djm18
Posts: 96
Joined: Mon Feb 24, 2014 6:19 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 4:40 pm

Bjorn’s Corner: Analysing the Lion Air JT610 crash, Part 2.

November 8, 2019, ©. Leeham News: We started the series on analyzing the Lion Air JT610 crash based on the final crash report last week by looking at what went wrong with the aircraft’s Angle of Attack sensors.

https://leehamnews.com/2019/11/08/bjorn ... sh-part-2/

Again, the below is a direct quote from Bjorn's Corner Lion Air Crash Analysis Part 2. It seems to me it helps to some degree frame much of the discussion taking place:



"MCAS, a system which should never activate"

"It’s also important to understand MCAS is a system augmenting the behavior of the MAX way outside the normal flight envelope. In daily operation, a 737 MAX flies with an Angle of Attack below 7° to 8° and never passes 1.2 G in load factor (in fact it rarely passes 1.15 G, the load factor for a 30° bank turn)."

"MCAS is programmed to activate at almost double this AoA value and the pilot need to pull around 2G or more to get to where MCAS will be active. No person would stand up in the cabin if the pilot is flying like this. A mega-crisis situation is needed for an airliner pilot to need to pull 2Gs or more. I know no airliner pilot which has been even close to 2G during their flying of airliners in regular operation. Test pilots can reach these values to control the correct behavior of a new or repaired aircraft but even this is rare."

"You only go to this corner of the flight envelope if the aircraft is in the utmost crisis. As MCAS is only needed when the wing is clean (no slats or flaps deployed), this means you are turning extremely hard to avoid a mid-air collision or maneuvering through extreme turbulence. If you hit clear air turbulence, you don’t maneuver as a pilot as this can worsen the effect of the turbulence. The only case where maneuvering might be needed is when passing strong wake turbulence of another aircraft (you can get a strong change in pitch and roll angle). But even then 2 G or more and more than 10° AoA is extreme maneuvering."

"The consequence is, the likelihood an airliner pilot ever running into a situation where a correctly triggered MCAS would go active is highly improbable."

"This is described to give context to why FAA accepted Boeing’s suggestion MCAS didn’t need to be described to the pilots. I don’t endorse this decision by writing the above. But as said, we need the correct context to be able to form a correct opinion. We can’t ask people to understand what is normal and what is abnormal in an airliner’s operation if we don’t spend time describing it."

"And if we don’t understand the unlikely event of MCAS ever going active when correctly triggered, we don’t understand the system and its implementation. (For those who think I’m writing this to later defend MCAS in its initial implementation, I’m not. It was awful and we will come to that.)"
 
dtw2hyd
Posts: 7308
Joined: Wed Jan 09, 2013 12:11 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 4:52 pm

morrisond wrote:
So human factors as contributing cause are allowed on AF447 but not on Lionair or ET302?


Some proper investigative authority has to claim than the human factor was the primary and leading cause.

I am still waiting on NTSB to put the blame solely on LionAir or Ethiopean. Not internet.

Do you seriously think JT601's FA didn't know how to use electric trim? Thought of 5000 hours flying by the just holding on to the control column is hillarious. Someone would have told, dude you can trim and sit back and relax.
 
sgrow787
Posts: 339
Joined: Fri May 16, 2014 8:12 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 5:15 pm

djm18 wrote:
Bjorn’s Corner: Analysing the Lion Air JT610 crash, Part 4

November 21, 2019, ©. Leeham News:

"...
And even if the MAX swings into stall it’s not the end of the world. Stall in an airliner like the 737 MAX is controllable, just release stick pressure and you are out of it. Not the big deal it’s made to be.

I describe all this to get some proportion into the discussion after the feel of doom around the 737 MAX which has been created by all the MCAS articles. Make no mistake about it, the original MCAS was terrible and dangerous but the revised is not. And the base aircraft has deficiencies, like most airliners, but it’s not a fundamentally dangerous aircraft."


Certainly we should go with the safest option at this point**, even if that means going without a benign MCAS system. But there seems to be a tug of war between what pilots want and what is expected of regulators. There seems to be a conflict of interest where pilots - whose jobs depend on planes not being grounded and/or are available to operators - are willing to say things are benign, not a problem, and regulators who are following regulations. Either way, it's apparent that Boeing broke a cardinal rule in engineering: if you create a product (eg MCAS) to solve a safety issue (stick lightening), the failure of that product cannot cause a more severe issue (uncontrolled nose dive into terrain). Which is why I and many in aerospace engineering are convinced it was an intentional gaff with the one sensor design, to get the plane to market and save market share that was threatened by the Airbus Neo.

**EDIT: But maybe Boeing should be held to the same rules like everyone else? Especially since they created this whole dilemma themselves.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
morrisond
Posts: 1816
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 5:27 pm

dtw2hyd wrote:
morrisond wrote:
So human factors as contributing cause are allowed on AF447 but not on Lionair or ET302?


Some proper investigative authority has to claim than the human factor was the primary and leading cause.

I am still waiting on NTSB to put the blame solely on LionAir or Ethiopean. Not internet.

Do you seriously think JT601's FA didn't know how to use electric trim? Thought of 5000 hours flying by the just holding on to the control column is hillarious. Someone would have told, dude you can trim and sit back and relax.


Yes I don't think he did. He was cited for it in training. I don't think I'm the only one with that Opinion either.
 
User avatar
seahawk
Posts: 8942
Joined: Fri May 27, 2005 1:29 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 5:41 pm

PW100 wrote:
seahawk wrote:
morrisond wrote:

Or why is there not a worldwide grounding of the frame until the issue is fixed?


No crash, no media attention, no grounding. The fume event in the A320 was more dangerous than MCAS, but it also showed the importance of correctly trained crews and how they are a key player for aviation safety. .

Are you implying/suggesting that a Lionair crew would probably crashed?


Maybe, maybe not, but it shows that crew training is the key factor for safety.
 
sgrow787
Posts: 339
Joined: Fri May 16, 2014 8:12 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 5:41 pm

flipdewaf wrote:
Nope, it was incorrectly certificated due to not understanding the level of competence required by the pilots to complete successful flights at the same or better rates than required.


But Boeing's assumption of pilot performance/competence is what drove their failure classification for MCAS as major rather than hazardous or catastrophic, which according to them justified a one sensor design. But like I've said many times now, aircraft manufacturers will choose sensor redundancy if it is available to them, rather than assumptions about operator performance any day of the week. If they choose to go with one sensor, it's because there's a problem with achieving the redundancy - either technically or because engineering time is not available. I'm not including engineering resources here because when program schedules get too compressed, no amount of additional engineering resources are going to make things happen any faster.

So the reality is, Boeing ran out of time to engineer AOA sensor redundancy, and instead of delaying the schedule, they went to the FMEA engineers and told them to fit pilot performance assumptions into it, specifically that repetitive MCAS cycles would be observed and triaged by pilots as a continuous stab trim runaway, something they're already supposed to be trained for. And if third world pilots don't have that runaway stab training, then so be it.
Last edited by sgrow787 on Tue Nov 26, 2019 6:09 pm, edited 1 time in total.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
shmerik
Posts: 55
Joined: Sun May 05, 2019 2:28 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 5:56 pm

sgrow787 wrote:
Either way, it's apparent that Boeing broke a cardinal rule in engineering: if you create a product (eg MCAS) to solve a safety issue (stick lightening), the failure of that product cannot cause a more severe issue (uncontrolled nose dive into terrain). Which is why I and many in aerospace engineering are convinced it was an intentional gaff with the one sensor design, to get the plane to market and save market share that was threatened by the Airbus Neo.


This is really what it all comes down to, just sit and think about the entire thing for a second. They supposedly needed the slightest amount of stick force added in some rare circumstance so the solution they thought up was move the one of the main control surfaces of the plane (a device whose entire point is to leave the ground and then avoid it for as long as needed) so that it tends toward the ground. Then they increased the authority so that it aggressively shifts the nose downwards for some reason, and also remove a redundancy that would allow the pilots to shut off automatic trim controls while still allowing the pilots to manually give electric trim commands. It's just such an obviously dangerous idea for resolution of what is a small technical certification requirement.

Either Boeing is hiding something else about the MAX's flight characteristics or they are simply incompetent, and in either case it doesn't say good things about the rest of the MAX as a whole or any other product they've worked on since then.

I'm eagerly awaiting the results of the testing with the bare airframe.
 
User avatar
aerolimani
Posts: 1293
Joined: Tue Jun 18, 2013 5:46 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 6:15 pm

djm18 wrote:
Bjorn’s Corner: Analysing the Lion Air JT610 crash, Part 2.

November 8, 2019, ©. Leeham News: We started the series on analyzing the Lion Air JT610 crash based on the final crash report last week by looking at what went wrong with the aircraft’s Angle of Attack sensors.

https://leehamnews.com/2019/11/08/bjorn ... sh-part-2/

Again, the below is a direct quote from Bjorn's Corner Lion Air Crash Analysis Part 2. It seems to me it helps to some degree frame much of the discussion taking place:



"MCAS, a system which should never activate"

"It’s also important to understand MCAS is a system augmenting the behavior of the MAX way outside the normal flight envelope. In daily operation, a 737 MAX flies with an Angle of Attack below 7° to 8° and never passes 1.2 G in load factor (in fact it rarely passes 1.15 G, the load factor for a 30° bank turn)."

"MCAS is programmed to activate at almost double this AoA value and the pilot need to pull around 2G or more to get to where MCAS will be active. No person would stand up in the cabin if the pilot is flying like this. A mega-crisis situation is needed for an airliner pilot to need to pull 2Gs or more. I know no airliner pilot which has been even close to 2G during their flying of airliners in regular operation. Test pilots can reach these values to control the correct behavior of a new or repaired aircraft but even this is rare."

"You only go to this corner of the flight envelope if the aircraft is in the utmost crisis. As MCAS is only needed when the wing is clean (no slats or flaps deployed), this means you are turning extremely hard to avoid a mid-air collision or maneuvering through extreme turbulence. If you hit clear air turbulence, you don’t maneuver as a pilot as this can worsen the effect of the turbulence. The only case where maneuvering might be needed is when passing strong wake turbulence of another aircraft (you can get a strong change in pitch and roll angle). But even then 2 G or more and more than 10° AoA is extreme maneuvering."

"The consequence is, the likelihood an airliner pilot ever running into a situation where a correctly triggered MCAS would go active is highly improbable."

"This is described to give context to why FAA accepted Boeing’s suggestion MCAS didn’t need to be described to the pilots. I don’t endorse this decision by writing the above. But as said, we need the correct context to be able to form a correct opinion. We can’t ask people to understand what is normal and what is abnormal in an airliner’s operation if we don’t spend time describing it."

"And if we don’t understand the unlikely event of MCAS ever going active when correctly triggered, we don’t understand the system and its implementation. (For those who think I’m writing this to later defend MCAS in its initial implementation, I’m not. It was awful and we will come to that.)"

Okay… a giant thing I don't understand in this. Originally, MCAS was designed to use one AOA sensor plus a G-force sensor, and it was only expected in certain high-speed manoeuvres. However, when it was found that MCAS was also needed at lower speeds, the G-force sensor was removed from the equation, supposedly because the G-forces would no longer be sufficient to activate MCAS when it was needed at low speeds. At least, that is what I understood as the reason from removing the G-force sensor. So, seriously, what is Bjorn Fehrm going on about? Is his information correct?
 
sgrow787
Posts: 339
Joined: Fri May 16, 2014 8:12 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 6:24 pm

aerolimani wrote:
Okay… a giant thing I don't understand in this. Originally, MCAS was designed to use one AOA sensor plus a G-force sensor, and it was only expected in certain high-speed manoeuvres. However, when it was found that MCAS was also needed at lower speeds, the G-force sensor was removed from the equation, supposedly because the G-forces would no longer be sufficient to activate MCAS when it was needed at low speeds. At least, that is what I understood as the reason from removing the G-force sensor. So, seriously, what is Bjorn Fehrm going on about? Is his information correct?


Good point. I'm not an aeronautical engineer, but apparently Bjorn overlooked the low-speed instability aspect of the Max. Or maybe not, since a pilot in a low-speed situation would let go of the stick when high-AOA was observed (which even without MCAS installed, they would see stick shaker). Maybe someone can chime in here..
Last edited by sgrow787 on Tue Nov 26, 2019 6:34 pm, edited 1 time in total.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
flipdewaf
Posts: 3058
Joined: Thu Jul 20, 2006 6:28 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 6:26 pm

sgrow787 wrote:
flipdewaf wrote:
Nope, it was incorrectly certificated due to not understanding the level of competence required by the pilots to complete successful flights at the same or better rates than required.


But Boeing's assumption of pilot performance/competence is what drove their failure classification for MCAS as major rather than hazardous or catastrophic, which according to them justified a one sensor design. But like I've said many times now, aircraft manufacturers will choose sensor redundancy if it is available to them, rather than assumptions about operator performance any day of the week. If they choose to go with one sensor, it's because there's a problem with achieving the redundancy - either technically or because engineering time is not available. I'm not including engineering resources here because when program schedules get too compressed, no amount of additional engineering resources are going to make things happen any faster.

So the reality is, Boeing ran out of time to engineer AOA sensor redundancy, and instead of delaying the schedule, they went to the FMEA engineers and told them to fit pilot performance assumptions into it, specifically that repetitive MCAS cycles would be observed and triaged by pilots as a continuous stab trim runaway, something they're already supposed to be trained for. And if third world pilots don't have that runaway stab training, then so be it.

I think I understand where you are coming from, it’s a cross between workplace pressure to complete, workplace culture and the human factors that we talk about so much with the pilots affecting the design engineers.

Fred


Sent from my iPhone using Tapatalk
Image
 
User avatar
aerolimani
Posts: 1293
Joined: Tue Jun 18, 2013 5:46 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 6:31 pm

sgrow787 wrote:
aerolimani wrote:
Okay… a giant thing I don't understand in this. Originally, MCAS was designed to use one AOA sensor plus a G-force sensor, and it was only expected in certain high-speed manoeuvres. However, when it was found that MCAS was also needed at lower speeds, the G-force sensor was removed from the equation, supposedly because the G-forces would no longer be sufficient to activate MCAS when it was needed at low speeds. At least, that is what I understood as the reason from removing the G-force sensor. So, seriously, what is Bjorn Fehrm going on about? Is his information correct?


Good point. I'm not an aeronautical engineer, but apparently Bjorn overlooked the low-speed instability aspect of the Max.

If that is the case, it's a pretty massive oversight, and rather erodes my confidence in his journalism, at least as regards MCAS.
 
sgrow787
Posts: 339
Joined: Fri May 16, 2014 8:12 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 6:52 pm

flipdewaf wrote:
I think I understand where you are coming from, it’s a cross between workplace pressure to complete, workplace culture and the human factors that we talk about so much with the pilots affecting the design engineers.


But it's been reported in the media that engineers in the trenches were not aware of the single sensor design. That points to engineering compartmentalization, which in turn points to top-down design where decisions are being made from those in Chicago. In the end, a bean counter said "ship it" and they made it so.

So not workplace culture or workplace pressure, but rather company organization. See the long forgotten flight:

https://www.theatlantic.com/ideas/archi ... gs/602188/
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
B777LRF
Posts: 2551
Joined: Sun Nov 02, 2008 4:23 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 7:08 pm

sgrow787 wrote:
So, seriously, what is Bjorn Fehrm going on about? Is his information correct?


The gentleman is losing a considerable amount of creditability by implying you can only get to a high (12-20) AoA value by pulling 2Gs. I would recommend D.P. Davies* for anyone interested in the deep technical do-da, suffice to say there's something called a power-on stall which, particularly if performed in a banking turn, is just about the worst thing you can do to any aircraft. That's carried out at relatively low speed, and the only Gs are those from the banked turn - something in the order of 1.1 or thereabouts.

*D.P. Davies infamously refused issuing a UK CoA for the 727 until it was fitted with a stick nudger, for its behaviour during this particular test (power on stall in a banking turn). He had previously refused CoA for the 707 until the empennage was enlarged, but that was for Mcga reasons. He wrote 'Handling the big jets' in the 70s, which is still the "bible" for airline pilots.
Signature. You just read one.
 
User avatar
767333ER
Posts: 1041
Joined: Wed Jun 15, 2016 5:14 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 7:15 pm

morrisond wrote:
767333ER wrote:
morrisond wrote:
Non-back driven systems have been one of the primary causes of more fatalities than MCAS.

Again, baseless and absolutely false claim. AF447 is not proof of this because we don’t know in these cases whether back driven controls would make a difference. I argue not. AF447 for example the two flying were both freaking out and weren’t thinking straight or at all in a good frame of mind. How do we know they wouldn’t just fight each other if the controls are linked or back driven? Well we don’t because that’s human factors, a very difficult rabbit hole to go down. At best the control architecture was a contributing cause and was said to be as much in the report. Sadly for some folks because only Airbus does it this way and because Sully said so having it as a primary cause is fact.

I have heard the opinions of various qualified people that fly commercial aircraft and they all generally are in line with what I say. Flying 100-some hours on a C172 won’t teach you the first thing about operating commercial aircraft or human factors.

Yet again this is not relevant in the discussion and you are arguing off point.



You may be right - we can't know for sure. However, I'm pretty sure though there has never been a stall that led to a fatal crash in an FBW aircraft that had back driven or at least linked controls.

So human factors as contributing cause are allowed on AF447 but not on Lionair or ET302?

Yes some 100 hours in a 172 won't teach you much about operating commercial aircraft or human factors - nor should slightly more hours qualify you to fly a 737 or A320. If you did do those hours in Canada though you would have a pretty good idea how to unstall an aircraft or get out of a Spin.

The point is as long as the MAX doesn't have some unknown aerodynamic behaviour that causes non-normal stall behavior it should be fine without MCAS and without FBW with the skills all Commercial Pilots should have.

A stall is a lot easier to figure out than multiple alarms going off and the plane doing weird things (MCAS effects).

I’ve been saying for years the folks down the US are stupid for not doing spins; it would probably stop a lot of general aviation accidents. It would not do anything for a transport category aircraft. 737s and A320s and evening Dash 8s don’t behave like a C172. Even within GA you have varying stall characteristics. An example is a crash that happened involving a P2006T at a local university flying school where I live. That plane had such unusual stall characteristics that you basically had to do what you usually aren’t supposed to do in a twin prop. Again GA stall training has very little to do with commercial other than identifying you are approaching one though some visual and tactile cues.

Again how many stalls have there been in FBW aircraft, not many. How many have linked controls? Most don’t. A sample doesn’t exist to make the generalization that back driven controls make a difference. Non-sequitur reasoning and a hasty generalization at best. Why are we even talking about this anyway?

The difference between the AF crash and this is where human factors falls on the list of factors. The A330 was perfectly flyable without needing to do anything at all. They initiated a stall and crashed it. The 737 MAX was trimming itself nose down trying to crash itself. In the former, human factors in the primary cause; in the latter it’s only a contributing cause.

You are right about the MAX characteristics, but if it’s fine why did they go to the trouble to make said system to cover up something if not much is there?

Reading comprehension man!
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
 
User avatar
aerolimani
Posts: 1293
Joined: Tue Jun 18, 2013 5:46 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 7:27 pm

B777LRF wrote:
sgrow787 wrote:
So, seriously, what is Bjorn Fehrm going on about? Is his information correct?


The gentleman is losing a considerable amount of creditability by implying you can only get to a high (12-20) AoA value by pulling 2Gs. I would recommend D.P. Davies* for anyone interested in the deep technical do-da, suffice to say there's something called a power-on stall which, particularly if performed in a banking turn, is just about the worst thing you can do to any aircraft. That's carried out at relatively low speed, and the only Gs are those from the banked turn - something in the order of 1.1 or thereabouts.

*D.P. Davies infamously refused issuing a UK CoA for the 727 until it was fitted with a stick nudger, for its behaviour during this particular test (power on stall in a banking turn). He had previously refused CoA for the 707 until the empennage was enlarged, but that was for Mcga reasons. He wrote 'Handling the big jets' in the 70s, which is still the "bible" for airline pilots.

That was actually me that said "So, seriously, what is Bjorn Fehrm going on about? Is his information correct?" In any case, thank you for your response. For someone writing at such lengths about MCAS, in his regular column in Leeham News, I would hope for better. While he doesn't directly argue for MCAS's removal, he does devote a lot of effort to downplaying its importance in the MAX. As such, I would expect a high level of knowledge.

I'll wait for some others here to (hopefully) weigh in on this, but I have to say that it's not looking good for Bjorn or Leeham News.
 
XRAYretired
Posts: 722
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 7:29 pm

aerolimani wrote:
djm18 wrote:
Bjorn’s Corner: Analysing the Lion Air JT610 crash, Part 2.

November 8, 2019, ©. Leeham News: We started the series on analyzing the Lion Air JT610 crash based on the final crash report last week by looking at what went wrong with the aircraft’s Angle of Attack sensors.

https://leehamnews.com/2019/11/08/bjorn ... sh-part-2/

Again, the below is a direct quote from Bjorn's Corner Lion Air Crash Analysis Part 2. It seems to me it helps to some degree frame much of the discussion taking place:


"MCAS, a system which should never activate"

"It’s also important to understand MCAS is a system augmenting the behavior of the MAX way outside the normal flight envelope. In daily operation, a 737 MAX flies with an Angle of Attack below 7° to 8° and never passes 1.2 G in load factor (in fact it rarely passes 1.15 G, the load factor for a 30° bank turn)."

"MCAS is programmed to activate at almost double this AoA value and the pilot need to pull around 2G or more to get to where MCAS will be active. No person would stand up in the cabin if the pilot is flying like this. A mega-crisis situation is needed for an airliner pilot to need to pull 2Gs or more. I know no airliner pilot which has been even close to 2G during their flying of airliners in regular operation. Test pilots can reach these values to control the correct behavior of a new or repaired aircraft but even this is rare."

"You only go to this corner of the flight envelope if the aircraft is in the utmost crisis. As MCAS is only needed when the wing is clean (no slats or flaps deployed), this means you are turning extremely hard to avoid a mid-air collision or maneuvering through extreme turbulence. If you hit clear air turbulence, you don’t maneuver as a pilot as this can worsen the effect of the turbulence. The only case where maneuvering might be needed is when passing strong wake turbulence of another aircraft (you can get a strong change in pitch and roll angle). But even then 2 G or more and more than 10° AoA is extreme maneuvering."

"The consequence is, the likelihood an airliner pilot ever running into a situation where a correctly triggered MCAS would go active is highly improbable."

"This is described to give context to why FAA accepted Boeing’s suggestion MCAS didn’t need to be described to the pilots. I don’t endorse this decision by writing the above. But as said, we need the correct context to be able to form a correct opinion. We can’t ask people to understand what is normal and what is abnormal in an airliner’s operation if we don’t spend time describing it."

"And if we don’t understand the unlikely event of MCAS ever going active when correctly triggered, we don’t understand the system and its implementation. (For those who think I’m writing this to later defend MCAS in its initial implementation, I’m not. It was awful and we will come to that.)"

Okay… a giant thing I don't understand in this. Originally, MCAS was designed to use one AOA sensor plus a G-force sensor, and it was only expected in certain high-speed manoeuvres. However, when it was found that MCAS was also needed at lower speeds, the G-force sensor was removed from the equation, supposedly because the G-forces would no longer be sufficient to activate MCAS when it was needed at low speeds. At least, that is what I understood as the reason from removing the G-force sensor. So, seriously, what is Bjorn Fehrm going on about? Is his information correct?

Yes. Its been pointed out before that his piece is as fundamentally flawed as MCAS V1.0 itself.

Ray
 
User avatar
aerolimani
Posts: 1293
Joined: Tue Jun 18, 2013 5:46 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 7:40 pm

XRAYretired wrote:
aerolimani wrote:
djm18 wrote:
Bjorn’s Corner: Analysing the Lion Air JT610 crash, Part 2.

November 8, 2019, ©. Leeham News: We started the series on analyzing the Lion Air JT610 crash based on the final crash report last week by looking at what went wrong with the aircraft’s Angle of Attack sensors.

https://leehamnews.com/2019/11/08/bjorn ... sh-part-2/

Again, the below is a direct quote from Bjorn's Corner Lion Air Crash Analysis Part 2. It seems to me it helps to some degree frame much of the discussion taking place:


"MCAS, a system which should never activate"

"It’s also important to understand MCAS is a system augmenting the behavior of the MAX way outside the normal flight envelope. In daily operation, a 737 MAX flies with an Angle of Attack below 7° to 8° and never passes 1.2 G in load factor (in fact it rarely passes 1.15 G, the load factor for a 30° bank turn)."

"MCAS is programmed to activate at almost double this AoA value and the pilot need to pull around 2G or more to get to where MCAS will be active. No person would stand up in the cabin if the pilot is flying like this. A mega-crisis situation is needed for an airliner pilot to need to pull 2Gs or more. I know no airliner pilot which has been even close to 2G during their flying of airliners in regular operation. Test pilots can reach these values to control the correct behavior of a new or repaired aircraft but even this is rare."

"You only go to this corner of the flight envelope if the aircraft is in the utmost crisis. As MCAS is only needed when the wing is clean (no slats or flaps deployed), this means you are turning extremely hard to avoid a mid-air collision or maneuvering through extreme turbulence. If you hit clear air turbulence, you don’t maneuver as a pilot as this can worsen the effect of the turbulence. The only case where maneuvering might be needed is when passing strong wake turbulence of another aircraft (you can get a strong change in pitch and roll angle). But even then 2 G or more and more than 10° AoA is extreme maneuvering."

"The consequence is, the likelihood an airliner pilot ever running into a situation where a correctly triggered MCAS would go active is highly improbable."

"This is described to give context to why FAA accepted Boeing’s suggestion MCAS didn’t need to be described to the pilots. I don’t endorse this decision by writing the above. But as said, we need the correct context to be able to form a correct opinion. We can’t ask people to understand what is normal and what is abnormal in an airliner’s operation if we don’t spend time describing it."

"And if we don’t understand the unlikely event of MCAS ever going active when correctly triggered, we don’t understand the system and its implementation. (For those who think I’m writing this to later defend MCAS in its initial implementation, I’m not. It was awful and we will come to that.)"

Okay… a giant thing I don't understand in this. Originally, MCAS was designed to use one AOA sensor plus a G-force sensor, and it was only expected in certain high-speed manoeuvres. However, when it was found that MCAS was also needed at lower speeds, the G-force sensor was removed from the equation, supposedly because the G-forces would no longer be sufficient to activate MCAS when it was needed at low speeds. At least, that is what I understood as the reason from removing the G-force sensor. So, seriously, what is Bjorn Fehrm going on about? Is his information correct?

Yes. Its been pointed out before that his piece is as fundamentally flawed as MCAS V1.0 itself.

Ray

Brutal, and sad. You'd think Leeham News would do something about it by now.

On the bright side, we can stop quoting it, since it's apparently not a reliable source of information.
 
hivue
Posts: 1957
Joined: Tue Feb 26, 2013 2:26 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 9:33 pm

aerolimani wrote:
Brutal, and sad. You'd think Leeham News would do something about it by now.

On the bright side, we can stop quoting it, since it's apparently not a reliable source of information.


So can anyone point to documentation verifying that MCAS 1.0 would ever activate in response to an airplane approaching a 1G stall? Despite the fact that Boeing expanded MCAS's authority (without telling the FAA) beyond the original ultra remote and miniscule corner of the envelope, I think it's authority still only extended to a pretty remote and tiny corner of the envelope. The Leeham News article's reference to 2G may simply be a reflection of this, pointing out that airliners flying at anything remotely like appropriate airspeeds for a particular stage of flight do not ever reach MCAS-activating AoA at less than about 2 G.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
XRAYretired
Posts: 722
Joined: Fri Mar 15, 2019 11:21 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 9:56 pm

hivue wrote:
aerolimani wrote:
Brutal, and sad. You'd think Leeham News would do something about it by now.

On the bright side, we can stop quoting it, since it's apparently not a reliable source of information.


So can anyone point to documentation verifying that MCAS 1.0 would ever activate in response to an airplane approaching a 1G stall? Despite the fact that Boeing expanded MCAS's authority (without telling the FAA) beyond the original ultra remote and miniscule corner of the envelope, I think it's authority still only extended to a pretty remote and tiny corner of the envelope. The Leeham News article's reference to 2G may simply be a reflection of this, pointing out that airliners flying at anything remotely like appropriate airspeeds for a particular stage of flight do not ever reach MCAS-activating AoA at less than about 2 G.

Confirmation from experts with access.

'....Observation O3.4-B: Extension of MCAS to the low-speed and 1g environment during the flight program was due to unacceptable stall characteristics with STS only. The possibility of a pitch-up tendency during approach to stall was identified for the flaps-up configuration prior to the implementation of MCAS....'
https://www.faa.gov/news/media/attachme ... t_2019.pdf

Ray
 
User avatar
aerolimani
Posts: 1293
Joined: Tue Jun 18, 2013 5:46 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 9:58 pm

hivue wrote:
aerolimani wrote:
Brutal, and sad. You'd think Leeham News would do something about it by now.

On the bright side, we can stop quoting it, since it's apparently not a reliable source of information.


So can anyone point to documentation verifying that MCAS 1.0 would ever activate in response to an airplane approaching a 1G stall? Despite the fact that Boeing expanded MCAS's authority (without telling the FAA) beyond the original ultra remote and miniscule corner of the envelope, I think it's authority still only extended to a pretty remote and tiny corner of the envelope. The Leeham News article's reference to 2G may simply be a reflection of this, pointing out that airliners flying at anything remotely like appropriate airspeeds for a particular stage of flight do not ever reach MCAS-activating AoA at less than about 2 G.

If it was always a high g-force scenario, then what need would there have been to remove the g-force sensor from the design? We would have a two-sensor design, and the accidents and grounding would probably never have happened.
 
oOfredOo
Posts: 42
Joined: Mon Oct 03, 2016 9:07 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 10:01 pm

morrisond wrote:
You may be right - we can't know for sure. However, I'm pretty sure though there has never been a stall that led to a fatal crash in an FBW aircraft that had back driven or at least linked controls.


At the risk of responding to an off-topic remark again, but this just begs for a correction. Asiana OZ-214, a B772 was an FBW aircraft with backdriven thrust levers and linked control columns. PF did not notice airspeed decaying and pulled several degrees aft for 30 seconds or so, up to the backstop 5 seconds before crashing. PM was a training captain and did not notice the column position either. Throttles did not move because of the hold mode, yet the fact that expected movement was absent, went unnoticed as well. I'm not sure whether the final 5 seconds of stick shaker and nose drop actually was a stall, but they were not far off and FBW was not going to intervene.

Ow, and people died.

http://avherald.com/h?article=464ef64f
 
smartplane
Posts: 1102
Joined: Fri Aug 03, 2018 9:23 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Tue Nov 26, 2019 11:00 pm

XRAYretired wrote:
hivue wrote:
So can anyone point to documentation verifying that MCAS 1.0 would ever activate in response to an airplane approaching a 1G stall? Despite the fact that Boeing expanded MCAS's authority (without telling the FAA) beyond the original ultra remote and miniscule corner of the envelope, I think it's authority still only extended to a pretty remote and tiny corner of the envelope. The Leeham News article's reference to 2G may simply be a reflection of this, pointing out that airliners flying at anything remotely like appropriate airspeeds for a particular stage of flight do not ever reach MCAS-activating AoA at less than about 2 G.

Confirmation from experts with access.

'....Observation O3.4-B: Extension of MCAS to the low-speed and 1g environment during the flight program was due to unacceptable stall characteristics with STS only. The possibility of a pitch-up tendency during approach to stall was identified for the flaps-up configuration prior to the implementation of MCAS....'
https://www.faa.gov/news/media/attachme ... t_2019.pdf

Boeing MCAS solution number ?? is to increase the scope / severity of previously OK / benign / approved STS, and scale back / switch off MCAS.

Anyone out there performing MCAS off tests, make sure STS code hasn't been 'enhanced' since the grounding for just such an eventuality.
 
FluidFlow
Posts: 419
Joined: Wed Apr 10, 2019 6:39 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 5:39 am

smartplane wrote:
XRAYretired wrote:
hivue wrote:
So can anyone point to documentation verifying that MCAS 1.0 would ever activate in response to an airplane approaching a 1G stall? Despite the fact that Boeing expanded MCAS's authority (without telling the FAA) beyond the original ultra remote and miniscule corner of the envelope, I think it's authority still only extended to a pretty remote and tiny corner of the envelope. The Leeham News article's reference to 2G may simply be a reflection of this, pointing out that airliners flying at anything remotely like appropriate airspeeds for a particular stage of flight do not ever reach MCAS-activating AoA at less than about 2 G.

Confirmation from experts with access.

'....Observation O3.4-B: Extension of MCAS to the low-speed and 1g environment during the flight program was due to unacceptable stall characteristics with STS only. The possibility of a pitch-up tendency during approach to stall was identified for the flaps-up configuration prior to the implementation of MCAS....'
https://www.faa.gov/news/media/attachme ... t_2019.pdf

Boeing MCAS solution number ?? is to increase the scope / severity of previously OK / benign / approved STS, and scale back / switch off MCAS.

Anyone out there performing MCAS off tests, make sure STS code hasn't been 'enhanced' since the grounding for just such an eventuality.


Did anyone saw a VW or Bosch guy walk around Seattle?
 
oschkosch
Posts: 352
Joined: Mon Oct 29, 2018 3:41 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 6:32 am

We slip from early 4th Quarter over middle 4th Quarter and now to 2020 definitely (or is it maybe??). At least in the news reports coming in:


https://www.cnbc.com/2019/11/26/faa-say ... ation.html

FAA says it again: Boeing’s 737 Max is not ready for certification
With just 35 days left in 2019, the FAA is making it increasingly clear it is unlikely to recertify the Boeing 737 Max this year, a target Boeing has been eyeing for months. For the third time in two weeks, the FAA said publicly it will take all the time it needs to deem the Max safe. The FAA issued a new statement, saying, “The FAA has not completed its review of the 737 Max aircraft design changes and associated pilot training. The agency will not approve the aircraft for return to service until it has completed numerous rounds of rigorous testing.”

This is the latest move by the FAA to publicly push back on Boeing’s belief that Max deliveries could resume soon. In its most recent 737 Max progress report issued on Nov. 11, Boeing said it is “possible that the resumption of Max deliveries to airline customers could begin in December, after certification, when the FAA issues an Airworthiness Directive rescinding the grounding order.”

Boeing’s suggestion the Max is close to returning did not sit well with the FAA and Administrator Steve Dickson. Four days after Boeing’s statement, Dickson released an internal letter he sent to the FAA’s associate administrator who oversees the Max certification process. “The FAA fully controls the approval process,” Dickson wrote.



And WSJ reports even more dilemma!

https://www.daily-news-media.com/boeing ... o-service/
In the latest hurdle confronting Boeing Co.’s bid to get its grounded 737 MAX fleet back in the air, federal regulators now intend to inspect and sign off on every jet individually before delivery to airlines.

The move, spelled out Tuesday by the Federal Aviation Administration in a letter to the plane maker, signals that resuming MAX flights will be more complicated and perhaps time-consuming than previously projected.



And to make it worse: Ryanair version has even more issues:
https://theaircurrent.com/aviation-safe ... ign-issue/
 
sgrow787
Posts: 339
Joined: Fri May 16, 2014 8:12 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 7:32 am

oschkosch wrote:
...
And to make it worse: Ryanair version has even more issues:
https://theaircurrent.com/aviation-safe ... ign-issue/


And so from that article it appears Boeing hasn't "formally" delivered the final software package to the FAA:

The FAA can't guarantee MCAS will be in its proposed changes until it is delivered for final certification, but there has been no sign that the plane maker is going in any other direction.


Apparently the updated Max is proceeding along much like a car sale at a dealership, or a purchase of a house. Boeing gives the FAA a peek at what they're doing, asks for input, then when they get requests from the FAA, EASA, TC on what is desired, they deliver a compromise, hoping everyone will eventually capitulate to the pressure. Otherwise, where has Boeing been with the transparency? The flight without MCAS? The sensor redundancy design and the FCC fail-safe design?
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
rheinwaldner
Posts: 1810
Joined: Wed Jan 02, 2008 4:58 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 8:47 am

Planetalk wrote:
The morrisond gap as you call it is made up of dead bodies. Aviation should always be looking at any ways to improve safety and in any accident absolutely any lessons that emerge should be studied and if necessary acted upon, whether they are the primary cause, or simply something that happened to occur on that flight that no-one would have ever thought about if it hadn't crashed. That doesn't necessarily even have to be someone doing anything wrong, just the fact that flight was investigated offers an opportunity to learn something.

Thats all fine and noble. But offtopic.

Can you tell me, why global aviation safety should be the prevalent topic in this thread? (imo: it should not) Why is any lesson to be learned from all accidents a dominant topic in the thread about a grounded aircraft? (imo: that is wrong) Would anybody including morrisond invest the verve we see to address the morrisond gap if the MAX would not be grounded? (no) Why don't these people post in a crash thread, where at least pilot fault is the main cause? There should be several threads around that qualify.

Therefore everbody senses, that by polluting this thread with pilot discussions and anything else than Boeings grounded aircraft, some people try to dilute the pain, this thread obviously would cause, if it would be ontopic.

It should be clear to anybody, that this thread is not a nice place for Boeing fans. Thats the nature of the topic. Probably similar like A380 threads for the Airbus camp.

I made another illustration, that shows the ontopic- and the offtopic aspect:
Image

Don't you think, that getting from 1 to 2 should have enough meat on the bone to discuss in this thread and that getting from 2 to 3 is distracting and off topic? Just look at the leverage, these two discussions have!
Many things are difficult, all things are possible!
 
jollo
Posts: 388
Joined: Mon Aug 08, 2011 7:24 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 9:10 am

shmerik wrote:
sgrow787 wrote:
Either way, it's apparent that Boeing broke a cardinal rule in engineering: if you create a product (eg MCAS) to solve a safety issue (stick lightening), the failure of that product cannot cause a more severe issue (uncontrolled nose dive into terrain). Which is why I and many in aerospace engineering are convinced it was an intentional gaff with the one sensor design, to get the plane to market and save market share that was threatened by the Airbus Neo.


This is really what it all comes down to, just sit and think about the entire thing for a second. They supposedly needed the slightest amount of stick force added in some rare circumstance so the solution they thought up was move the one of the main control surfaces of the plane (a device whose entire point is to leave the ground and then avoid it for as long as needed) so that it tends toward the ground. Then they increased the authority so that it aggressively shifts the nose downwards for some reason, and also remove a redundancy that would allow the pilots to shut off automatic trim controls while still allowing the pilots to manually give electric trim commands. It's just such an obviously dangerous idea for resolution of what is a small technical certification requirement.

Either Boeing is hiding something else about the MAX's flight characteristics or they are simply incompetent, and in either case it doesn't say good things about the rest of the MAX as a whole or any other product they've worked on since then.


It's even worse than that. Boeing didn't only increase the authority (as in speed of control surface travel and max travel per activation cycle) of an automatic control for no properly documented reason (that we know of, at least), they also:
  • increased dramatically the activation envelope of the automatic control by removing G-load from the control logic
  • by the same stroke, they removed an input channel making MCAS a single input channel architecture without adding the required input sanitation logic
  • made the controller's authority effectively unlimited by allowing multiple activation cycles.

As if this wasn't already enough, they also modified the stab trim cut out switches logic - mind you - not by "removing a redundancy", but by removing the one manual control, already present in the ancestor design, that would have effectively disabled the controller without disabling the electric stab trim motor. The reason for this change was not only not properly documented, but actively camouflaged as a mere "labeling change".

Even worse than that: the new cut out switch labeling (PRImary + Back/Up) is indicative of the intention to add redundancy to the electric stab trim motor cut off switch. C'mon, really? You've got a single active FCC, driven by a single active air data sensor suite, and you worry about adding redundancy to a mechanical switch? And you do this by removing the only switch that would have disabled a runaway controller?

Many posters here claim they believe this incredible design was the result of a series of good-faith mistakes, driven by a mix of incompetence, schedule pressure and budget constraints. But even if I would really like to subscribe to this opinion, I just cannot bring myself to imagine someone *that* incompetent (let alone an engineering team).

shmerik wrote:
I'm eagerly awaiting the results of the testing with the bare airframe.

So it's confirmed that this test still has not been flown?
 
User avatar
PixelFlight
Posts: 795
Joined: Thu Nov 08, 2018 11:09 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 9:30 am

rheinwaldner wrote:
It should be clear to anybody, that this thread is not a nice place for Boeing fans. Thats the nature of the topic. Probably similar like A380 threads for the Airbus camp.

I made another illustration, that shows the ontopic- and the offtopic aspect:
Image

Don't you think, that getting from 1 to 2 should have enough meat on the bone to discuss in this thread and that getting from 2 to 3 is distracting and off topic? Just look at the leverage, these two discussions have!

:checkmark: :thumbsup: Such perfect graph ! xkcd level :D https://xkcd.com/

I think that the experiment to merge the specifics accidents threads into the grounding thread is a failure. I would prefer 4 threads: JT610, ET302, Grounding, Training. As for the fans, this more depend on the ability to collaborate by exchanging knowledge than confronting emotional irrationality...
 
oschkosch
Posts: 352
Joined: Mon Oct 29, 2018 3:41 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 11:12 am

sgrow787 wrote:
oschkosch wrote:
...
And to make it worse: Ryanair version has even more issues:
https://theaircurrent.com/aviation-safe ... ign-issue/


And so from that article it appears Boeing hasn't "formally" delivered the final software package to the FAA:

The FAA can't guarantee MCAS will be in its proposed changes until it is delivered for final certification, but there has been no sign that the plane maker is going in any other direction.


Apparently the updated Max is proceeding along much like a car sale at a dealership, or a purchase of a house. Boeing gives the FAA a peek at what they're doing, asks for input, then when they get requests from the FAA, EASA, TC on what is desired, they deliver a compromise, hoping everyone will eventually capitulate to the pressure. Otherwise, where has Boeing been with the transparency? The flight without MCAS? The sensor redundancy design and the FCC fail-safe design?




yeah, it doesn't really sound rather promising at all!
 
ACATROYAL
Posts: 58
Joined: Mon Aug 20, 2007 11:25 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 11:31 am

Well it looks like this thread on the Max won't end anytime soon with the recent news on the Max recertification delays now extending well into 2020. How much more endless jibber jabber can we all endure on this topic. Yes you're all experts on the 737, engineers, pilots etc...MCAS this and that, charts and graphs galore...After reading close to 400 pages on this subject we should all be given honorary 737 Max Ph.D'S for all the knowledge that has been so expertly presented by all of you!
Thank you for expanding my knowledge on the 737... I guess...
 
Noshow
Posts: 1127
Joined: Wed Jun 15, 2016 3:20 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 12:00 pm

So what is the reported "design issue" with Ryanair's 737-8-200 about? The exit door itself? Structure? High density passenger loading becoming too tail heavy?
Last edited by Noshow on Wed Nov 27, 2019 12:01 pm, edited 1 time in total.
 
art
Posts: 2997
Joined: Tue Feb 08, 2005 11:46 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 12:01 pm

ACATROYAL wrote:
Well it looks like this thread on the Max won't end anytime soon...


I see Boeing 737MAX Grounded Worldwide Q1 2020 looming. Pretty much a cert. Hope it's the last!
 
User avatar
par13del
Posts: 9251
Joined: Sun Dec 18, 2005 9:14 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 12:20 pm

So with all the who is bigger than who, has the FAA revealed anything new other than they are the one's who will approve the MAX for RTS?
The FAA had no problems issuing public details after its initial test of MCAS ver 1.X resulting in the bit flip delay, changes to computers logic etc etc etc, now we are being told they will certify when they are ready, are we giving them a pass that we did not give Boeing when they released no information?
Other than the obvious that the FAA does not have the staff, what are they looking at, anything new, how long are they going to be able to say we are working on it and will RTS when we think the a/c is safe without providing any details?

I can only hope than when Boeing further reduces productions levels that the ripple effect will finally allow the FAA to provide more details on its current position.
 
User avatar
keesje
Posts: 13308
Joined: Thu Apr 12, 2001 2:08 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 12:48 pm

Asked to comment about the FAA's change, Boeing says, "We continue to work with the FAA on the safe return to service for the Max".

The FAA adds that its 737 Max work continues.

"The FAA has not completed its review of the 737 Max design changes and associated pilot training," it says. "The agency will not approve the aircraft for return-to-service until it has completed numerous rounds of rigorous testing."

Boeing has said it aims for regulators to lift the grounding before year-end.


https://www.flightglobal.com/news/articles/faa-takes-737-max-airworthiness-certificate-issuance-462555/

The question arises why FAA took this step to take back the (CRS) for each seperate MAX.
This could delay RTS of the grounded fleet I assume, leading more mandatory checks on the grounded aircraft.

https://www.boeing.com/737-max-updates/wp-content/uploads/2019/10/737-MAX-Return-to-Service-Update.pdf
"Never mistake motion for action." Ernest Hemingway
 
mjoelnir
Posts: 8945
Joined: Sun Feb 03, 2013 11:06 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 1:00 pm

par13del wrote:
So with all the who is bigger than who, has the FAA revealed anything new other than they are the one's who will approve the MAX for RTS?
The FAA had no problems issuing public details after its initial test of MCAS ver 1.X resulting in the bit flip delay, changes to computers logic etc etc etc, now we are being told they will certify when they are ready, are we giving them a pass that we did not give Boeing when they released no information?
Other than the obvious that the FAA does not have the staff, what are they looking at, anything new, how long are they going to be able to say we are working on it and will RTS when we think the a/c is safe without providing any details?

I can only hope than when Boeing further reduces productions levels that the ripple effect will finally allow the FAA to provide more details on its current position.


Your complaint could have some merit, if one could say that Boeing has done all it's work. But they seem not to have supplied all the information requested by the FAA and seem still to be staling in regards to EASA.
Boeing is still playing chicken, trying to get away with something and hoping that political pressure will compel the FAA to accept Boeing's view on things.
 
User avatar
par13del
Posts: 9251
Joined: Sun Dec 18, 2005 9:14 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 1:16 pm

mjoelnir wrote:
Your complaint could have some merit, if one could say that Boeing has done all it's work. But they seem not to have supplied all the information requested by the FAA and seem still to be staling in regards to EASA.
Boeing is still playing chicken, trying to get away with something and hoping that political pressure will compel the FAA to accept Boeing's view on things.

As stated, kindly provide details since you are aware of what Boeing is playing chicken with while the FAA has said nothing.
 
asdf
Posts: 505
Joined: Tue Mar 18, 2014 12:03 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 2:55 pm

mjoelnir wrote:
... and hoping that political pressure will compel the FAA to accept Boeing's view on things.


and it will work

the more 737MAX frames are lurking around the more pressure builds up from the stake holders, the political elite, the government
they simply need to go on and build a few more hundreds 737MAX and the MCAS problem will magically disappear from itself

and if the 737MAX flys again and the next crash happens a year later because of the inherent flight attitude it will be a lot more hundreds build in the meantime and a permanent grounding of thousands of 737MAX planes will be completely unthinkable ...

Boeing simply need to carry on now like in the last months....
 
User avatar
par13del
Posts: 9251
Joined: Sun Dec 18, 2005 9:14 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 3:04 pm

asdf wrote:
Boeing simply need to carry on now like in the last months....

I disagree, I think Boeing needs to stop acting as if they are the only one's to blame for the current situation.
A decrease in the production rate to 20 per month will see Boeing and their vendors start laying off employee's or putting them on short shifts, cease ordering long lead items, which will results in suppliers slowing their production which will have a ripple effect across the country, it may not stop the share buy back or xmas bonuses for management which is so desired.
Note that no one states they want Boeing to go chpt.11 they just want them to hurt and drain the well of capital that they are sitting on.

Now all those workers in states all over the USA have politicians who work in Washington who have been cutting the FAA budget and out-sourcing certification jobs without adequate oversight of the process, until those chickens come home to roost nothing will change, especially if Boeing continues to pay.
Unfortunately for me, I did not read the JTAR reports concerns about certification as a ringing endorsement of the FAA and abject failure of Boeing.
My bad.
 
FluidFlow
Posts: 419
Joined: Wed Apr 10, 2019 6:39 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 3:10 pm

Does anyone here, that is familiar with the technical aspects of the 737, know if the structural wash out of the wing got changed when the new winglet on the MAX got planned/installed and how much influence the new winglet has on tip stall characteristics of the 737 compared to the older/no winglets.

The reason I ask is, that as the winglet alone might not be a problem, in combination with the new nacelle the stall characteristics might actually become really nasty. If MCAS really is needed only to provide enough feed back before the stall, then fine but what happens when we enter stall conditions. As the tip (in general) will stall first and then the rest of the wing, the combination of lift in front of the CoG by the nacelles and a tip stall and therefore loss of lift behind the CoG could result in a really strong pitch up moment.

If the horizontal stabilizer does not have enough authority in a situation like that, the 737 would be in a stall similar to a deep stall. Now this is of course pretty bad and hopefully just overstated but the aggressiveness of MCAS and the fact that we still have no actual clue how the 737 MAX behaves close to a stall without electronic helpers points to very bad flight characteristics that needed solutions to avoid them situations by all means.

This would also mean that a broken AoA probe would degrade the 737 into a really dangerous state.
 
shmerik
Posts: 55
Joined: Sun May 05, 2019 2:28 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 3:51 pm

jollo wrote:
Many posters here claim they believe this incredible design was the result of a series of good-faith mistakes, driven by a mix of incompetence, schedule pressure and budget constraints. But even if I would really like to subscribe to this opinion, I just cannot bring myself to imagine someone *that* incompetent (let alone an engineering team).

shmerik wrote:
I'm eagerly awaiting the results of the testing with the bare airframe.

So it's confirmed that this test still has not been flown?



It's really tough to believe that any aerospace company, especially Boeing, could make that sort of mistake.

Not confirmed, the tests could have taken place but I haven't seen any info released of results.
 
morrisond
Posts: 1816
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 3:57 pm

rheinwaldner wrote:
Can you tell me, why global aviation safety should be the prevalent topic in this thread?


It's because you keep making it with some of your ridiculous statements that need to be refuted when you know that whatever version of the MAX flies again won't be the same as MAX with MCAS V1.0 and it won't crash X times more often than average.
 
morrisond
Posts: 1816
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 4:02 pm

rheinwaldner wrote:
Don't you think, that getting from 1 to 2 should have enough meat on the bone to discuss in this thread and that getting from 2 to 3 is distracting and off topic? Just look at the leverage, these two discussions have!


Ok then let's discuss that - what pearls of wisdom would you like to offer?

Did you miss yesterday's discussion about how the MAX might be safer without MCAS at all or would you like to talk about the pilot's again and want to stear it back to that topic?
 
morrisond
Posts: 1816
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 4:07 pm

FluidFlow wrote:
Does anyone here, that is familiar with the technical aspects of the 737, know if the structural wash out of the wing got changed when the new winglet on the MAX got planned/installed and how much influence the new winglet has on tip stall characteristics of the 737 compared to the older/no winglets.

The reason I ask is, that as the winglet alone might not be a problem, in combination with the new nacelle the stall characteristics might actually become really nasty. If MCAS really is needed only to provide enough feed back before the stall, then fine but what happens when we enter stall conditions. As the tip (in general) will stall first and then the rest of the wing, the combination of lift in front of the CoG by the nacelles and a tip stall and therefore loss of lift behind the CoG could result in a really strong pitch up moment.

If the horizontal stabilizer does not have enough authority in a situation like that, the 737 would be in a stall similar to a deep stall. Now this is of course pretty bad and hopefully just overstated but the aggressiveness of MCAS and the fact that we still have no actual clue how the 737 MAX behaves close to a stall without electronic helpers points to very bad flight characteristics that needed solutions to avoid them situations by all means.

This would also mean that a broken AoA probe would degrade the 737 into a really dangerous state.


That is a totally plausible scenario.

There was an Aviation Week article that talked about them modifying the surface devices on the wing to take into account the the bigger engines and different wingtips.
 
User avatar
JetBuddy
Posts: 2275
Joined: Wed Dec 25, 2013 1:04 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 4:23 pm

As mentioned earlier, "The FAA has taken further control over certification of individual 737 Max aircraft, saying it will not allow Boeing itself to issue the airworthiness certificates that permit specific aircraft to be flown."

FAA will now inspect and sign off on every single frame individually, and issue Airworthyness Certificates to each of them. And only after a general Airworthyness Directive is issued for the 737 MAX type.

I think this is a good move, and will increase the confidence of the flying public with regards to the 737 MAX. At least that's how I feel about it.

https://www.flightglobal.com/news/artic ... ce-462555/
 
morrisond
Posts: 1816
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 4:40 pm

JetBuddy wrote:
As mentioned earlier, "The FAA has taken further control over certification of individual 737 Max aircraft, saying it will not allow Boeing itself to issue the airworthiness certificates that permit specific aircraft to be flown."

FAA will now inspect and sign off on every single frame individually, and issue Airworthyness Certificates to each of them. And only after a general Airworthyness Directive is issued for the 737 MAX type.

I think this is a good move, and will increase the confidence of the flying public with regards to the 737 MAX. At least that's how I feel about it.

https://www.flightglobal.com/news/artic ... ce-462555/


Good idea. Maybe they should be signing off on each individual pilot as well or training organization.
 
User avatar
JetBuddy
Posts: 2275
Joined: Wed Dec 25, 2013 1:04 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 4:49 pm

morrisond wrote:
JetBuddy wrote:
As mentioned earlier, "The FAA has taken further control over certification of individual 737 Max aircraft, saying it will not allow Boeing itself to issue the airworthiness certificates that permit specific aircraft to be flown."

FAA will now inspect and sign off on every single frame individually, and issue Airworthyness Certificates to each of them. And only after a general Airworthyness Directive is issued for the 737 MAX type.

I think this is a good move, and will increase the confidence of the flying public with regards to the 737 MAX. At least that's how I feel about it.

https://www.flightglobal.com/news/artic ... ce-462555/


Good idea. Maybe they should be signing off on each individual pilot as well or training organization.


Sarcasm noted. But they already do that. Don't they?
 
art
Posts: 2997
Joined: Tue Feb 08, 2005 11:46 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 5:06 pm

morrisond wrote:
JetBuddy wrote:
As mentioned earlier, "The FAA has taken further control over certification of individual 737 Max aircraft, saying it will not allow Boeing itself to issue the airworthiness certificates that permit specific aircraft to be flown."

FAA will now inspect and sign off on every single frame individually, and issue Airworthyness Certificates to each of them. And only after a general Airworthyness Directive is issued for the 737 MAX type.

I think this is a good move, and will increase the confidence of the flying public with regards to the 737 MAX. At least that's how I feel about it.

https://www.flightglobal.com/news/artic ... ce-462555/


Good idea. Maybe they should be signing off on each individual pilot as well or training organization.


Actually I, too, think it is a good idea in terms of winning back public confidence in the MAX. I guess a lot of average Joe's have lost faith in Boeing. I think the more involvement the FAA is seen to have, the more confidence in the airplane will return.
 
jollo
Posts: 388
Joined: Mon Aug 08, 2011 7:24 pm

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 5:13 pm

morrisond wrote:
rheinwaldner wrote:
Don't you think, that getting from 1 to 2 should have enough meat on the bone to discuss in this thread and that getting from 2 to 3 is distracting and off topic? Just look at the leverage, these two discussions have!


Ok then let's discuss that - what pearls of wisdom would you like to offer?


Oh, you know, the same very basic automation advice that was already given in Q2, such as:
  • make sure automations with significant authority disable themselves on unreliable inputs
  • when this happens, make sure there's a prominent annunciation to human operators of the degraded protection status
  • make sure there's a manual override/disable switch for non-triple redundant automations
  • make sure operators are trained to recognise automation runaway scenarios and to react appropriately
  • make sure operators are trained to operate safely with disabled augmentations/protections (i.e. with a much limited operating envelope)

Problem is, AFAIK we still have no evidence that any of these very basic principles have been heeded at last. Some evidence would be very appreciated, and perfectly on-topic.
 
Sooner787
Posts: 2615
Joined: Thu Jul 18, 2013 1:44 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 5:20 pm

art wrote:
morrisond wrote:
JetBuddy wrote:
As mentioned earlier, "The FAA has taken further control over certification of individual 737 Max aircraft, saying it will not allow Boeing itself to issue the airworthiness certificates that permit specific aircraft to be flown."

FAA will now inspect and sign off on every single frame individually, and issue Airworthyness Certificates to each of them. And only after a general Airworthyness Directive is issued for the 737 MAX type.

I think this is a good move, and will increase the confidence of the flying public with regards to the 737 MAX. At least that's how I feel about it.

https://www.flightglobal.com/news/artic ... ce-462555/


Good idea. Maybe they should be signing off on each individual pilot as well or training organization.


Actually I, too, think it is a good idea in terms of winning back public confidence in the MAX. I guess a lot of average Joe's have lost faith in Boeing. I think the more involvement the FAA is seen to have, the more confidence in the airplane will return.


Valid points, but this will slow down the process of clearing the backlog of undelivered Max's .
But FAA's running the show now, so all Boeing can do is salute, say yes sir and carry on.
 
morrisond
Posts: 1816
Joined: Thu Jan 07, 2010 12:22 am

Re: Boeing 737MAX Grounded Worldwide Q4 2019

Wed Nov 27, 2019 6:04 pm

jollo wrote:
morrisond wrote:
rheinwaldner wrote:
Don't you think, that getting from 1 to 2 should have enough meat on the bone to discuss in this thread and that getting from 2 to 3 is distracting and off topic? Just look at the leverage, these two discussions have!


Ok then let's discuss that - what pearls of wisdom would you like to offer?


Oh, you know, the same very basic automation advice that was already given in Q2, such as:
  • make sure automations with significant authority disable themselves on unreliable inputs
  • when this happens, make sure there's a prominent annunciation to human operators of the degraded protection status
  • make sure there's a manual override/disable switch for non-triple redundant automations
  • make sure operators are trained to recognise automation runaway scenarios and to react appropriately
  • make sure operators are trained to operate safely with disabled augmentations/protections (i.e. with a much limited operating envelope)

Problem is, AFAIK we still have no evidence that any of these very basic principles have been heeded at last. Some evidence would be very appreciated, and perfectly on-topic.


That's a good list.

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos