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PW100
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:00 pm

OldAeroGuy wrote:
I doubt that Boeing was surprised with the amount of lift the nacelles were providing near stall. That is the sort of thing that is easy to determine, either by CFD or wind tunnel testing. I suspect the reason the MAX was having trouble passing FAR 25.203 was that the new engine size/position changed the wing stall pattern.

Flight test wing stall progression is always a bit of a crap shoot. CFD in its current state can't handle the 3D viscous effects and wind tunnels suffer from Reynolds Number (ie scaling) effects. Until an airplane is stalled for the first time, how it will stall really is an unknown.

If the outboard portions of the wing begin to stall earlier than predicted, stick forces needed to increase AoA to the full wing stall level may lighten. It is not unusual to spend time in flight test trying to get the wing stall pattern right or by adjusting a stability augmentation system to pass FAR 25.203 handling requirements.

The change in MCAS travel from 0.6 deg to 2.5 deg is probably due to flight test tailoring shown necessary to pass FAR 25.203.


Fully concur.

Perhaps they should hire NASA Ames facility for some full scale testing.
It may not be able reach to reach the speeds where MCAS is needed, but may help in optimizing CFD modeling into stall territory.
Image
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OldAeroGuy
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:02 pm

Jamie514 wrote:
If the stick lightening differences are non appreciable to a human and the entry to and recovery from stall is not tangibly altered with or without MCAS, why is it there?

Why wouldn't Boeing apply for a waiver on the stick force for such a purportedly negligible change in feel or in actual handling characteristics?

Not adding up.


Perhaps because the FAA will not wavier the condition?
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PW100
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:11 pm

morrisond wrote:
PW100 wrote:
. . . .


I think we are going to have to disagree on whether or not the plane was stable in pitch. Lighter control feel does not mean it’s unstable except in some draconian interpretation of the English language..


Why would we have to disagree? Where did I write that it was unstable in pitch??? I did not claim such.

It think it was during one of my first aerodynamic lessons where it was stated that control forces are closely related to stability margins. The more stable a platform is, the more (control column) force will be required to get it out of that stable condition. And vice versa of course.

The 737 is (probably) not unstable. But it lacks sufficient stability margins at certain part of the flight envelope. This presents itself as lower control column forces than desired.
I'm fully onboard with OldAeroGuy's theory on how this happened and took Boeing by surprise.
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PW100
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:18 pm

OldAeroGuy wrote:
ArgentoSystems wrote:
Either way, judging from the amount of intervention that MCAS was designed to do, this behavior was not as innocent as you and OAG are trying to portray.


I am relying on the pilot comments after stalling the MAX with MCAS off in the simulator and the lack of redundancy in the whole MCAS system, either MCAS.v1 or MCAS.v2. If the MAX was "inherently unstable" as some have said, the whole MCAS system would be much more complex.

https://aviationweek.com/commercial-avi ... lator-demo

"A full aerodynamic stall with the MCAS inoperative is another exercise pilots experience in the MAX engineering cab simulator. “We reduced thrust at 5,000 ft. and slowed the aircraft at about 1 kt. per sec. We were at a midrange cg [center of gravity] with gear, slats and flats up. We trimmed until we reached 30% above stall speed and then just continued to ease back on the control wheel,” one of the pilots says.

“Pitch feel was natural, progressively increasing as airspeed decayed. Somewhere between the audible low airspeed warning and stickshaker, I felt the slightest lightening on control pressure in my fingertips. Quite candidly, if I had not been watching for it, I don’t think I would have noticed any difference between the MAX and the Next Gen [NG] models. I kept pulling back through stickshaker, then buffet, then elevator feel shift [a function that doubles the artificial control feel forces near stall] and finally until the yoke was buried in my lap. The nose just flopped down gently at the stall, and I initiated recovery as I would in most other airplanes I’ve flown,” he adds."


But is the above fully representative for the flight envelope area where MCAS was meant for? The above describes slow speed stall, where MCAS was needed for a higher speed condition (if I remember correctly)?

Thanks.
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smartplane
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:24 pm

OldAeroGuy wrote:
Another opinion relative to the Ethiopian accident.

https://www.flightglobal.com/news/artic ... -a-457693/

With Boeing and their PR crisis management teams operating at full speed, consider the ultimate source and motives of 'information' and 'news' which deflect from the OEM. Crew have no ability or budget to counter.

Surely, as Interested has stated here repeatedly, balanced articles will highlight no OEM should be designing and building aircraft today, that require a higher level of training and expertise than similar aircraft built a decade or more ago. Referred to as progress / raising the bar.
 
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PW100
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:29 pm

7BOEING7 wrote:
RickNRoll wrote:
morrisond wrote:
There are reports from MAX and NG pilots that within normal operating speeds the manual trim wheel works fine and no unusual effort is needed.

You can see the mentour pilot YouTube video. They were in normal flight operating speeds and the effort required to manually trim was surprising.

The manual effort required to manually trim went up significantly with the change to the NG when the larger instrument panels required the trim weeks to be made smaller and a damper had to be added to stop snap back. Boeing was aware from the early days that excessive force could be required to manually trim and used to publish advice on how to make manual trim possible when the physical force required was too high.

Don't know what "normal flight operating speeds" mentour was simulating, but based on my experience manually trimming the 737 (Jurrasic, Classic and Next Gen -- several hundred times) at altitudes from 15000ft to FL350 at "normal flight operating speeds" his simulation looked bogus.

I also didn't notice any "significant" difference between the Classic and Next Gen when using manual trim and none of the pilots I flew with be they male or female had an issue either.
As for the "published advice" that apparently was issued in the days of the -200, 40 years ago, I never heard it discussed or trained too during my career.


The trimming becomes a problem in a (severely) mis-trimmed condition. Did you try manual trimming with the wheel with full yoke back as well?
The problem apparently is that the nose-up elevator force is working against the jack screw and thus trim wheel.
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OldAeroGuy
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:30 pm

PW100 wrote:
OldAeroGuy wrote:
I doubt that Boeing was surprised with the amount of lift the nacelles were providing near stall. That is the sort of thing that is easy to determine, either by CFD or wind tunnel testing. I suspect the reason the MAX was having trouble passing FAR 25.203 was that the new engine size/position changed the wing stall pattern.

Flight test wing stall progression is always a bit of a crap shoot. CFD in its current state can't handle the 3D viscous effects and wind tunnels suffer from Reynolds Number (ie scaling) effects. Until an airplane is stalled for the first time, how it will stall really is an unknown.

If the outboard portions of the wing begin to stall earlier than predicted, stick forces needed to increase AoA to the full wing stall level may lighten. It is not unusual to spend time in flight test trying to get the wing stall pattern right or by adjusting a stability augmentation system to pass FAR 25.203 handling requirements.

The change in MCAS travel from 0.6 deg to 2.5 deg is probably due to flight test tailoring shown necessary to pass FAR 25.203.


Fully concur.

Perhaps they should hire NASA Ames facility for some full scale testing.


It may not be able reach to reach the speeds where MCAS is needed, but may help in optimizing CFD modeling into stall territory.
Image


Despite what the NASA PR says, a 737 MAX is too large for the facility.

Getting accurate wind tunnel data and flow patterns requires that the model span be limited to about 75% of the test section width. If the wing tips are too close to the tunnel walls, the solid wall boundary prevents the flow near the wing tips from accurately representing free air behavior. With a test section width of 120', models would be limited to spans of 90'.

With a span of nearly 118', the 737 MAX is clearly too large to accurately test for wing stall patterns in the Ames 80' x 120'
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art
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:42 pm

Venturing into the world of speculation here. What gap would there be between FAA and peers approving Boeing's fix including, as part of the approval, stipulated extra training and the first modified aircraft with pilots with modified training coming into service again? Say that on June 1st approval is given to fly updated MAX and pilots, when will that first happen?

And as an afterthought how long will it take for all grounded aircraft and pilots to get back to how rhey were?
Last edited by art on Sun Apr 28, 2019 9:59 pm, edited 1 time in total.
 
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PW100
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:46 pm

Interested wrote:
Reading the article - there was a standard alert on earlier 737s.
For the Max some new alerts were also introduced that you had to pay for extra. But only if you paid extra was the previous standard alert also enabled
And neither the FAA nor the airlines were aware that the standard alert they were used to having was removed and now part of the add on package
This happened in 2017. It only became known to the FAA and airlines after the Lion Crash.
So it wasn't just new MCAS alerts that you had to pay for. The Max was being used with the existing standard alert disabled. And this was a decision taken by Boeing employees without informing anybody else.

Shockingly bad IMO

After the Lion crash FAA under pressure from South West insisted the standard alert was re-enabled. Obviously we also eventually ended up with the add on paid for package being made standard as well at some stage.


And in what way do you think that would that have affected or prevented the Lion air crash, if the crew would have this warning available to them?

I have given this some thought a while back when these stories first emerged, but I haven't been able to close the circle. Mainly because the pilots were unaware of MCAS. Let alone they would be aware that it was fed by only one single AoA sensor. Let alone they would understand the impact of AoA disagree on MCAS system level.

To me this whole story of "optional safety feature" is mainly hot air. But I'm open to suggestions differently.
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aerolimani
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:46 pm

In one region of the flight test envelope, where a Pilot would have disregarded multiple policy and procedural steps, at an airspeed below BUFFET ALERT, AIRSPEED LOW, and stick shaker, there exists a regime where stick forces do not continue on a linear path as AOA increases.


I’m trying to understand this sentence. Does it mean that the pilot would, or would not, see the above warnings, in this region where MCAS is needed?
 
smartplane
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 9:56 pm

ltbewr wrote:
There needs to be better grooming and training of pilots, less expensive to learn how to become a pilot, better pay for pilots in their early years and on smaller 'commuter' airlines. It is not very good to pay someone flying humans more like in term of real time working for a pay rate like a worker at McDonald's. If they are smart and good enough to be pilots they will look to areas of work that pay better up front, allow them to afford to pay off loans and don't have the responsibility of flying.

Agreed.

OEM's need to ensure they test aircraft initially with test pilots, and then real pilots with different proficiency levels.

Perhaps a future feature for passengers selecting a flight, will be the ability to check crew experience based on training and hours on type. If below a certain threshold, the ability to cancel and re-book at no extra cost.
 
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PW100
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 10:01 pm

OldAeroGuy wrote:
PW100 wrote:
OldAeroGuy wrote:
I doubt that Boeing was surprised with the amount of lift the nacelles were providing near stall. That is the sort of thing that is easy to determine, either by CFD or wind tunnel testing. I suspect the reason the MAX was having trouble passing FAR 25.203 was that the new engine size/position changed the wing stall pattern.

Flight test wing stall progression is always a bit of a crap shoot. CFD in its current state can't handle the 3D viscous effects and wind tunnels suffer from Reynolds Number (ie scaling) effects. Until an airplane is stalled for the first time, how it will stall really is an unknown.

If the outboard portions of the wing begin to stall earlier than predicted, stick forces needed to increase AoA to the full wing stall level may lighten. It is not unusual to spend time in flight test trying to get the wing stall pattern right or by adjusting a stability augmentation system to pass FAR 25.203 handling requirements.

The change in MCAS travel from 0.6 deg to 2.5 deg is probably due to flight test tailoring shown necessary to pass FAR 25.203.


Fully concur.

Perhaps they should hire NASA Ames facility for some full scale testing.


It may not be able reach to reach the speeds where MCAS is needed, but may help in optimizing CFD modeling into stall territory.
Image


Despite what the NASA PR says, a 737 MAX is too large for the facility.

Getting accurate wind tunnel data and flow patterns requires that the model span be limited to about 75% of the test section width. If the wing tips are too close to the tunnel walls, the solid wall boundary prevents the flow near the wing tips from accurately representing free air behavior. With a test section width of 120', models would be limited to spans of 90'.

With a span of nearly 118', the 737 MAX is clearly too large to accurately test for wing stall patterns in the Ames 80' x 120'


Yes, I know (wasn't expecting an answer anyway). But can't argue that it would still be a pretty cool exercise!
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Jamie514
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 10:07 pm

OldAeroGuy wrote:
Jamie514 wrote:
If the stick lightening differences are non appreciable to a human and the entry to and recovery from stall is not tangibly altered with or without MCAS, why is it there?

Why wouldn't Boeing apply for a waiver on the stick force for such a purportedly negligible change in feel or in actual handling characteristics?

Not adding up.


Perhaps because the FAA will not wavier the condition?


Sorry it is not right now possible to reconcile

deviation is detectable by test equipment, but not by most Pilots (it is in single digits of pounds of force)


And

flight tests with an -800, a MAX 8 with MCAS, and a MAX 8 without MCAS indicated no appreciable differences between the three test conditions


With a suggestion that Boeing sought and was denied any exemptions for a system designed to address control feel that the same folks are telling us makes no appreciable difference when on or off.

Once again today, the triangle has three sides but some can only ever acknowledge two of them.
 
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par13del
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 10:09 pm

smartplane wrote:
Perhaps a future feature for passengers selecting a flight, will be the ability to check crew experience based on training and hours on type. If below a certain threshold, the ability to cancel and re-book at no extra cost.

How would this work in Europe based on current practice?
 
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7BOEING7
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 10:14 pm

aerolimani wrote:
In one region of the flight test envelope, where a Pilot would have disregarded multiple policy and procedural steps, at an airspeed below BUFFET ALERT, AIRSPEED LOW, and stick shaker, there exists a regime where stick forces do not continue on a linear path as AOA increases.


I’m trying to understand this sentence. Does it mean that the pilot would, or would not, see the above warnings, in this region where MCAS is needed?


Under normal MCAS operation the pilot would have not acted on a 1) BUFFET ALERT advisory message on the FMC CDU, 2) Would not have seen the airspeed in the amber bar region/airspeed box flashing amber or heard the "AIRSPEED LOW, AIRSPEED LOW" voice alert (optional on the NG, don't know about the MAX), 3) disregarded the stick shaker and 4) not noticed the increase in force required while continuing to pull back on the stick before he gets to MCAS trimming nose down.

In short "would".
 
art
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 10:15 pm

smartplane wrote:
Perhaps a future feature for passengers selecting a flight, will be the ability to check crew experience based on training and hours on type. If below a certain threshold, the ability to cancel and re-book at no extra cost.


Or give a discount related to how few hours pilots had on type. Given the right price I'm sure there would be loads of takers for pilots with zero hours but who had spent all of 90 minutes on an iPad learning the ins and outs of flying this plane they had never actually flown. ;) and :x
 
kalvado
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 10:34 pm

OldAeroGuy wrote:
Despite what the NASA PR says, a 737 MAX is too large for the facility.

Getting accurate wind tunnel data and flow patterns requires that the model span be limited to about 75% of the test section width. If the wing tips are too close to the tunnel walls, the solid wall boundary prevents the flow near the wing tips from accurately representing free air behavior. With a test section width of 120', models would be limited to spans of 90'.

With a span of nearly 118', the 737 MAX is clearly too large to accurately test for wing stall patterns in the Ames 80' x 120'

Would it make sense to have part of a plane, as opposed to scaled model? Say chop off one wing - even half of it - and look at the flow over the other. Force on supports will be different, of course, but wing flow likely will be there.
Using production, or even test plane may be problematic, of course...
 
smartplane
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 10:36 pm

art wrote:
smartplane wrote:
Perhaps a future feature for passengers selecting a flight, will be the ability to check crew experience based on training and hours on type. If below a certain threshold, the ability to cancel and re-book at no extra cost.


Or give a discount related to how few hours pilots had on type. Given the right price I'm sure there would be loads of takers for pilots with zero hours but who had spent all of 90 minutes on an iPad learning the ins and outs of flying this plane they had never actually flown.

Perhaps discounts for self-fly pilots, with high hours on home simulators might be taking it too far.

My first suggestion was somewhat tongue in cheek. But, if training and experience are, and will increasingly become issues, then focus on them by airlines, OEM's, passengers, authorities, insurers, etc, will ensure sustainable positive changes occur.
 
OldAeroGuy
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 11:20 pm

Jamie514 wrote:
OldAeroGuy wrote:
Jamie514 wrote:
If the stick lightening differences are non appreciable to a human and the entry to and recovery from stall is not tangibly altered with or without MCAS, why is it there?

Why wouldn't Boeing apply for a waiver on the stick force for such a purportedly negligible change in feel or in actual handling characteristics?

Not adding up.


Perhaps because the FAA will not wavier the condition?


Sorry it is not right now possible to reconcile

deviation is detectable by test equipment, but not by most Pilots (it is in single digits of pounds of force)


And

flight tests with an -800, a MAX 8 with MCAS, and a MAX 8 without MCAS indicated no appreciable differences between the three test conditions


With a suggestion that Boeing sought and was denied any exemptions for a system designed to address control feel that the same folks are telling us makes no appreciable difference when on or off.

Once again today, the triangle has three sides but some can only ever acknowledge two of them.


What's so difficult to reconcile?

Side 1: The FAA has a standard for stall handling characteristics
Side2: Without MCAS, the 737 MAX will not meet the FAA stall handling characteristics
Side3: The FAA will not certify the 737 MAX unless it meets the stall handling characteristics.

See, all three sides of the triangle are complete.

Why do you think the FAA is willing to hand out waivers to their regulations? If a wavier was granted and the airplane had an accident in any way related to stall, do you think the wavier and the FAA employee granting it would be free from scrutiny?

Have you ever been responsible for certifying a Part 25 airplane?
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
OldAeroGuy
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 11:24 pm

kalvado wrote:
OldAeroGuy wrote:
Despite what the NASA PR says, a 737 MAX is too large for the facility.

Getting accurate wind tunnel data and flow patterns requires that the model span be limited to about 75% of the test section width. If the wing tips are too close to the tunnel walls, the solid wall boundary prevents the flow near the wing tips from accurately representing free air behavior. With a test section width of 120', models would be limited to spans of 90'.

With a span of nearly 118', the 737 MAX is clearly too large to accurately test for wing stall patterns in the Ames 80' x 120'

Would it make sense to have part of a plane, as opposed to scaled model? Say chop off one wing - even half of it - and look at the flow over the other. Force on supports will be different, of course, but wing flow likely will be there.
Using production, or even test plane may be problematic, of course...


And why go to the expense of chopping a 737 MAX in half when a whole one is out there flying?

Remember, the wind tunnel is static but you're looking at a dynamic condition. What you're suggesting would help in the preflight stage but would be very, very, very expensive. Once the airplane is in flight test, it's the better experimental vehicle.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
kalvado
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Re: B737MAX Grounded Worldwide

Sun Apr 28, 2019 11:56 pm

OldAeroGuy wrote:
kalvado wrote:
OldAeroGuy wrote:
Despite what the NASA PR says, a 737 MAX is too large for the facility.

Getting accurate wind tunnel data and flow patterns requires that the model span be limited to about 75% of the test section width. If the wing tips are too close to the tunnel walls, the solid wall boundary prevents the flow near the wing tips from accurately representing free air behavior. With a test section width of 120', models would be limited to spans of 90'.

With a span of nearly 118', the 737 MAX is clearly too large to accurately test for wing stall patterns in the Ames 80' x 120'

Would it make sense to have part of a plane, as opposed to scaled model? Say chop off one wing - even half of it - and look at the flow over the other. Force on supports will be different, of course, but wing flow likely will be there.
Using production, or even test plane may be problematic, of course...


And why go to the expense of chopping a 737 MAX in half when a whole one is out there flying?

Remember, the wind tunnel is static but you're looking at a dynamic condition. What you're suggesting would help in the preflight stage but would be very, very, very expensive. Once the airplane is in flight test, it's the better experimental vehicle.

More thinking about how to justify such oversize facility. One wing off model is probably on par with 75% model cost-wise -but when I think about per-hour costs involved for something like that... Instrumentation may still be better than what you can get flying... maybe..
 
Jamie514
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 1:05 am

Jamie514 wrote:
OldAeroGuy wrote:
Jamie514 wrote:

Sorry it is not right now possible to reconcile



And



With a suggestion that Boeing sought and was denied any exemptions for a system designed to address control feel that the same folks are telling us makes no appreciable difference when on or off.

Once again today, the triangle has three sides but some can only ever acknowledge two of them.


What's so difficult to reconcile?

Side 1: The FAA has a standard for stall handling characteristics
Side2: Without MCAS, the 737 MAX will not meet the FAA stall handling characteristics
Side3: The FAA will not certify the 737 MAX unless it meets the stall handling characteristics.

See, all three sides of the triangle are complete.

Why do you think the FAA is willing to hand out waivers to their regulations? If a wavier was granted and the airplane had an accident in any way related to stall, do you think the wavier and the FAA employee granting it would be free from scrutiny?

Have you ever been responsible for certifying a Part 25 airplane?


Oh my goodness no I don't work in the industry.

I was confused.

It was explained over and over that the system was in place to provide control stick feedback that was just a hair away from meeting FAR standards, well before actual stall.

Now, that the handling changes with or without MCAS were not perceptible.

And that the system will disable after a single activation per flight, and plane still airworthy.

See how you have to ignore one for the rest to make sense?
 
kayik
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 1:25 am

As Interested said "it is a huge market" in terms of value. However, it is a very small market in terms of customer base. You are not selling cars or sailing boats, there are a couple of hundred customers available. So, every customer counts, you have to make each one of them happy for your own future happiness. Would you dare to go into a legal war with them? Nobody will sue anybody. If a customer wants to cancel orders, they will cancel orders. If they want to be compensated for their losses, they will be compensated. There will be some meetings with those customers to provide assurances first then will come the negotiation stage. Every single MAX owner will eventually get what they want. Fact of life.

There is not a single reason why people should choose MAX over A320 family. Oh,sorry, there is one. Political. We have quite a number ordered to get something in return from the orange guy. Fortunately, half of it is optional.

Personally, I will never fly in this tube and make sure nobody around me will. In addition; I don't want to hassle of searching for a non-MAX flight each time I am flying somewhere. What a waste of time an effort.

Paris air show is coming, what will Boeing be trying to sell there?
 
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zkojq
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 2:03 am

SEPilot wrote:
kalvado wrote:
SEPilot wrote:
Actually, it is an extremely well designed plane. It has competed on even terms with a design that is twenty years newer. That is no easy feat. It is much, much easier to start with blank paper than to update an old design in order to compete with a new one. The fact that Boeing has been able to do so is an incredible feat of engineering.

An extremely optimized design where some parameters - like safety - are sacrificed to achieve other targets.
See Concorde - the plane with worst crash to hours flown ratio in modern history; space shuttle - with two spectacular failures.
To put in a different perspective: present safety record of MAX is such that 1 out of 10 pilots will not live to retirement due to a crash. Helps to save on pensions...

This is a gross exaggeration. Yes, two crashes occurred because Boeing engineers failed to understand how dense some pilots can be. That will be fixed. You obviously believe that situation will continue. It won’t. The 737 prior to the MAX accumulated an excellent safety record; once it gets cleared to fly again (which it will) the MAX will continue that record.

What a ridiculous thing to say: "if you exclude all the crashes, it's a very safe plane". Of course not including very relevant factors can be used to massage statistics to show what you want. "If you don't include the debt, Asiana, Jet Airways and Norwegian all have fantastic balance sheets". "If you don't include all future crashes which might or might not happen, the A320neo has an unbeatable safety record". "If you don't include the ones that don't deploy when they're meant to, Takata makes fantastic airbags".

The hyperbole here has gotten way over the top and your comments about the flight crew is sickening
Last edited by zkojq on Mon Apr 29, 2019 2:16 am, edited 1 time in total.
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ArgentoSystems
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 2:07 am

Jamie514 wrote:
If the stick lightening differences are non appreciable to a human and the entry to and recovery from stall is not tangibly altered with or without MCAS, why is it there?

Why wouldn't Boeing apply for a waiver on the stick force for such a purportedly negligible change in feel or in actual handling characteristics?

Not adding up.

My thoughts exactly. It does not make sense. On one hand - minute difference that most pilots won't notice, on the other hand - a device that controls stabilizer to fix that. I'm not buying it.
 
ArgentoSystems
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 2:12 am

aerolimani wrote:
In one region of the flight test envelope, where a Pilot would have disregarded multiple policy and procedural steps, at an airspeed below BUFFET ALERT, AIRSPEED LOW, and stick shaker, there exists a regime where stick forces do not continue on a linear path as AOA increases.


I’m trying to understand this sentence. Does it mean that the pilot would, or would not, see the above warnings, in this region where MCAS is needed?

I'm reading it as no, before the alerts. But at the same time they are saying to get into that region pilots have disregard multiple things?
Edit. No. At airspeed BELOW these alerts. So yes, the pilots see and ignore those alerts. Well in this case, how can they maintain with a straight face that is NOT a stall protection device? We are talking about non-normal part of the envelope, where the plane should never ever be, and the only way for it to be there is for pilot to ignore multiple alerts. Excuse me, but in this case MCAS acts a last line of defense!
 
luv2cattlecall
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 2:54 am

7BOEING7 wrote:
aerolimani wrote:
, 2) Would not have seen the airspeed in the amber bar region/airspeed box flashing amber or heard the "AIRSPEED LOW, AIRSPEED LOW" voice alert (optional on the NG, don't know about the MAX), .


Why would such a thing be optional?
 
GalaxyFlyer
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 3:22 am

smartplane wrote:
ltbewr wrote:
There needs to be better grooming and training of pilots, less expensive to learn how to become a pilot, better pay for pilots in their early years and on smaller 'commuter' airlines. It is not very good to pay someone flying humans more like in term of real time working for a pay rate like a worker at McDonald's. If they are smart and good enough to be pilots they will look to areas of work that pay better up front, allow them to afford to pay off loans and don't have the responsibility of flying.

Agreed.

OEM's need to ensure they test aircraft initially with test pilots, and then real pilots with different proficiency levels.

Perhaps a future feature for passengers selecting a flight, will be the ability to check crew experience based on training and hours on type. If below a certain threshold, the ability to cancel and re-book at no extra cost.


Charter operators are already doing that kind of background check. When my schedulers booked a charter (corporate operator needing lift), they would present me with a brief on the crew’s licensing and flight experience, aircraft status. If the crew didn’t meet our standards, I’d approve a waiver or disapprove the crew and ask the operator to change crew or rebook the charter. The most frequent red flag was a high experience captain and newly rated co-pilot. I’d call, verify it was a FO in training with an instructor.

There’s no dangerous planes, no dangerous pilots, no dangerous weather. There’s only dangerous operations. A Cub can just barely kill you, Bob Hoover crashed a plane having not checked the tanks had the proper fuel and thunderstorms have been safely penetrated. The more hysterical here, ten years on, will be flying MAXs without a thought especially, if the choice is driving for days or swimming.


gf
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 4:06 am

https://www.nytimes.com/2019/04/08/busi ... -max-.html

I missed this article earlier in the month from New York Times

1960s design, 1990s technology and a Paper Manual

Is it true what it says about how you start a 737?
 
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7BOEING7
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 4:17 am

[twoid][/twoid]
luv2cattlecall wrote:
7BOEING7 wrote:
aerolimani wrote:
, 2) Would not have seen the airspeed in the amber bar region/airspeed box flashing amber or heard the "AIRSPEED LOW, AIRSPEED LOW" voice alert (optional on the NG, don't know about the MAX), .


Why would such a thing be optional?


It’s not required for the safe operation of the airplane.
 
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william
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 4:20 am

smartplane wrote:
OldAeroGuy wrote:
Another opinion relative to the Ethiopian accident.

https://www.flightglobal.com/news/artic ... -a-457693/

With Boeing and their PR crisis management teams operating at full speed, consider the ultimate source and motives of 'information' and 'news' which deflect from the OEM. Crew have no ability or budget to counter.

Surely, as Interested has stated here repeatedly, balanced articles will highlight no OEM should be designing and building aircraft today, that require a higher level of training and expertise than similar aircraft built a decade or more ago. Referred to as progress / raising the bar.


Or maybe what you thought happened didn’t and the article is correct. This isn’t a MSNBC/ Fox News thing .
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 4:25 am

william wrote:
smartplane wrote:
OldAeroGuy wrote:
Another opinion relative to the Ethiopian accident.

https://www.flightglobal.com/news/artic ... -a-457693/

With Boeing and their PR crisis management teams operating at full speed, consider the ultimate source and motives of 'information' and 'news' which deflect from the OEM. Crew have no ability or budget to counter.

Surely, as Interested has stated here repeatedly, balanced articles will highlight no OEM should be designing and building aircraft today, that require a higher level of training and expertise than similar aircraft built a decade or more ago. Referred to as progress / raising the bar.


Or maybe what you thought happened didn’t and the article is correct. This isn’t a MSNBC/ Fox News thing .


Various articles in US Media today running stories that American Pilot Unions are unhappy with the draft proposals they have seen on extra training before Max returns to flying. If US pilots aren't happy with the remote training proposals then that's not a good indicator for how the rest of the world will react


https://uk.mobile.reuters.com/article/amp/idUKKCN1S40IC
 
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william
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 4:37 am

Interested wrote:
william wrote:
smartplane wrote:
With Boeing and their PR crisis management teams operating at full speed, consider the ultimate source and motives of 'information' and 'news' which deflect from the OEM. Crew have no ability or budget to counter.

Surely, as Interested has stated here repeatedly, balanced articles will highlight no OEM should be designing and building aircraft today, that require a higher level of training and expertise than similar aircraft built a decade or more ago. Referred to as progress / raising the bar.


Or maybe what you thought happened didn’t and the article is correct. This isn’t a MSNBC/ Fox News thing .


Various articles in US Media today running stories that American Pilot Unions are unhappy with the draft proposals they have seen on extra training before Max returns to flying. If US pilots aren't happy with the remote training proposals then that's not a good indicator for how the rest of the world will react


https://uk.mobile.reuters.com/article/amp/idUKKCN1S40IC


Union pilots for Southwest Airlines Co, the world's largest operator of the MAX with 34 jets and dozens more on order, have said they were satisfied with the FAA draft report but would decide on additional training once they see Boeing's final proposals.

You left out the union for the carrier that flies the 737 24/7.

No pilot will strap into a cockpit he or she deems unsafe. It’s up to Boeing and the regulators to remove all doubts and if that means more expensive sim time then so be it.
 
IADFCO
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 4:59 am

kalvado wrote:
OldAeroGuy wrote:
kalvado wrote:
Would it make sense to have part of a plane, as opposed to scaled model? Say chop off one wing - even half of it - and look at the flow over the other. Force on supports will be different, of course, but wing flow likely will be there.
Using production, or even test plane may be problematic, of course...


And why go to the expense of chopping a 737 MAX in half when a whole one is out there flying?

Remember, the wind tunnel is static but you're looking at a dynamic condition. What you're suggesting would help in the preflight stage but would be very, very, very expensive. Once the airplane is in flight test, it's the better experimental vehicle.

More thinking about how to justify such oversize facility. One wing off model is probably on par with 75% model cost-wise -but when I think about per-hour costs involved for something like that... Instrumentation may still be better than what you can get flying... maybe..


In the 80' x 120' Ames tunnel you can definitely fit one half of a full size 737NG attaching it to a sufficiently large plate, so that no flow from the "real" half goes toward the "nonexisting" half. Probably the "half aircraft" would be turned on the side, with the wing sticking up. In doing so, however, you limit yourself to situations where the flow is symmetric with respect to the longitudinal plane of the aircraft, i.e., you cannot have any sideslip or test any nonsymmetric configurations, e.g., one with flaps deployed on just one wing.

WInd tunnel test vs flight test is not an either/or proposition. In the wind tunnel you can generate much more precise and repeatable flow conditions, and take flow measurements that would be hard or impossible to get on a flying aircraft. This could be useful, for example, to calibrate your aerodynamic prediction models. You can also test several configurations, e.g., different engine positions with respect to the wing, or separate effects, e.g., wing vs tail.

To do this you don't obviously take an aircraft off the production line and physically saw it in half, seats, wiring, and all. Every aircraft manufacturer and most aerospace research organizations have model shops that build specialized wind tunnel models.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 5:30 am

william wrote:
Interested wrote:
william wrote:

Or maybe what you thought happened didn’t and the article is correct. This isn’t a MSNBC/ Fox News thing .


Various articles in US Media today running stories that American Pilot Unions are unhappy with the draft proposals they have seen on extra training before Max returns to flying. If US pilots aren't happy with the remote training proposals then that's not a good indicator for how the rest of the world will react


https://uk.mobile.reuters.com/article/amp/idUKKCN1S40IC


Union pilots for Southwest Airlines Co, the world's largest operator of the MAX with 34 jets and dozens more on order, have said they were satisfied with the FAA draft report but would decide on additional training once they see Boeing's final proposals.

You left out the union for the carrier that flies the 737 24/7.



Not sure what you mean by "left out"

I've just posted a link to an article ?
 
A3801000
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 7:50 am

art wrote:
crimsonchin wrote:
AirwayBill wrote:


Interesting. I wonder if these people are liars and angry pro-union workers too, seeing as that's the only reason anyone would ever want to call out Boeing's practices.


Like a little sarcasm now and then. ;)

Re: FO damage, foreign objects have been discovered on a number of occasions on the 767 tanker. What is happening at Boeing?


Well, let's see if the mods finally allow me to add a bit of recent history here:

747/8 - Software problems/flutter problems (FAA issued a warning to ground it if problems not resolved)
787 - Batteries, grounded
767 Tanker - FOD, customer refuses to accept
737 MAX - grounded

To me, as just a average passenger, it does not look too great. String of bad luck? Sure could be. Or the result of cutting corners wherever possible.
The way Boeing now tries to get the MAX back in the air does not help at all. Sounds very much like 'no big deal, we changed some lines of code, all good now'.

I really hope it will be resolved soon, in a way I feel confident again and also, please no hiccups with the 777X.
 
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scbriml
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 7:57 am

Revelation wrote:
scbriml wrote:
That's the sound of furious backpedaling.

In what way?


In the usual sense of the expression. It seems I'm not the only person who sees it that way...

https://leehamnews.com/2019/04/29/ponti ... wn-it-but/
It took months before Boeing CEO Dennis Muilenburg issued a video in which, among other things, he said, “We own it.” He was referring to safety of the MAX.

This was widely interpreted as Boeing stepping up and taking responsibility for at least some of the causes of the Lion Air and Ethiopian Airlines crashes.

Last Wednesday, he took it all back.
Time flies like an arrow. Fruit flies like a banana!
There are 10 types of people in the World - those that understand binary and those that don't.
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 8:20 am

scbriml wrote:
Revelation wrote:
scbriml wrote:
That's the sound of furious backpedaling.

In what way?


In the usual sense of the expression. It seems I'm not the only person who sees it that way...

https://leehamnews.com/2019/04/29/ponti ... wn-it-but/
It took months before Boeing CEO Dennis Muilenburg issued a video in which, among other things, he said, “We own it.” He was referring to safety of the MAX.

This was widely interpreted as Boeing stepping up and taking responsibility for at least some of the causes of the Lion Air and Ethiopian Airlines crashes.

Last Wednesday, he took it all back.


In summary - Boeing CEO:

"We own it"

Becomes

"We own it but......"

I thought it was strange at the time
 
art
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 9:02 am

Boeing is sharing a proposed computer-based pilot training session with US pilot unions as part of its work to return the 737 Max to service, several sources familiar with Max’s re-certification efforts say.

The computer-based training session reviews the 737 Max’s speed trim system and the manoeuvring characteristics augmentation system (MCAS), which has been identified as among factors contributing to two 737 Max crashes.

Boeing has said it is developing new training, as well as updating the MCAS software, but the Chicago-based company has released few details.


Later in the article:

Boeing’s proposed computer-based training can be completed on laptop or tablet computer, and takes as little as 15min, sources say.


https://www.flightglobal.com/news/artic ... in-457736/

So NG pilots graduating to MAX only need a further 15 minutes or so training on a computer to be adequately trained to handle any MCAS system misbehaviour in real flight?

To me all that seems to matter to Boeing is to avoid real training in a SIM. Put another way, to avoid NG to MAX conversion costing any $$$.
 
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Revelation
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 9:18 am

scbriml wrote:
Revelation wrote:
scbriml wrote:
That's the sound of furious backpedaling.

In what way?

In the usual sense of the expression. It seems I'm not the only person who sees it that way...

https://leehamnews.com/2019/04/29/ponti ... wn-it-but/
It took months before Boeing CEO Dennis Muilenburg issued a video in which, among other things, he said, “We own it.” He was referring to safety of the MAX.

This was widely interpreted as Boeing stepping up and taking responsibility for at least some of the causes of the Lion Air and Ethiopian Airlines crashes.

Last Wednesday, he took it all back.

The Leeham article quotes Muilenberg:

I can tell you with confidence that we understand our airplane, we understand how the design was accomplished, how the certification was accomplished, and we main fully confident in the product that we put in the field. But we also know there are areas that we can improve, and that is the source of the software update here. But there was no surprise or gap or unknown here or something that somehow slipped through a certification process. Quite the opposite. We know exactly how the airplane was designed. We know exactly how it was certified. We have taken the time to understand that. That has led to the software update that we’ve been implementing and testing, and we’re very confident that when the fleet comes back up, the MAX will be one of the safest airplanes ever to fly.

It's no different than earlier messaging.

All along they've been saying that the mistake was putting too much workload on to the pilots rather than some deeper systematic failing.

The Leeham article also says:

There have been press reports that US pilots, citing superior training here vs overseas, believe pilot error is the principal cause of the two accidents. I wrote a column April 15 on this very topic. I’ve talked with the flight safety director of a US airline who is adamant the pilots should have successfully flown through the incidents had training been better.

So there is some grounds for the idea that the pilot workload management was less than Boeing expected.

Of course he's not focusing on any explanation that would lead to a broader examination of the MAX and/or Boeing itself, but he never did.

He apologized for the crashes, and he said they own fixing it, and he's saying the software update is the fix.

As I wrote earlier, the company is gambling they can make this reasoning stick, and IMHO it's a damn risky gamble, for if they lose, they will have spent months pursuing what turned out to be a losing strategy, and the clock will start all over on the grounding.
Last edited by Revelation on Mon Apr 29, 2019 9:21 am, edited 1 time in total.
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Paolo18
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 9:20 am

So what's the latest?
Is 737 max ready for take off?
 
Interested
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 9:27 am

Paolo18 wrote:
So what's the latest?
Is 737 max ready for take off?


Boeing PR are working hard to convince everyone it will be soon
 
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Revelation
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 9:35 am

Flight Global ( https://www.flightglobal.com/news/artic ... -a-457693/ ) writes:

This boundary has instead been blurred by preliminary findings that raise awkward questions about airmanship and training, ones which are unlikely to sit easily with those who would prefer blame to be an exclusively external, rather than internal, affair.

Ethiopian Airlines has claimed its pilots were well-briefed on the Lion Air 737 Max accident which occurred less than five months earlier.

But the Ethiopian inquiry has not indicated whether either pilot recognised critical warning signs that emerged immediately after take-off, such as the one-sided stick-shaker and disagreeing instruments, or made a connection over the behavioural similarities with the ill-fated Lion jet.

Procedures for unreliable airspeed indications typically require the autopilot and autothrottle to be disengaged. But the crew persisted with activating the autopilot on the unreliable side, proceeding with an intended climb to cruise altitude – apparently selecting 32,000ft rather than the cleared 34,000ft – and leaving the thrust at the take-off, rather than climb, setting. Despite the continuing stick-shaker activation, the flaps were retracted.

Context is everything, of course, and the inquiry has months to run before a full explanation emerges. It has not yet released a full cockpit-voice recorder transcript.

But the impression is less that of a well-conducted flight interrupted by a software system gone rogue, than an escalation of small problems into a major one.

For those who keep track of these things, FG is a publication of Reed Business Information Limited, a UK-based business with Anglo-Dutch parentage ( ref: https://en.wikipedia.org/wiki/RELX ).
Wake up to find out that you are the eyes of the world
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keesje
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 9:45 am

Stick shaker -> stall, IAS 250 kts, TOGA, but don't retract the flaps (with their nose down moment) while fighting unexplained nose down forces! .. yeah.. If an airlines average pilots aren't good enough to fly that aircraft, they better don't buy such aircraft.

There was an article about an ($ optional $) OAG malfunction indicator, that was standard on previous 737 versions. Can't find it back..
"Never mistake motion for action." Ernest Hemingway
 
Amiga500
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 9:55 am

zeke wrote:
Amiga500 wrote:
1. failures in the flight control system =/= failed flight control system


The engineering context of that FAR means structurally broken. For example a cable snaps, a rod snaps, bolt shears.


Absolutely not.

So you are trying to argue a FBW system could be assembled with single failure points all over the place - but that is fine as long as the physical connection between actuator and the control surface is redundant?


zeke wrote:
I would prefer to keep flaps extended if the stick shaker is activated to provide more lift. Aircraft are certified to come back for immediate landings.


Which of course is why aircraft sometimes have to fly around to burn or dump fuel before landing if they have had to return immediately to their departure airport.
 
Amiga500
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 9:57 am

OldAeroGuy wrote:
Zeke is correct.

- Overweight landings are permitted if circumstances dictate the need
- Twins have no problem meeting the one engine inoperative approach climb requirement of FAR 25.121(d). Basically, if you can takeoff from an airport, you can do an immediate return to land.

Fuel dump systems on Twins are there mainly for convenience of operations. They are not needed for airplane performance requirements, neither approach/landing climb or approach speed.


- Yet no one does them unless in a dire time-dependent emergency. For good reason. Your putting the airframe out of action pending a C or D check (localised).
- Not worried about the engine thrust - its more structural loading through the u/c.
Last edited by Amiga500 on Mon Apr 29, 2019 10:08 am, edited 2 times in total.
 
Amiga500
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 10:03 am

OldAeroGuy wrote:
<SNIP>


That is good information. Thanks.

OldAeroGuy wrote:
As Zeke has pointed out, the 737 QRH says don't retract the Flaps with the stick shaker active. Why did Lion Air crews and the Ethiopian crews retract the Flaps?


Without being in their head, I would suspect because of confidence in airspeed, engine thrust and inclination - furthermore at that point, the pilots did not make a wrong problem diagnosis.
 
jollo
Posts: 349
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 10:59 am

keesje wrote:
There was an article about an ($ optional $) OAG malfunction indicator, that was standard on previous 737 versions. Can't find it back..


I'll second this question: there have been hints in the last couple of pages of this thread about a warning light which was standard in the NG but became an optional extra with the MAX. To be clear: I'm not talking about the "AoA disagree" flag and AoA indicator, which were optional both for the NG and for the MAX. So is there any warning (other than AoA disagree) that was standard in the NG but became optional with the MAX?
 
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zeke
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 11:02 am

Amiga500 wrote:
So you are trying to argue a FBW system could be assembled with single failure points all over the place - but that is fine as long as the physical connection between actuator and the control surface is redundant?


The software, wiring, and hydraulics are covered elsewhere. A FBW aircraft is certified the same way as a non FBW for that requirement, it needs to demonstrate that if a surface is jammed or failed the aircraft is still controlled.

Amiga500 wrote:
Which of course is why aircraft sometimes have to fly around to burn or dump fuel before landing if they have had to return immediately to their departure airport.


You can return to land immediately for any emergency.

Amiga500 wrote:
Yet no one does them unless in a dire time-dependent emergency. For good reason. Your putting the airframe out of action pending a C or D check (localised).
- Not worried about the engine thrust - its more structural loading through the u/c.


You can return immediately for any emergency, no such thing as a “dire time-dependent emergency”.

I am not aware of any C or D check required, we print out a Load 15 report, if the rate of descent on touchdown is within the zone nothing further is required.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
kalvado
Posts: 1809
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Re: B737MAX Grounded Worldwide

Mon Apr 29, 2019 11:15 am

IADFCO wrote:
kalvado wrote:
OldAeroGuy wrote:

And why go to the expense of chopping a 737 MAX in half when a whole one is out there flying?

Remember, the wind tunnel is static but you're looking at a dynamic condition. What you're suggesting would help in the preflight stage but would be very, very, very expensive. Once the airplane is in flight test, it's the better experimental vehicle.

More thinking about how to justify such oversize facility. One wing off model is probably on par with 75% model cost-wise -but when I think about per-hour costs involved for something like that... Instrumentation may still be better than what you can get flying... maybe..


In the 80' x 120' Ames tunnel you can definitely fit one half of a full size 737NG attaching it to a sufficiently large plate, so that no flow from the "real" half goes toward the "nonexisting" half. Probably the "half aircraft" would be turned on the side, with the wing sticking up. In doing so, however, you limit yourself to situations where the flow is symmetric with respect to the longitudinal plane of the aircraft, i.e., you cannot have any sideslip or test any nonsymmetric configurations, e.g., one with flaps deployed on just one wing.

WInd tunnel test vs flight test is not an either/or proposition. In the wind tunnel you can generate much more precise and repeatable flow conditions, and take flow measurements that would be hard or impossible to get on a flying aircraft. This could be useful, for example, to calibrate your aerodynamic prediction models. You can also test several configurations, e.g., different engine positions with respect to the wing, or separate effects, e.g., wing vs tail.

To do this you don't obviously take an aircraft off the production line and physically saw it in half, seats, wiring, and all. Every aircraft manufacturer and most aerospace research organizations have model shops that build specialized wind tunnel models.

Obvious, simple and an incorrect solution. There will be flow interaction with dividing plane, unless you make it super slippery. If you know how to achieve that, I beg you to use private message so we can think of commercial application!
Other than that, there is no guarantee that flow will be perfectly symmetric. Vortex may form somewhere, with a random rotation direction.
Last edited by kalvado on Mon Apr 29, 2019 11:16 am, edited 1 time in total.

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