disabling the actuator).

All true, but also we have the Boeing post-JT presentation to FAA saying it was decided in a meeting among engineer and test pilots that airline pilots would be able to deal with single and that multiple MCAS activations were no worse than single MCAS activations. This "assesement" to my thinking was as noteworthy a mistake as the design itself, and seemed to be where the main opportunity to push for realistic end to end testing was lost, so just as much a help in guaranteeing the holes would line up.

art wrote:
And Boeing say they are going to resume deliveries in December?

You do understand there is a difference between delivery and return to service, right?
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Scotron12
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 12:58 pm

Once delivered they get the check, right? Put's the onus back on airlines and Boeing can start the bonus pool again.
 
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smittythepirate
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 1:06 pm

gia777 wrote:
Flight simulator all u want, I am not stepping into any B737max. The only thing that can make me confident in flying 737max is if they did 1 full year real live flight test 365 days 5 flight per day without any crash.


Cool story
www.jbweather.com
 
zoom321
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 1:09 pm

keesje wrote:
Interesting. Boeing still hopes to certifiy by December. Breaking news, stcocks jumped.

https://www.barrons.com/articles/boeing-stock-737-max-timeline-slip-faa-flight-control-software-51573512041

A short break from reality?


Stock near all time high with all the free money, no one goes to jail, little wonder boeing sees little incentive for safety.
 
frmrCapCadet
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 2:38 pm

Art - your "thens" implies it is entirely a series set of problems. I suspect it is more of a parallel set of problems, and teams are working on setting up all of them. Including final pilot training.
Buffet: the airline business...has eaten up capital...like..no other (business)
 
djm18
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 3:03 pm

9w748capt wrote:
So will these fixes solve the underlying problem that the MAX is an unstable airplane at baseline? So it'll still have a tendency to stall more often than comparable airplanes, right? So what's the software going to actually fix?


I am not sure that is entirely fair. The bigger engines mounted forward slightly created a tendency for a pitch up attitude in certain (more extreme) parts of the flight envelope which could then lead to a stall. MCAS was put in to correct this and make it behave/feel more like the NG. But MCAS was not well designed and not well implemented; It in fact was the key contributing factor to both these accidents. I am going out on a limb here but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident; Especially since they were both flying in VFR conditions.

And also remember that there were a good number of MAXs flying before the grounding, so not sure it is fair to say that it is an unstable airplane at baseline
 
Whiteguy
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 3:19 pm

djm18 wrote:
9w748capt wrote:
So will these fixes solve the underlying problem that the MAX is an unstable airplane at baseline? So it'll still have a tendency to stall more often than comparable airplanes, right? So what's the software going to actually fix?


I am not sure that is entirely fair. The bigger engines mounted forward slightly created a tendency for a pitch up attitude in certain (more extreme) parts of the flight envelope which could then lead to a stall. MCAS was put in to correct this and make it behave/feel more like the NG. But MCAS was not well designed and not well implemented; It in fact was the key contributing factor to both these accidents. I am going out on a limb here but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident; Especially since they were both flying in VFR conditions.

And also remember that there were a good number of MAXs flying before the grounding, so not sure it is fair to say that it is an unstable airplane at baseline


And many have flown since then groundings without incident.....MCAS was also to help break the stall because the larger engine cowls created lift. One also has to look at the airlines, and crew training, experience and airmanship. The only one that seemed to be handling the situation was the Lion Air Captain, he was controlling the situation while not know knowing the cause. As soon as he hand control to the FO it was game over, a simple briefing may have helped the situation.
 
seb76
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 3:32 pm

art wrote:
keesje wrote:
Interesting. Boeing still hopes to certifiy by December. Breaking news, stcocks jumped.

https://www.barrons.com/articles/boeing-stock-737-max-timeline-slip-faa-flight-control-software-51573512041

A short break from reality?


According to flightglobal steps towards RTS are:

a "simulator session with airline pilots to assess human factors and crew workload under various test conditions"
then
an FAA certification flight test, according to the airframer
then
Boeing would have to submit its final Max aircraft software modifications to the FAA
then
a Joint Operational Evaluation Board representing several regulatory agencies would conduct another multi-day simulator session with pilots to determine training requirements
then
the FAA Flight Standardization Board would publish a report on the proposed training, review any public comments about it, and determine whether to approve the pilot training for Max aircraft

https://www.flightglobal.com/news/artic ... er-462143/

And Boeing say they are going to resume deliveries in December? :lol:


It's perfectly fine : every time Boeing repeats a lie (or maybe just some "wishful thinking" from them) about the delay before un-grounding, the BA stock gains a few percents in the NYSE. Then it makes sense to keep using unrealistic deadlines so you can do it often ;-)
 
2175301
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 4:12 pm

gia777 wrote:
Flight simulator all u want, I am not stepping into any B737max. The only thing that can make me confident in flying 737max is if they did 1 full year real live flight test 365 days 5 flight per day without any crash.


That works out to 1825 flights before you apparently consider a model safe.

I'm curious if you apply the same standard to all new aircraft or aircraft derivatives. I estimate that would be between 3 and 6 years for most long distance wide-body aircraft that typically do 1 or 2 cycles a day.

I'm OK if that is your personal standard (and you apply it uniformly).

Honestly, for me I'm willing to fly the latest models right away after certification. I think you're missing out on a lot of great aircraft - but, that's up to you. Different strokes for different folks...

Have a great day,
 
kalvado
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 4:40 pm

2175301 wrote:
gia777 wrote:
Flight simulator all u want, I am not stepping into any B737max. The only thing that can make me confident in flying 737max is if they did 1 full year real live flight test 365 days 5 flight per day without any crash.


That works out to 1825 flights before you apparently consider a model safe.

I'm curious if you apply the same standard to all new aircraft or aircraft derivatives. I estimate that would be between 3 and 6 years for most long distance wide-body aircraft that typically do 1 or 2 cycles a day.

I'm OK if that is your personal standard (and you apply it uniformly).

Honestly, for me I'm willing to fly the latest models right away after certification. I think you're missing out on a lot of great aircraft - but, that's up to you. Different strokes for different folks...

Have a great day,

I thought certification flight campaign is about the same number of flights - its a few frames flying for a few months, and in some extreme conditions to make things interesting.
And 2000 flights is pretty much nothing if you compare that with a fleet of MAXes flying before first crash. There were 74 MAXes delivered in 2017 alone. Assuming they were flying just 1 flight a day beginning New Year day - that 2000 flights requirement was satisfied by the end of January 2018. It took almost another year and 200 more deliveries for Lion Air to run into MCAS scenario....
 
DenverTed
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 5:19 pm

Will they rebrand it the 737 Mozel?
 
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JetBuddy
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 5:20 pm

chiki wrote:
I will fly the max anytime as I have confidence it's now safe, Boeing will not let it fly unless they are sure its safe.

Sent from my SM-J415F using Tapatalk


Seems a bit naive.

Boeing insisted it was safe all up until the whole world had grounded the aircraft, including the FAA and announced by the President. In fact, they've insisted it's safe all along.

If it was up to Boeing, it would still be flying.
 
benbeny
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 5:45 pm

JetBuddy wrote:
chiki wrote:
I will fly the max anytime as I have confidence it's now safe, Boeing will not let it fly unless they are sure its safe.

Sent from my SM-J415F using Tapatalk


Seems a bit naive.

Boeing insisted it was safe all up until the whole world had grounded the aircraft, including the FAA and announced by the President. In fact, they've insisted it's safe all along.

If it was up to Boeing, it would still be flying.

And not before Trump called Canada. Imagine how cozy relationship you have when you have private phone number of the POTUS.
 
Sooner787
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 5:46 pm

questions wrote:
Will Boeing and/or the airlines do any sort of marketing to build the public's confidence in the aircraft? If so, what could it look like?

Will this aircraft be forever maligned in the media for any incident moving forward, e.g., blown tire, wing clip on the ground?

What impact would a third, equally serious incident, regardless of cause, have on the 737 program and Boeing’s viability?


If the US airlines are smart, the first revenue day of revenue flights have the CEO's of their airlines ( AA / UA / WN)
aboard for not just the first flight, but several flights that first day.

It would also be smart to invite local media types to ride along on a test flight to see and learn what fixes have been made
before the resumption of revenue flights. WN had said they were planning a few weeks of training flights.
 
asdf
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 6:34 pm

djm18 wrote:
.... but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident;


a lot of movement and plane behavior in both crashes is not really explaned till now

its pretty clear that MCAS was the trigger for the disasters
but its not know how much the aerodynamical behavior of the MAX was contributing to the complete loss of control

in the LionAir crash report they didnt list it als contributing

regulators, besides the FAA, want to testflight the 737MAX without MCAS augmentation to see how strange the behavior is
the still didnt get a chance for that

so no one really knows if the crews would have been able to return the flight without incident
 
KarlB737
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 6:53 pm

Courtesy: Reuters

Boeing Orders Sink As Customers Opt To Swap MAX

"Net orders so far this year came to just 45 at the end of October, down from 56 in September, further widening the gap on sales this year with the company’s European rival Airbus SE (AIR.PA) which has now sold nearly 500 more planes."

https://www.reuters.com/article/us-boeing-deliveries/boeing-orders-sink-as-customers-opt-to-swap-max-idUSKBN1XM24M?il=0
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 6:54 pm

asdf wrote:
djm18 wrote:
.... but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident;


a lot of movement and plane behavior in both crashes is not really explaned till now

its pretty clear that MCAS was the trigger for the disasters
but its not know how much the aerodynamical behavior of the MAX was contributing to the complete loss of control

in the LionAir crash report they didnt list it als contributing

regulators, besides the FAA, want to testflight the 737MAX without MCAS augmentation to see how strange the behavior is
the still didnt get a chance for that

so no one really knows if the crews would have been able to return the flight without incident


So where in the Flight Profile of the two crashes (you can see all the traces) do you propose that the MAX's supposed Aerodynamic Instability was a contributing factor in the accidents?

Although the controls were hard to use it seemed pretty aerodynamically stable well past VMO on ET - and on Lionair it seemed pretty stable as well.

They also got no where near a stall situation.

There is probably a reason it wasn't included in the Lionair final report - it doesn't exist (at least there was no evidence of any instability on the crash flight).
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 6:59 pm

KarlB737 wrote:
Courtesy: Reuters

Boeing Orders Sink As Customers Opt To Swap MAX

"Net orders so far this year came to just 45 at the end of October, down from 56 in September, further widening the gap on sales this year with the company’s European rival Airbus SE (AIR.PA) which has now sold nearly 500 more planes."

https://www.reuters.com/article/us-boeing-deliveries/boeing-orders-sink-as-customers-opt-to-swap-max-idUSKBN1XM24M?il=0


Reuters will probably be able to take almost this exact story and reverse it 12 months from now when the MAX is delivering again and Boeing offers big discounts on more MAX's to existing customers to compensate for the grounding.

I won't be surprised to see 1,000+ MAX's ordered next year (IAG will most likely confirm their 200 and Southwest has 500 737-7's they still need to replace to start with).
 
asdf
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 6:59 pm

morrisond wrote:
asdf wrote:
djm18 wrote:
.... but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident;


a lot of movement and plane behavior in both crashes is not really explaned till now

its pretty clear that MCAS was the trigger for the disasters
but its not know how much the aerodynamical behavior of the MAX was contributing to the complete loss of control

in the LionAir crash report they didnt list it als contributing

regulators, besides the FAA, want to testflight the 737MAX without MCAS augmentation to see how strange the behavior is
the still didnt get a chance for that

so no one really knows if the crews would have been able to return the flight without incident


So where in the Flight Profile of the two crashes (you can see all the traces) do you propose that the MAX's supposed Aerodynamic Instability was a contributing factor in the accidents?

Although the controls were hard to use it seemed pretty aerodynamically stable well past VMO on ET - and on Lionair it seemed pretty stable as well.

They also got no where near a stall situation.

There is probably a reason it wasn't included in the Lionair final report - it doesn't exist (at least there was no evidence of any instability on the crash flight).


as long as we do not see a transcript of the cockpit voices we have no clear picture of the problems the flightdeck crew had to fight with
usually the transscript (never the original audio) of a crashed plane is included in the report
i dont know why this important part is missing

lion has a lot of 737MAX on order
they have interest in downplaying the problem
they have influence in there region and they have the power to get wishes fullfilled

who knows ...
 
Opus99
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:08 pm

2019 has not been Boeing’s year at all and rightfully so. But I think from 2020 onwards with the max back and the 777x well on it’s way to certification Boeing is going to bounce back even higher. I look forward to seeing both the max and the 777x in the skies. And I believe the FAA will grant certification just before year end. I also think they’ll secured more orders for both the max and 777x next year.
 
morrisond
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Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:12 pm

asdf wrote:
morrisond wrote:
asdf wrote:

a lot of movement and plane behavior in both crashes is not really explaned till now

its pretty clear that MCAS was the trigger for the disasters
but its not know how much the aerodynamical behavior of the MAX was contributing to the complete loss of control

in the LionAir crash report they didnt list it als contributing

regulators, besides the FAA, want to testflight the 737MAX without MCAS augmentation to see how strange the behavior is
the still didnt get a chance for that

so no one really knows if the crews would have been able to return the flight without incident


So where in the Flight Profile of the two crashes (you can see all the traces) do you propose that the MAX's supposed Aerodynamic Instability was a contributing factor in the accidents?

Although the controls were hard to use it seemed pretty aerodynamically stable well past VMO on ET - and on Lionair it seemed pretty stable as well.

They also got no where near a stall situation.

There is probably a reason it wasn't included in the Lionair final report - it doesn't exist (at least there was no evidence of any instability on the crash flight).


as long as we do not see a transcript of the cockpit voices we have no clear picture of the problems the flightdeck crew had to fight with
usually the transscript (never the original audio) of a crashed plane is included in the report
i dont know why this important part is missing

lion has a lot of 737MAX on order
they have interest in downplaying the problem
they have influence in there region and they have the power to get wishes fullfilled

who knows ...


Here you go - starts on Page 79 the second entry is the Pilot talking about having the FLU.

Lots of conflicting warnings but no mention of instability.

http://knkt.dephub.go.id/knkt/ntsc_avia ... Report.pdf
 
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aerolimani
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:17 pm

dtw2hyd wrote:
9w748capt wrote:
So will these fixes solve the underlying problem that the MAX is an unstable airplane at baseline? So it'll still have a tendency to stall more often than comparable airplanes, right? So what's the software going to actually fix?


It gives the authority back to the crew. In layman terms, Creepy McCassey still on board but gets a off switch.

In the long run, BCA can pull a 788 trick on the MAX family. Introduce MAX10 landing gear to others, introduce bigger fin making it relatively more inherently stable. Swap orders to updated models. No one will ever notice. Everyone prises 789 improvements and no one misses 788.

The MAX10 gear’s only benefit is to increase the angle at which the aircraft can take off and land, reducing the amount of runway needed. When on the ground, other than at times of rotation and touchdown, the MAX10 will be at the same height as all the other 737 MAX models. The gear offers no advantage to any of the shorter models.

As to changing the empennage, I doubt they would want to make any changes, as it would likely reduce efficiency, not to mention the host of problems it would create by altering the COG.

I doubt we are likely to see any significant future changes to the fuselage or hear of the currently offered 737MAX models. For better or worse, I think MCAS is the only solution which allows the MAX to remain competitive with the A320 family. They’re already losing to the A220.
 
djm18
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:19 pm

asdf wrote:
djm18 wrote:
.... but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident;


a lot of movement and plane behavior in both crashes is not really explaned till now

its pretty clear that MCAS was the trigger for the disasters
but its not know how much the aerodynamical behavior of the MAX was contributing to the complete loss of control

in the LionAir crash report they didnt list it als contributing

regulators, besides the FAA, want to testflight the 737MAX without MCAS augmentation to see how strange the behavior is
the still didnt get a chance for that

so no one really knows if the crews would have been able to return the flight without incident


One important data point to consider is the LionAir flight the night before the crash, they disabled MCAS and then completed the flight without further incident; And that was at night. Yes they were lucky that they had a third pilot with them in the cockpit but after they turned off the trim, eliminating MCAS, they did not seem to have issues handling the plane.
 
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Revelation
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:19 pm

zoom321 wrote:
keesje wrote:
Interesting. Boeing still hopes to certifiy by December. Breaking news, stcocks jumped.

https://www.barrons.com/articles/boeing-stock-737-max-timeline-slip-faa-flight-control-software-51573512041

A short break from reality?

Stock near all time high with all the free money, no one goes to jail, little wonder boeing sees little incentive for safety.

Stock underperforming the market, DM pulls himself out of the bonus pool, and:

KarlB737 wrote:
Courtesy: Reuters

Boeing Orders Sink As Customers Opt To Swap MAX

"Net orders so far this year came to just 45 at the end of October, down from 56 in September, further widening the gap on sales this year with the company’s European rival Airbus SE (AIR.PA) which has now sold nearly 500 more planes."

https://www.reuters.com/article/us-boeing-deliveries/boeing-orders-sink-as-customers-opt-to-swap-max-idUSKBN1XM24M?il=0

... the idea that there is little fiscal impact from the MAX tragedy is pretty misguided.
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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shmerik
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:24 pm

morrisond wrote:
So where in the Flight Profile of the two crashes (you can see all the traces) do you propose that the MAX's supposed Aerodynamic Instability was a contributing factor in the accidents?

Although the controls were hard to use it seemed pretty aerodynamically stable well past VMO on ET - and on Lionair it seemed pretty stable as well.

They also got no where near a stall situation.

There is probably a reason it wasn't included in the Lionair final report - it doesn't exist (at least there was no evidence of any instability on the crash flight).


There are a few things in the ET report that seem more bizarre than the Indonesian one but it may just be my lack of experience with what constitutes normal in crash reports.

I'm thinking of these two statements:

Six seconds after the autopilot engagement, there were small amplitude roll oscillations accompanied by lateral acceleration, rudder oscillations and slight heading changes. These oscillations continued also after the autopilot was disengaged.


Is this expected in this period of flight and if so why did they make a point of including it in the report?

At 05:39:57, the Captain advised again the First-Officer to request to maintain runway heading and that they are having flight control problems.


The pilot talks about flight control issues just before the first MCAS AND activation, and this also aligns with the first time that their climb is arrested, before MCAS has had a chance to kick in.

However don't take this as me trying to argue that the aircraft is inherently unstable or anything, I've just had questions about these tidbits for a while and haven't found any significant discussion about it.

There are also the eyewitness reports from farmers in the area who reported that smoke and debris were coming from the plane as it flew overhead. Not that we can ever know for sure either way but there isn't there the very slight possibility that there were manufacturing defects that caused issues in addition to MCAS?
 
asdf
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:27 pm

morrisond wrote:
Here you go - starts on Page 79 the second entry is the Pilot talking about having the FLU.
Lots of conflicting warnings but no mention of instability.
http://knkt.dephub.go.id/knkt/ntsc_avia ... Report.pdf


the FLU (or a influenza infect) was not the problem
i think we know ...

but thanks
i seem to have overlooked it ..

sry
 
morrisond
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Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:31 pm

asdf wrote:
morrisond wrote:
Here you go - starts on Page 79 the second entry is the Pilot talking about having the FLU.
Lots of conflicting warnings but no mention of instability.
http://knkt.dephub.go.id/knkt/ntsc_avia ... Report.pdf


the FLU (or a influenza infect) was not the problem
i think we know ...

but thanks
i seem to have overlooked it ..

sry


Your welcome.
 
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aerolimani
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 7:33 pm

djm18 wrote:
9w748capt wrote:
So will these fixes solve the underlying problem that the MAX is an unstable airplane at baseline? So it'll still have a tendency to stall more often than comparable airplanes, right? So what's the software going to actually fix?


I am not sure that is entirely fair. The bigger engines mounted forward slightly created a tendency for a pitch up attitude in certain (more extreme) parts of the flight envelope which could then lead to a stall. MCAS was put in to correct this and make it behave/feel more like the NG. But MCAS was not well designed and not well implemented; It in fact was the key contributing factor to both these accidents. I am going out on a limb here but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident; Especially since they were both flying in VFR conditions.

And also remember that there were a good number of MAXs flying before the grounding, so not sure it is fair to say that it is an unstable airplane at baseline

I know this is how Boeing likes to phrase it; “to behave like the NG.” It’s not an untruthful statement, but it’s not the whole story either. The MAX is not certifiable without MCAS compensating for an aerodynamic issue; the extra lift generates by the nacelles at high angles of attack, causing a lightening of pressure on the yoke, in violation of the regulation 14 CFR § 25.203 - Stall characteristics. So, Boeing is only making the MAX fly like an NG in the way that the NG does not violate this regulation, and MCAS helps the MAX to also not violate this regulation.

As to stable or unstable… that depends whether you think inconsistent yoke pressure on approach to stall is an instability in itself, or not. There’s no question that the regulation exists to ensure safe aircraft, so does violating that regulation mean unsafe? Personally, my opinion lands on the side of unsafe. Of course, I recognize that safe can be a relative term. There are many shades of grey between safe and unsafe.

Regardless, for me, there must be a line somewhere. The regulation makes that line clear. So, I believe the plane must meet the regulation. That is the safest way forward. It should be noted that this regulation has been in place since before the original 737 was certified.
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 8:11 pm

aerolimani wrote:
djm18 wrote:
9w748capt wrote:
So will these fixes solve the underlying problem that the MAX is an unstable airplane at baseline? So it'll still have a tendency to stall more often than comparable airplanes, right? So what's the software going to actually fix?


I am not sure that is entirely fair. The bigger engines mounted forward slightly created a tendency for a pitch up attitude in certain (more extreme) parts of the flight envelope which could then lead to a stall. MCAS was put in to correct this and make it behave/feel more like the NG. But MCAS was not well designed and not well implemented; It in fact was the key contributing factor to both these accidents. I am going out on a limb here but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident; Especially since they were both flying in VFR conditions.

And also remember that there were a good number of MAXs flying before the grounding, so not sure it is fair to say that it is an unstable airplane at baseline

I know this is how Boeing likes to phrase it; “to behave like the NG.” It’s not an untruthful statement, but it’s not the whole story either. The MAX is not certifiable without MCAS compensating for an aerodynamic issue; the extra lift generates by the nacelles at high angles of attack, causing a lightening of pressure on the yoke, in violation of the regulation 14 CFR § 25.203 - Stall characteristics. So, Boeing is only making the MAX fly like an NG in the way that the NG does not violate this regulation, and MCAS helps the MAX to also not violate this regulation.

As to stable or unstable… that depends whether you think inconsistent yoke pressure on approach to stall is an instability in itself, or not. There’s no question that the regulation exists to ensure safe aircraft, so does violating that regulation mean unsafe? Personally, my opinion lands on the side of unsafe. Of course, I recognize that safe can be a relative term. There are many shades of grey between safe and unsafe.

Regardless, for me, there must be a line somewhere. The regulation makes that line clear. So, I believe the plane must meet the regulation. That is the safest way forward. It should be noted that this regulation has been in place since before the original 737 was certified.


Are you sure that the relevant regulation has been in place since the 737 was certified? Others on here have reported that the REG was modded after NG certification to be a consistent increase I believe.

But that is a dark whole if we start debating that one again.
 
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PITingres
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 8:21 pm

aerolimani wrote:
...
As to stable or unstable… that depends whether you think inconsistent yoke pressure on approach to stall is an instability in itself, or not. ...


Instability in aerodynamics has a well defined meaning, so it's not a matter of opinion. It's not unstable, period.

I don't know if the certification issue is the change in feel by itself, or or the change relative to the original certification. There's obviously a certification issue either way, but it's not an instability.
Fly, you fools! Fly!
 
asdf
Posts: 704
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 8:50 pm

PITingres wrote:
Instability in aerodynamics has a well defined meaning, so it's not a matter of opinion. It's not unstable, period.


if we have the big luck that someone with an inside knowenledge about aerodynamical instability is with us ..... would you please explain why you are in the opinion that a plane with a negativ stick load in normal manoevering envelope would be "stable"
 
justloveplanes
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 8:51 pm

aerolimani wrote:
dtw2hyd wrote:
9w748capt wrote:
So will these fixes solve the underlying problem that the MAX is an unstable airplane at baseline? So it'll still have a tendency to stall more often than comparable airplanes, right? So what's the software going to actually fix?


It gives the authority back to the crew. In layman terms, Creepy McCassey still on board but gets a off switch.

In the long run, BCA can pull a 788 trick on the MAX family. Introduce MAX10 landing gear to others, introduce bigger fin making it relatively more inherently stable. Swap orders to updated models. No one will ever notice. Everyone prises 789 improvements and no one misses 788.

The MAX10 gear’s only benefit is to increase the angle at which the aircraft can take off and land, reducing the amount of runway needed. When on the ground, other than at times of rotation and touchdown, the MAX10 will be at the same height as all the other 737 MAX models. The gear offers no advantage to any of the shorter models.

As to changing the empennage, I doubt they would want to make any changes, as it would likely reduce efficiency, not to mention the host of problems it would create by altering the COG.

I doubt we are likely to see any significant future changes to the fuselage or hear of the currently offered 737MAX models. For better or worse, I think MCAS is the only solution which allows the MAX to remain competitive with the A320 family. They’re already losing to the A220.


Partly agree/disagree. Changing the rear aero surfaces will change the COG, but more importantly, the center of rotation. Exactly what the plane needs, a longer tail like a kite to minimize the pitch.

I do agree this is more weight and drag, which is why it wasn't done. If the 737 gets only as efficient as an a320, why buy it?
 
XRAYretired
Posts: 870
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 8:51 pm

morrisond wrote:
aerolimani wrote:
djm18 wrote:

I am not sure that is entirely fair. The bigger engines mounted forward slightly created a tendency for a pitch up attitude in certain (more extreme) parts of the flight envelope which could then lead to a stall. MCAS was put in to correct this and make it behave/feel more like the NG. But MCAS was not well designed and not well implemented; It in fact was the key contributing factor to both these accidents. I am going out on a limb here but without MCAS pushing the nose down on a single sensor AOA failure, both crews should have been able to return the flight without incident; Especially since they were both flying in VFR conditions.

And also remember that there were a good number of MAXs flying before the grounding, so not sure it is fair to say that it is an unstable airplane at baseline

I know this is how Boeing likes to phrase it; “to behave like the NG.” It’s not an untruthful statement, but it’s not the whole story either. The MAX is not certifiable without MCAS compensating for an aerodynamic issue; the extra lift generates by the nacelles at high angles of attack, causing a lightening of pressure on the yoke, in violation of the regulation 14 CFR § 25.203 - Stall characteristics. So, Boeing is only making the MAX fly like an NG in the way that the NG does not violate this regulation, and MCAS helps the MAX to also not violate this regulation.

As to stable or unstable… that depends whether you think inconsistent yoke pressure on approach to stall is an instability in itself, or not. There’s no question that the regulation exists to ensure safe aircraft, so does violating that regulation mean unsafe? Personally, my opinion lands on the side of unsafe. Of course, I recognize that safe can be a relative term. There are many shades of grey between safe and unsafe.

Regardless, for me, there must be a line somewhere. The regulation makes that line clear. So, I believe the plane must meet the regulation. That is the safest way forward. It should be noted that this regulation has been in place since before the original 737 was certified.


Are you sure that the relevant regulation has been in place since the 737 was certified? Others on here have reported that the REG was modded after NG certification to be a consistent increase I believe.

But that is a dark whole if we start debating that one again.


Just another little story.

As previously advised, 25-203 was at revison b in 1964 and revised to c in 1995. The change was in relation to specified roll angles - nothing else. Do ones own search and one will not need to question statements with uncorroborated alternatives.

Ray
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:02 pm

asdf wrote:
PITingres wrote:
Instability in aerodynamics has a well defined meaning, so it's not a matter of opinion. It's not unstable, period.


if we have the big luck that someone with an inside knowenledge about aerodynamical instability is with us ..... would you please explain why you are in the opinion that a plane with a negativ stick load in normal manoevering envelope would be "stable"


It does not have a negative stick load - the load just gets lighter.
 
asdf
Posts: 704
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:08 pm

morrisond wrote:
asdf wrote:
PITingres wrote:
Instability in aerodynamics has a well defined meaning, so it's not a matter of opinion. It's not unstable, period.


if we have the big luck that someone with an inside knowenledge about aerodynamical instability is with us ..... would you please explain why you are in the opinion that a plane with a negativ stick load in normal manoevering envelope would be "stable"


It does not have a negative stick load - the load just gets lighter.


yes, maybe
or, maybe not
they dont show
we dont know

see it as a hypothetically question

can the 737MAX be called "aerodynamical instable" if it has a negativ stick load within the authorized flight envelope?
 
morrisond
Posts: 2844
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:25 pm

XRAYretired wrote:
2.5.1.1 Reason MCAS added to Aircraft
......During the preliminary design stage of the Boeing 737-8 (MAX), Boeing tests and analysis revealed that the addition of the LEAP-1B engine and associated nacelle changes was deemed likely to negatively affect the stick force per g (FS/g) characteristics required by 14 FAR 25.255 and the controllability and maneuverability requirements of 14 FAR 25.143(f). After the study of various options for addressing this issue, Boeing implemented aerodynamic changes as well as a stability augmentation function called the Maneuvering Characteristics Augmentation System (MCAS), as an extension of the existing Speed Trim System (STS), to improve aircraft handling characteristics at elevated angles of attack. The MCAS was needed in order to make the Boeing 737-8 (MAX) handling characteristics so similar to the NG versions that no simulator training was needed for type rating. It was also required so that the 737 MAX passed the certification that the pitch controls could not get lighter on the approach to stall................'


From our own Ray. See above the relevant FAR's are 25.255 and 25.143 - it wasn't 25-203.

I'm sure he can tell us when and why they were revised.
 
morrisond
Posts: 2844
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:27 pm

asdf wrote:
morrisond wrote:
asdf wrote:

if we have the big luck that someone with an inside knowenledge about aerodynamical instability is with us ..... would you please explain why you are in the opinion that a plane with a negativ stick load in normal manoevering envelope would be "stable"


It does not have a negative stick load - the load just gets lighter.


yes, maybe
or, maybe not
they dont show
we dont know

see it as a hypothetically question

can the 737MAX be called "aerodynamical instable" if it has a negativ stick load within the authorized flight envelope?


The stick loads have nothing to do with it being Aerodynamically stable or unstable. If you had negative stick loads that would just be really Sh***y control design.
 
XRAYretired
Posts: 870
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:38 pm

morrisond wrote:
XRAYretired wrote:
2.5.1.1 Reason MCAS added to Aircraft
......During the preliminary design stage of the Boeing 737-8 (MAX), Boeing tests and analysis revealed that the addition of the LEAP-1B engine and associated nacelle changes was deemed likely to negatively affect the stick force per g (FS/g) characteristics required by 14 FAR 25.255 and the controllability and maneuverability requirements of 14 FAR 25.143(f). After the study of various options for addressing this issue, Boeing implemented aerodynamic changes as well as a stability augmentation function called the Maneuvering Characteristics Augmentation System (MCAS), as an extension of the existing Speed Trim System (STS), to improve aircraft handling characteristics at elevated angles of attack. The MCAS was needed in order to make the Boeing 737-8 (MAX) handling characteristics so similar to the NG versions that no simulator training was needed for type rating. It was also required so that the 737 MAX passed the certification that the pitch controls could not get lighter on the approach to stall................'


From our own Ray. See above the relevant FAR's are 25.255 and 25.143 - it wasn't 25-203.

I'm sure he can tell us when and why they were revised.

'................certification that the pitch controls could not get lighter on the approach to stall…….' i.e. 25-203.

Do your own research.

Ray
 
User avatar
Revelation
Posts: 24775
Joined: Wed Feb 09, 2005 9:37 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:40 pm

asdf wrote:
morrisond wrote:
asdf wrote:
if we have the big luck that someone with an inside knowenledge about aerodynamical instability is with us ..... would you please explain why you are in the opinion that a plane with a negativ stick load in normal manoevering envelope would be "stable"

It does not have a negative stick load - the load just gets lighter.

yes, maybe
or, maybe not
they dont show
we dont know

see it as a hypothetically question

can the 737MAX be called "aerodynamical instable" if it has a negativ stick load within the authorized flight envelope?

The people "with an inside knowenledge about aerodynamical instability" have largely left the discussion due to all the grief they get when their explanations don't match other people's expectations.

A bit of google led me to a relevant post on our own site:

WPIAeroGuy wrote:
Stability just requires the pitching moment is always a restoring force, (typically negative) using normal conventions. What I was saying was look at the rate of change of that curve, the curve should become increasingly more negative for increased stick forces. If it reverses, you can still have a stabile pitching moment but with decreasing stick force, which is where MCAS is required.

Ref: viewtopic.php?t=1418079&start=150#p21276769
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
 
morrisond
Posts: 2844
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:50 pm

XRAYretired wrote:
morrisond wrote:
XRAYretired wrote:
2.5.1.1 Reason MCAS added to Aircraft
......During the preliminary design stage of the Boeing 737-8 (MAX), Boeing tests and analysis revealed that the addition of the LEAP-1B engine and associated nacelle changes was deemed likely to negatively affect the stick force per g (FS/g) characteristics required by 14 FAR 25.255 and the controllability and maneuverability requirements of 14 FAR 25.143(f). After the study of various options for addressing this issue, Boeing implemented aerodynamic changes as well as a stability augmentation function called the Maneuvering Characteristics Augmentation System (MCAS), as an extension of the existing Speed Trim System (STS), to improve aircraft handling characteristics at elevated angles of attack. The MCAS was needed in order to make the Boeing 737-8 (MAX) handling characteristics so similar to the NG versions that no simulator training was needed for type rating. It was also required so that the 737 MAX passed the certification that the pitch controls could not get lighter on the approach to stall................'


From our own Ray. See above the relevant FAR's are 25.255 and 25.143 - it wasn't 25-203.

I'm sure he can tell us when and why they were revised.

'................certification that the pitch controls could not get lighter on the approach to stall…….' i.e. 25-203.

Do your own research.

Ray


I did I quoted you. 25.255 requires increasing stick force per g, which is the more stringent requirement than just not getting lighter under 25-203 - that is what came into place after NG certification.

And once again we go down into the black hole.
 
morrisond
Posts: 2844
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 12, 2019 9:56 pm

I particularly like this quote from WPIAeroGuy from 6 Months ago. See post 6181 viewtopic.php?f=3&t=1417545&start=6150

"It’s because morrisond and OldAeroGuy are correct and are using the aerodynamic definition of stability. Stability has NOTHING to do with control feel. The reason those two are being so ‘stubborn’ is because there’s a huge physical difference between a stable and an unstable plane. The F-117A was unstable. It could not be flown without computer augmentation. Most modern fighters are similar.

Look at it this way. An aircraft stability analysis, based on the classical industry accepted definition of stability, is done without even knowing what the control system looks like. It is based solely off the lift, drag and moment curves of the external surfaces, fuselage, any external components, and thrust effects. For longitudinal stability, this would be looked at with the elevator fixed, and with the elevator floating.

Now, once the aircraft stability is determined, THEN you would look at the control system to make sure the control feel is correct. At this point the MAX was stable: this is not an argument, there is a very precise mathematical definition based on the analysis above. However, the control system needed to be designed to meet the stick feel inputs. I liked Zeke’s explanation several pages back about the cone and the string - the physics linkages could have been designed to increase loading at high AoA, or in a pure FBW plane this could have been baked into the software.

Basically to summarize - the stability of an airplane is an aerodynamic property and is determined independently from the design of the control system. The control system is designed to give the pilot the necessary feedback. The control system does not change the inherent aerodynamic stability of the airplane. To use a converse example: the F-117 is not aerodynamically stable because the control system makes it flyable. It is still unstable, but the control system is constantly applying control surface forces to maintain trajectory. It is controllable, but not stable."

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