milhaus
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 11:15 am

To mjoelnir: I have checked PN of AOA that are used on MAX, they are the same like ones on NG. ( I did not have access to JT or ET manuals just another big operator) Also instalation test is not rockett science, You just hold it in zero position marked on sensor flange and check values shown on computer itself.
 
asdf
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 11:20 am

milhaus wrote:
Also instalation test is not rockett science, You just hold it in zero position marked on sensor flange and check values shown on computer itself.


doese the installation test enable you recognise a gradual derivation from zero or does it only show if movement of the flange is free and it moves up and down
 
milhaus
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 12:01 pm

On Airbus ADIRU You can see exact values. I can not remember on 737, it is too many years ago. But I thing it is the same. They are really not changed so often.
 
XRAYretired
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 12:54 pm

asdf wrote:
milhaus wrote:
Also instalation test is not rockett science, You just hold it in zero position marked on sensor flange and check values shown on computer itself.


doese the installation test enable you recognise a gradual derivation from zero or does it only show if movement of the flange is free and it moves up and down

Read the investigation report. No guessing required (page 87).
knkt.dephub.go.id/knkt/ntsc_aviation/baru/2018%20-%20035%20-%20PK-LQP%20Final%20Report.pdf

Ray
 
maint123
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 1:28 pm

seahawk wrote:
maint123 wrote:
milhaus wrote:
To jrmy: 90000FH is nothing in terms of part reliability of aircraft parts, especially AOA sensors, in my 23 years experience as AMT on line mtce environment together with ten years at maintenance control center I can remember of only one AOA failure like this. I still can not get how it can fail on brand new aircrat.

Exactly. Everyone assumes that both crashes were due to AOA sensor failures but these sensors are being used in thousands of other Boeings and airbuses. Unless special sensors were made for max, the fault could be in some other aspect of the feedback loop. Boeing might be happily diverting attention from other issues. The probability of 2 max sensors damaged in such a short interval while 1000s of other models are not effected is very low.


Well it seems like the Lion Air sensor was infact defective, while the second crash looks like a bird strike damaged the sensor.

Just keeping a open mind. In the case of lion air their were 2 defective AOA sensors while in the case of ethiopian air, the bird managed to damage the AOA sensor. If you go to the ethiopian thread, the birdstrike theory was floated very soon after the crash. So 3 AOA sensors defective, while as milhaus said, he has hardly seen any similar issues with the 1000s of other Boeings flying?
The problem obviously is the MCAS circuit but is it solely related to the sensor is my doubt.
 
mjoelnir
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 1:40 pm

milhaus wrote:
To mjoelnir: I have checked PN of AOA that are used on MAX, they are the same like ones on NG. ( I did not have access to JT or ET manuals just another big operator) Also instalation test is not rockett science, You just hold it in zero position marked on sensor flange and check values shown on computer itself.


Yes the AoA sensors are the same, what they trigger is not. On an NG an AoA sensor failure is just that, yes you can get stick shaker and some warnings and an AoA disagree will warn you that an AoA sensor is bust.
On the MAX one AoA sensor failing high can trigger a deadly sequence. You will get stick shaker and a lot of other warnings, no AoA disagree warning and MCAS trying to ram your frame into the ground.
 
mjoelnir
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 1:44 pm

maint123 wrote:
seahawk wrote:
maint123 wrote:
Exactly. Everyone assumes that both crashes were due to AOA sensor failures but these sensors are being used in thousands of other Boeings and airbuses. Unless special sensors were made for max, the fault could be in some other aspect of the feedback loop. Boeing might be happily diverting attention from other issues. The probability of 2 max sensors damaged in such a short interval while 1000s of other models are not effected is very low.


Well it seems like the Lion Air sensor was infact defective, while the second crash looks like a bird strike damaged the sensor.

Just keeping a open mind. In the case of lion air their were 2 defective AOA sensors while in the case of ethiopian air, the bird managed to damage the AOA sensor. If you go to the ethiopian thread, the birdstrike theory was floated very soon after the crash. So 3 AOA sensors defective, while as milhaus said, he has hardly seen any similar issues with the 1000s of other Boeings flying?
The problem obviously is the MCAS circuit but is it solely related to the sensor is my doubt.


As MCAS uses one sensor only, one sensor failing high, if it is the active sensor, will trigger MCAS. That is the beauty of the Boeing design. Relying on one sensor only, no redundancies that could disturb the deadly action of MCAS.
 
maint123
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 2:07 pm

XRAYretired wrote:
asdf wrote:
milhaus wrote:
Also instalation test is not rockett science, You just hold it in zero position marked on sensor flange and check values shown on computer itself.


doese the installation test enable you recognise a gradual derivation from zero or does it only show if movement of the flange is free and it moves up and down

Read the investigation report. No guessing required (page 87).
knkt.dephub.go.id/knkt/ntsc_aviation/baru/2018%20-%20035%20-%20PK-LQP%20Final%20Report.pdf

Ray

Thanks. Just went through it.
Seems like a perfect storm.
The AOA calibration procedure is very informative.
 
asdf
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 2:14 pm

XRAYretired wrote:
asdf wrote:
milhaus wrote:
Also instalation test is not rockett science, You just hold it in zero position marked on sensor flange and check values shown on computer itself.


doese the installation test enable you recognise a gradual derivation from zero or does it only show if movement of the flange is free and it moves up and down

Read the investigation report. No guessing required (page 87).
knkt.dephub.go.id/knkt/ntsc_aviation/baru/2018%20-%20035%20-%20PK-LQP%20Final%20Report.pdf

Ray


thank you!
a competent mechanic should have catched the derivation on the installation test

interesting that a declination of +/-5 degrees (=10 degrees) is allowed but a declination of 20 degrees leeds to a catastrophic outcome ...
is it so complicated to calibrate them properly ...?
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 4:08 pm

seahawk wrote:
PixelFlight wrote:
milhaus wrote:
To jrmy: 90000FH is nothing in terms of part reliability of aircraft parts, especially AOA sensors, in my 23 years experience as AMT on line mtce environment together with ten years at maintenance control center I can remember of only one AOA failure like this. I still can not get how it can fail on brand new aircrat.

On all aircrafts others than the 737-8/9 MAX with MCAS v1, an erratic high value will be identified as a banal AoA sensors disagreement and/or failure.
You can you be certain that all the AoA sensors you see replaced did not expose an erratic high value ?


That is the actual amazing thing that they did not implement at least one cross check in the system. It would not even need to be the other sensor, it would have been enough to check the elevator / stick position and the engine setting.

There is a lot of agreement on that remark now, but at the 737-8/9 MAX design time the cross check in manual flight mode was determined by a flawed safety assessment to be implemented by the pilots using the stab trim runaway procedure. To be very exact, Boeing did implement one AoA cross check in the system, but in autopilot flight mode only...
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 4:12 pm

milhaus wrote:
AOA sensors value are also send to DFDR and are monitored and checked by flight safety department together wiht hundred of other parameters on each flight. Aditionally AOA outputs are used by ADC or ADIRU in Airbus to compute speed, so when AOA values between sensors are different You get indicated airspeed difference too. Most AOA are being removed due to heating failure, mechanical damage and for modifications

Did you ever see AoA sensors that fail to pass the installation check ?
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 4:42 pm

asdf wrote:
XRAYretired wrote:
asdf wrote:

doese the installation test enable you recognise a gradual derivation from zero or does it only show if movement of the flange is free and it moves up and down

Read the investigation report. No guessing required (page 87).
knkt.dephub.go.id/knkt/ntsc_aviation/baru/2018%20-%20035%20-%20PK-LQP%20Final%20Report.pdf

Ray


thank you!
a competent mechanic should have catched the derivation on the installation test

interesting that a declination of +/-5 degrees (=10 degrees) is allowed but a declination of 20 degrees leeds to a catastrophic outcome ...
is it so complicated to calibrate them properly ...?

Depend of what you define by "complicated", see:
point 1.16.2 starting from page 91
point 1.17.3 staring from page 140
point 2.6 starting from page 204

I am very surprised that today AoA sensors still have to be manually adjusted for calibration. Absolute angle sensors are common in the industry and extremely reliable, The mechanic can be designed to allow a single mounting position of all the parts. The internals of the type of AoA sensor used today look like a pre-1980 design that have almost not evolved.
 
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hilram
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 4:44 pm

aerolimani wrote:
Vladex wrote:
Aviation737 wrote:
Can someone tell me why the MAX was a bad idea? I mean to me it makes perfect sense for them to developed it.


It was a bad idea because it's totally outdated design , it looks absurd and has misfitting parts like engines. It was just a financial short term decision and a purported cash grab at the expense and the risk against everyone else. It would never happen in a competitive non government regulated industry

To be fair to Boeing, it was also a move to cling to market share. Not moving quickly would have surrendered more share to Airbus and Bombardier. Getting that share back, further down the road, with a new design, would be a much slower process. While I'm sure an NSA (instead of the MAX) would have eventually paid off, it would likely be a decade or more before Boeing got itself back to something close to 50% share of the NB market, if that. As it is, the 737 is only at 45%.

The bad idea was to spend all that Boeing cash on Share-buybacks over the years leading up to the A320 neo, as well as outsourcing engineering and expertise?
What if money had been spent on an NSA right away?
Flown on: A319, 320, 321, 332, 333, 343 | B732, 734, 735, 736, 73G, 738, 743, 744, 772, 77W | CRJ9 | BAe-146 | DHC-6, 7, 8 | F50 | E195 | MD DC-9 41, MD-82, MD-87
 
milhaus
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 5:17 pm

To pixelFlight: no, they are really reliable, it is just selsyn in it, which is already many years proven technology. Many of them are installed on A /C for many many years. Those which have to be removed is 90% heating system failure, then mechanical damage of wing from FOD and lightning...
 
DenverTed
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 6:45 pm

Boeing initially thought the MAX would fly the end of May 2019. It is now six months from that, and six months until June 1, 2020, the start of the busier summer season. Will the MAX be somewhat operational by then?
 
Sooner787
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 7:06 pm

DenverTed wrote:
Boeing initially thought the MAX would fly the end of May 2019. It is now six months from that, and six months until June 1, 2020, the start of the busier summer season. Will the MAX be somewhat operational by then?


I read this past week the FAA will approve RTS in January, but between the additional pilot training and
MX to bring these jets out of storage , it'll be late March before we see any back in service again.

Leeham surmised it'll take til end of 2021 to completely clear the backlog of undelivered frames.
 
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scbriml
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 10:13 pm

Sooner787 wrote:
I read this past week the FAA will approve RTS in January


Where did you read this? I thought the FAA were adamant that they weren’t working to a specific deadline.
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Agrajag
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 10:29 pm

How many Maxs' should have been flying by now if this awful turn of events hadnt happened?
The plural of anecdote is anecdotes, not data.
Slartibartfast had a point
 
RickNRoll
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 10:32 pm

morrisond wrote:
PixelFlight wrote:
morrisond wrote:

We were talking about ET and the Bulletins and information that came out after Lionair - sorry I was not that clear.

The only information that was out before Lionair was what was in the maintenance manual.

And this was part of the problem according to many (USA) pilots:

"Dispute arises among U.S. pilots on Boeing 737 MAX system linked to Lion Air crash"
https://www.seattletimes.com/business/boeing-aerospace/dispute-arises-among-u-s-pilots-on-boeing-737-max-system-linked-to-lion-air-crash/

"Boeing 737 MAX Pilots Had No Idea What They Were Up Against"
https://www.engineering.com/Hardware/ArticleID/19269/Boeing-737-MAX-Pilots-Had-No-Idea-What-They-Were-Up-Against.aspx

"At meeting with Boeing staff, pilots fumed about being left in dark on 737 software"
https://www.latimes.com/business/la-fi-boeing-737-max-pilots-meeting-20190314-story.html

Could certainly find more examples...


You just proved my point - yes the Lionair pilots had no idea - but by the time of ET they sure should have.
The ET pilots had an idea but were still overloaded.
 
marvindroid
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 10:49 pm

Agrajag wrote:
How many Maxs' should have been flying by now if this awful turn of events hadnt happened?


Delivered: 387 [1]
In storage @ Boeing: 363 [2]
Total: 750

They reduced production rate from 52 to 42 per month after the grounding. Apx. 80 less planes built due to the grounding and reduced production rate. So there should have been apx. 830 MAXs' flying.

[1] http://active.boeing.com/commercial/ord ... iew+Report
[2] https://737-max.blogspot.com/2019/04/73 ... aebfi.html
 
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PW100
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sat Nov 30, 2019 11:01 pm

RickNRoll wrote:
morrisond wrote:
PixelFlight wrote:
And this was part of the problem according to many (USA) pilots:
"Dispute arises among U.S. pilots on Boeing 737 MAX system linked to Lion Air crash"
https://www.seattletimes.com/business/boeing-aerospace/dispute-arises-among-u-s-pilots-on-boeing-737-max-system-linked-to-lion-air-crash/
"Boeing 737 MAX Pilots Had No Idea What They Were Up Against"
https://www.engineering.com/Hardware/ArticleID/19269/Boeing-737-MAX-Pilots-Had-No-Idea-What-They-Were-Up-Against.aspx
"At meeting with Boeing staff, pilots fumed about being left in dark on 737 software"
https://www.latimes.com/business/la-fi-boeing-737-max-pilots-meeting-20190314-story.html
Could certainly find more examples...

You just proved my point - yes the Lionair pilots had no idea - but by the time of ET they sure should have.
The ET pilots had an idea but were still overloaded.


They even performed the recommended action: Stabelizer Cut off Switches. But were still overlaoded and did not manage to regain sufficient control.
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
Chemist
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 5:30 am

PW100 wrote:
RickNRoll wrote:
morrisond wrote:
You just proved my point - yes the Lionair pilots had no idea - but by the time of ET they sure should have.
The ET pilots had an idea but were still overloaded.


They even performed the recommended action: Stabelizer Cut off Switches. But were still overlaoded and did not manage to regain sufficient control.


Did the recommended action include trimming electrically to neutral trim before cutting the switches?
I ask because after thousands of posts, I don't remember if I imagined that or it is the case.
 
DenverTed
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 5:59 am

By the end of 2019, there will be about 800 MAX, then Boeing wants to produce about 1,200 in the next two years. Can they feed 2,000 MAX into the market in two years? That will be a good challenge.
 
mjoelnir
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 7:52 am

marvindroid wrote:
Agrajag wrote:
How many Maxs' should have been flying by now if this awful turn of events hadnt happened?


Delivered: 387 [1]
In storage @ Boeing: 363 [2]
Total: 750

They reduced production rate from 52 to 42 per month after the grounding. Apx. 80 less planes built due to the grounding and reduced production rate. So there should have been apx. 830 MAXs' flying.

[1] http://active.boeing.com/commercial/ord ... iew+Report
[2] https://737-max.blogspot.com/2019/04/73 ... aebfi.html


You forget in your numbers that a ramp from 52 frames to 57 frames a month production was planed. So the 80 frames not produced is low.
 
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seahawk
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 8:35 am

PixelFlight wrote:
seahawk wrote:
PixelFlight wrote:
On all aircrafts others than the 737-8/9 MAX with MCAS v1, an erratic high value will be identified as a banal AoA sensors disagreement and/or failure.
You can you be certain that all the AoA sensors you see replaced did not expose an erratic high value ?


That is the actual amazing thing that they did not implement at least one cross check in the system. It would not even need to be the other sensor, it would have been enough to check the elevator / stick position and the engine setting.

There is a lot of agreement on that remark now, but at the 737-8/9 MAX design time the cross check in manual flight mode was determined by a flawed safety assessment to be implemented by the pilots using the stab trim runaway procedure. To be very exact, Boeing did implement one AoA cross check in the system, but in autopilot flight mode only...


The cynic in me believes that this was the explanation but not the reason.
 
oschkosch
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 10:51 am

Since we now enter the last month of the year, is there any info if and when Boeing will cut back production rate even further? Maybe even suspend it totally? I mean, it cannot be sustainable for them to continue to build planes that cannot be delivered due to grounding.
 
asdf
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 11:04 am

oschkosch wrote:
Since we now enter the last month of the year, is there any info if and when Boeing will cut back production rate even further? Maybe even suspend it totally? I mean, it cannot be sustainable for them to continue to build planes that cannot be delivered due to grounding.


Since Boeing has been denying regulators the flight test of the 737max for several months without any augmentation, the question of a general non-certifiable flight behavior of the 737MAX remains unanswered.

In the event that the flight behavior (without FBW) is not certifiable (and since no FBW can be retrofitted) are the produced frames the guarantee ( you could call it hostages) for boeing that it must come to a kind of solution in which the 737max be allowed anyway.

like changing the rules of certification

one maybe would not do that for threehundred frames
but for threethousand .... well ... other story
national interests come in play here ...
 
uta999
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 11:08 am

Another thing to consider is the enormous financing involved once the RTS begins. Can the markets keep pace with the amount of money involved?
Your computer just got better
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 12:02 pm

PW100 wrote:
RickNRoll wrote:
morrisond wrote:
You just proved my point - yes the Lionair pilots had no idea - but by the time of ET they sure should have.
The ET pilots had an idea but were still overloaded.


They even performed the recommended action: Stabelizer Cut off Switches. But were still overlaoded and did not manage to regain sufficient control.


Everyone here accuses me of making it all about the training/pilots when in reality it's people like yourselves that keep bringing up these issues.

I'm not on here every Six hours doing the lack of training equivalent of a "It's a deadly airplane, All the executives at Boeing should hang".

But if you really want to go there every day so you have a place to vent your frustrations - so be it.

Yes they did hit the cut-off switches but given that they did not put the plane back in trim before doing so, did not disengage the auto throttle and allowed the plane to accelerate past Vmo, barely tried the Manual wheels (it's debatable they even did this - they may not have extended the helper handle and they both didn't try together) and then they re-engaged the electric trim with no crew communication whatsoever I would say turning it off at first was a lucky guess and in no way shape or form proves that they understood the issue or the way to counteract it.

It just strongly suggests that even if they did have the proper procedure they barely glanced at it - did not have it in the cockpit with them and basically put about as much personal effort into being a good safe pilot who have the responsibility of safely getting there passengers back to the ground in one piece as big city cab drivers do in following the rules of the road.
 
kyu
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 12:37 pm

asdf wrote:
In the event that the flight behavior (without FBW) is not certifiable (and since no FBW can be retrofitted) are the produced frames the guarantee ( you could call it hostages) for boeing that it must come to a kind of solution in which the 737max be allowed anyway.

like changing the rules of certification

one maybe would not do that for threehundred frames
but for threethousand .... well ... other story
national interests come in play here ...

Very much this.
 
mjoelnir
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 1:02 pm

morrisond wrote:
PW100 wrote:
RickNRoll wrote:
The ET pilots had an idea but were still overloaded.


They even performed the recommended action: Stabelizer Cut off Switches. But were still overlaoded and did not manage to regain sufficient control.


Everyone here accuses me of making it all about the training/pilots when in reality it's people like yourselves that keep bringing up these issues.

I'm not on here every Six hours doing the lack of training equivalent of a "It's a deadly airplane, All the executives at Boeing should hang".

But if you really want to go there every day so you have a place to vent your frustrations - so be it.

Yes they did hit the cut-off switches but given that they did not put the plane back in trim before doing so, did not disengage the auto throttle and allowed the plane to accelerate past Vmo, barely tried the Manual wheels (it's debatable they even did this - they may not have extended the helper handle and they both didn't try together) and then they re-engaged the electric trim with no crew communication whatsoever I would say turning it off at first was a lucky guess and in no way shape or form proves that they understood the issue or the way to counteract it.

It just strongly suggests that even if they did have the proper procedure they barely glanced at it - did not have it in the cockpit with them and basically put about as much personal effort into being a good safe pilot who have the responsibility of safely getting there passengers back to the ground in one piece as big city cab drivers do in following the rules of the road.


Yes every time you try to point away from Boeing, by pointing to the pilots as the real reason, one has to come and to remind you that the Lion Air crash report points to Boeing's design as the main reason for the crash. Every regulator agrees and grounded the MAX.

Try to get it, Boeing produced a dangerous design turning the MAX into a flying death trap.
 
2175301
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 2:20 pm

asdf wrote:
Since Boeing has been denying regulators the flight test of the 737max for several months without any augmentation, the question of a general non-certifiable flight behavior of the 737MAX remains unanswered.

In the event that the flight behavior (without FBW) is not certifiable (and since no FBW can be retrofitted) are the produced frames the guarantee ( you could call it hostages) for boeing that it must come to a kind of solution in which the 737max be allowed anyway.

like changing the rules of certification

one maybe would not do that for threehundred frames
but for threethousand .... well ... other story
national interests come in play here ...


What evidence exist that Boeing has not done the test flights without any augmentation. They have clearly been doing test flights. The leaked email from the Transport Canada employee indicates that they thought that the 737 Max could be somehow waivered without any MCAS... which would only likely be thought possible if those test flights had already been done and shown that there was no issues with unusual flight behavior of the 737Max.

Just because no one has provided proof that the flights have not yet happened; does not mean they have not yet happened.

Or, do you have a source for your claim?

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

Sun Dec 01, 2019 2:53 pm

morrisond wrote:
Yes they did hit the cut-off switches but given that they did not put the plane back in trim before doing so, did not disengage the auto throttle and allowed the plane to accelerate past Vmo, barely tried the Manual wheels (it's debatable they even did this - they may not have extended the helper handle and they both didn't try together) and then they re-engaged the electric trim with no crew communication whatsoever

[I removed from your message the paranoid and the questionable respect]

* ~10% over Vmo is not an issue from a design and technical point of view. There should not, but this have no consequences know to them. This small over speed was the last of there priority compared to the very dangerous nose down MCAS actions at low altitude.

* The pilots have only two possibles ways to control the trim in manual flight mode: the electrical trim thumb switches, or the manual trim wheels. The ET302 CVR transcript have a clear communication that indicate that there tried two possibles ways to control the trim in manual flight mode. Guess what there can be ?

* The control deficiency of the manual trim wheels was not known to them and there was no procedure nor training to overcome that unexpected problem in implementing the Boeing runaway procedure.

* The re-engagement of the electrical trim was a desperate tentative to trim because the runaway procedure failed to solve that problem.

* It must be noted that the runaway stab trim is badly redacted and did not emphasis how important is to trim electrically before the cutoff, instead the procedure allow to manually trim after the cutoff.

* It must be noted that no procedure warned them that the MCAS will reset 5 seconds after there last electrical trim.

* It must be noted that no procedure instructed them to set flaps not up to disable MCAS.

* It must be noted that the constant noise of the left stick shaker certainly make the noise of the automatic trim less perceptible.

* It must be noted that the situation forced the pilots to heavily pitch up together, reducing there ability to do others tasks.

* It must be noted that the situation produced both high stress and high workload, reducing even more the pilots performances.

* It's only within the last minute of the flight that the pilots was able to recognize that the cause of there problems is the "left alpha vane" because the AoA disagreement indication was not working as expected.

But you perfectly known all of those facts already.
 
checklist350
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 3:08 pm

Sooner787 wrote:
DenverTed wrote:
Boeing initially thought the MAX would fly the end of May 2019. It is now six months from that, and six months until June 1, 2020, the start of the busier summer season. Will the MAX be somewhat operational by then?


Leeham surmised it'll take til end of 2021 to completely clear the backlog of undelivered frames.


The analytics quoted by Leeham do not take into account the staged RTS worldwide. They calculate as if from the moment FAA recertificies 100% will be deliverable.

In reality, only the American planes will be deliverable (~ 20%). This means still 80% go to storage. Then when the other authorities clear the plane will deliverable rate go towards 100%.

If the deliverable rate goes from 0 to 100 from February to say august it means there is on average still full inventory build up to may (equals a full RTS
With 100% deliverable production from may).

They still calculate as if there will be full deliverable production from January/ February. But if we calculate from may (=staged RTS from Feb to aug) there will be 630 stored planes that will take until June '22 to clear out at a 25 per month rate. Again. This is at the current most optimistic scenario.
 
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PixelFlight
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 4:01 pm

2175301 wrote:
asdf wrote:
Since Boeing has been denying regulators the flight test of the 737max for several months without any augmentation, the question of a general non-certifiable flight behavior of the 737MAX remains unanswered.

In the event that the flight behavior (without FBW) is not certifiable (and since no FBW can be retrofitted) are the produced frames the guarantee ( you could call it hostages) for boeing that it must come to a kind of solution in which the 737max be allowed anyway.

like changing the rules of certification

one maybe would not do that for threehundred frames
but for threethousand .... well ... other story
national interests come in play here ...


What evidence exist that Boeing has not done the test flights without any augmentation. They have clearly been doing test flights. The leaked email from the Transport Canada employee indicates that they thought that the 737 Max could be somehow waivered without any MCAS... which would only likely be thought possible if those test flights had already been done and shown that there was no issues with unusual flight behavior of the 737Max.

Just because no one has provided proof that the flights have not yet happened; does not mean they have not yet happened.

Or, do you have a source for your claim?

Have a great day,

It's actually the most strange and obfuscated aspect of this grounding. No one have actually published credible detailed information about the 737-8/9 MAX maneuvering characteristics without MCAS, and the information we got from the regulators, including the famous Transport Canada employee, seem to indicate that there are not in a better position. The only clear indication is the JATR that point to a "unacceptable characteristic" for one aspect of the MCAS only. This seem to indicate that the regulators have no access to the MCAS schedule table values, because there are by definition directly proportional to the maneuvering characteristics to be corrected. The fact that the MCAS schedule table values exists imply that Boeing did got those maneuvering characteristics values to be corrected somehow, either from a simulator, from a test flight, or from a combination of the two. But it look like Boeing is not willing to share that values to anyone, including the regulators, since months causing more and more attention on that aspect. This is not a detail in the grounding, but the most fundamental aspect that have motivated the MCAS system in the first place. In addition, this raise concern up to the pilots that could potentially face a situation where there have to do unusual maneuvers in manual flight mode with a MCAS disabled or stab trim cutoff for whatever reason.
 
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767333ER
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 4:39 pm

2175301 wrote:
asdf wrote:
Since Boeing has been denying regulators the flight test of the 737max for several months without any augmentation, the question of a general non-certifiable flight behavior of the 737MAX remains unanswered.

In the event that the flight behavior (without FBW) is not certifiable (and since no FBW can be retrofitted) are the produced frames the guarantee ( you could call it hostages) for boeing that it must come to a kind of solution in which the 737max be allowed anyway.

like changing the rules of certification

one maybe would not do that for threehundred frames
but for threethousand .... well ... other story
national interests come in play here ...


What evidence exist that Boeing has not done the test flights without any augmentation. They have clearly been doing test flights. The leaked email from the Transport Canada employee indicates that they thought that the 737 Max could be somehow waivered without any MCAS... which would only likely be thought possible if those test flights had already been done and shown that there was no issues with unusual flight behavior of the 737Max.

Just because no one has provided proof that the flights have not yet happened; does not mean they have not yet happened.

Or, do you have a source for your claim?

Have a great day,

This is an ad ignorantium situation. No proof either way. The only thing I would say is if we had positive action from Boeing we would likely hear about it given the people that are in the know and the amount of coverage this topic still gets. If Boeing hasn’t done it yet we’ll probably get no proof because it hasn’t happened and there has been no action to report.
Been on: 732 733 734 73G 738 752 763 A319 A320 A321 CRJ CR7 CRA/CR9 E145 E175 E190 F28 MD-82 MD-83 C172R C172S P2006T
 
Agrajag
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 5:39 pm

Pilot training is not the reason 850 max aircraft are not flying today. Poor engineering/decision making by Boeing is the reason. Its a tragedy.
The plural of anecdote is anecdotes, not data.
Slartibartfast had a point
 
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PW100
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 5:40 pm

morrisond wrote:
PW100 wrote:
RickNRoll wrote:
The ET pilots had an idea but were still overloaded.

They even performed the recommended action: Stabelizer Cut off Switches. But were still overlaoded and did not manage to regain sufficient control.

Everyone here accuses me of making it all about the training/pilots when in reality it's people like yourselves that keep bringing up these issues.
I'm not on here every Six hours doing the lack of training equivalent of a "It's a deadly airplane, All the executives at Boeing should hang".
But if you really want to go there every day so you have a place to vent your frustrations - so be it.

Yes they did hit the cut-off switches but given that they did not put the plane back in trim before doing so, did not disengage the auto throttle and allowed the plane to accelerate past Vmo, barely tried the Manual wheels (it's debatable they even did this - they may not have extended the helper handle and they both didn't try together) and then they re-engaged the electric trim with no crew communication whatsoever I would say turning it off at first was a lucky guess and in no way shape or form proves that they understood the issue or the way to counteract it.

It just strongly suggests that even if they did have the proper procedure they barely glanced at it - did not have it in the cockpit with them and basically put about as much personal effort into being a good safe pilot who have the responsibility of safely getting there passengers back to the ground in one piece as big city cab drivers do in following the rules of the road.


Not sure why you feel the need to write I'm not on here every Six hours, when your number of posts in this thread dwarf my number of posts . . .

There is no evidence that they did not try to put the plane back in trim. I have argued, and will continue to so until proven otherwise by some authorities source (like the Final Report) that AFTER MCAS BECAME ALIVE, no less than FOUR manual electric up-trim commands were made by the crew (strongly indicating they knew how that worked - some even doubt that). And all FOUR up-trim commands stop at exactly the same stabilizer pitch position. Coincidence? Or is there something in the plane (Aero / Software) that had some limitation affects om the up-trimming?

How can you be so sure that the crew did try to further uptrim? You have ZERO evidence that they did not TRY to so, while there are definitely strong indications that they knew how manual electric up-trimming works, and some other FORCE was impeding with their trimming efforts.


Vmo wasn't exceeded until 60 seconds AFTER MCAS BECAME alive. They had stall warning going off, unreliable airspeed, nose dive tendency, and sort of Christmas tree light up cockpit. Not to mention that reducing power usually isn't a great idea on stall warning. Not to mention that power helps keeping the nose up, which they were heavily struggling with.

Reaching Vmo was just another side effect of stuck AoA sensor induced MCAS run-away. It was a sign that the folks upfront were overwhelmed with the issues thrown at them.
With the benefit of hindsight you seem to have no issues throwing them under the bus for not sorting out this puzzle in 30 seconds, where you had six months to sort the puzzle . . .
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
Vladex
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Sun Dec 01, 2019 10:12 pm

aerolimani wrote:
Vladex wrote:
Aviation737 wrote:
Can someone tell me why the MAX was a bad idea? I mean to me it makes perfect sense for them to developed it.


It was a bad idea because it's totally outdated design , it looks absurd and has misfitting parts like engines. It was just a financial short term decision and a purported cash grab at the expense and the risk against everyone else. It would never happen in a competitive non government regulated industry

To be fair to Boeing, it was also a move to cling to market share. Not moving quickly would have surrendered more share to Airbus and Bombardier. Getting that share back, further down the road, with a new design, would be a much slower process. While I'm sure an NSA (instead of the MAX) would have eventually paid off, it would likely be a decade or more before Boeing got itself back to something close to 50% share of the NB market, if that. As it is, the 737 is only at 45%.



Clinging to a market share is a losing strategy long term but what market share is there in a government imposed duopoly anyway? Will market share not be an issue in the future? In the phone industry for example, Nokia and Blackberry were the biggest players 10 years ago but then refused to change when they were on top and clung to their share until it fell all under them . In any other industry clinging to market share produces bad products that no one wants and it completely shuts down innovation as it does in any form of life . It's limiting, it's a fear of failure and then when they try to innovate again then they find that they have totally lost it as they have too much burden from the past.
 
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SomebodyInTLS
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 1:34 pm

PW100 wrote:
Not sure why you feel the need to write I'm not on here every Six hours, when your number of posts in this thread dwarf my number of posts . . .


I recently discovered the joys of the ignore list. My blood pressure thanks me.
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
jollo
Posts: 388
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 2:20 pm

Chemist wrote:
PW100 wrote:
RickNRoll wrote:
The ET pilots had an idea but were still overloaded.


They even performed the recommended action: Stabelizer Cut off Switches. But were still overlaoded and did not manage to regain sufficient control.


Did the recommended action include trimming electrically to neutral trim before cutting the switches?
I ask because after thousands of posts, I don't remember if I imagined that or it is the case.


The bulletin published by Boeing in the aftermath of the LionAir crash was, in my opinion, a masterpiece of (intentional? unintended?) obfuscation. It managed, in a single document, to:
  • avoid mentioning MCAS
  • avoid describing its function (even without calling it by name) and why it could have been relevant to the LionAir crash
  • focus only on the need to abide by the Runaway Stabilizer NNC as already published in the FCOM, without mentioning that the condition (continuous un-commanded trim movement) was not to be taken at face value, because a MCAS-induced runaway would pause for 5 seconds between activation cycles
  • mention only as a footnote the possibility that the NNC "as is" may be insufficient and mentioning returning trim to neutral with electric trim just as a possibile helper, not as a critical, needed action

If, in my line of business, I ever delivered an operating procedure document stating something like: "When [wrong condition] then proceed to steps A, B and C. Note: operators may find that C is difficult/impossible to execute; enacting step D before step B could help" I would be (rightly) fired and my professional license revoked. And I don't design anything remotely as critical as airliners for civilian revenue service.

Moreover (but that's just my opinion) I also find that the tone of Boeing's bulletin rings kind of condescending, especially after 150+ innocent casualties: "You just need to run the NNC, you dumb pilot. Ah, you ran the NNC and found that the manual trim wheel is too heavy to move? Didn't you trim back to neutral before cutting off the trim electrical motor? Well, no, that's not a step of the NNC, but c'mon, it's just a matter of basic airmanship: you can't expect us to write everything in checklists, can you?"
 
morrisond
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 2:31 pm

jollo wrote:
Chemist wrote:
PW100 wrote:

They even performed the recommended action: Stabelizer Cut off Switches. But were still overlaoded and did not manage to regain sufficient control.


Did the recommended action include trimming electrically to neutral trim before cutting the switches?
I ask because after thousands of posts, I don't remember if I imagined that or it is the case.


The bulletin published by Boeing in the aftermath of the LionAir crash was, in my opinion, a masterpiece of (intentional? unintended?) obfuscation. It managed, in a single document, to:
  • avoid mentioning MCAS
  • avoid describing its function (even without calling it by name) and why it could have been relevant to the LionAir crash
  • focus only on the need to abide by the Runaway Stabilizer NNC as already published in the FCOM, without mentioning that the condition (continuous un-commanded trim movement) was not to be taken at face value, because a MCAS-induced runaway would pause for 5 seconds between activation cycles
  • mention only as a footnote the possibility that the NNC "as is" may be insufficient and mentioning returning trim to neutral with electric trim just as a possibile helper, not as a critical, needed action

If, in my line of business, I ever delivered an operating procedure document stating something like: "When [wrong condition] then proceed to steps A, B and C. Note: operators may find that C is difficult/impossible to execute; enacting step D before step B could help" I would be (rightly) fired and my professional license revoked. And I don't design anything remotely as critical as airliners for civilian revenue service.

Moreover (but that's just my opinion) I also find that the tone of Boeing's bulletin rings kind of condescending, especially after 150+ innocent casualties: "You just need to run the NNC, you dumb pilot. Ah, you ran the NNC and found that the manual trim wheel is too heavy to move? Didn't you trim back to neutral before cutting off the trim electrical motor? Well, no, that's not a step of the NNC, but c'mon, it's just a matter of basic airmanship: you can't expect us to write everything in checklists, can you?"


You need to read the Runaway Stabilizer AD 2018-23-51 on this page and the Folllowing OPS bulletin which was put out by Boeing MLI-15

Then maybe restate your position before starting the every 6 hour flamefest.

Just scroll down on this page and you will find them http://www.b737.org.uk/mcas.htm

Boeing also put out Memo's to it's airline partners specifically talking about MCAS after Lionair. They have been shared on here repeatedly.
 
jollo
Posts: 388
Joined: Mon Aug 08, 2011 7:24 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 2:46 pm

morrisond wrote:
jollo wrote:
Chemist wrote:

Did the recommended action include trimming electrically to neutral trim before cutting the switches?
I ask because after thousands of posts, I don't remember if I imagined that or it is the case.


The bulletin published by Boeing in the aftermath of the LionAir crash was, in my opinion, a masterpiece of (intentional? unintended?) obfuscation. It managed, in a single document, to:
  • avoid mentioning MCAS
  • avoid describing its function (even without calling it by name) and why it could have been relevant to the LionAir crash
  • focus only on the need to abide by the Runaway Stabilizer NNC as already published in the FCOM, without mentioning that the condition (continuous un-commanded trim movement) was not to be taken at face value, because a MCAS-induced runaway would pause for 5 seconds between activation cycles
  • mention only as a footnote the possibility that the NNC "as is" may be insufficient and mentioning returning trim to neutral with electric trim just as a possibile helper, not as a critical, needed action

If, in my line of business, I ever delivered an operating procedure document stating something like: "When [wrong condition] then proceed to steps A, B and C. Note: operators may find that C is difficult/impossible to execute; enacting step D before step B could help" I would be (rightly) fired and my professional license revoked. And I don't design anything remotely as critical as airliners for civilian revenue service.

Moreover (but that's just my opinion) I also find that the tone of Boeing's bulletin rings kind of condescending, especially after 150+ innocent casualties: "You just need to run the NNC, you dumb pilot. Ah, you ran the NNC and found that the manual trim wheel is too heavy to move? Didn't you trim back to neutral before cutting off the trim electrical motor? Well, no, that's not a step of the NNC, but c'mon, it's just a matter of basic airmanship: you can't expect us to write everything in checklists, can you?"


You need to read the Runaway Stabilizer AD 2018-23-51 on this page and the Folllowing OPS bulletin which was put out by Boeing MLI-15

Then maybe restate your position before starting the every 6 hour flamefest.

Just scroll down on this page and you will find them http://www.b737.org.uk/mcas.htm

Boeing also put out Memo's to it's airline partners specifically talking about MCAS after Lionair. They have been shared on here repeatedly.


You have a point: the OMB issued Nov 6, 2018 did indeed contain a functional description of how a MCAS-induced runaway would look like (taking generically about the "pitch trim system"). My bad: strike out the second bullet of my post. The other points stand, though.
 
morrisond
Posts: 1816
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 2:56 pm

jollo wrote:
morrisond wrote:
jollo wrote:

The bulletin published by Boeing in the aftermath of the LionAir crash was, in my opinion, a masterpiece of (intentional? unintended?) obfuscation. It managed, in a single document, to:
  • avoid mentioning MCAS
  • avoid describing its function (even without calling it by name) and why it could have been relevant to the LionAir crash
  • focus only on the need to abide by the Runaway Stabilizer NNC as already published in the FCOM, without mentioning that the condition (continuous un-commanded trim movement) was not to be taken at face value, because a MCAS-induced runaway would pause for 5 seconds between activation cycles
  • mention only as a footnote the possibility that the NNC "as is" may be insufficient and mentioning returning trim to neutral with electric trim just as a possibile helper, not as a critical, needed action

If, in my line of business, I ever delivered an operating procedure document stating something like: "When [wrong condition] then proceed to steps A, B and C. Note: operators may find that C is difficult/impossible to execute; enacting step D before step B could help" I would be (rightly) fired and my professional license revoked. And I don't design anything remotely as critical as airliners for civilian revenue service.

Moreover (but that's just my opinion) I also find that the tone of Boeing's bulletin rings kind of condescending, especially after 150+ innocent casualties: "You just need to run the NNC, you dumb pilot. Ah, you ran the NNC and found that the manual trim wheel is too heavy to move? Didn't you trim back to neutral before cutting off the trim electrical motor? Well, no, that's not a step of the NNC, but c'mon, it's just a matter of basic airmanship: you can't expect us to write everything in checklists, can you?"


You need to read the Runaway Stabilizer AD 2018-23-51 on this page and the Folllowing OPS bulletin which was put out by Boeing MLI-15

Then maybe restate your position before starting the every 6 hour flamefest.

Just scroll down on this page and you will find them http://www.b737.org.uk/mcas.htm

Boeing also put out Memo's to it's airline partners specifically talking about MCAS after Lionair. They have been shared on here repeatedly.


You have a point: the OMB issued Nov 6, 2018 did indeed contain a functional description of how a MCAS-induced runaway would look like (taking generically about the "pitch trim system"). My bad: strike out the second bullet of my post. The other points stand, though.


I didn't find the memo but here is the excerpt from AVHerald that Boeing sent to it's operators on Nov .10.

"On Nov 10th 2018 Boeing sent out multi-operator messages informing operators about the MCAS (Maneouvering Characteristics Augementation System) stating:

A pitch augmentation system function called 'Maneuvering Characteristics Augmentation System’ (MCAS) is implemented on the 737-8, -9 (MAX) to enhance pitch characteristics with flaps UP and at elevated angles of attack. The MCAS function commands nose down stabilizer to enhance pitch characteristics during steep turns with elevated load factors and dunng flaps up flight at airspeeds approaching stall. MCAS is activated without pilot input and only operates in manual, flaps up flight. The system is designed to allow the flight crew to use column tnm switch or stabilizer aisle stand cutout switches to override MCAS input. The function is commanded by the Flight Control computer using Input data from sensors and other airplane systems.

The MCAS function becomes active when the airplane Angle of Attack exceeds a threshold based on airspeed and altitude. Stabilizer Incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer Input is lower at high Mach number and greater at low Mach numbers. The function Is reset once angle of attack falls below the Angle of Attack threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AOA condition persists, the MCAS function commands another incremental stabilizer nose down command according to current aircraft Mach number at actuation."


So how do all three sources not cover your points?
 
mjoelnir
Posts: 8945
Joined: Sun Feb 03, 2013 11:06 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 3:21 pm

morrisond wrote:
jollo wrote:
Chemist wrote:

Did the recommended action include trimming electrically to neutral trim before cutting the switches?
I ask because after thousands of posts, I don't remember if I imagined that or it is the case.


The bulletin published by Boeing in the aftermath of the LionAir crash was, in my opinion, a masterpiece of (intentional? unintended?) obfuscation. It managed, in a single document, to:
  • avoid mentioning MCAS
  • avoid describing its function (even without calling it by name) and why it could have been relevant to the LionAir crash
  • focus only on the need to abide by the Runaway Stabilizer NNC as already published in the FCOM, without mentioning that the condition (continuous un-commanded trim movement) was not to be taken at face value, because a MCAS-induced runaway would pause for 5 seconds between activation cycles
  • mention only as a footnote the possibility that the NNC "as is" may be insufficient and mentioning returning trim to neutral with electric trim just as a possibile helper, not as a critical, needed action

If, in my line of business, I ever delivered an operating procedure document stating something like: "When [wrong condition] then proceed to steps A, B and C. Note: operators may find that C is difficult/impossible to execute; enacting step D before step B could help" I would be (rightly) fired and my professional license revoked. And I don't design anything remotely as critical as airliners for civilian revenue service.

Moreover (but that's just my opinion) I also find that the tone of Boeing's bulletin rings kind of condescending, especially after 150+ innocent casualties: "You just need to run the NNC, you dumb pilot. Ah, you ran the NNC and found that the manual trim wheel is too heavy to move? Didn't you trim back to neutral before cutting off the trim electrical motor? Well, no, that's not a step of the NNC, but c'mon, it's just a matter of basic airmanship: you can't expect us to write everything in checklists, can you?"


You need to read the Runaway Stabilizer AD 2018-23-51 on this page and the Folllowing OPS bulletin which was put out by Boeing MLI-15

Then maybe restate your position before starting the every 6 hour flamefest.

Just scroll down on this page and you will find them http://www.b737.org.uk/mcas.htm

Boeing also put out Memo's to it's airline partners specifically talking about MCAS after Lionair. They have been shared on here repeatedly.


We were talking about what Boeing and the FAA did after the LionAir crash and what the FAA and Boeing did after the Etiopian Air crash, before they were forced to ground the MAX.
Perhaps you point out where in the emergency AD, MCAS is mentioned, explained how it works, mentioned that MCAS cuts out the column switch off, that the AoA disagree warning is not working and mentioned that the manual trim wheel will not work. Neither it is mentioned the time MCAS trims, the rate of those trim action and that the will start after 5 seconds again. You will find non of the above.

Also the ops manual buletin does not mention or even explain the working of MCAS. Neither does it mention that the manual trim wheel will not work and that you can only use the cut out switches after having electrical trimmed the nose up.

It is actually not mentioned, that a MAX will behave differently from a NG.
 
morrisond
Posts: 1816
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 3:31 pm

mjoelnir wrote:
morrisond wrote:
jollo wrote:

The bulletin published by Boeing in the aftermath of the LionAir crash was, in my opinion, a masterpiece of (intentional? unintended?) obfuscation. It managed, in a single document, to:
  • avoid mentioning MCAS
  • avoid describing its function (even without calling it by name) and why it could have been relevant to the LionAir crash
  • focus only on the need to abide by the Runaway Stabilizer NNC as already published in the FCOM, without mentioning that the condition (continuous un-commanded trim movement) was not to be taken at face value, because a MCAS-induced runaway would pause for 5 seconds between activation cycles
  • mention only as a footnote the possibility that the NNC "as is" may be insufficient and mentioning returning trim to neutral with electric trim just as a possibile helper, not as a critical, needed action

If, in my line of business, I ever delivered an operating procedure document stating something like: "When [wrong condition] then proceed to steps A, B and C. Note: operators may find that C is difficult/impossible to execute; enacting step D before step B could help" I would be (rightly) fired and my professional license revoked. And I don't design anything remotely as critical as airliners for civilian revenue service.

Moreover (but that's just my opinion) I also find that the tone of Boeing's bulletin rings kind of condescending, especially after 150+ innocent casualties: "You just need to run the NNC, you dumb pilot. Ah, you ran the NNC and found that the manual trim wheel is too heavy to move? Didn't you trim back to neutral before cutting off the trim electrical motor? Well, no, that's not a step of the NNC, but c'mon, it's just a matter of basic airmanship: you can't expect us to write everything in checklists, can you?"


You need to read the Runaway Stabilizer AD 2018-23-51 on this page and the Folllowing OPS bulletin which was put out by Boeing MLI-15

Then maybe restate your position before starting the every 6 hour flamefest.

Just scroll down on this page and you will find them http://www.b737.org.uk/mcas.htm

Boeing also put out Memo's to it's airline partners specifically talking about MCAS after Lionair. They have been shared on here repeatedly.


We were talking about what Boeing and the FAA did after the LionAir crash and what the FAA and Boeing did after the Etiopian Air crash, before they were forced to ground the MAX.
Perhaps you point out where in the emergency AD, MCAS is mentioned, explained how it works, mentioned that MCAS cuts out the column switch off, that the AoA disagree warning is not working and mentioned that the manual trim wheel will not work. Neither it is mentioned the time MCAS trims, the rate of those trim action and that the will start after 5 seconds again. You will find non of the above.

Also the ops manual buletin does not mention or even explain the working of MCAS. Neither does it mention that the manual trim wheel will not work and that you can only use the cut out switches after having electrical trimmed the nose up.

It is actually not mentioned, that a MAX will behave differently from a NG.


I'll assume you didn't see my last post before responding to my previous one.

Actually if you read all three sources it about covers everything you mentioned as well. The OPS bulletin covers the 5 second issue.

You said Boeing and the FAA did nothing after Lionair and kept it secret.

You would be wrong on that point.

Do they really need to point out that one of the controls might not work if they are outside the normal operating envelope?

Most of the controls won't work so well below stall speed either.
 
User avatar
767333ER
Posts: 1041
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Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 4:51 pm

morrisond wrote:
mjoelnir wrote:
morrisond wrote:

You need to read the Runaway Stabilizer AD 2018-23-51 on this page and the Folllowing OPS bulletin which was put out by Boeing MLI-15

Then maybe restate your position before starting the every 6 hour flamefest.

Just scroll down on this page and you will find them http://www.b737.org.uk/mcas.htm

Boeing also put out Memo's to it's airline partners specifically talking about MCAS after Lionair. They have been shared on here repeatedly.


We were talking about what Boeing and the FAA did after the LionAir crash and what the FAA and Boeing did after the Etiopian Air crash, before they were forced to ground the MAX.
Perhaps you point out where in the emergency AD, MCAS is mentioned, explained how it works, mentioned that MCAS cuts out the column switch off, that the AoA disagree warning is not working and mentioned that the manual trim wheel will not work. Neither it is mentioned the time MCAS trims, the rate of those trim action and that the will start after 5 seconds again. You will find non of the above.

Also the ops manual buletin does not mention or even explain the working of MCAS. Neither does it mention that the manual trim wheel will not work and that you can only use the cut out switches after having electrical trimmed the nose up.

It is actually not mentioned, that a MAX will behave differently from a NG.


I'll assume you didn't see my last post before responding to my previous one.

Actually if you read all three sources it about covers everything you mentioned as well. The OPS bulletin covers the 5 second issue.

You said Boeing and the FAA did nothing after Lionair and kept it secret.

You would be wrong on that point.

Do they really need to point out that one of the controls might not work if they are outside the normal operating envelope?

Most of the controls won't work so well below stall speed either.

That AD 2018-23-51 draws on the recovery technique for runaway trim for the NG. It erroneously does not mention that if you hit the cutout once the trim has been running and is out of trim, you won’t get it back manually. Neither the AD or the OPS bulletin precisely describe how MCAS works or mention it by name. It says it can go “up to” 10 seconds with a 5 second delay between increments. It is not specific enough as to how long it will run or how much trim it can apply in that window even though it should be.

They most definitely do need to point out that the trim wheel doesn’t work when overspeed since a runaway trim would have you over speed in no time. Again it is vague/indecisive as it says one “can” use electric trim to recover the trim before hitting the cutout. Words like “can” and “up to” do not belong in ADs and OPS Bulletins. With this language one has to encounter the situation before they know for sure what is actually the case rather than what “can” be the case. The AD and OPS aren’t technically wrong, but they make me scratch my head with imprecise language like that.
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jollo
Posts: 388
Joined: Mon Aug 08, 2011 7:24 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 5:13 pm

morrisond wrote:
mjoelnir wrote:
morrisond wrote:

You need to read the Runaway Stabilizer AD 2018-23-51 on this page and the Folllowing OPS bulletin which was put out by Boeing MLI-15

Then maybe restate your position before starting the every 6 hour flamefest.

Just scroll down on this page and you will find them http://www.b737.org.uk/mcas.htm

Boeing also put out Memo's to it's airline partners specifically talking about MCAS after Lionair. They have been shared on here repeatedly.


We were talking about what Boeing and the FAA did after the LionAir crash and what the FAA and Boeing did after the Etiopian Air crash, before they were forced to ground the MAX.
Perhaps you point out where in the emergency AD, MCAS is mentioned, explained how it works, mentioned that MCAS cuts out the column switch off, that the AoA disagree warning is not working and mentioned that the manual trim wheel will not work. Neither it is mentioned the time MCAS trims, the rate of those trim action and that the will start after 5 seconds again. You will find non of the above.

Also the ops manual buletin does not mention or even explain the working of MCAS. Neither does it mention that the manual trim wheel will not work and that you can only use the cut out switches after having electrical trimmed the nose up.

It is actually not mentioned, that a MAX will behave differently from a NG.


I'll assume you didn't see my last post before responding to my previous one.

Actually if you read all three sources it about covers everything you mentioned as well. The OPS bulletin covers the 5 second issue.

You said Boeing and the FAA did nothing after Lionair and kept it secret.

You would be wrong on that point.

Do they really need to point out that one of the controls might not work if they are outside the normal operating envelope?

Most of the controls won't work so well below stall speed either.



Please notice that I was responding to the question "Did the recommended actions include trimming electrically to neutral trim before cutting the switches?". You may argue that puzzling together bits and pieces of various communications would have enabled inquiring minds to string together a set of "recommended actions" which would have saved the accident flights. Maybe in a courtroom this would be accepted as evidence, but this would be strictly with the benefit of hindsight and the luxury of lots of idle time.

The middle of an upset is no time to assemble sources. The only things pilots should turn to in a crisis are: training, NNCs and ADs. MAX-specific training was actively prevented, the relevant NNC went through MAX certification and the aftermath of a fatal accident unchanged, and FAA's AD (verbatim copy of Boeing's OMB) mentioned only as a footnote that electric trim can - not "must" - be used (before stab trim cut out, obviously) to help overcome excessive aero loads. So IMO the answer to the original question is: no, not where it would have mattered.
 
Alfons
Posts: 272
Joined: Sun Feb 03, 2013 1:17 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 5:17 pm

SomebodyInTLS wrote:
PW100 wrote:
Not sure why you feel the need to write I'm not on here every Six hours, when your number of posts in this thread dwarf my number of posts . . .


I recently discovered the joys of the ignore list. My blood pressure thanks me.


Me too, amazing how fast this thread became enjoyus again after deleting the background noise which are not topic relevant.
 
barney captain
Posts: 2260
Joined: Tue Nov 06, 2001 5:47 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Mon Dec 02, 2019 5:21 pm

PW100 wrote:

Vmo wasn't exceeded until 60 seconds AFTER MCAS BECAME alive. They had stall warning going off, unreliable airspeed, nose dive tendency, and sort of Christmas tree light up cockpit. Not to mention that reducing power usually isn't a great idea on stall warning. Not to mention that power helps keeping the nose up, which they were heavily struggling with.



And a First Officer that had a set of perfectly functioning flight instruments right in front of them without the stall warning or "Christmas Tree" lights.

Not to mention the functioning stand-by instruments.

And they both had windows, in day VFR conditions.

MCAS is a flawed design, but a huge part of proper pilot training is knowing how to fly the aircraft when it breaks, which all machines are capable of doing.
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