patrickjp93
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 7:29 pm

SheikhDjibouti wrote:
patrickjp93 wrote:
scbriml wrote:
That gear doesn't raise the height of the 737-10 by a single mm. It only helps at rotation. Next idea?

It DOES raise the MAX 10 off the ground an additional 4 inches during rotation to avoid tail strike.
It can be pilot controlled and have a failsafe activation in the case where the flight control computer can no longer communicate with the gear.
Not. Good. Enough.

Revelation wrote:
...so it allows for a longer tail, but not a bigger engine. The extension at rotation happens because gravity pulls the gear down once the aircraft weight is removed which in turn fills a cylinder with air which allows the gear be supported once it is elongated, it is not a powered lift mechanism.
Rev; I first got a handle on this several months ago, but your description of the system takes it further, and leaves me with some questions.
(Hopefully answering them will assist Patrick too.)
What happens to this "air suspension" following take-off (when there is even less weight on the undercarriage)? I'm guessing that whilst still on the runway, as ground speed increases, the wings generate lift and take some of the load, allowing the gear to extend naturally via it's own spring mechanism. But it surely needs to be "locked" at that height, else at rotation when the weight firstly comes off the nosewheel, there will be a momentary transfer to the main u/c causing it to collapse again. I'm a bit fuzzy on this part, so pretend you are explaining it to a complete idiot. :wave:

Apart from that, my understanding is....
The gear extension at rotation is purely to (help) avoid a tail strike.
It can only happen at rotation because at all other times the gear must NOT raise the height of any 737, otherwise it would invalidate the (grandfathered) overwing emergency exits.
Finally, it must exhibit a failsafe default whereby when all other systems fail (electric, hydraulic, whatever) the gear allows the aircraft to sit low enough that pax can use the overwing emergency exits. This is just about do-able for the MAX10.

But if you are relying on this extending undercarriage to re-position the LEAP engines underneath the wing, it simply cannot be there for you, and you will find that even whilst taxying towards the runway, anything more than a crisp packet on the pavement, will bring the MAX to a halt.
(At this point I have an absurd mental image of a re-engined 737 MAXv2 stranded somewhere on a taxiway, balanced on a combination of it's nosewheel and the undersides of the two engine nacelles, whilst the main undercarriage itself is "airborne". Kinda like a wheels up landing, but in a more gentle way)

Summary; designing an extending undercarriage that is both totally failsafe, and yet also fits within the existing wheel wells is only part of the answer. You need to factor in new emergency exits, with new doors that are easier to open than the existing 1967 design. And suddenly grandfathering becomes impossible. Add several more $$$billion to the cost.

Have I missed anything?

And basically everything you just said proves to me the regulations are too rigid for their own good. It's a perfectly safe, valid solution to the problem, usually a mark of excellent engineering. And no, no new emergency exits.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 7:33 pm

mwananchi wrote:
patrickjp93 wrote:
And you don't need the AoA to get your air speed. Using triangulation from the radar sensors or Boeing's upcoming Lidar implementation, you can derive craft speed based on the bounce time of reflected beams at a given distance ahead since Special Relativity is a well-understood scheme at this point.


Take the case of over-water flights: whether radar would provide actual craft speed readings is probably a question for the forum experts to chew over.

Lidar at high altitude over water for speed measurement purposes sounds like quite an advanced application too.

Special relativity doesn't give a damn about being overwater, or did you forget we have overseas satellites. You can use light's deflection off the air and the time it takes to receive the reflection, because the speed of light is constant regardless of its emitter having non-zero speed.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 7:33 pm

patrickjp93 wrote:
And you don't need the AoA to get your air speed.


Right. A pitot/static system works great. Figured out before the Wright Bros flew. (Now those are some really old geezers.)
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 7:34 pm

patrickjp93 wrote:
because the speed of light is constant


In a vacuum.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 7:35 pm

SheikhDjibouti wrote:
patrickjp93 wrote:
scbriml wrote:
That gear doesn't raise the height of the 737-10 by a single mm. It only helps at rotation. Next idea?

It DOES raise the MAX 10 off the ground an additional 4 inches during rotation to avoid tail strike.
It can be pilot controlled and have a failsafe activation in the case where the flight control computer can no longer communicate with the gear.
Not. Good. Enough.

Revelation wrote:
...so it allows for a longer tail, but not a bigger engine. The extension at rotation happens because gravity pulls the gear down once the aircraft weight is removed which in turn fills a cylinder with air which allows the gear be supported once it is elongated, it is not a powered lift mechanism.
Rev; I first got a handle on this several months ago, but your description of the system takes it further, and leaves me with some questions.
(Hopefully answering them will assist Patrick too.)
What happens to this "air suspension" following take-off (when there is even less weight on the undercarriage)? I'm guessing that whilst still on the runway, as ground speed increases, the wings generate lift and take some of the load, allowing the gear to extend naturally via it's own spring mechanism. But it surely needs to be "locked" at that height, else at rotation when the weight firstly comes off the nosewheel, there will be a momentary transfer to the main u/c causing it to collapse again. I'm a bit fuzzy on this part, so pretend you are explaining it to a complete idiot. :wave:

Apart from that, my understanding is....
The gear extension at rotation is purely to (help) avoid a tail strike.
It can only happen at rotation because at all other times the gear must NOT raise the height of any 737, otherwise it would invalidate the (grandfathered) overwing emergency exits.
Finally, it must exhibit a failsafe default whereby when all other systems fail (electric, hydraulic, whatever) the gear allows the aircraft to sit low enough that pax can use the overwing emergency exits. This is just about do-able for the MAX10.

But if you are relying on this extending undercarriage to re-position the LEAP engines underneath the wing, it simply cannot be there for you, and you will find that even whilst taxying towards the runway, anything more than a crisp packet on the pavement, will bring the MAX to a halt.
(At this point I have an absurd mental image of a re-engined 737 MAXv2 stranded somewhere on a taxiway, balanced on a combination of it's nosewheel and the undersides of the two engine nacelles, whilst the main undercarriage itself is "airborne". Kinda like a wheels up landing, but in a more gentle way)

Summary; designing an extending undercarriage that is both totally failsafe, and yet also fits within the existing wheel wells is only part of the answer. You need to factor in new emergency exits, with new doors that are easier to open than the existing 1967 design. And suddenly grandfathering becomes impossible. Add several more $$$billion to the cost.

Have I missed anything?

viewtopic.php?t=1402777 was our six page mega-thread on how this works.

In it I explained that I suck at visualizing mechanical things so needed a lot of help sorting out how it worked.

In essence it is using an shock that expands when weight is off the wheels, much like the shocks in most autos use energy gained when hitting a bump to ease the jolt when the auto body wants to land back onto the wheels. Linkages from the current landing gear extension/retraction mechanisms and an additional actuator are used to guide its compression as the gear retracts and its expansion as the gear lowers. It is all being done with these mechanical elements as opposed to some computer controlled air cushion mechanism, presumably to keep it simple and thus more reliable.

I wish there was a layman friendly write up of how all this works but I don't think we ever got there. The thread starter shows video of a mechanical model of its operation and viewtopic.php?f=5&t=1402777&start=50#p20680135 gives some related patents. viewtopic.php?f=5&t=1402777&start=50#p20682075 or viewtopic.php?f=5&t=1402777&start=50#p20691781 may have been my best shot at explaining things. Unfortunately the thread degraded into pedantry about some minor aspects of the gear's operation along with obligatory A vs B rhetoric so I don't think we ever could fully explain how it operated to everyone's satisfaction.

As per that thread, a useful thought experiment is "what if a takeoff is rejected at Vr minus one knot/mph/whatever -- what happens with the extended gear?" -- it's almost the same thing you are asking, no? I think #79 through #87 of that thread gave as good an answer as we are going to get.

Perhaps more relevant to this thread, viewtopic.php?t=1402777#p20679997 said:

Okcflyer wrote:
- Recall the Max10 only stretches 26” behind but 40” in front of wing.
- To rebalance weight distribution and prevent excessive downforce/drag from the tail, the pylons move the engines backwards a couple inches to help realigning COG.

Seems to help explain why MCAS *might* not be necessary for MAX10, but I guess it'll still be there to keep the software the same on all the platforms.
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Re: Boeing 737MAX Grounding News and Reference Thread 2020

Tue Jan 14, 2020 7:45 pm

Polot wrote:
SRQLOT wrote:
ShamrockBoi330 wrote:
AA pushes RTS out to June

MAX taken off American Air schedules through June 3

https://seekingalpha.com/news/3531747?source=ansh


While Ryanair now says April? When just recently it was October.

https://www.yahoo.com/finance/news/ryan ... 08241.html

Airlines don’t know when RTS is, because it is depends on the regulators and know one is sure how long they are going to take. Most airlines are erring on the side of caution now (better to ‘uncancel’ flights or have fleet slack if RTS is before end of schedule than have to cancel flights in the near future).


Of course I know that, it’s been like that since last summer. What I don’t understand is why they still keep putting out the info when hey have no idea.
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patrickjp93
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 7:46 pm

hivue wrote:
patrickjp93 wrote:
because the speed of light is constant


In a vacuum.

It's constant in any set of circumstances, but it does not maintain the same constant across those sets of circumstances, and the fundamental fact remains you can't accelerate it beyond that constant. If you know the outside air temperature and pressure, you're good.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 7:56 pm

patrickjp93 wrote:
PW100 wrote:
patrickjp93 wrote:
I gave a perfectly reasonable explanation of what is wrong with the rigid framework of grandfathering. It was more expensive to develop MCAS and move the engines forward than it would have been to raise the landing gear, but raising the gear was made off-limits under grandfathering for the type. That's a failure of the regulation framework, simple as that. Iterative improvement has to be allowed.


Seriously????

There were a lot of reaons for Boeing not to raise the landing gear, regulation framework though is very low on the list.

Regulation framework is not stopping iterative improvement. If you want a prime example of iterative improvement, look no further than A320ceo, staying more than competative from 1988 to 2015 thanks to non-stopping effort of iterative improvement . . .

That the EASA allowed and the FAA did not. They share a treaty to respect each other's certifications, but does not bind either one to follow the same process as the other.

Please list the reasons. This should be fun.


That treaty is the result of 25 years of harmonisation and cross checking.

There is no, I repeat no difference between FAA and EASA when it comes to "iterative improvement". I really struggle to understand where you got that idea from.
Maybe you should check out the number of SBs on B737-800, or CF6 for that matter to understand how much "iterative improvements" thoseFAA certified products underwent.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 7:58 pm

patrickjp93 wrote:
mwananchi wrote:
patrickjp93 wrote:
And you don't need the AoA to get your air speed. Using triangulation from the radar sensors or Boeing's upcoming Lidar implementation, you can derive craft speed based on the bounce time of reflected beams at a given distance ahead since Special Relativity is a well-understood scheme at this point.


Take the case of over-water flights: whether radar would provide actual craft speed readings is probably a question for the forum experts to chew over.

Lidar at high altitude over water for speed measurement purposes sounds like quite an advanced application too.

Special relativity doesn't give a damn about being overwater, or did you forget we have overseas satellites. You can use light's deflection off the air and the time it takes to receive the reflection, because the speed of light is constant regardless of its emitter having non-zero speed.

So would you pleas elaborate where special relativity comes into play, and how exactly air scattering is going to work?
There were some EASA experiments on doppler measurements of air data. My impression is that it is less than perfect.. they didn't use "air deflection", though. And Doppler is not relativistic effect, btw.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:04 pm

patrickjp93 wrote:
PW100 wrote:
patrickjp93 wrote:
It DOES raise the MAX 10 off the ground an additional 4 inches during rotation to avoid tail strike.

How does preventing tailstrikes helps fitting larger engines??
I must be missing something, so it would be helpful if you explain that to me like I'm a nine-year old.

One of two ways, and no, like you're an eighteen year old whose brain isn't pickled by too many years of hitting the sauce.

And preventing the tail strike isn't important here.

Then why did YOU feel the need to bring it up in the first place???

What the telescoping CAN ENABLE is what is important. Sure, the bays may not be expandable without significant rework. Okay, that being the case, if you make the gear telescopic, it can extend to full length for ALL ground phases and then retract for flight stowage. All of a sudden the effective height of craft off the ground--barring a crash landing--is greater than before, which increases ground clearance for the engine, allowing it to be moved further back to fix the aerodynamic characteristics back to something more akin to the 737 NG.

Now, I'm sure I'm about to get hounded over how you'd engineer such a gear, and the answer that immediately comes to mind is hydraulics for the telescoping action and more maintenance to go with it. That's the cost of getting the plane cheap up front.


The fact that not a single commercial plane today employs such a gear, should be a strong hint that this is indeed not feasable. While especially the 737 could use it (because of all the design constraints), even here it is not used. Your false understanding of FAA rigid framework of grandfathering should be an even more stronger reason to employ it on the 737. But it doesn't.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:07 pm

hivue wrote:
PW100 wrote:
patrickjp93 wrote:
It DOES raise the MAX 10 off the ground an additional 4 inches during rotation to avoid tail strike.


How does preventing tailstrikes helps fitting larger engines??

I must be missing something, so it would be helpful if you explain that to me like I'm a nine-year old.


Forget the engines. The MAX 10's fuselage is long. The (1960s design) 737 sits very low to the ground. The tail is thus low to the ground. It extends far back because it is long. Thus when the airplane rotates there is an increased likelihood of a tail strike. Thus the main gear are designed to push the fuselage higher from the ground at rotation.

BTW, this sounds a little too kludgey for me. The MAX itself is sounding more like a kludge all the time.


That is all fine and well, but the discussion was how to fit bigger (diameter) engines. The MAX 10 gear for rotation angle isn't going to help.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:08 pm

patrickjp93 wrote:
And you don't need the AoA to get your air speed.

Close to max Cl you will get an error of 3.4% from the airspeed sensor without AoA. Please bow to the fact.

patrickjp93 wrote:
Using triangulation from the radar sensors or Boeing's upcoming Lidar implementation, you can derive craft speed based on the bounce time of reflected beams at a given distance ahead since Special Relativity is a well-understood scheme at this point.

Are you aware, that Boeing was following the "keep changes at a minimum"-mantra like cracy? Not because of the FAA, as you claim wrongly, but because any change meant more cost up and later EIS? Boeing at all cost wanted to avoid any scope creep in the MAX project.

Also, speed derived from radar is not airspeed, but groundspeed, or even worse, relative speed to a target which is moving by itself (if the weather radar e.g. is receiving echos from a cloud). So more half baken, unuseable suggestions from your side.

patrickjp93 wrote:
Or if you're happy with a dirtier approximation, if you know the outside air temperature and pressure and have historical altimeter data you can get within a few percent of the real speed.

You can get only IAS from TAS like that. But from where to you get TAS? Even more pipe dreams from your side.

If you think, that the radar could use the doppler response from landmarks to get TAS (an operation mode which is not implemented in aircraft radar -> more cost to add the feature), then I ask, whether you are aware, that you need to know the elevation of the landmark in order to correct the error which comes from not flying directly towards the landmark. Due to this you now need a 3D terrain model of the world surface -> more complexity and cost. All just to get TAS from radar. What a naive suggestion.

patrickjp93 wrote:
It wouldn't have the same precision, but bearing in mind the speed you have to be flying to gain/lose/maintain altitude at a given drag (we know the overall drag of the craft after we've done flight testing +/- 1% for natural frame variability).

You are aware that identical aircraft, from ship to ship, can have differing fuel burns by several percent points?

patrickjp93 wrote:
That estimation, of course, is only in a completely reliable form when you have an undamaged frame, but it's usable if your AoA goes AWOL. And if the sensors fail (which is also detectable or assignable by the pilots) then that estimation goes away too. By the time you're having that many failures simultaneously, chances are you've got a fire in your flight computer or electrical system and you're going into manual control law anyway which is more based on visual than system readings when you know the system is bogus.

You present some fascinating mental leaps just to avoid 3 AoA sensors installed. Pilot 1 to pilot 2: "AoA data now really seems to be fishy, but never mind, our board electronics anyway is burning by now...!"

patrickjp93 wrote:
I believe all of the sensors I said I'd use for that secondary calculation have failure rates of e-12 or better

Engineering by believe is quite a contrast to the super skills you claimed to have. I for example believe these sensors have far worse failure rates than that.

Anyway by these considerations it becomes clear, that you wont easily get reliable AoA data just by computation.

patrickjp93 wrote:
There's plenty of room to expand the gear. Remember the 737's landing gear doesn't raise into a closed bay. It's just flush with the underside of the fuselage. It's fairly trivial to expand it. Yes, some geometry would change a little, but given the turbulent flow the landing gear causes anyway, I'm not convinced it would change the handling in the slightest.

The change would be overwing exit slides. More development cost on Boeings side. Clearly hampering the business case of the MAX (more weight&complexity, worse efficiency).

patrickjp93 wrote:
It DOES raise the MAX 10 off the ground an additional 4 inches during rotation to avoid tail strike.

And during taxi, the engines shall be dragged over the tarmac?

And - something else you seem to ignore - if Boeing would want equip the MAX with longer gears now, the entire engine pylon would have to designed from scratch once more -> more cost + rework on the already built MAXes (quite possibly on a scale, that would make all now built MAXs write offs).
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:13 pm

scbriml wrote:
Not forgetting that he was a member of the Board that oversaw Boeing's slide to its current position, so he's not [u]exactly untainted[/u].


It's a baseless accusation
This does not constitute a proof for me...
Last edited by Checklist787 on Tue Jan 14, 2020 8:30 pm, edited 3 times in total.
 
patrickjp93
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:16 pm

PW100 wrote:
patrickjp93 wrote:
PW100 wrote:

Seriously????

There were a lot of reaons for Boeing not to raise the landing gear, regulation framework though is very low on the list.

Regulation framework is not stopping iterative improvement. If you want a prime example of iterative improvement, look no further than A320ceo, staying more than competative from 1988 to 2015 thanks to non-stopping effort of iterative improvement . . .

That the EASA allowed and the FAA did not. They share a treaty to respect each other's certifications, but does not bind either one to follow the same process as the other.

Please list the reasons. This should be fun.


That treaty is the result of 25 years of harmonisation and cross checking.

There is no, I repeat no difference between FAA and EASA when it comes to "iterative improvement". I really struggle to understand where you got that idea from.
Maybe you should check out the number of SBs on B737-800, or CF6 for that matter to understand how much "iterative improvements" thoseFAA certified products underwent.

That's all irrelevant. The processes are not the same, not even close, and we have years of certification threads on here for the A330 NEO, A320 NEO, and 777X. They are different methodologies, though both are logically sound for the most part.

Neither of them received that much iteration at a cursory reading. It's all mostly cosmetic or longevity items apart from a very minor geometry change on engine blades and the split scimitar winglets for the 737 NG.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:16 pm

morrisond wrote:
WillyEckers wrote:
morrisond wrote:
Unless of course you don't think Pilot's can be trained to counter a runaway trim and run a Runaway Trim NNC? That is a required Pilot skill of many type ratings.


I should not feed the troll but...

These quotes exist in various places but the AVweb article is asy to access https://www.avweb.com/insider/two-tragi ... -sim-time/

Boeing assumed that in the unlikely event that the system failed, pilots would be the last backstop to keep things from spinning out of control. But consider what the pilots of Ethiopian Airlines Flight 302 that crashed in March faced. The list included an active stick shaker inaccurately warning of an impending stall, an overspeed clacker, an aural “don’t sink” warning and several other disagree and warning lights. Sullenberger said he struggled to regain control in a simulator run mimicking the accident flight.

It's not a Runaway Trim NNC

In delivering his testimony, APA President Daniel Carey was blunt in brushing back a budding movement to blame the pilots. “I can tell you that the members of APA are offended by remarks made by those who seem to blame the pilots killed in those two crashes,” he said. “I am here to tell you that I worked in Africa and trained African pilots to fly large aircraft. I am very familiar with Ethiopian Air’s pilot training program and facilities, and I can tell you that they are world-class,” he added.

I think it's sad that you, who seems to have little experience (C172 but you don't say if that's XPlane or FSX...), needs to be so critical of the pilots who are firstly - not here to defend themselves and secondly, pretty much everybody of any stature has understood that it is not a pilot problem, it's an aircraft problem.

Anyway, I'm out of here :-)


Yes it a Runaway Trim NNC as per ET's own procedures as seen in the ET302 Preliminary report - if these symptoms happen - run this checklist - See pages 28-33 https://leehamnews.com/wp-content/uploa ... ET-AVJ.pdf

And when have I ever said there wasn't a problem with the aircraft? Or are you one of those who deny that there was anything wrong with Lionair maintenance or at the FAA as well and there is only issues at Boeing?

Please stop accusing me of blaming the Pilot's I am blaming ET's training system as my post from this morning demonstrates.

"From this article - Scroll down past the damning Maintenance issues at ET to get to the training Part https://www.businessinsider.com/boeing- ... er-2019-10

"Another whistleblower from Ethiopian, veteran pilot Bernd Kai von Hoesslin, told the AP in May that after Indonesia's Lion Air crash, he pleaded with Ethiopian's top executives to give pilots better training on the Max, predicting that if pilots are not sufficiently drilled on Boeing's protocols for how to disable the autopilot system in the event of a misfire, "it will be a crash for sure."


Ethiopian has said the pilots followed all the steps Boeing laid out. But the preliminary report on the crash showed they deviated from the directives and made other mistakes, notably flying the plane at an unusually high speed and inexplicably reactivating the anti-stall system shortly after manually overriding it. Six minutes into the Max flight, the plane with passengers from nearly a dozen countries cratered into the ground about 40 miles from the airport."

From AVHerald https://avherald.com/h?article=4c534c4a

"On Apr 11th 2019 The Aviation Herald received a full copy of the Flight Operations Manual (FOM), Revision 18B released on Nov 30th 2018, which is currently being used by Ethiopian Airlines (verified in April 2019 to be current). Although Boeing had issued an operator's bulletin on Nov 6th 2018, which was put into Emergency Airworthiness Directive 2018-23-51 dated Nov 7th 2018 requiring the stab trim runaway procedure to be incorporated into the FOM ahead of the sign off of this version of the FOM (the entire document is on file but not available for publishing), there is no trace of such an addition in the entire 699 pages of the FOM.

Quite the opposite, in section 2.6 of the FOM "Operational Irregularities" the last revision is provided as Revision 18 dated "Nov 1st 2017".

According to information The Aviation Herald had received in March 2019, the Airline Management needed to be reminded to distribute the Boeing Operator's Bulletin as well as the EAD to their pilots, eventually the documents were distributed to the flight crew. However, it was never verified, whether those documents had arrived, were read or had been understood. No deeper explanation of the MCAS, mentioned but not explained in both documents, was offered.

It turned out, that only very cursory knowledge about the stab trim runaway procedure exists amongst the flight crew of Ethiopian Airlines even 5 months after the EAD was distributed. In particular, none of the conditions suggesting an MCAS related stab trim runaway was known with any degree of certainty. In that context the recommendation by the accident flight's first officer to use the TRIM CUTOUT switches suggests, that he was partially aware of the contents of the EAD and reproduced some but not all of the provisions and not all of the procedure, which may or may not explain some of the obvious omissions in following the procedure in full."

The references speak for themselves. I'll just keep posting this whenever someone else insinuates I'm a liar and making this stuff up.

As I've said I am not blaming the pilots - I am blaming the ET training system that seems to have done a terrible job of instructing there Pilots on how to deal with MCAS."

I don't insinuate that you are a liar, as you provides some plausible facts, and that ET will certainly benefit from improvement.
But I strongly disagree that the EAD was an appropriate move from Boeing that did know at that time that the risk of accident was unacceptable with the mitigation of the pilots only.
See the excellent paper cited on post #1016 by
Thorkel wrote:
Not sure if this has been posted before - just came across this paper, written by somebody from Boeing surprisingly (although on their own dime), on the performance of pilots from a US airline when completing memory line items. It includes how well they did at executing the runaway stabiliser checklist in a non stressful situation.

http://www.code7700.com/pdfs/line_pilot ... _items.pdf

EAD and NCC are not magic papers that makes humans perfect. If I remember correctly a post on the previous thread, the regulation assume that a risk control done by the pilots only reduce the risk by 10 on average. The paper results are not only the consequences of the operators training, but also the consequences of the quality of the NCC redaction as discussed into the paper. I think that those considerations should also be on the table instead of focusing only on ET operator.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:21 pm

par13del wrote:
Yes, but we cannot discuss the FAA role in this unless we first state and restate all the Boeing errors, including share buy back, bribing congress, etc etc. etc.

ST ( https://www.seattletimes.com/business/b ... sumptions/ ) gave us a good summation of the critical errors, IMO:

The presentation shows that Boeing in its original certification of the MAX:
  • Presented MCAS to the FAA as not being a “new and novel” technology — and thus not requiring deeper scrutiny. The justification given was a doubtful comparison with the 767 tanker.
  • Did not consider in its safety assessment the effect of multiple system failures and how this would affect the reactions of the pilots.
  • Used questionable math to downgrade the system’s risk classification below a level that would have required more redundancy with at least two sensors to activate it.
  • Made a key safety assessment prior to a major change in the design of MCAS, and did not reevaluate the system again before certification.
  • Dismissed one scenario in which an MCAS failure was assessed as “catastrophic,” sticking — despite the Lion Air experience — to its prior assumption that “appropriate flight crew action” would save the aircraft.

It went on to say:

Laying out how Boeing originally assessed MCAS internally, the December 2018 presentation tells how first a standard preliminary risk assessment was done — it’s called a Functional Hazard Assessment (FHA) — by pilots in flight simulators.

They did not simulate the real-world scenario that occurred in the crash flights when a single sensor failed and prompted the cascade of warnings in the cockpit. Instead, the pilots simply induced the horizontal tail, also known as the stabilizer, to swivel as MCAS would have moved it to pitch the nose down in a single activation.

The pilots successfully demonstrated that they could then recover the aircraft. They did so simply by pulling back on the control column. They didn’t even have to use what Boeing later described as the final step to stopping MCAS: hitting the cut-off switches that would have killed electrical power to the stabilizer.

And:

Those pilots also did not simulate the crash flight scenario of MCAS misfiring multiple times — in the case of Lion Air, 27 times before the plane nose-dived into the sea.

Boeing notes in the presentation that much later, in June 2016 during flight tests of the MAX, its engineers did discuss this scenario of “repeated unintended MCAS activation” with its test pilots. They concluded that this would be “no worse than single unintended activation.”

As proof that discussion occurred, Boeing’s presentation mentions an internal email summary. Yet Boeing concedes that the discussion and its conclusion apparently never made it to the ears of the FAA. Boeing said it was “not documented in formal certification” papers.


Note how all the "bribes to Congress" and delegated authority and share buy-backs are really just second order noise.

The primary issue was a bunch of engineers and test pilots did an abysmal job at analyzing MCAS's modes of operation and its impact on safety.

I personally don't give them a "get out of jail free" card due to management greed. That on its own doesn't explain how Boeing's engineering side let such a bad design and implementation get out to the field. Maybe managers played "jedi mind tricks" on front line engineers, but in my experience managers simply don't know enough to be able to pull one over on line engineers, unless said line engineers were already devoid of ethics and integrity and were willing to turn a blind eye for any one of a number of reasons.

As I wrote earlier, if there is a smoking gun to be found, it will be found in the design, implementation and test phases of MCAS, rather than the sim certification and training phases.

patrickjp93 wrote:
So you believe the narrative that blames front line engineers instead of management.

Rightly or wrongly the system is constructed in a way that demands that front line engineers push back when management wants to do dubious things to save money. In the end it is the engineers that are accountable, that's why they are the ones who sign the documents. Engineers need the cajones to refuse to sign when things are not right, and yes, even if this means career damage. I should know, I've paid the price in terms of career damage for not signing off on something that was dubious. It's not fair that the system is set up this way, but I guess we know we can't count on managers to be ethical so the burden is dumped onto engineers.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:25 pm

kalvado wrote:
patrickjp93 wrote:
mwananchi wrote:

Take the case of over-water flights: whether radar would provide actual craft speed readings is probably a question for the forum experts to chew over.

Lidar at high altitude over water for speed measurement purposes sounds like quite an advanced application too.

Special relativity doesn't give a damn about being overwater, or did you forget we have overseas satellites. You can use light's deflection off the air and the time it takes to receive the reflection, because the speed of light is constant regardless of its emitter having non-zero speed.

So would you pleas elaborate where special relativity comes into play, and how exactly air scattering is going to work?
There were some EASA experiments on doppler measurements of air data. My impression is that it is less than perfect.. they didn't use "air deflection", though. And Doppler is not relativistic effect, btw.

Doppler is kid's play and is used to check density of weather systems. It's looking at resonant modes of light, not the turnaround time from particles a known distance away.

Special Relativity is the enveloping theory (and long since tested and proven) around how light interacts with objects in moving reference frames. The best way to understand how it is applied here is probably using the light speed train tunnel paradox. Because the speed of light does not change in a given set of conditions (in this case an air body's elemental composition and pressure) regardless of how fast its source is, you can use the difference in time for light to bounce back from a known distance to get your speed.

If you're running and throw a ball in front of you, the speed/velocity of the ball increases in the line you're traveling on above your running speed. However, this breaks down at the speed of light where it is impossible to exceed that speed. You running forward with a laser pointer in hand does not increase the propagation speed of the laser. Therefore, any change in time for a particle to leave the pointer and collide with what's in front of you and return which exceeds this absolute speed limit is your speed going in the opposite direction. That's why Special Relativity and Lidar can be used for this. Even radar can, but because it relies on some oscillatory modes to not come back as pure noise, it's probably easier to make such a system with Lidar.
Last edited by patrickjp93 on Tue Jan 14, 2020 8:31 pm, edited 1 time in total.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:29 pm

PW100 wrote:
patrickjp93 wrote:
PW100 wrote:
How does preventing tailstrikes helps fitting larger engines??
I must be missing something, so it would be helpful if you explain that to me like I'm a nine-year old.

One of two ways, and no, like you're an eighteen year old whose brain isn't pickled by too many years of hitting the sauce.

And preventing the tail strike isn't important here.

Then why did YOU feel the need to bring it up in the first place???

What the telescoping CAN ENABLE is what is important. Sure, the bays may not be expandable without significant rework. Okay, that being the case, if you make the gear telescopic, it can extend to full length for ALL ground phases and then retract for flight stowage. All of a sudden the effective height of craft off the ground--barring a crash landing--is greater than before, which increases ground clearance for the engine, allowing it to be moved further back to fix the aerodynamic characteristics back to something more akin to the 737 NG.

Now, I'm sure I'm about to get hounded over how you'd engineer such a gear, and the answer that immediately comes to mind is hydraulics for the telescoping action and more maintenance to go with it. That's the cost of getting the plane cheap up front.


The fact that not a single commercial plane today employs such a gear, should be a strong hint that this is indeed not feasable. While especially the 737 could use it (because of all the design constraints), even here it is not used. Your false understanding of FAA rigid framework of grandfathering should be an even more stronger reason to employ it on the 737. But it doesn't.

I think your language barrier is getting in the way. I brought it up as a starting point to then propose a more robust telescoping landing gear that can be used to raise the plane when on the ground and deactivated when an evacuation is required to satisfy both the overawing exit grandfathering AND allow the engines to sit further back on the wing with ground clearance.

That something has never been done does not make it a stupid idea. As I've said, aerospace manufacturing is over fifteen years behind the bleeding edge of automation and AI-driven improvement in process over time. Just because you're skeptical is not justification to reject it.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:29 pm

patrickjp93 wrote:
If grandfathering frameworks were more flexible in iterative improvement Boeing would have just raised the landing gear and not spend $300 million USD on building MCAS v1.0 and risked this nightmare.

Grandfathering did not dictate the short gears. Boeing wanted it so cheap. Longer gears are terribly costly and the promised EIS would have been terribly missed by a longleg 737.

Revelation wrote:
The extension at rotation happens because gravity pulls the gear down once the aircraft weight is removed which in turn fills a cylinder with air which allows the gear be supported once it is elongated, it is not a powered lift mechanism.

No force, no power, no lift. Physics is brutal in that regards.

If it works the way you describe (which I doubt) the force would come from the pressurized air, which is filled into the cylinder. If it is not pressurized, there would be no effect on the tail clearance.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:33 pm

Revelation wrote:
par13del wrote:
Yes, but we cannot discuss the FAA role in this unless we first state and restate all the Boeing errors, including share buy back, bribing congress, etc etc. etc.

ST ( https://www.seattletimes.com/business/b ... sumptions/ ) gave us a good summation of the critical errors, IMO:

The presentation shows that Boeing in its original certification of the MAX:
  • Presented MCAS to the FAA as not being a “new and novel” technology — and thus not requiring deeper scrutiny. The justification given was a doubtful comparison with the 767 tanker.
  • Did not consider in its safety assessment the effect of multiple system failures and how this would affect the reactions of the pilots.
  • Used questionable math to downgrade the system’s risk classification below a level that would have required more redundancy with at least two sensors to activate it.
  • Made a key safety assessment prior to a major change in the design of MCAS, and did not reevaluate the system again before certification.
  • Dismissed one scenario in which an MCAS failure was assessed as “catastrophic,” sticking — despite the Lion Air experience — to its prior assumption that “appropriate flight crew action” would save the aircraft.

It went on to say:

Laying out how Boeing originally assessed MCAS internally, the December 2018 presentation tells how first a standard preliminary risk assessment was done — it’s called a Functional Hazard Assessment (FHA) — by pilots in flight simulators.

They did not simulate the real-world scenario that occurred in the crash flights when a single sensor failed and prompted the cascade of warnings in the cockpit. Instead, the pilots simply induced the horizontal tail, also known as the stabilizer, to swivel as MCAS would have moved it to pitch the nose down in a single activation.

The pilots successfully demonstrated that they could then recover the aircraft. They did so simply by pulling back on the control column. They didn’t even have to use what Boeing later described as the final step to stopping MCAS: hitting the cut-off switches that would have killed electrical power to the stabilizer.

And:

Those pilots also did not simulate the crash flight scenario of MCAS misfiring multiple times — in the case of Lion Air, 27 times before the plane nose-dived into the sea.

Boeing notes in the presentation that much later, in June 2016 during flight tests of the MAX, its engineers did discuss this scenario of “repeated unintended MCAS activation” with its test pilots. They concluded that this would be “no worse than single unintended activation.”

As proof that discussion occurred, Boeing’s presentation mentions an internal email summary. Yet Boeing concedes that the discussion and its conclusion apparently never made it to the ears of the FAA. Boeing said it was “not documented in formal certification” papers.


Note how all the "bribes to Congress" and delegated authority and share buy-backs are really just second order noise.

The primary issue was a bunch of engineers and test pilots did an abysmal job at analyzing MCAS's modes of operation and its impact on safety.

I personally don't give them a "get out of jail free" card due to management greed. That on its own doesn't explain how Boeing's engineering side let such a bad design and implementation get out to the field. Maybe managers played "jedi mind tricks" on front line engineers, but in my experience managers simply don't know enough to be able to pull one over on line engineers, unless said line engineers were already devoid of ethics and integrity and were willing to turn a blind eye for any one of a number of reasons.

As I wrote earlier, if there is a smoking gun to be found, it will be found in the design, implementation and test phases of MCAS, rather than the sim certification and training phases.

patrickjp93 wrote:
So you believe the narrative that blames front line engineers instead of management.

Rightly or wrongly the system is constructed in a way that demands that front line engineers push back when management wants to do dubious things to save money. In the end it is the engineers that are accountable, that's why they are the ones who sign the documents. Engineers need the cajones to refuse to sign when things are not right, and yes, even if this means career damage. I should know, I've paid the price in terms of career damage for not signing off on something that was dubious. It's not fair that the system is set up this way, but I guess we know we can't count on managers to be ethical so the burden is dumped onto engineers.

That summation is woefully incomplete just based on the data dump so far.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:37 pm

rheinwaldner wrote:
patrickjp93 wrote:
If grandfathering frameworks were more flexible in iterative improvement Boeing would have just raised the landing gear and not spend $300 million USD on building MCAS v1.0 and risked this nightmare.

Grandfathering did not dictate the short gears. Boeing wanted it so cheap. Longer gears are terribly costly and the promised EIS would have been terribly missed by a longleg 737.

Revelation wrote:
The extension at rotation happens because gravity pulls the gear down once the aircraft weight is removed which in turn fills a cylinder with air which allows the gear be supported once it is elongated, it is not a powered lift mechanism.

No force, no power, no lift. Physics is brutal in that regards.

If it works the way you describe (which I doubt) the force would come from the pressurized air, which is filled into the cylinder. If it is not pressurized, there would be no effect on the tail clearance.

Yes it did. Increasing the gear height and mandating exit slides and the other necessary modifications to the fuselage would have broken the type rating. This has already been discussed at length in last year's 737 MAX grounding thread and I believe further up this thread as well.

The regulatory framework needs an overhaul, probably with a lot of input from people in my field who actually ARE experienced in the sort of improvement over time to large, complex systems sometimes far older than the oldest 737s flying in Cuba today.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:51 pm

patrickjp93 wrote:
That summation is woefully incomplete just based on the data dump so far.

Do tell. The recent text/message dump is mostly about qualifying the simulator and setting the training requirements, and AFAIK not about any "jedi mind tricks" that may or may not have been played during the design and certification of MCAS.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:57 pm

kurtverbose wrote:
Interesting article from Leeham news.

Boeing likely faces an extended timeline to clear its inventory of 400 737 MAXes. LNA estimates it will be well into 2022 before these new-production airplanes are delivered to customers.


I had previously mentioned that WN might need to acquire some more used 737-700's that will become available in the next 4 years with (a) SK having plans to retire its 23 737-700's by 2023, (b) KL having plans to retire its 16 737-700's by 2022, and (c) WN not likely to be back to normal in the next 3 years, even if the 737 MAX is ungrounded later this year.

SK's plans to retire its 23 737-700's and 28 737-800's isn't affected by the 737 MAX grounding as SK already has additional A320neos on order to replace its 737NG aircraft.

While KL doesn't currently have any 737 MAX or A320neo family planes on order, KL's plans to retire its 737-700's is probably not affected by the 737 MAX grounding due to KL currently not having any 737 MAX planes on order.

WN acquiring used 737-700's from SK and/or KL would allow WN to get operations back to normal more quickly, even if the 737 MAX is ungrounded later this year, as WN will likely be facing plane shortages for another 2 to 3 years due to the 737 MAX grounding, the backlog of 737 MAX deliveries, and delays in getting the 737 MAX back into production.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:57 pm

Revelation wrote:
patrickjp93 wrote:
That summation is woefully incomplete just based on the data dump so far.

Do tell. The recent text/message dump is mostly about qualifying the simulator and setting the training requirements, and AFAIK not about any "jedi mind tricks" that may or may not have been played during the design and certification of MCAS.

Because we also know Boeing employees were being brought out and publicly shamed in front of their peers for not meeting deadlines and goals on the project. That sort of abusive management practice will be corroding everything it touches. As usual with anything involving government entities, absolutely no getting to the heart of the matter.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 8:58 pm

patrickjp93 wrote:
scbriml wrote:
patrickjp93 wrote:
Telescoping gear that retract before being stowed. Good lord they already know how to do that for the MAX 10 just for takeoff to prevent tail strikes.


That gear doesn't raise the height of the 737-10 by a single mm. It only helps at rotation. Next idea?

It DOES raise the MAX 10 off the ground an additional 4 inches during rotation to avoid tail strike.


My understanding is that it's passive and doesn't actively 'lift' the plane higher off the ground at all - it extends 9.5 inches (not 4) as the plane rises providing a slightly higher pivot point for rotation. The MAX 10 sits the same height off the ground as all other MAXes. The gear does nothing to solve the issues of engine clearance and position which necessitated MCAS in the first place.

patrickjp93 wrote:
Now, I'm sure I'm about to get hounded over how you'd engineer such a gear, and the answer that immediately comes to mind is hydraulics for the telescoping action and more maintenance to go with it. That's the cost of getting the plane cheap up front.


Plus significant additional weight. I'm pretty sure the gear is 'dumb'.

patrickjp93 wrote:
It can be pilot controlled and have a failsafe activation in the case where the flight control computer can no longer communicate with the gear.


I'd really like to see some supporting evidence for this. Again, my understanding is the gear is essentially mechanically dumb and requires no pilot intervention.

Revelation wrote:
viewtopic.php?t=1402777 was our six page mega-thread on how this works.

In it I explained that I suck at visualizing mechanical things so needed a lot of help sorting out how it worked.

In essence it is using an shock that expands when weight is off the wheels, much like the shocks in most autos use energy gained when hitting a bump to ease the jolt when the auto body wants to land back onto the wheels. Linkages from the current landing gear extension/retraction mechanisms and an additional actuator are used to guide its compression as the gear retracts and its expansion as the gear lowers. It is all being done with these mechanical elements as opposed to some computer controlled air cushion mechanism, presumably to keep it simple and thus more reliable.


That was my understanding as well. I found this video very helpful in visualising how it works: https://www.youtube.com/watch?v=F4IGl4OizM4
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:07 pm

[twoid][/twoid]
Revelation wrote:
patrickjp93 wrote:
That summation is woefully incomplete just based on the data dump so far.

Do tell. The recent text/message dump is mostly about qualifying the simulator and setting the training requirements, and AFAIK not about any "jedi mind tricks" that may or may not have been played during the design and certification of MCAS.


Excuse me but the thread has become too long and there are many technical terms in your discussions. Can you explain to us what's going on?

And what is this "Jedi mind tricks" (StarWars?) you seem to dispute that Boeing is wrong when Muilenburg acknowledged the wrong and several emails clearly from rogue Boeing employers have been seized which prove that they have bypassed the FAA?

So please what's the problem ? ...
Last edited by Checklist787 on Tue Jan 14, 2020 9:08 pm, edited 1 time in total.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:07 pm

Checklist787 wrote:
scbriml wrote:
Not forgetting that he was a member of the Board that oversaw Boeing's slide to its current position, so he's not [u]exactly untainted[/u].


It's a baseless accusation
This does not constitute a proof for me...


He's served on the Board at Boeing for the last ten years. He's played a role in Boeing ending up where they are now. He's not the new blood that Boeing needs.

https://leehamnews.com/2020/01/12/guest ... -year-ceo/
This is where Calhoun’s resume is concerning. Aside from a few years at GE Aircraft Engines, he hasn’t been an aerospace executive. Much of his experience has been in top management in Jack Welch-era GE, the same as McNerney. Much of his recent experience has been with private equity, which can be useful in leaning out fat companies, but that’s hardly Boeing’s problem right now. And, as fellow commentator Scott Hamilton put it, “He’s been on the Board since 2009. He’s been part of the Board policy-making that led to the cost-cutting some say had deleterious impact on the development of the MAX. He’s been part of the Board decisions that shareholder value is the No. 1 priority at Boeing.” In short, Calhoun looks a lot like the people who brought Boeing to the position it’s in today.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:11 pm

I agree with Revelation that the primary issue was the poor safety evaluation done of the MCAS system.

As both the JATR and NTSB reports indicated these mistakes happened because of use of "out of date" or "not the most relevant" assumptions/standards (and I believe anyone who reads and fully understands both reports knows that these same assumptions most likely were previously used by other aircraft manufactures and certification authorities).

A major contributor, in my opinion, was that the standards only required each system to be analyzed by itself and not from a total integrated impact:

"The JATR team reviewed how the Changed Product Rule process was applied to the certification
of the flight control system of the B737 MAX. The JATR team determined that the Changed
Product Rule process was followed and that the process was effective for addressing discrete
changes. However, the team determined that the process did not adequately address cumulative
effects, system integration, and human factors issues. The Changed Product Rule process allows
the applicant6 to only address in a limited way changed aspects (and areas affected by the
change) and does not require analysis of all interactions at the aircraft level."

My reading of the NTSB report is that it says essentially the same thing. Boeing was not required to test all the reasons, with all the alarms and stick shakers, that could cause MCAS malfunction. Thus, the testers never experienced what at least the Lion Air crews did.

I have personally been on Nuclear Safety Failure Assessment Teams that review FHA's (or FMEA's as we called them) and no one involved ever even talked about financial impact. Just what were the failure modes, what level of significance, and what probability. Then, if the analysis was too severe; could a different solution with a lower severity be effectively and practically used (that's the only place I've ever seen cost considered as there are almost always solutions that are not economical to implement, and many times it's cheaper to accept the higher severity rating than a major design change).

It takes the vast majority of the entire team to agree with the rating on every question (actually, objections are almost always addressed as part of the process).

I've also been on Root Cause investigations (Team Lead/Official Investigator Lead on several) where incorrect FMEA's were analyzed to determine why they were wrong - and how the mistake was made.

I've never seen any hint that anyone doing these evaluations considered economic impact into determining a rating score.

I've had some discussions with my counterparts in the Aviation field; and they tell me the same thing.

Once the Safety Assessment got it wrong... everything else followed. It's not a crime to build an item as low cost as possible as long as it meets the regulations.

Had the safety assessment of MCAS V1 correctly identified that it had problems; we most likely would have ended up with something like (if not exactly) the current MCAS V2; which would have been approved by the process in place at that time.

While MCAS V2 may have prevented the crashes (I'm not so sure of that on ET); the one "good" effect was that these events have forced the entire industry to look at how aircraft certification and regulation is done. While Boeing is paying the biggest price. I am sure that every aircraft builder and regulator of new build/certified aircraft has taken notice - and I'm sure there are international committees working on new standards to address issues identified in both the JATR and NTSB reports.

Within the USA - Congress has affected the process; and I hope that they pass appropriate legislation and appropriately fund the FAA to eliminate the current legal degree and process of self certification activities within the USA. I'm not saying to eliminate such practices. But, the FAA needs to have better oversight and better control than they currently have.

My personal suspicion is that one of the reasons the current FAA head has so involved the international community in the solution is that the international community can require things that legally the FAA cannot at this point.

Future aircraft certifications worldwide will be more robust, and aviation safety will increase as a result.

The 737Max will likely be the safest (best reviewed) aircraft in the world when it returns to service.

I am sure that the 777X certification process will be changed to adopt realistic response times and a total integrated system review of the impacts on pilot workload, and required training.

Any aircraft beyond that will have other new standards to meet. By then you can expect a lot more human performance standards and other factors to have been agreed to by the international committees.

Have a great day,
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:11 pm

Checklist787 wrote:
several emails clearly from rogue Boeing employers have been seized which prove that they have bypassed the FAA?

So please what's the problem ? ...


You are absolutely correct, employers not employees.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:17 pm

Revelation wrote:
scbriml wrote:
patrickjp93 wrote:
It wasn't impossible or unreasonable. The rules were wrong. They should have been changed.

So we need to add "The rules were wrong" to the list of reasons why it's not Boeing's fault?

Shouldn't we be able to explore the FAA's role in the MAX tragedy without triggering the fear of Boeing absolution gag reflex?


Fair point, mea culpa.

Revelation wrote:
scbriml wrote:
What do you think has changed at Boeing since "Dave" started work at his new job yesterday morning? Not forgetting that he was a member of the Board that oversaw Boeing's slide to its current position, so he's not exactly untainted.

Or, for that matter, what has changed since McAllister walked the plank and Deal was installed many weeks ago?

IMO the Calhoun email still has a large amount of corporate doublespeak in it. Is their new transparency going to extend to examining how the "no sim training" mantra became established? It seems all the communications in the dump happened after the mantra was installed so we can't figure out exactly who in engineering signed off on accepting such a condition, which clearly happened very early in the program.


It's about as corporate as it gets. I worked for a global American company for 35 years and saw quite a few emails like this after mergers/acquisitions/downsizing/rightsizing/business process reengineering/whatever this week's mba fad is, hence my dig about stirring music and soaring eagles.

It takes a long time to change attitudes and practices in a large corporation, it cannot happen overnight or in a few weeks. And it absolutely has to start at the top and be pushed vigorously through the ranks. Talk is cheap.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:31 pm

Checklist787 wrote:
[twoid][/twoid]
Revelation wrote:
patrickjp93 wrote:
That summation is woefully incomplete just based on the data dump so far.

Do tell. The recent text/message dump is mostly about qualifying the simulator and setting the training requirements, and AFAIK not about any "jedi mind tricks" that may or may not have been played during the design and certification of MCAS.


Excuse me but the thread has become too long and there are many technical terms in your discussions. Can you explain to us what's going on?

And what is this "Jedi mind tricks" (StarWars?) you seem to dispute that Boeing is wrong when Muilenburg acknowledged the wrong and several emails clearly from rogue Boeing employers have been seized which prove that they have bypassed the FAA?

So please what's the problem ? ...

Sorry for not being as clear as I could be.

I do not "dispute that Boeing is wrong when Muilenburg acknowledged the wrong and several emails clearly from rogue Boeing employers have been seized which prove that they have bypassed the FAA".

My point is those emails/text are focused on one phase of the project, the "qualifying the simulator and setting the training requirements" phase, something which happens pretty late in the project.

We really don't know much if anything about what happened in the earlier phases, where MCAS itself itself was designed, implemented and tested.

As I wrote earlier, perhaps this is because the emails from that phase were scrubbed and nothing dubious was found, or maybe it's because the company wants to focus on the bad actors already identified so that the scope of the investigations does not grow. I think we simply do not know which of these possibilities is true.
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morrisond
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:32 pm

PixelFlight wrote:
morrisond wrote:
WillyEckers wrote:

I should not feed the troll but...

These quotes exist in various places but the AVweb article is asy to access https://www.avweb.com/insider/two-tragi ... -sim-time/

Boeing assumed that in the unlikely event that the system failed, pilots would be the last backstop to keep things from spinning out of control. But consider what the pilots of Ethiopian Airlines Flight 302 that crashed in March faced. The list included an active stick shaker inaccurately warning of an impending stall, an overspeed clacker, an aural “don’t sink” warning and several other disagree and warning lights. Sullenberger said he struggled to regain control in a simulator run mimicking the accident flight.

It's not a Runaway Trim NNC

In delivering his testimony, APA President Daniel Carey was blunt in brushing back a budding movement to blame the pilots. “I can tell you that the members of APA are offended by remarks made by those who seem to blame the pilots killed in those two crashes,” he said. “I am here to tell you that I worked in Africa and trained African pilots to fly large aircraft. I am very familiar with Ethiopian Air’s pilot training program and facilities, and I can tell you that they are world-class,” he added.

I think it's sad that you, who seems to have little experience (C172 but you don't say if that's XPlane or FSX...), needs to be so critical of the pilots who are firstly - not here to defend themselves and secondly, pretty much everybody of any stature has understood that it is not a pilot problem, it's an aircraft problem.

Anyway, I'm out of here :-)


Yes it a Runaway Trim NNC as per ET's own procedures as seen in the ET302 Preliminary report - if these symptoms happen - run this checklist - See pages 28-33 https://leehamnews.com/wp-content/uploa ... ET-AVJ.pdf

And when have I ever said there wasn't a problem with the aircraft? Or are you one of those who deny that there was anything wrong with Lionair maintenance or at the FAA as well and there is only issues at Boeing?

Please stop accusing me of blaming the Pilot's I am blaming ET's training system as my post from this morning demonstrates.

"From this article - Scroll down past the damning Maintenance issues at ET to get to the training Part https://www.businessinsider.com/boeing- ... er-2019-10

"Another whistleblower from Ethiopian, veteran pilot Bernd Kai von Hoesslin, told the AP in May that after Indonesia's Lion Air crash, he pleaded with Ethiopian's top executives to give pilots better training on the Max, predicting that if pilots are not sufficiently drilled on Boeing's protocols for how to disable the autopilot system in the event of a misfire, "it will be a crash for sure."


Ethiopian has said the pilots followed all the steps Boeing laid out. But the preliminary report on the crash showed they deviated from the directives and made other mistakes, notably flying the plane at an unusually high speed and inexplicably reactivating the anti-stall system shortly after manually overriding it. Six minutes into the Max flight, the plane with passengers from nearly a dozen countries cratered into the ground about 40 miles from the airport."

From AVHerald https://avherald.com/h?article=4c534c4a

"On Apr 11th 2019 The Aviation Herald received a full copy of the Flight Operations Manual (FOM), Revision 18B released on Nov 30th 2018, which is currently being used by Ethiopian Airlines (verified in April 2019 to be current). Although Boeing had issued an operator's bulletin on Nov 6th 2018, which was put into Emergency Airworthiness Directive 2018-23-51 dated Nov 7th 2018 requiring the stab trim runaway procedure to be incorporated into the FOM ahead of the sign off of this version of the FOM (the entire document is on file but not available for publishing), there is no trace of such an addition in the entire 699 pages of the FOM.

Quite the opposite, in section 2.6 of the FOM "Operational Irregularities" the last revision is provided as Revision 18 dated "Nov 1st 2017".

According to information The Aviation Herald had received in March 2019, the Airline Management needed to be reminded to distribute the Boeing Operator's Bulletin as well as the EAD to their pilots, eventually the documents were distributed to the flight crew. However, it was never verified, whether those documents had arrived, were read or had been understood. No deeper explanation of the MCAS, mentioned but not explained in both documents, was offered.

It turned out, that only very cursory knowledge about the stab trim runaway procedure exists amongst the flight crew of Ethiopian Airlines even 5 months after the EAD was distributed. In particular, none of the conditions suggesting an MCAS related stab trim runaway was known with any degree of certainty. In that context the recommendation by the accident flight's first officer to use the TRIM CUTOUT switches suggests, that he was partially aware of the contents of the EAD and reproduced some but not all of the provisions and not all of the procedure, which may or may not explain some of the obvious omissions in following the procedure in full."

The references speak for themselves. I'll just keep posting this whenever someone else insinuates I'm a liar and making this stuff up.

As I've said I am not blaming the pilots - I am blaming the ET training system that seems to have done a terrible job of instructing there Pilots on how to deal with MCAS."

I don't insinuate that you are a liar, as you provides some plausible facts, and that ET will certainly benefit from improvement.
But I strongly disagree that the EAD was an appropriate move from Boeing that did know at that time that the risk of accident was unacceptable with the mitigation of the pilots only.
See the excellent paper cited on post #1016 by
Thorkel wrote:
Not sure if this has been posted before - just came across this paper, written by somebody from Boeing surprisingly (although on their own dime), on the performance of pilots from a US airline when completing memory line items. It includes how well they did at executing the runaway stabiliser checklist in a non stressful situation.

http://www.code7700.com/pdfs/line_pilot ... _items.pdf

EAD and NCC are not magic papers that makes humans perfect. If I remember correctly a post on the previous thread, the regulation assume that a risk control done by the pilots only reduce the risk by 10 on average. The paper results are not only the consequences of the operators training, but also the consequences of the quality of the NCC redaction as discussed into the paper. I think that those considerations should also be on the table instead of focusing only on ET operator.


I saw that paper and agree with you that Humans aren't perfect. The problem is that all Airliners have been certified on the basis and the Pilots type rated on all types with the understanding that if certain things happened they would be able to rely on their memory to apply the proper procedure or use a Quick Reference Handbook (QRH) to look up the proper procedure for more remote things they couldn't quickly diagnose.

We know from the Lionair final report that it took them minutes to find the QRH and find a procedure which wasn't the right one (not really there fault as they had no knowledge of MCAS). There is no indication that they even looked for it on ET (they had minutes and if they had found it I'm sure they would have applied the right procedure) or had it memorized (obviously).

Which leads me to believe that what they needed to know about MCAS and what to do wasn't in the cockpit either - much less committed to memory or they were even told about it in the first place as the articles above speculate.

If Pilot's are no longer required to have to rely on there Memories (and most of the crashes in the last 15 years are because Pilots could not recall or find the right procedure) - or to even be able to run a NNC from a QRH - we have a problem and the certification for all Airplanes needs to be redone to take this into account.

Or the pilots just do more training - Worldwide.
 
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Revelation
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:38 pm

scbriml wrote:
It takes a long time to change attitudes and practices in a large corporation, it cannot happen overnight or in a few weeks. And it absolutely has to start at the top and be pushed vigorously through the ranks. Talk is cheap.

Indeed, and it's hard to see someone with Calhoun's background leading the revolution.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 9:50 pm

Revelation wrote:
Rightly or wrongly the system is constructed in a way that demands that front line engineers push back when management wants to do dubious things to save money. In the end it is the engineers that are accountable, that's why they are the ones who sign the documents. Engineers need the cajones to refuse to sign when things are not right, and yes, even if this means career damage. I should know, I've paid the price in terms of career damage for not signing off on something that was dubious. It's not fair that the system is set up this way, but I guess we know we can't count on managers to be ethical so the burden is dumped onto engineers.


:checkmark:

Very well said. Exactly how it should work within a company. However, someones career shouldn't be on the line for not signing off.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:06 pm

patrickjp93 wrote:
kalvado wrote:
patrickjp93 wrote:
Special relativity doesn't give a damn about being overwater, or did you forget we have overseas satellites. You can use light's deflection off the air and the time it takes to receive the reflection, because the speed of light is constant regardless of its emitter having non-zero speed.

So would you pleas elaborate where special relativity comes into play, and how exactly air scattering is going to work?
There were some EASA experiments on doppler measurements of air data. My impression is that it is less than perfect.. they didn't use "air deflection", though. And Doppler is not relativistic effect, btw.

Doppler is kid's play and is used to check density of weather systems. It's looking at resonant modes of light, not the turnaround time from particles a known distance away.

Special Relativity is the enveloping theory (and long since tested and proven) around how light interacts with objects in moving reference frames. The best way to understand how it is applied here is probably using the light speed train tunnel paradox. Because the speed of light does not change in a given set of conditions (in this case an air body's elemental composition and pressure) regardless of how fast its source is, you can use the difference in time for light to bounce back from a known distance to get your speed.

If you're running and throw a ball in front of you, the speed/velocity of the ball increases in the line you're traveling on above your running speed. However, this breaks down at the speed of light where it is impossible to exceed that speed. You running forward with a laser pointer in hand does not increase the propagation speed of the laser. Therefore, any change in time for a particle to leave the pointer and collide with what's in front of you and return which exceeds this absolute speed limit is your speed going in the opposite direction. That's why Special Relativity and Lidar can be used for this. Even radar can, but because it relies on some oscillatory modes to not come back as pure noise, it's probably easier to make such a system with Lidar.

OK. Just to make it clear - my PhD is in physics. And I know relativity a bit.
For the plane traveling at 3e2 m/s = 1e-6 c special relativity effects are in the noise. Lidar doesn't use relativistic effects.
So, try again.
 
morrisond
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:07 pm

Revelation wrote:
scbriml wrote:
It takes a long time to change attitudes and practices in a large corporation, it cannot happen overnight or in a few weeks. And it absolutely has to start at the top and be pushed vigorously through the ranks. Talk is cheap.

Indeed, and it's hard to see someone with Calhoun's background leading the revolution.


Yeh - I don't think that is going to work out so well either.

Time to bring back Alan Mullaly.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:29 pm

Revelation wrote:
Checklist787 wrote:
[twoid][/twoid]
Revelation wrote:
My point is those emails/text are focused on one phase of the project, the "qualifying the simulator and setting the training requirements" phase, something which happens pretty late in the project.

We really don't know much if anything about what happened in the earlier phases, where MCAS itself itself was designed, implemented and tested.

As I wrote earlier, perhaps this is because the emails from that phase were scrubbed and nothing dubious was found, or maybe it's because the company wants to focus on the bad actors already identified so that the scope of the investigations does not grow. I think we simply do not know which of these possibilities is true.

It’s neither of those. These messages weren’t released on Boeing’s initiative, but requested by the House Committee on Transportation and Infrastructure. https://transportation.house.gov/news/p ... faa-boeing

The request was specifically about documents relating to the certification by the FAA, and all the released messages indeed have in common that there is some relation to the FAA. Documents relating to the development of the aircraft/MCAS don’t fall under the scope of the request and that’s why we haven’t seen them. It wouldn’t surprise me if they’ll be requested and leaked later and then we’ll likely see even more damning revelations.
 
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PixelFlight
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:37 pm

kalvado wrote:
patrickjp93 wrote:
Special Relativity is the enveloping theory (and long since tested and proven) around how light interacts with objects in moving reference frames. The best way to understand how it is applied here is probably using the light speed train tunnel paradox. Because the speed of light does not change in a given set of conditions (in this case an air body's elemental composition and pressure) regardless of how fast its source is, you can use the difference in time for light to bounce back from a known distance to get your speed.

If you're running and throw a ball in front of you, the speed/velocity of the ball increases in the line you're traveling on above your running speed. However, this breaks down at the speed of light where it is impossible to exceed that speed. You running forward with a laser pointer in hand does not increase the propagation speed of the laser. Therefore, any change in time for a particle to leave the pointer and collide with what's in front of you and return which exceeds this absolute speed limit is your speed going in the opposite direction. That's why Special Relativity and Lidar can be used for this. Even radar can, but because it relies on some oscillatory modes to not come back as pure noise, it's probably easier to make such a system with Lidar.

OK. Just to make it clear - my PhD is in physics. And I know relativity a bit.
For the plane traveling at 3e2 m/s = 1e-6 c special relativity effects are in the noise. Lidar doesn't use relativistic effects.
So, try again.

Excellent! :rotfl:
It's fascinating how this thread is hit by massive flooding within a few days of unusual calm... The actual wave spread false claims at an unbelievable speed. Any real facts seem to be useless, so I give up.
Last edited by PixelFlight on Tue Jan 14, 2020 10:37 pm, edited 1 time in total.
 
dtw2hyd
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:37 pm

morrisond wrote:
...
Or the pilots just do more training - Worldwide.


But Boeing was fighting against training. Indonesian DGCA got the Stupid award, Indian DGCA got the Stupider award and I am eager to know who got the Stupidest award for asking for more training.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:43 pm

phollingsworth wrote:
asdf wrote:
phollingsworth wrote:
....Without having access to Boeing's specific tech trades it is really impossible to know where they would have sited the engines on a clean sheet design; and therefore, how much augmentation they would need.


so unbelivable ...
what are you guys writing of here?

one never ever needed augmentation of stickforce in any manual controlled airplane before the clown&monkey 737MAX


Except the A300/A310. Peter Lemming presented a whole blog post on that system.


please provide a source
i dont find anything on google about it
thank you
 
Checklist787
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:43 pm

Revelation wrote:
scbriml wrote:
It takes a long time to change attitudes and practices in a large corporation, it cannot happen overnight or in a few weeks. And it absolutely has to start at the top and be pushed vigorously through the ranks. Talk is cheap.

Indeed, and it's hard to see someone with Calhoun's background leading the revolution.

Yeh - I don't think that is going to work out so well either.


Well if D. Calhoun is the "economist par excellence" and that the cash flow of 2019 has melted and that of 2020 will continue, his mission would not it just be limited to being an "economist par excellence" and must do certified the 737MAX which will cost money?

We have learned that the grounded 800 737MAX's needs to be constantly maintained outside and then 800 MCAS 2.0's will soon have to be installed. There is going to be a lot of work out there.


https://boeing.mediaroom.com/2020-01-14 ... Deliveries


morrisond wrote:
Time to bring back Alan Mullaly.


He was an excellent manager already!

He managed the 6 months delay of the 777 with a smile
He was the man of 777

He left Boeing for Ford because the situation no longer suited him and it was under Mc Nerney for that matter. He obviously did not follow the principles of these "new arrivals".

A. Mullaly was a respectable Boeing veteran...
Last edited by Checklist787 on Tue Jan 14, 2020 10:53 pm, edited 4 times in total.
 
Strato2
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:46 pm

2175301 wrote:
While Boeing is paying the biggest price.


No. 346.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 10:49 pm

patrickjp93 wrote:
Revelation wrote:
patrickjp93 wrote:
That summation is woefully incomplete just based on the data dump so far.

Do tell. The recent text/message dump is mostly about qualifying the simulator and setting the training requirements, and AFAIK not about any "jedi mind tricks" that may or may not have been played during the design and certification of MCAS.

Because we also know Boeing employees were being brought out and publicly shamed in front of their peers for not meeting deadlines and goals on the project. That sort of abusive management practice will be corroding everything it touches. As usual with anything involving government entities, absolutely no getting to the heart of the matter.

Naming and shaming doesn't work well in an era of full employment. Talented engineers can leave and get another job in short order and management is now stuck short handed dealing with more work than before, with those remaining being fully aware of the failure of management's tactics and thus resentful and now more likely to leave themselves. Again, this is something I know from my own personal experience. Having to leave under such circumstances isn't fun, but staying under such circumstances is far worse to one's morale, dignity and sense of ethics.

2175301 wrote:
A major contributor, in my opinion, was that the standards only required each system to be analyzed by itself and not from a total integrated impact:

"The JATR team reviewed how the Changed Product Rule process was applied to the certification
of the flight control system of the B737 MAX. The JATR team determined that the Changed
Product Rule process was followed and that the process was effective for addressing discrete
changes. However, the team determined that the process did not adequately address cumulative
effects, system integration, and human factors issues. The Changed Product Rule process allows
the applicant6 to only address in a limited way changed aspects (and areas affected by the
change) and does not require analysis of all interactions at the aircraft level."

My reading of the NTSB report is that it says essentially the same thing. Boeing was not required to test all the reasons, with all the alarms and stick shakers, that could cause MCAS malfunction. Thus, the testers never experienced what at least the Lion Air crews did.

The way ST ( https://www.seattletimes.com/business/b ... sumptions/ ) explains it, during the Functional Health Assessment phase Boeing only did the simplest of MCAS use cases, one single activation, then used nothing more formal than an email from minutes of a test pilot's meeting to justify that multiple activation was no worse than single activation. This allowed them to classify MCAS as "major" rather than "hazardous" inside the normal flight envelope, which in turn allowed them to avoid doing a Fault Tree Analysis and a Failure Modes and Effects Analysis for MCAS which may have turned up all the issues with sensor erross and with multiple activations, and allowed use of a single AoA sensor. The dubious math of the "accepted method" was used to then say that the risk outside the normal flight envelope also was not "hazardous" since the odds of being outside the normal flight envelope were low. Then the evaluation was not changed after MCAS was extended to the low speed end of the flight envelope which would have changed the dubious math in an unfavorable way.

It's kind of hard for me to see how all of these decisions were made with no emails/texts questioning their rationale being generated along the way. It really seems like everyone is singing from the same sheet music in a pretty suspicious way.

Jetty wrote:
It’s neither of those. These messages weren’t released on Boeing’s initiative, but requested by the House Committee on Transportation and Infrastructure. https://transportation.house.gov/news/p ... faa-boeing

The request was specifically about documents relating to the certification by the FAA, and all the released messages indeed have in common that there is some relation to the FAA. Documents relating to the development of the aircraft/MCAS don’t fall under the scope of the request and that’s why we haven’t seen them. It wouldn’t surprise me if they’ll be requested and leaked later and then we’ll likely see even more damning revelations.

Yet all these things were known by FAA in March (the date of the PDF I pointed to earlier) and written about by ST in November. I'm not sure why Congress hasn't requested more, nor why Boeing hasn't just given them a dump to get it all over with rather than dragging it out for months on end. Boeing is running out of time to blame it all on DM.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Tue Jan 14, 2020 11:49 pm

morrisond wrote:
Time to bring back Alan Mullaly.


He's 74 and been retired for five and a half years. Why on Earth would he want to go back to Boeing to sort out someone else's mess? He certainly doesn't need the money.

I'd say as much chance of that happening as Bill Boeing walking through the door and banging heads together.
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Wed Jan 15, 2020 12:12 am

Those latest mail revelations really hurt your eyes. E.g. Indonesian authorities asked for sim training but are turned down, and:

In a later email, Forkner said he was fairly sure the FAA’s Aircraft Evaluation Group would want to require some training on RCAS in a simulator. “We are going to push back very hard on this, and will likely need support at the highest levels when it comes time for the final negotiation.”

Failure to avoid simulator training because of RCAS would be a “planet-killer for the Max,” he wrote.

In the end, he and Boeing got their way.


https://www.google.com/amp/s/www.inquir ... utType=amp
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Wed Jan 15, 2020 12:53 am

scbriml wrote:
patrickjp93 wrote:
scbriml wrote:

That gear doesn't raise the height of the 737-10 by a single mm. It only helps at rotation. Next idea?

It DOES raise the MAX 10 off the ground an additional 4 inches during rotation to avoid tail strike.


My understanding is that it's passive and doesn't actively 'lift' the plane higher off the ground at all - it extends 9.5 inches (not 4) as the plane rises providing a slightly higher pivot point for rotation. The MAX 10 sits the same height off the ground as all other MAXes. The gear does nothing to solve the issues of engine clearance and position which necessitated MCAS in the first place.

patrickjp93 wrote:
Now, I'm sure I'm about to get hounded over how you'd engineer such a gear, and the answer that immediately comes to mind is hydraulics for the telescoping action and more maintenance to go with it. That's the cost of getting the plane cheap up front.


Plus significant additional weight. I'm pretty sure the gear is 'dumb'.

patrickjp93 wrote:
It can be pilot controlled and have a failsafe activation in the case where the flight control computer can no longer communicate with the gear.


I'd really like to see some supporting evidence for this. Again, my understanding is the gear is essentially mechanically dumb and requires no pilot intervention.

Revelation wrote:
viewtopic.php?t=1402777 was our six page mega-thread on how this works.

In it I explained that I suck at visualizing mechanical things so needed a lot of help sorting out how it worked.

In essence it is using an shock that expands when weight is off the wheels, much like the shocks in most autos use energy gained when hitting a bump to ease the jolt when the auto body wants to land back onto the wheels. Linkages from the current landing gear extension/retraction mechanisms and an additional actuator are used to guide its compression as the gear retracts and its expansion as the gear lowers. It is all being done with these mechanical elements as opposed to some computer controlled air cushion mechanism, presumably to keep it simple and thus more reliable.


That was my understanding as well. I found this video very helpful in visualising how it works: https://www.youtube.com/watch?v=F4IGl4OizM4

I'm really not sure at this point how to make my posts more crystal clear, but here goes.

When I said you could use a telescoping gear to fix the MAX with the improvements I mentioned, that was a theoretical, clean implementation of telescoping tech. Yes, you'd have to make it active. No, flipping, duh. I never said you could use the MAX 10's gear. I said you could tweak the idea. Now that I've clarified, what do you think? A flipping active landing gear would take less than a month to design, blueprint, 3D print, and test now that we have 3D printers capable of working with and tempering molten metal. The paperwork for safety criticality certification would take longer to do.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Wed Jan 15, 2020 1:00 am

kalvado wrote:
patrickjp93 wrote:
kalvado wrote:
So would you pleas elaborate where special relativity comes into play, and how exactly air scattering is going to work?
There were some EASA experiments on doppler measurements of air data. My impression is that it is less than perfect.. they didn't use "air deflection", though. And Doppler is not relativistic effect, btw.

Doppler is kid's play and is used to check density of weather systems. It's looking at resonant modes of light, not the turnaround time from particles a known distance away.

Special Relativity is the enveloping theory (and long since tested and proven) around how light interacts with objects in moving reference frames. The best way to understand how it is applied here is probably using the light speed train tunnel paradox. Because the speed of light does not change in a given set of conditions (in this case an air body's elemental composition and pressure) regardless of how fast its source is, you can use the difference in time for light to bounce back from a known distance to get your speed.

If you're running and throw a ball in front of you, the speed/velocity of the ball increases in the line you're traveling on above your running speed. However, this breaks down at the speed of light where it is impossible to exceed that speed. You running forward with a laser pointer in hand does not increase the propagation speed of the laser. Therefore, any change in time for a particle to leave the pointer and collide with what's in front of you and return which exceeds this absolute speed limit is your speed going in the opposite direction. That's why Special Relativity and Lidar can be used for this. Even radar can, but because it relies on some oscillatory modes to not come back as pure noise, it's probably easier to make such a system with Lidar.

OK. Just to make it clear - my PhD is in physics. And I know relativity a bit.
For the plane traveling at 3e2 m/s = 1e-6 c special relativity effects are in the noise. Lidar doesn't use relativistic effects.
So, try again.

I'm afraid Boeing (and a basic textbook) disagree with you, as they'll be using Lidar to detect turbulent flow up to 10 miles away, and the only way you can do that is detect multiple velocities of air streams simultaneously. https://www.aviationtoday.com/2018/03/2 ... onstrator/

You can claim to have a PhD, but that doesn't matter to me. Let's see you prove the argument rather than rest on your laurels.
 
patrickjp93
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Wed Jan 15, 2020 1:08 am

Checklist787 wrote:
[twoid][/twoid]
Revelation wrote:
patrickjp93 wrote:
That summation is woefully incomplete just based on the data dump so far.

Do tell. The recent text/message dump is mostly about qualifying the simulator and setting the training requirements, and AFAIK not about any "jedi mind tricks" that may or may not have been played during the design and certification of MCAS.


Excuse me but the thread has become too long and there are many technical terms in your discussions. Can you explain to us what's going on?

And what is this "Jedi mind tricks" (StarWars?) you seem to dispute that Boeing is wrong when Muilenburg acknowledged the wrong and several emails clearly from rogue Boeing employers have been seized which prove that they have bypassed the FAA?

So please what's the problem ? ...

I know I just chewed someone else out for being a snarky git, but it would be more expedient for you to go back to page 17 of this thread and start from the top there. Most of these technical terms are arising out of Boeing's own papers linked in posts as we go along, the definitions of safety criticality in the context of global standards, and otherwise easily Googled information.
 
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Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Wed Jan 15, 2020 1:10 am

patrickjp93 wrote:
When I said you could use a telescoping gear to fix the MAX with the improvements I mentioned, that was a theoretical, clean implementation of telescoping tech. Yes, you'd have to make it active. No, flipping, duh. I never said you could use the MAX 10's gear. I said you could tweak the idea. Now that I've clarified, what do you think? A flipping active landing gear would take less than a month to design, blueprint, 3D print, and test now that we have 3D printers capable of working with and tempering molten metal. The paperwork for safety criticality certification would take longer to do.

FWIW I was responding to a tangential thread about how MAX10 worked not how your idea works. With regard to your idea, I doubt the 1 month estimate is valid. Boeing has access to all that tech and more and it took them much longer to work out the (passive) MAX10 solution. The paperwork isn't just paperwork, it's doing a lot of testing to produce data that is needed to complete the paperwork. As others have indicated, there are boatloads of use cases to consider. Waving your hands and saying they don't matter is how we got MCAS.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
patrickjp93
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Joined: Thu Aug 22, 2019 12:00 pm

Re: Boeing 737MAX Grounding, General Discussion Thread, January 2020

Wed Jan 15, 2020 1:18 am

Revelation wrote:
patrickjp93 wrote:
When I said you could use a telescoping gear to fix the MAX with the improvements I mentioned, that was a theoretical, clean implementation of telescoping tech. Yes, you'd have to make it active. No, flipping, duh. I never said you could use the MAX 10's gear. I said you could tweak the idea. Now that I've clarified, what do you think? A flipping active landing gear would take less than a month to design, blueprint, 3D print, and test now that we have 3D printers capable of working with and tempering molten metal. The paperwork for safety criticality certification would take longer to do.

FWIW I was responding to a tangential thread about how MAX10 worked not how your idea works. With regard to your idea, I doubt the 1 month estimate is valid. Boeing has access to all that tech and more and it took them much longer to work out the (passive) MAX10 solution. The paperwork isn't just paperwork, it's doing a lot of testing to produce data that is needed to complete the paperwork. As others have indicated, there are boatloads of use cases to consider. Waving your hands and saying they don't matter is how we got MCAS.

No they don't. Boeing and Airbus both are a long ways behind the leading edge of manufacturing tech. GE you could maybe argue for, but not Boeing. Easily 15 years behind.

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