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Polot
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:14 pm

mjoelnir wrote:
IMO the Ethiopian crash with MCAS pushing the frame into a dive, showed up the underlying fragility of the 737 trimming system. Manual trimming just did not have enough authority to save the plane. Yes, the 737NG has an exemplary safety record, but it could be many years of luck that the wholes never aligned. The frame never been pushed into the areas of the flight envelop where the deficiencies of the manual trim system mattered.

I would assume a review of the complete trim system, should be part of recertifying the 737MAX.

It’s a question of how easy (and likely) it is for the plane to get “pushed into the areas of the flight envelop where the deficiencies of the manual trim system mattered.”

MCAS was (likely inadventrely on Boeing’s part through poor software that was never thought through) pushing the plane into that area. The question is with the software fix and proper training how likely is it to get into a situation wheee you can overcome the trim? I suppose a 737 pilot today can push the 737NG into a situation where they could not recover, but that (based on the 737NG’s service history) would require either deliberate action or seriously poor pilot training.
Last edited by Polot on Thu Apr 04, 2019 1:15 pm, edited 1 time in total.
 
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hilram
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:14 pm

Aesma wrote:
speedbored wrote:
Polot wrote:
Manual/training/checklist changes are a given.

I doubt that Boeing are seeing them as "a given". Boeing will be robustly resisting any such changes as it likely negates a major one of their MAX selling points - minimal differences training with zero sim time.


That boat has sailed, in my opinion.

Some airlines are questioning their purchase of the MAX, most will probably keep it, but ensure pilots are significantly trained for it specifically. Imagine if another accident happens, nothing to do with the current issue, just a "typical" CFIT. If the public discovers that the airline has no MAX simulator, that their pilots have still only gotten 1 hour training on an iPad, forget about it, the airline will be crucified in the eyes of the public. And the MAX would suffer too.

With EASA, that boat had actually sailed to begin with, as their own requirements for certification of MAX mandates specific documentation/ manual updates and simulator training related to MCAS.

Only when deliveries started rolling out they forgot to enforce it...

I am sure Bjørn Kjos finds that to be a waste of everybody’s time, AS Boeing now has made an already safe Aircraft Even safer...
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mjoelnir
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:16 pm

cledaybuck wrote:
mjoelnir wrote:
IMO the Ethiopian crash with MCAS pushing the frame into a dive, showed up the underlying fragility of the 737 trimming system. Manual trimming just did not have enough authority to save the plane. Yes, the 737NG has an exemplary safety record, but it could be many years of luck that the wholes never aligned. The frame never been pushed into the areas of the flight envelop where the deficiencies of the manual trim system mattered.

I would assume a review of the complete trim system, should be part of recertifying the 737MAX.

So the holes never lined up for over 20 years on the NG but did line up twice in less than 2 years on the MAX? I find that very unlikely. Much more likely is that changes to the MAX are responsible.


If it is impossible to manual trim the 737MAX under certain flight conditions, I assume it would have been impossible on the NG too. Perhaps NG pilots were never pushed into this part of the flight envelope, while needing to trim manually.

Some holes never line up, because the conditions never arise. How often does a 737NG pilot has to switch off electrical trim in his carrier as a pilot, apart from training on a sim. And if he has to switch off electrical trim, how often does that happen, while having unreliable airspeed indication and perhaps than flying with a rather high speed, to avoid stall.
 
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zkojq
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:16 pm

smartplane wrote:
Interested wrote:
If these planes are ever allowed to fly again should they have some kind of warning message branded on the outside of them that they could seriously endanger your life so the general public can be warned before we get on them?

I would like those warnings myself

I don't want to rely on 90 per cent of pilots being capable of saving me if the plane misbehaves again. I really don't.

(We have those messages by law in UK on the outside of cigarette packets)

Can be confident all trace of the word 'MAX' will disappear from the aircraft themselves while grounded, as well as in promotional material.

Probably not a bad thing IMO. 'MAX' always sounded a bit tacky and cheap to me. I hope Boeing can come up with a better name.

klm617 wrote:
No Boeing can sell planes to whomever they want but there must be a training standard to which all airlines comply to before operating the planes.

It's called a "type-rating".

DocLightning wrote:
Amiga500 wrote:
It is dawning on me that there is a slim but non-zero possibility that the 737max may never be cleared to operate again - unless Boeing are allowed to do something no other aircraft has been under FAR25. The FAA might buy off on it, but really dunno how that will go down across the rest of the world.


This has occurred to me, too. They might have to step so far back into the design that it might go outside the boundaries of certification for the type. To make it worse, I understand that the FAA will not certify any more 737 derivatives.

I hope not, because the lead time on a clean-sheet design would be years and Airbus simply can't build enough A320NEOs and A220s to cover the 737 backlog. Ooof, what a mess that would be.


It would be difficult, but it wouldn't bring the world to a standstill by any means. Keep in mind that ever since the GFC (and all the cheap money floating around due to low interest rates) airlines have been scrapping narrow-bodies at younger and younger ages - far, far before the end of their economic lives. Easyjet was scrapping 737NGs at 7 years old at one point. Obviously this scenario is would be great for MRO operations as there will be a lot more heavy maintenance work that needs to be done.

Interested wrote:
Why is there such a focus in defending airlines but blaming pilots for stuff?

Because dead pilots can't defend themselves.

GEUltraFan9XGTF wrote:
Tinfoil hat time: could China be hacking Boeings? Is it feasible? Tampering with the onboard computer?

Why would they do that?

morrisond wrote:
Training standards have fallen since 2002 as clearly evidenced that a FO with only 300 hours was given control of aCommercial airplane with over 150 souls onboard.


Easyjet has been hiring pilots with ~250 hours total time for around 20 years. They have a perfect safety record.

morrisond wrote:
ET302 should never have happened with properly trained pilots - this was a known issue.


That comment didn't age well. :lol:


Amiga500 wrote:
StTim wrote:
I have just read the latest Leeham news article on this. How scary that you know the issue, you follow the instructions and yet it is still impossible to recover the plane.

Blooming scary and really unforgivable in the modern world?



Ah, but 'murican pilots with superior training to Johnny Foreigner would have dealt with it. :rolleyes:


I wonder if we can expect some apologies for the American folks who spent much of the first 30 pages of this thread trying to blame everything on the First Officer's experience.

bob75013 wrote:
Boeing's new 737 MAX flight control system 'seems foolproof': Norwegian CEO

"Boeing's new MCAS flight control system for its 737 MAX aircraft appears foolproof, Norwegian Air Chief Executive Bjoern Kjos said on Wednesday after visiting the plane maker in Seattle.

Kjos said he had tested the old and the new MCAS software "under a malfunction", saying the new system seemed foolproof.

"I hope the regulators will have safety in focus as always and not be directed by politics. I will gladly take my family on board a Norwegian MAX," he added.


"Airline CEO wants his 18 MAXs ungrounded. More news at 6."

smartplane wrote:
Perhaps as a Boeing global PR exercise, all operators will be persuaded to fly their Directors on a MAX when ready to return to the air. And senior FAA personnel, Boeing Board and family members, and all those involved in 'fixing' MCAS too. That would be a massive vote of support, and re-assurance to crews and passengers.


Why not make them fly circuits aboard a MAX with an extreme (but acceptable CoG) its elevator trim right on the limit of the green-zone and with the stabalizer trim cutout, so that they have to be putting backpressure on the stick manually. See how many speed/altitude tolerances the crew can maintain.
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planecane
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:18 pm

AirlineCritic wrote:
So, finally we know the cause of the accident: those damn, badly trained third world birds colliding with our beautifully designed plane!

Sigh.

I'm frustrated at this thread, the evasive response from the manufacturer, and much of the news and aviation community. But I do still trust the Seattle Times, WSJ/WP, Leehamn and the majority opinion of world's aviation administrators.

It has always been very likely that this accident and so many others are due to a combination of factors, from the machine to process and to the humans. The constant blame placement on this thread is tiring, and frankly, at times disingenuous and unethical. But based on most recent reports, it really does seem like the situation is far more complex than simply hitting some switches. How many seconds do you have to do it? How can you recognise it from other trimming events? What other alarms and issues are going in the cockpit at that time? And can you physically exert the necessary power to make a change? In time at a low altitude? What parts of the 737MAX flight envelope can the plane actually be handled if the automation breaks down, as any automation system is likely to do. How clear was the new procedure released after the Lion Air accident? To my eyes, it did not stress the use of electric trim enough. And how well has that procedure been flight tested? In short, we cannot escape the conclusions that the machine will have to bear part of the blame as well.

I think it would benefit Boeing and the aviation industry to take a big step back and make sure the next iteration is done properly and perfectly. The consequences from a third accident would be too horrible to think. I think at least the following needs to happen:

1. Redesign the system to significantly reduce the likelihood of failed automation. I'd rather see 3 sensors than 2, as well as three separate devices that do the analysis and vote about the result. Right now the fix is just 2 instead of the original one. I'd say they are risking it.

2. Clear indications to the crew about when the MCAS automation is active and when it has failed.

3. New flight testing and analysis of the factors that lead to the original aggressive MCAS parameters: what are we trying to protect against from, and are there any safety issues that will present themselves if MCAS is toned down? Publicise the results.

4. New flight testing and analysis of how quickly and with what effort one can adjust the trim system back to its proper state, if MCAS has taken it off too far in some direction. Analysis should be done for both the electric trim and manual trim. Are there corners of the flight envelope where trimming is not possible? Again, publicise results.

5. Based on the above, make a decision to tone down MCAS aggressiveness, and report what the consequences of that are, either for the things that MCAS was trying to do originally or for the ability of pilots to recover after a failure. Publicise the results.

6. Redesign the procedure for the pilots to recognise MCAS failures.

7. Redesign the procedure to deal with the MCAS failures.

8. Build a simulator that can simulate MCAS failures.

9. Test the new procedures with real-life crews (including with surprise of what's ahead) to see how well and in what conditions the pilots can execute the new procedures.

10. Evaluate results. Publicise them.

11. Make a decision to certify the plane for flying again. Institute new training on ipad, course and simulators. And, possibly, limit parts of the flight envelope and conditions the 737MAX can fly in.

12. Back into use.

13. Institute a monitoring system to collect information about MCAS and trimming failures, feed back to regulators and Boeing, and adjust as needed.

FWIW, while Boeing is publicly addressing some of this and probably internally looking at some others, I don't feel they are currently going full steam on the above list. Rather, they seem to have to be dragged to do anything here. This is wrong.


Most of what you list here is unneccessary. First of all, with respect to the number of AoA sensors, two is sufficient. For a FBW aircraft, triple redundancy is necessary because the flight control computer needs valid data in order for the plane to fly. In the case of MCAS, it just needs to recognize a failed sensor and shut off. If two sensors simultaneously fail with similar invalid measurements, it is likely that a 3rd or 10th would fail as well.

The fix is toning down the aggressiveness. Pilots will be trained on what to do when MCAS is disabled due to AoA disagree if they get themselves into the speed/AoA scenario that MCAS was designed to mitigate.

There was a fatal flaw in the failure analysis for the MCAS design. They just need to implement the software that should have been designed from the beginning and MCAS won't cause any more crashes.
 
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:22 pm

In fact repairing the public perception, if possible, will be some big topic after the technical issues themselves have been solved. I think this has become quite different in the internet age. Just look at booking engines and filters. Now the final "joe public" consumer and passenger must be convinced not only the industry insiders.
 
PixelPilot
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:27 pm

capshandler wrote:
freakyrat wrote:
Waterbomber2 wrote:

I doubt it.
The reason I doubt it is that pilots on both flights lost both AoA and airspeed indication accuracy.
You can't catch two sensors with one bird...

Same story with Lion Air.
The AoA sensor was replaced and tested, and the next flight same story, well, almost...

Issues in the ADIRU or wiring more likely.


Sensors could have gotten blocked by bugs etc. It has happened before.

As far as issues with the ADIRU or wiring, this is a possibilitythat I wonder is getting overlooked. One of the US carriers operating the MAX had to replace an AOA sensor on one of their MAX aircraft and also replaced the ADIRU just to be on the safe side.


An AoA sensor can’t be blocked by bugs as the pitot. It’s visible during the walkaround so if something external happened you’re able to see it.

Walkaround during taxi or takeoff itself??
Show me a pilot "willing" to do that? :roll: :roll: :roll:
Last edited by PixelPilot on Thu Apr 04, 2019 1:37 pm, edited 1 time in total.
 
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Polot
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:40 pm

mjoelnir wrote:
cledaybuck wrote:
mjoelnir wrote:
IMO the Ethiopian crash with MCAS pushing the frame into a dive, showed up the underlying fragility of the 737 trimming system. Manual trimming just did not have enough authority to save the plane. Yes, the 737NG has an exemplary safety record, but it could be many years of luck that the wholes never aligned. The frame never been pushed into the areas of the flight envelop where the deficiencies of the manual trim system mattered.

I would assume a review of the complete trim system, should be part of recertifying the 737MAX.

So the holes never lined up for over 20 years on the NG but did line up twice in less than 2 years on the MAX? I find that very unlikely. Much more likely is that changes to the MAX are responsible.


If it is impossible to manual trim the 737MAX under certain flight conditions, I assume it would have been impossible on the NG too. Perhaps NG pilots were never pushed into this part of the flight envelope, while needing to trim manually.

Some holes never line up, because the conditions never arise.

And if the condition never arises then does the design need to account for it? The condition was arising with the Max because the new automation was forcing the condition, not because the condition was actually necessary to keep the aircraft in the air at the time MCAS activated.

In 2004 some Pinnacle pilots crashed a CRJ200 on a ferry flight because they were exploring the limits of the empty plane and doing nonapproved manuevers. Should we now ground the CRJ until BBD is able to make sure the plane can safely fly if it ever encounters those flight conditions again?

At some point you have to trust automation and also trust pilot training. Yes, Boeing dropped the ball and will pay for it with the Max, but the remedy isn’t ensuring the trim system can never crash the plane again. It is making sure the trim doesn’t crash the plane within normal flight, and it can be recovered if something goes wrong. Limiting what automation can do makes it easier to determine how pilots can recover. You are never going to build a crash proof plane.
 
ELBOB
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 1:49 pm

I'm confident they'll just drop the MAX moniker and go with 737-8 / -9 / -10 as is on the TCDS anyhow.

MAX was only a marketing name, though interestingly it did sneak into the ICAO codes ( B38M etc )
 
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 2:22 pm

mjoelnir wrote:
IMO the Ethiopian crash with MCAS pushing the frame into a dive, showed up the underlying fragility of the 737 trimming system. Manual trimming just did not have enough authority to save the plane. Yes, the 737NG has an exemplary safety record, but it could be many years of luck that the wholes never aligned. The frame never been pushed into the areas of the flight envelop where the deficiencies of the manual trim system mattered.

I would assume a review of the complete trim system, should be part of recertifying the 737MAX.


You could that luck, you could also call that clever engineering.

It's not bad to have a critical area in the flight envelope. As long as you make sure you have (sufficient) protections preventing one from closing in (let alone entering) that part of the envelope. I mean, that is what stall protection is all about, in every airframe.
So if Boeing can develop some sort of software that prevent reaching that part of the flight envelope (or in better words, make it extremely unlikely (<E-10), that that is perfectly satisfactory from aircraft certification point of view.

Problem of course is that that POS (Piece Of Software - MCAS) does not even come close to that reliability statistic . . .
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 2:30 pm

Only way to salvage the MAX is that Boeings test pilots should replicate the AOA error on a real airborne plane, say at a height of 1000 ft. Let MCAS do its nose down job and the expert pilots can recover it without electric trim.
 
Elementalism
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 2:30 pm

Noshow wrote:
In fact repairing the public perception, if possible, will be some big topic after the technical issues themselves have been solved. I think this has become quite different in the internet age. Just look at booking engines and filters. Now the final "joe public" consumer and passenger must be convinced not only the industry insiders.


It will be a rough going in he short term. But over time people will forgive and forget provided the issue is fixed. At some point in the next decade or so about 5000 of these planes will be flying around the globe. The sheer volume\evidence will cause people to move on provided the plane becomes as safe as the NG.

I am old enough to remember all the news reports about the A320 crashing at an air show. And then the subsequent news reports about pilots having to fight the automated systems on the A320. Airbus ironed out the systems and pushed through. The A320 has been a very successful product and people fly on it without issue today.
 
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Revelation
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 2:41 pm

mjoelnir wrote:
It seems that an unnamed pilot of an USA airline, having asked for more training including simulator, because he was uncomfortable to fly the MAX with the minimal difference training provided, was heavily leaned upon by his airline and did not find a lot of help at his union either. That happened before the two accidents.
So if you would have been an pilot at this USA airline and asked for more training, you would have had a black mark against you, without being provided with extra training.

I guess if I was in that position (which I am not) and I was genuinely concerned, I would not worry very much about such black marks. Maybe I would embarrass management by offering to pay for such sim time so I could fly with confidence. I did something very similar early in my career. There was a conference where some very unique training was available, and management would not pay for a trip, so I told them I would pay for the trip and the training if they would allow me to not have to charge the time to vacation, and I was fully committed to doing so. That embarrassed them to the point where they decided to pay for it all. I guess I'm a maverick in some ways.

speedbored wrote:
Revelation wrote:
Given how the situation has evolved as more data has become available, I have a hard time seeing minimal differences training with zero sim time passing muster.

Nor do I. But that doesn't mean that Boeing aren't going to try. They have $280m riding on it at Southwest.

And now WN is paying by having MAXes it paid for sitting on the ground for weeks if not months. Another sad irony.

Polot wrote:
The question is with the software fix and proper training how likely is it to get into a situation wheee you can overcome the trim?

And, the next question is if Boeing can convince all the regulators that they've proven that you cannot get into a situation where you cannot overcome the trim. Maybe, maybe not...
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 2:46 pm

maint123 wrote:
Only way to salvage the MAX is that Boeings test pilots should replicate the AOA error on a real airborne plane, say at a height of 1000 ft. Let MCAS do its nose down job and the expert pilots can recover it without electric trim.

With the Boeing CEO in the jumpseat.
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Polot
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 2:50 pm

PW100 wrote:
mjoelnir wrote:
IMO the Ethiopian crash with MCAS pushing the frame into a dive, showed up the underlying fragility of the 737 trimming system. Manual trimming just did not have enough authority to save the plane. Yes, the 737NG has an exemplary safety record, but it could be many years of luck that the wholes never aligned. The frame never been pushed into the areas of the flight envelop where the deficiencies of the manual trim system mattered.

I would assume a review of the complete trim system, should be part of recertifying the 737MAX.


You could that luck, you could also call that clever engineering.

It's not bad to have a critical area in the flight envelope. As long as you make sure you have (sufficient) protections preventing one from closing in (let alone entering) that part of the envelope. I mean, that is what stall protection is all about, in every airframe.
So if Boeing can develop some sort of software that prevent reaching that part of the flight envelope (or in better words, make it extremely unlikely (<E-10), that that is perfectly satisfactory from aircraft certification point of view.

Problem of course is that that POS (Piece Of Software - MCAS) does not even come close to that reliability statistic . . .

Indeed that is the entire point of flight envelope protection on Airbuses. In fact that is why they call it flight envelope protection. The safety of the aircraft is compromised beyond the defined parameters, which is why the computer won’t take the plane past them. That doesn’t stop a pilot from going into that envelope and crashing the aircraft in alternate law if poorly trained.
 
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 2:50 pm

Polot wrote:
mjoelnir wrote:
cledaybuck wrote:
So the holes never lined up for over 20 years on the NG but did line up twice in less than 2 years on the MAX? I find that very unlikely. Much more likely is that changes to the MAX are responsible.


If it is impossible to manual trim the 737MAX under certain flight conditions, I assume it would have been impossible on the NG too. Perhaps NG pilots were never pushed into this part of the flight envelope, while needing to trim manually.

Some holes never line up, because the conditions never arise.

And if the condition never arises then does the design need to account for it? The condition was arising with the Max because the new automation was forcing the condition, not because the condition was actually necessary to keep the aircraft in the air at the time MCAS activated.

In 2004 some Pinnacle pilots crashed a CRJ200 on a ferry flight because they were exploring the limits of the empty plane and doing nonapproved manuevers. Should we now ground the CRJ until BBD is able to make sure the plane can safely fly if it ever encounters those flight conditions again?

At some point you have to trust automation and also trust pilot training. Yes, Boeing dropped the ball and will pay for it with the Max, but the remedy isn’t ensuring the trim system can never crash the plane again. It is making sure the trim doesn’t crash the plane within normal flight, and it can be recovered if something goes wrong. Limiting what automation can do makes it easier to determine how pilots can recover. You are never going to build a crash proof plane.


Manual trim is a safety that is touted in every abnormal trim checklist for the 737. When MCAS pushed the nose down, the safety touted in the checklist had disappeared. Manual trim was not working under those conditions. But the Boeing instructions to use when in trouble, was depending on the manual trim working.

So manual trim in a 737 is like a safety switch, always shown, but does not work when you pull it. As false a safety as can be. If you have a backup that does not work, you can not tout it as a backup. Without a backup you have reevaluate the things depending on this backup.

So Boeing better reevaluate the complete trim system to see, if it is working in emergency like it is supposed to be. And if Boeing and the FAA are not doing it, I hope the other regulators will.
 
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Polot
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 2:58 pm

mjoelnir wrote:
Polot wrote:
mjoelnir wrote:

If it is impossible to manual trim the 737MAX under certain flight conditions, I assume it would have been impossible on the NG too. Perhaps NG pilots were never pushed into this part of the flight envelope, while needing to trim manually.

Some holes never line up, because the conditions never arise.

And if the condition never arises then does the design need to account for it? The condition was arising with the Max because the new automation was forcing the condition, not because the condition was actually necessary to keep the aircraft in the air at the time MCAS activated.

In 2004 some Pinnacle pilots crashed a CRJ200 on a ferry flight because they were exploring the limits of the empty plane and doing nonapproved manuevers. Should we now ground the CRJ until BBD is able to make sure the plane can safely fly if it ever encounters those flight conditions again?

At some point you have to trust automation and also trust pilot training. Yes, Boeing dropped the ball and will pay for it with the Max, but the remedy isn’t ensuring the trim system can never crash the plane again. It is making sure the trim doesn’t crash the plane within normal flight, and it can be recovered if something goes wrong. Limiting what automation can do makes it easier to determine how pilots can recover. You are never going to build a crash proof plane.


Manual trim is a safety that is touted in every abnormal trim checklist for the 737. When MCAS pushed the nose down, the safety touted in the checklist had disappeared. Manual trim was not working under those conditions. But the Boeing instructions to use when in trouble, was depending on the manual trim working.

So manual trim in a 737 is like a safety switch, always shown, but does not work when you pull it. As false a safety as can be. If you have a backup that does not work, you can not tout it as a backup. Without a backup you have reevaluate the things depending on this backup.

So Boeing better reevaluate the complete trim system to see, if it is working in emergency like it is supposed to be. And if Boeing and the FAA are not doing it, I hope the other regulators will.


You are stuck on manual trim. As someone else said earlier trim is trim. Automatic trim is the same as manual trim, it is just a computer making the decision and not a human being. The issue with the MCAS is that the computer was automatically trimming the aircraft, due to faulty data, to such a degree and with such repeated force that the pilots couldn’t counteract it manually.

So what you do is change the aircraft so A) it does not automatically trim based off faulty data, B) the computer never trims the aircraft to such a degree that the pilots can’t counteract it, and C) the computer gives up control and allows the pilot’s trim when necessary (ie during false adata scenarios). This can all be accomplished with software, and not redesigning an entire trim system. Authorities are being extra careful now though to ensure the software will work as everyone expects it to.
 
Noshow
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 3:03 pm

But the amount of trim MCAS provided was needed because of the different MAX flight behavior.
If MCAS gets softened now where will the "more brutal" control authority needed come from? MCAS was invented to counter the MAX's nose going up in certain situations.
 
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 3:20 pm

Polot wrote:
speedbored wrote:
Revelation wrote:
Given how the situation has evolved as more data has become available, I have a hard time seeing minimal differences training with zero sim time passing muster.

Nor do I. But that doesn't mean that Boeing aren't going to try. They have $280m riding on it at Southwest.

And now WN is paying by having MAXes it paid for sitting on the ground for weeks if not months. Another sad irony.

Polot wrote:
The question is with the software fix and proper training how likely is it to get into a situation wheee you can overcome the trim?

And, the next question is if Boeing can convince all the regulators that they've proven that you cannot get into a situation where you cannot overcome the trim. Maybe, maybe not...


I always appreciate your comments. As a non-specialist, what I am reading in these threads is that the JT and ET AoA sensor(s) were faulty (are other necessary factors at play as well in the JT/ET cases?) and that precipitated the accidents. Have there been other occurrences of this type of failure? What happened (no crashes, obviously)?
Last edited by spinotter on Thu Apr 04, 2019 3:22 pm, edited 3 times in total.
 
mjoelnir
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 3:21 pm

Polot wrote:
mjoelnir wrote:
Polot wrote:
And if the condition never arises then does the design need to account for it? The condition was arising with the Max because the new automation was forcing the condition, not because the condition was actually necessary to keep the aircraft in the air at the time MCAS activated.

In 2004 some Pinnacle pilots crashed a CRJ200 on a ferry flight because they were exploring the limits of the empty plane and doing nonapproved manuevers. Should we now ground the CRJ until BBD is able to make sure the plane can safely fly if it ever encounters those flight conditions again?

At some point you have to trust automation and also trust pilot training. Yes, Boeing dropped the ball and will pay for it with the Max, but the remedy isn’t ensuring the trim system can never crash the plane again. It is making sure the trim doesn’t crash the plane within normal flight, and it can be recovered if something goes wrong. Limiting what automation can do makes it easier to determine how pilots can recover. You are never going to build a crash proof plane.


Manual trim is a safety that is touted in every abnormal trim checklist for the 737. When MCAS pushed the nose down, the safety touted in the checklist had disappeared. Manual trim was not working under those conditions. But the Boeing instructions to use when in trouble, was depending on the manual trim working.

So manual trim in a 737 is like a safety switch, always shown, but does not work when you pull it. As false a safety as can be. If you have a backup that does not work, you can not tout it as a backup. Without a backup you have reevaluate the things depending on this backup.

So Boeing better reevaluate the complete trim system to see, if it is working in emergency like it is supposed to be. And if Boeing and the FAA are not doing it, I hope the other regulators will.


You are stuck on manual trim. As someone else said earlier trim is trim. Automatic trim is the same as manual trim, it is just a computer making the decision and not a human being. The issue with the MCAS is that the computer was automatically trimming the aircraft, due to faulty data, to such a degree and with such repeated force that the pilots couldn’t counteract it manually.

So what you do is change the aircraft so A) it does not automatically trim based off faulty data, B) the computer never trims the aircraft to such a degree that the pilots can’t counteract it, and C) the computer gives up control and allows the pilot’s trim when necessary (ie during false adata scenarios). This can all be accomplished with software, and not redesigning an entire trim system. Authorities are being extra careful now though to ensure the software will work as everyone expects it to.


I am stuck on it because the checklist says switch off electric trim and depend on manual, turn the wheels. If the checklist does say that, you have to be able to depend on it, but when they switched off electric trim, it was not possible to turn the wheels because the load on tailplane and elevator.
If you do not understand that I can not help you. You would fly with a parachute that is sure to not open, that is the way you lock at the manual backup system and find it OK.
 
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spinotter
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 3:27 pm

Revelation wrote:
And now WN is paying by having MAXes it paid for sitting on the ground for weeks if not months. Another sad irony.


Revelation wrote:
And, the next question is if Boeing can convince all the regulators that they've proven that you cannot get into a situation where you cannot overcome the trim. Maybe, maybe not...


I always appreciate your comments, Revelation. As a non-specialist, what I am reading in these threads is that the JT and ET AoA sensor(s) were faulty (are other necessary factors at play as well in the JT/ET cases?) and that precipitated the accidents. Have there been other occurrences of this type of failure? What happened (no crashes, obviously)?
 
mjoelnir
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 3:40 pm

Revelation wrote:
mjoelnir wrote:
It seems that an unnamed pilot of an USA airline, having asked for more training including simulator, because he was uncomfortable to fly the MAX with the minimal difference training provided, was heavily leaned upon by his airline and did not find a lot of help at his union either. That happened before the two accidents.
So if you would have been an pilot at this USA airline and asked for more training, you would have had a black mark against you, without being provided with extra training.

I guess if I was in that position (which I am not) and I was genuinely concerned, I would not worry very much about such black marks. Maybe I would embarrass management by offering to pay for such sim time so I could fly with confidence. I did something very similar early in my career. There was a conference where some very unique training was available, and management would not pay for a trip, so I told them I would pay for the trip and the training if they would allow me to not have to charge the time to vacation, and I was fully committed to doing so. That embarrassed them to the point where they decided to pay for it all. I guess I'm a maverick in some ways.
.


It would have been difficult for you, not pay it yourself, but to find advanced training on the MAX. Not even for money a 737MAX simulator would have been available.
 
marcelh
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 3:43 pm

Noshow wrote:
If MCAS gets softened now where will the "more brutal" control authority needed come from? MCAS was invented to counter the MAX's nose going up in certain situations.

Specific training for those sitting in the front. And yes, that will probably mean that the MAX doesn’t fly like a NG.
 
Interested
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 4:07 pm

maint123 wrote:
Only way to salvage the MAX is that Boeings test pilots should replicate the AOA error on a real airborne plane, say at a height of 1000 ft. Let MCAS do its nose down job and the expert pilots can recover it without electric trim.


Are they allowed ejector seats and parachutes?
 
kalvado
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 4:19 pm

Interested wrote:
maint123 wrote:
Only way to salvage the MAX is that Boeings test pilots should replicate the AOA error on a real airborne plane, say at a height of 1000 ft. Let MCAS do its nose down job and the expert pilots can recover it without electric trim.


Are they allowed ejector seats and parachutes?

As far as I remember from A-380 test campaign info, for the first few flights pilots have parachutes and pre-determined evacuation path; possibly same for certain high risk tests (stalls, etc). However those parachutes seem to be mostly feel good stuff, as getting to escape hatch is in no way guaranteed, as well as safe separation from the airplane.
I assume Boeing is on the same page.
More humane approach would be to run the test at FL100 and consider it a fail if plane sinks below FL90 in progress.
 
smokeybandit
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 4:25 pm

morrisond wrote:

There are conflicting reports on whether or not they followed "All Procedures" (granted that procedure was not written well). Apparently they did not use Electric Trim to offset MCAS before turning off the system. I would have to guess they did not use it the 4 times they turned it back on either.

I doubt you will find in any procedure either to allow the plane to accelerate beyond it's normal Airspeed limit of 230 knots either.

Scroll down in this ABC story

https://abcnews.go.com/International/da ... dlines_hed


"and the plane's takeoff appeared to be "very normal." "

Wasn't the whole issue that started it all the fact that it wasn't a normal takeoff at all?
 
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Revelation
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 4:28 pm

Seattle Times: Why Boeing’s emergency directions may have failed to save 737 MAX is a very good write up of the recent findings discussed in this thread and elsewhere.

It wraps up with a good news vs bad news perspective for Boeing:

The good news for Boeing is that the proposed software fix announced for MCAS should prevent the failure that led to this scenario in the cockpit.

“I think the MAX will be safe with the improved MCAS,” said Fehrm of Leeham.net.

The bad news for Boeing is twofold, according to Fehrm. First, the original MCAS design was badly flawed and appears to be the principal cause of the Lion Air crash. Second, the procedure Boeing offered after that accident to keep planes safe now appears to have been woefully inadequate and may have doomed the Ethiopian Airlines jet.

On Wednesday the FAA , facing worldwide skepticism of its oversight, announced that it is establishing a team including foreign regulators to conduct a “comprehensive review of the certification of the automated flight control system on the Boeing 737 MAX aircraft.”

IMO the bad news far outweighs the good news, but at least the future fix is said to be workable.
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Revelation
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 4:37 pm

mjoelnir wrote:
It would have been difficult for you, not pay it yourself, but to find advanced training on the MAX. Not even for money a 737MAX simulator would have been available.

That's a good point, and one to keep in mind going forward, that there aren't that many MAX-specific simulators available.

Could the current NG-era simulators at least give the pilots some hands-on training for runaway stab issues now that their importance is better understood?

Or could they be modified (maybe via software, or maybe via software + hardware mods) to provide such?

kalvado wrote:
]
As far as I remember from A-380 test campaign info, for the first few flights pilots have parachutes and pre-determined evacuation path; possibly same for certain high risk tests (stalls, etc). However those parachutes seem to be mostly feel good stuff, as getting to escape hatch is in no way guaranteed, as well as safe separation from the airplane.
I assume Boeing is on the same page.

There was an interesting discussion on this site about why USAF stopped issuing parachutes to KC-135 pilots.

It was based on similar reasoning: that the reality is that there is almost no scenario where they could be relied upon to save the crew.
Wake up to find out that you are the eyes of the world
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casinterest
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 4:58 pm

morrisond wrote:
RickNRoll wrote:
casinterest wrote:
Boeing didn't lie. They omitted details about a subsystem behavioral change that they though would save lies. Without a review process from external safety experts , they allowed a change to be made that cost many lives. Lives that cannot be reclaimed. The bargain of the change was that the pilots would remember their memory items to stop a runaway stabilizer. This was not checked with the pilots, and what the pilots didn't know cost many lives , and there can be no amount of bargaining to make up for those lost lives.

However stating the above. Boeing is making good on making a change to fix the MCAS, and a hearty review should be made by the FAA, and other certifying agencies including the airlines. The airplane manufacturing association is not like many other industries in the US. There are few manufacturers, and few certifying agencies. EASA should be involved. Their skipping of the initial rollout of a potential fix is bullshit. They should have been front and center even if not invited as a vested interest in Aviation safety. Their input should be valuable within and without, and that is the issue currently . Airbus and Boeing incestuously breed their own vesting parties. We need all parties present to represent the airlines, the consumers, and the airline industry to present a safe product.

When the final reports come out, Boeing will own a lot of the blame for the undocumented changes to MCAS, but the Pilots and Airlines will own a lot of issues due to CRM and training. If the Ethiopian crash is as similar to the Lion Air crash as we are all led to believe, then a lot of questions need to be asked of their Chief Pilots and Trainers as Boeing issued guidance 4 months before the crash to deal with these issues with MCAS.

The FAA and ETAS should retrench in light of the above and work hard to cross certify and verify vital changes to flight control behavior.


You are behind the news cycle. The Ethiopian pilots followed the Boeing recommendation and found the plane to be uncontrollable. Boeing should have grounded the MAX after the Indonesian crash instead of sending out a bulletin that was inadequate and misleading.

Did Boeing even test their recommendation?



There are conflicting reports on whether or not they followed "All Procedures" (granted that procedure was not written well). Apparently they did not use Electric Trim to offset MCAS before turning off the system. I would have to guess they did not use it the 4 times they turned it back on either.

I doubt you will find in any procedure either to allow the plane to accelerate beyond it's normal Airspeed limit of 230 knots either.

Scroll down in this ABC story

https://abcnews.go.com/International/da ... dlines_hed


If they applied the correct procedures then we need to see what caused them to fail at recovery. initial reports I have read today indicate over speed may have caused an issue with the ability to use manual trim, and they restarted the Stab Trim which restarted MCAS and then control was lost.

Do we have the full prelim report yet?
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lowbank
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 5:03 pm

Revelation wrote:
Seattle Times: Why Boeing’s emergency directions may have failed to save 737 MAX is a very good write up of the recent findings discussed in this thread and elsewhere.

It wraps up with a good news vs bad news perspective for Boeing:

The good news for Boeing is that the proposed software fix announced for MCAS should prevent the failure that led to this scenario in the cockpit.

“I think the MAX will be safe with the improved MCAS,” said Fehrm of Leeham.net.

The bad news for Boeing is twofold, according to Fehrm. First, the original MCAS design was badly flawed and appears to be the principal cause of the Lion Air crash. Second, the procedure Boeing offered after that accident to keep planes safe now appears to have been woefully inadequate and may have doomed the Ethiopian Airlines jet.

On Wednesday the FAA , facing worldwide skepticism of its oversight, announced that it is establishing a team including foreign regulators to conduct a “comprehensive review of the certification of the automated flight control system on the Boeing 737 MAX aircraft.”

IMO the bad news far outweighs the good news, but at least the future fix is said to be workable.


Remember this is PR, they are never going to say anything other than it’s workable.

I hope it is, as more than anything else we need safe Boeing aircraft in the sky’s.
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scbriml
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 5:20 pm

casinterest wrote:
Do we have the full prelim report yet?


Yes.

http://www.ecaa.gov.et/documents/20435/ ... AVJ%29.pdf

Boeing's response to the report:
http://www.boeing.com/commercial/737max ... /statement
The preliminary report contains flight data recorder information indicating the airplane had an erroneous angle of attack sensor input that activated the Maneuvering Characteristics Augmentation System (MCAS) function during the flight, as it had during the Lion Air 610 flight.


So MCAS was involved in both crashes. The grounding looks to be fully justified.
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StTim
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 5:25 pm

I hear you re the potential overspeed BUT stick shakers are going off. Airspeed indicators are unreliable. Alarms everywhere and it takes balls then at 1,000 ft to reduce the throttle!

It might have been the right action but....
 
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 5:29 pm

StTim wrote:
I hear you re the potential overspeed BUT stick shakers are going off. Airspeed indicators are unreliable. Alarms everywhere and it takes balls then at 1,000 ft to reduce the throttle!

It might have been the right action but....



From the FDR traces it looks like they were 7-8000' above ground level.
 
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 5:45 pm

Somewhere in this thread, somebody shared a procedure for operating the hand-crank manual trim. I believe it was from the operating manual of a 737 classic. It had to do with the situation where the wheels were near to impossible to turn by hand. I believe the advised procedure in the manual was push the yoke forward to to relieve some pressure on the stabilizer, and to allow the trim wheels to be more easily turned by hand. So, it would seem that the issue (of the the manual trim being difficult to operate) goes back a long ways in the design of the 737, if not to the very beginning.

Of course, the problem gets even worse if an erroneous MCAS activation starts flying you into the ground at a relatively low altitude. Add to that the airspeed disagree, and its corrective procedure which apparently results in flying the plane faster, thus increasing the difficulty of operating the trim by hand. I'm guessing there's an altitude below which one cannot even hope to use the above described procedure for allowing the operation of the manual trim.

So… I come to two questions:
1) Is this procedure for operating the manual trim still in the MAX manual?
2) Have all the previous generations of 737 simply been fortunate enough not to need to need to operate trim manually, at a low altitude, to recover from a nose-down, out-of-trim situation?
 
StTim
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 5:45 pm

I think, but I could be wrong, that they were at 7,000 ft or so above sea level but about 1,000 ft above ground level due to the local terrain being at altitude!
 
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kczombie
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 5:52 pm

Late to the conversation, but maybe install an on/off switch for the MCAS? (sorry, I couldn't resist)
 
787Driver
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 5:52 pm

Damn Boeing is in deep shit if indeed the pilots used the stab trim cutout but were still unable to control the aircraft. I wonder how many lawsuits are waiting and how much compensation Boeing will end up having to pay?
 
kalvado
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:00 pm

787Driver wrote:
Damn Boeing is in deep shit if indeed the pilots used the stab trim cutout but were still unable to control the aircraft. I wonder how many lawsuits are waiting and how much compensation Boeing will end up having to pay?

And how it would affect the cash position for 797 development.
737 used to be a cash cow to carry Boeing through 787 turbulent development. I wonder if 787 has enough potential to fill that role, while 777 is in transit as well.
 
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SheikhDjibouti
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:01 pm

StTim wrote:
I hear you re the potential overspeed BUT stick shakers are going off. Airspeed indicators are unreliable. Alarms everywhere and it takes balls then at 1,000 ft to reduce the throttle!
It might have been the right action but....

Whilst overspeed and elevator blowback are both being blamed for the apparent inability of pilots to restore control via the yoke & elevators, I would like to revisit a comment I made way back in the Lion Air crash thread.
Note:- this is from the previous flight (JT043) where they all lived to tell the story.
After three automatic AND trim occurrences, the SIC commented that the control column was too heavy to hold back

Elsewhere I read a comment that most female pilots would simply be unable to come close to applying enough physical strength.

Adding two and two together here, I looked beyond the overspeed and blowback contributions to control forces, and realised that MCAS itself was providing an artificial "feel" in the name of blurring the differences between NG & MAX, and that this "feel" was adding heavier control column forces to dissuade pilots from pulling up.

That being the case, we have both aerodynamic forces and a suicidal computer system combining to overwhelm the biceps of the average pilot.
I am reminded of a wartime incident involving a Short Sunderland flying boat, hydraulics all shot up by Ju-88s, with both pilots pulling back hard on the yokes, assisted by the Flight Engineer assisting by pulling one yoke with aid of a length of rope.

The stab trim cut-out prevented MCAS from pitching the nose down aerodynamically, but every time it activated did it still affect the control columns by making them heavier to handle?
Humans suffer fatigue; the machine never does....

Somebody please tell me if I've got this wrong?
Or is it so obvious that no-one has mentioned it before, and I am just the last idiot to find out?
Nothing to see here; move along please.
 
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PixelFlight
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:05 pm

planecane wrote:
PixelFlight wrote:
jollo wrote:
Both seem to convey the idea that in the NG the two switches have different effects.

On the other hand, your diagram (dated 2017, so referring to the MAX) seems to indicate that operating any one (or both) switches results in the electric trim actuator to be disbled, so the same net effect.

And the schematic have a "MCAS ENGAGE" function into the FCC A/B box (center bottom). MCAS only exists on the 737 MAX.

jollo wrote:
So why the change between NG and MAX?

BTW, the labels PRI and B/U in the MAX are consistent with the fact that both have the same effect, but it's the whole setup that doesn't make sense: why 2 switches in series that should always be operated together per FCOM?.

Excellent question. There is certainly a lot of possible scenarios. I try this one: The new MCAS ENGAGE signal is different from the older autopilot signals and can't be mixed before the cutout switches. So Boeing have to add a third cutout switch for the MCAS signal, and this imply pilot training about the handling of this new switch and about the MCAS. As the goal was to not add any MAX training for the NG pilots, there redesigned the cutout switches to what's actually into the MAX. Maybe the confusion about the events that could require to cutout the stab trim was already there when the MAX was designed.

I may be misreading your post but I think you are confusing the cutout switches that operate based on control column movement with the cutout switches that turn off the electric trim. The MCAS signal is before those switches.

The stab trim cutout switches need to be both ON to still have power to the actuator. This is now confirmed by the ET302 preliminary report, so I was right on this. If there wanted to only cut the MCAS, there no other way than adding a yet another cutout switch just to cut the MCAS signal only. And this was not allowed by the MAX design goal, confirmed by the 1 M$ per MAX payback in case pilot training was required to flight the MAX from the NG. Finally the FAA FSB report rev 15 about the training requirement due to 737 model variation clearly show that relabeled the cutout switch only already required a B level training, the last without flight training device. Adding a switch would have be level >B and breaking the design goal.
:stirthepot: 737-8 MAX: "For all speeds higher than 220 Kts and trim set at a value of 2.5 units, the difficulity level of turning the manual trim wheel was level A (trim wheel not movable)." :stirthepot:
 
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Pellegrine
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:07 pm

morrisond wrote:
StTim wrote:
I hear you re the potential overspeed BUT stick shakers are going off. Airspeed indicators are unreliable. Alarms everywhere and it takes balls then at 1,000 ft to reduce the throttle!

It might have been the right action but....



From the FDR traces it looks like they were 7-8000' above ground level.


:rotfl: Above sea level. And the airport and terrain surrounding ADD is how high?
Last edited by Pellegrine on Thu Apr 04, 2019 6:09 pm, edited 1 time in total.
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casinterest
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:08 pm

scbriml wrote:
casinterest wrote:
Do we have the full prelim report yet?


Yes.

http://www.ecaa.gov.et/documents/20435/ ... AVJ%29.pdf

Boeing's response to the report:
http://www.boeing.com/commercial/737max ... /statement
The preliminary report contains flight data recorder information indicating the airplane had an erroneous angle of attack sensor input that activated the Maneuvering Characteristics Augmentation System (MCAS) function during the flight, as it had during the Lion Air 610 flight.


So MCAS was involved in both crashes. The grounding looks to be fully justified.

MCAS was involved as suspected. We will have to see the full report, but it seems all hell broke lose when the plane's turn stopped. Based on the report (heading ) the plane was in a slow turn the whole time they were troubleshooting ( Might explain why manual trim wasn't working well, in conjunction with the overspeed).
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seahawk
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:11 pm

Revelation wrote:
Seattle Times: Why Boeing’s emergency directions may have failed to save 737 MAX is a very good write up of the recent findings discussed in this thread and elsewhere.

It wraps up with a good news vs bad news perspective for Boeing:

The good news for Boeing is that the proposed software fix announced for MCAS should prevent the failure that led to this scenario in the cockpit.

“I think the MAX will be safe with the improved MCAS,” said Fehrm of Leeham.net.

The bad news for Boeing is twofold, according to Fehrm. First, the original MCAS design was badly flawed and appears to be the principal cause of the Lion Air crash. Second, the procedure Boeing offered after that accident to keep planes safe now appears to have been woefully inadequate and may have doomed the Ethiopian Airlines jet.

On Wednesday the FAA , facing worldwide skepticism of its oversight, announced that it is establishing a team including foreign regulators to conduct a “comprehensive review of the certification of the automated flight control system on the Boeing 737 MAX aircraft.”

IMO the bad news far outweighs the good news, but at least the future fix is said to be workable.


The fix is fine if the aggressive input of the MCAS is not needed. But if it snot needed why was it implemented? Furthermore I think a pure software fix won´t cut it after the findings of both incidents.
In addition I see the following.

1. 2 AoA sensors that are compared for all 737MAX
2. AoA disagree warning for all 737MAX
3. MCAS active warning
4. an extra switch to turn off MCAS without turning off electric trim
 
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:13 pm

morrisond wrote:
StTim wrote:
I hear you re the potential overspeed BUT stick shakers are going off. Airspeed indicators are unreliable. Alarms everywhere and it takes balls then at 1,000 ft to reduce the throttle!

It might have been the right action but....



From the FDR traces it looks like they were 7-8000' above ground level.


I know this is a very long thread but the issue of the aircraft being 7000 above sea level and not ground level was covered probably 60 pages ago.
 
trex8
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:15 pm

787Driver wrote:
Damn Boeing is in deep shit if indeed the pilots used the stab trim cutout but were still unable to control the aircraft. I wonder how many lawsuits are waiting and how much compensation Boeing will end up having to pay?

Probably as much as they would have spent designing, building and certifying a new tailpane!!
 
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scbriml
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:16 pm

morrisond wrote:
StTim wrote:
I hear you re the potential overspeed BUT stick shakers are going off. Airspeed indicators are unreliable. Alarms everywhere and it takes balls then at 1,000 ft to reduce the throttle!

It might have been the right action but....



From the FDR traces it looks like they were 7-8000' above ground level.


The FDR altitude trace on page 26 shows Pressure Alt on left vertical axis and Radio Alt on right vertical axis.

Altitudes mentioned in the text of the report are all given as pressure altitudes with the following note - "The FDR records standard pressure altitude values which are not corrected for the airport barometer setting"

To me it looks as though they got to around 7,000ft above ADD altitude (but crash location terrain was higher than ADD).
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smokeybandit
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:16 pm

scbriml wrote:
So MCAS was involved in both crashes. The grounding looks to be fully justified.


MCAS was just doing what data from the AOA told it to do. Obviously MCAS needs refinement. But there were other problems that led to MCAS issues.
 
JibberJim
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:22 pm

So the report is interestingly and surprisingly light on info on what the CVR said after the FO said they couldn't work the manual trim. I can't imagine the (seemingly) re-enabling of the electrical trim was done without verbal comment? I can certainly imagine that the troubleshooting and discussion that led them to that cause of action is the reason it was delayed from Monday after Boeing got a look - I think that originally had more information.
 
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:26 pm

zkojq wrote:
morrisond wrote:
ET302 should never have happened with properly trained pilots - this was a known issue.


That comment didn't age well. :lol:


All of these comments blaming the Ethiopian pilots, and saying how this situation could never befall US (and Canadian) pilots, was nothing but pure racism.

These comments were coming from people who otherwise were demanding that the MAX not be grounded until "all the facts were in." (Which overlooks the point of a grounding, but I digress.) Apparently when it came to blame-the-African-pilots, a rush to judgment, sans any facts, was hunky dory.
 
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scbriml
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Re: B737MAX Grounded Worldwide

Thu Apr 04, 2019 6:32 pm

Pellegrine wrote:
Above sea level. And the airport and terrain surrounding ADD is how high?


trex8 wrote:
I know this is a very long thread but the issue of the aircraft being 7000 above sea level and not ground level was covered probably 60 pages ago.


I've disagreed with many things that morrisond has said in these MAX threads, but in this instance I think he's right.

Look at the FDR altitude trace on page 26 of the report, it shows both pressure and radio altitude.

The report also says:
At 05:41:21, the selected altitude was changed from 32000 ft to 14000 ft.
...
At 05:43:11, about 32 seconds before the end of the recording, at approximately 13,400* ft...
...
The last recorded pressure altitude was 5,419* ft on the left and 8,399* ft on the right.


*The FDR records standard pressure altitude values which are not corrected for the airport barometer setting.

Assuming the right altitude reading was correct, they were some 5,000ft above the ground before the fatal dive.
Last edited by scbriml on Thu Apr 04, 2019 6:38 pm, edited 1 time in total.
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