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Ethiopian airliner down in Africa

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Ethiopian airliner down in Africa

Old 1st May 2019, 13:13
  #4681 (permalink)  
 
Join Date: Dec 2014
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Originally Posted by GordonR_Cape View Post
@meleagertoo
To take a contrarian viewpoint: If an aircraft is not safe to be operated by airlines in countries whose pilots are not top-notch, then it should not be sold to those airlines/countries. Or fix the aircraft, so that it is safe to be operated by less-than-perfect pilots. End of (my version of) the story...
My version would be: if a pilot cannot fly stick and rudder, pitch and power when all else fails, no aircraft can be considered safe. If a airline or country is unable or unwilling to train their pilots in the basics of flying unassisted, then they should not be operating air transport services.
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Old 1st May 2019, 13:33
  #4682 (permalink)  
 
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Originally Posted by GordonR_Cape View Post

I previously asked the question: How could the autopilot ever get into a high AOA situation? One answer was if the autothrottle is disabled. The implication being that the autopilot could keep increasing the nose up pitch until the stall warning activates, and the crew intervenes. I hope that scenario has been carefully tested?
In the 737 as well as every other aircraft I have flown, the autopilot will attempt to do exactly what you told it do - until it can’t. It then disconnects with whatever alerts that it provides at whatever trim state and power settings were in place. This will often result in the pilots suddenly having to take command of an aircraft that is in, to use the popular euphemism, an “undesired aircraft state.” This can potentially be a very shocking moment.

Even when the autopilot is in use, at least one of the pilots is expected to actively monitor the aircraft. If the autopilot is struggling, then there will be signs depending on what exactly the problem is. The pilot is then expected to intervene and correct the problem. Until the technology progresses to a point that this active monitoring role is no longer needed, this is not a “design” issue, it is a pilot training issue.




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Old 1st May 2019, 13:41
  #4683 (permalink)  
 
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Salute!

I shall stick with my interpretation of the reason MCAS was implemented.

It was to counter a nose up pitch moment.

If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.

I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.

PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.

Gotta see the dentist. So later..
...
Gums...


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Old 1st May 2019, 14:16
  #4684 (permalink)  
 
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Originally Posted by ams6110 View Post
My version would be: if a pilot cannot fly stick and rudder, pitch and power when all else fails, no aircraft can be considered safe. If a airline or country is unable or unwilling to train their pilots in the basics of flying unassisted, then they should not be operating air transport services.
Amen to the gist of that, but it isn't fair or reasonable to describe anything "unsafe" if it comes to harm through excessive mishandling. A Moscow bus isn't in itself unsafe because the driver's necked a quart of Stolly, is it?

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Old 1st May 2019, 14:20
  #4685 (permalink)  
 
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Originally Posted by gums View Post
Salute!

I shall stick with my interpretation of the reason MCAS was implemented.

It was to counter a nose up pitch moment.

If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.

I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.

PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.

Gotta see the dentist. So later..
...
Gums...
I think your interpretation is wrong.

My understanding is that MCAS was implemented ONLY to satisfy FAA Section 25.173


25.173 Static longitudinal stability.

Under the conditions specified in
§ 25.175, the characteristics of the elevator control forces (including friction) must be as follows:

(a) A pull must be required to obtain and maintain speeds below the specified trim speed, and a push must be required to obtain and maintain speeds above the specified trim speed. This must be shown at any speed that can be obtained except speeds higher than the landing gear or wing flap operating limit speeds or VFC/MFC, whichever is appropriate, or lower than the minimum speed for steady unstalled flight.

(b) The airspeed must return to within 10 percent of the original trim speed for the climb, approach, and landing conditions specified in
§ 25.175 (a), (c), and (d), and must return to within 7.5 percent of the original trim speed for the cruising condition specified in § 25.175(b), when the control force is slowly released from any speed within the range specified in paragraph (a) of this section.

(c) The average gradient of the stable slope of the stick force versus speed curve may not be less than 1 pound for each 6 knots.

(d) Within the free return speed range specified in
paragraph (b) of this section, it is permissible for the airplane, without control forces, to stabilize on speeds above or below the desired trim speeds if exceptional attention on the part of the pilot is not required to return to and maintain the desired trim speed and altitude.


This link provides some good information. 737 MAX Maneuvering Characteristics Augmentation System (MCAS)

"MCAS is a longitudinal stability enhancement. It is not for stall prevention (although indirectly it helps) or to make the MAX handle like the NG (although it does); it was introduced to counteract the non-linear lift generated by the LEAP-1B engine nacelles at high AoA and give a steady increase in stick force as the stall is approached as required by regulation."

Last edited by Lost in Saigon; 1st May 2019 at 14:33.
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Old 1st May 2019, 14:49
  #4686 (permalink)  
 
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Originally Posted by ams6110 View Post
My version would be: if a pilot cannot fly stick and rudder, pitch and power when all else fails, no aircraft can be considered safe. If a airline or country is unable or unwilling to train their pilots in the basics of flying unassisted, then they should not be operating air transport services.
What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly, it was a case of undesirable interference by the automatics during hand flight. The criteria being debated is how skillful should pilots be at responding to a design flaw and if it is safe for a manufacturer to know of the flaw and assume that pilots would all be that skillful.
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Old 1st May 2019, 15:26
  #4687 (permalink)  
 
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Originally Posted by Water pilot View Post

What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly, it was a case of undesirable interference by the automatics during hand flight. The criteria being debated is how skillful should pilots be at responding to a design flaw and if it is safe for a manufacturer to know of the flaw and assume that pilots would all be that skillful.
As outlined countless times by 737 Driver, attention to pitch and power would have saved the day in both cases. Why is that so difficult?
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Old 1st May 2019, 15:30
  #4688 (permalink)  
 
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Originally Posted by Water pilot View Post

What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly, it was a case of undesirable interference by the automatics during hand flight. The criteria being debated is how skillful should pilots be at responding to a design flaw and if it is safe for a manufacturer to know of the flaw and assume that pilots would all be that skillful.
One question should be whether the manufacturer was really aware of the “flaw” or even characterized it as such. If so, it would be unconscionable not to design it out. To have a known flaw and then presume pilots will find a some way to overcome it (without even telling them about it) is crazy. That is not engineering and it is not the Boeing of old.

I suspect that the combination of events following the particular malfunction of AOA sensor on MCAS was not foreseen, which I am afraid would be a flaw in the engineering. Regardless, now they know and they ought to do more than tweak the software. This failure mode was twice demonstrated to be catastrophic and the redesign must make it extremely improbable. Will they?
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Old 1st May 2019, 15:41
  #4689 (permalink)  
 
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Originally Posted by ams6110 View Post
My version would be: if a pilot cannot fly stick and rudder, pitch and power when all else fails, no aircraft can be considered safe. If a airline or country is unable or unwilling to train their pilots in the basics of flying unassisted, then they should not be operating air transport services.
Originally Posted by Water pilot View Post

What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly, it was a case of undesirable interference by the automatics during hand flight. The criteria being debated is how skillful should pilots be at responding to a design flaw and if it is safe for a manufacturer to know of the flaw and assume that pilots would all be that skillful.
"stick and rudder, pitch and power" also means basic airmanship. Basic airmanship also involves keeping your aircraft in trim at all times.

In both accidents the pilots were unable to properly deal with a stick shaker at takeoff. Basic airmanship would dictate not raising the flaps when faced with a stick shaker at takeoff. That act lone should have saved the day.
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Old 1st May 2019, 15:52
  #4690 (permalink)  
 
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Originally Posted by gums View Post
Salute!

I shall stick with my interpretation of the reason MCAS was implemented.

It was to counter a nose up pitch moment.

If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.

I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.

PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.

Gotta see the dentist. So later..
...
Gums...
Lost in Saigon is correct. I’ll ad some to his post:
If there really was a pitch up moment at high AoA/stall that is not an acceptable behaviour and in that case the model would need a stick pusher to keep it from getting there.( § 25.203 Stall characteristics )

Also, if the Max had a pitch up moment, the MCAS downtrimming of the stab could easily be overridden by more elevator( elevator pitch up canceling out the stab downtrim) making sum= status quo. Then the pitch up moment still would be there. If there was a pitch up moment it could only be fixed with a stick pusher.

There is a pitch up moment from the engine nacell’s at high alfa but it is allways less than the pitch down comming from the CG being forward of the centre of pressure center. The nacelles pitch up moment ease the elevator work to pitch up /decrease speed, making the stick force gradient to low.

Gums, you have my respect for many excellent posts and a very good carreer! Thumbs up :-)

Last edited by AAKEE; 1st May 2019 at 15:56. Reason: Iphone spelling...
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Old 1st May 2019, 16:15
  #4691 (permalink)  
 
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Originally Posted by Organfreak View Post
… attention to pitch and power would have saved the day in both cases. Why is that so difficult?
Pitch / power is an aspect of UAS drill, which was diagnosed immediately after takeoff and managed by the crew as they saw the situation.
You and others appear to misunderstand the operation of MCAS trim and control power of the tail.
Once the flap retracted, MCAS started to apply nose down trim, 9 sec on, 5 sec off. There are no additional alerts to indicate that MCAS would generate unwanted trim inputs - no forewarning; thus the only cue was a change in stick force (not looking at the trim wheel). This in part was counteracted by manual trim, which was the crew’s initial and then continuing attempt to manage pitch.

The consensus, but not authoritative view is that pilot electric trim does not override MCAS; thus the summed tail trim movement is nose down at high rate. With increasing tail trim the counteracting electric trim may be progressively ineffective (summed tail forces), similarly the reduced manual trim wheel operation after electric trim is inhibited.
At some point it is likely that the elevator power, stick forces, reach a condition where further pitch control is unavailable. There are no conventional piloting skills which will be able to ‘fly the aircraft’.

Originally Posted by Lost in Saigon View Post
Basic airmanship would dictate not raising the flaps when faced with a stick shaker at takeoff. That act lone should have saved the day.
No aspect of airmanship would ensure that flaps were not retracted. You assume that the crew had deduced the possibility of MCAS problems; but they could have been highly focussed on flying the aircraft with UAS. There were no warnings indications to the possibility of trim problems; no change with flaps up.
Check your assumptions; provide a supporting argument for alternative views.

Originally Posted by AAKEE View Post
…, if the Max had a pitch up moment, the MCAS downtrimming of the stab could easily be overridden by more elevator( elevator pitch up canceling out the stab downtrim).
There is a pitch up moment from the engine nacell’s at high alfa but it is allways less than the pitch down comming from the CG being forward of the centre of pressure center. The nacelles pitch up moment ease the elevator work to pitch up /decrease speed, making the stick force gradient to low.
Re elevator forces, see above.
Your appreciation of aerodynamics, controls, cg, etc, differs from mine, and I suspect many other aviators.
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Old 1st May 2019, 16:31
  #4692 (permalink)  
 
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Originally Posted by alf5071h View Post

The consensus, but not authoritative view is that pilot electric trim does not override MCAS; thus the summed tail trim movement is nose down at high rate. With increasing tail trim the counteracting electric trim may be progressively ineffective (summed tail forces), similarly the reduced manual trim wheel operation after electric trim is inhibited.
At some point it is likely that the elevator power, stick forces, reach a condition where further pitch control is unavailable. There are no conventional piloting skills which will be able to ‘fly the aircraft’.

The consensus is WRONG. Boeing clearly states that electric trim will STOP and even REVERSE unwanted MCAS operation.







Last edited by Lost in Saigon; 1st May 2019 at 16:47.
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Old 1st May 2019, 16:34
  #4693 (permalink)  
 
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Originally Posted by Water pilot View Post
What does that have to do with this thread? This was not a case of the automatics failing and the pilots not knowing how to fly,
Yes, it was. The "automatics" failed by providing undesired and uncommanded control inputs, but this was not the initiating failure that the pilots failed to react to. MCAS did not become a factor until a full minute and fifteen seconds into the flight. The inital failure that was presented to the pilots was stickshaker on takeoff with UAS. Rather than manually flying the aircraft using pitch and power as required by the memory items on the UAS NNC checklist, the accident pilots tried to re-engage the autopilot multiple times, and relied on the autothrottle to manage power, which put them above VMo. This directly contradicts the UAS NNC checklist which has the pilots disengage the autopilot, autothrottle, and flight director as memory items for the first three steps, and further goes on to state "Do not use the the autopilot, autothrottle, or flight directors." Look at the timeline:

5:37:34 ATC clears flight for takeoff
5:38:44 (just after liftoff) AOA disagree, airspeed disagree, altitude disagree, and stickshaker are indicated in FDR
5:38:46 Master Caution light illuminates.
5:38:58 Pilots attempt to engage autopilot
5:39:00 Pilots attempt to engage autopilot
5:39:22 Pilots successfully engage autopilot
5:39:45 Flap retraction begins
5:39:55 Autopilot disengages
5:40:00 MCAS begins MCAS-ing

So, it was a minute and fifteen seconds between the initial indication of a failure, and the undesired, uncommanded trim input. During that time, the pilots did not execute a single step of the UAS NNC checklist that they should have been following from memory. But they sure spent a lot of time heads-down button-pushing that autopilot. It's clear that they were not comfortable manually flying the aircraft as the checklist requires. To be noted, until 5:40:00, the airplane would have been behaving exactly as an NG would during the same type of AOA vane failure, and the procedure to follow during UAS is identical.
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Old 1st May 2019, 16:37
  #4694 (permalink)  
 
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Originally Posted by gums View Post
Salute!

I shall stick with my interpretation of the reason MCAS was implemented.

It was to counter a nose up pitch moment.

If all it had to do was stiffen or increase back stick, there would not have been two crashes where the stab trimmed so far down that recovery was a big problem. Oh yeah, then the 5 sec pause and here we go again.

I would love to have Driver or another 737 jock fly the MAX with no MCAS and pull until the stall shaker. Let us know if the stick got lighter and if it was a problem. Real plane, not a sim.

PLease see the other forum where the pitch versus AoA charts are shown/discussed. and somewhere here we have the same chart.

Gotta see the dentist. So later..
...
Gums...
Hi Gums, Hope the dentist was kind... Saw the charts before, ta.

I think the point is:

- As they say on the news (and here for once they are right...) MCAS is a function which can/will push the nose down whereas

A feel increase mechanism will make pulling back harder - but won’t push the nose down.

Now I know which I would rather have.

Let’s imagine that such a system had been fitted instead of MCAS in the three AoA anomaly cases which we have discussed. What would have happened?

All the accompanying warnings for stall and speed disagree etc. would still have gone off. While the crew were sorting this out - with or without autopilot, with or without flap - there would have been no further distraction except a stiffer pull force, which could have been trimmed out as required. No big hand forcing the flight path down - no trim “runaway”.

The chances for survival would have been good, crew skills here or there I reckon.

Greetings, B
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Old 1st May 2019, 16:41
  #4695 (permalink)  
 
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Originally Posted by bill fly View Post


Hi Gums, Hope the dentist was kind... Saw the charts before, ta.

I think the point is:

- As they say on the news (and here for once they are right...) MCAS is a function which can/will push the nose down whereas

A feel increase mechanism will make pulling back harder - but won’t push the nose down.

Now I know which I would rather have.

Let’s imagine that such a system had been fitted instead of MCAS in the three AoA anomaly cases which we have discussed. What would have happened?

All the accompanying warnings for stall and speed disagree etc. would still have gone off. While the crew were sorting this out - with or without autopilot, with or without flap - there would have been no further distraction except a stiffer pull force, which could have been trimmed out as required. No big hand forcing the flight path down - no trim “runaway”.

The chances for survival would have been good, crew skills here or there I reckon.

Greetings, B
this for me is THE best post on this entire thread

G
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Old 1st May 2019, 16:47
  #4696 (permalink)  
 
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Originally Posted by alf5071h View Post
Pitch / power is an aspect of UAS drill, which was diagnosed immediately after takeoff and managed by the crew as they saw the situation.


Please show us where in the preliminary report timeline that the crew diagnosed the UAS, and took any action that was consistent with following the UAS NNC checklist.
https://leehamnews.com/wp-content/up...MAX-ET-AVJ.pdf
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Old 1st May 2019, 16:50
  #4697 (permalink)  
 
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Salute!

Great discussion.
I gotta get one of our test pilot golden arms to talk a bit.
While I go thru old stuff discussing the pitch moments of the 737, I will leave you a few thots.

Unless you only wish to change what the pilot feels, you do not screw around with the largest aero surface on the plane besides the main wing. You screw around with the artificial feel system. GASP!!

Pushers are not a really neat fix when all you want to do is reduce the nose up pitching moment. You have to deal with the aero as well as the artificial feel system.. And before more research and consulting, I comment:

The Airbus FBW in 320 plus does not give a rat’s about the “feel” close to a stall AoA. You can command max or min and that stick has the same spring force as if you were in a dogfight in the F-22 or Typhoon. Huh? It was certified because the basic aero met the criteria and the plane design would do just fine with ropes, levers, pulleys, pushrods and such. That was not what I flew in the Viper, due to inherent stability designed in from day one. But I can use my experience using a stick with zero feedback, and it commanded roll rate and gee according to how many pounds I exerted on the thing (Airbus stick is displacement mainly, but Viper was all pressure sensors)

PEI..... We need some test community inputs to this discussion

Gums.....
P.S. tanks for tolerating this old fart that flew ropes, pulleys and then hybrids and finally no sierra FBW that had zero mechanical anything before some here were born.






Last edited by gums; 1st May 2019 at 16:58. Reason: added comment
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Old 1st May 2019, 16:59
  #4698 (permalink)  
 
Join Date: Mar 2014
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Who owns the CVR and FDR data?

A complete CVR transcript would shed a lot of light on the question of whether or not an MCAS runaway is beyond the capability of the average MAX pilot. A complete FDR dataset would fill in some of the blanks that continue to cause confusion and argument. Many posters say, "Let's wait for the final report."

Waiting is not an acceptable option for Boeing and their MAX-customers.

Does anyone know if Boeing/FAA/NTSB have seen the complete CVR and FDR data?

The Ethiopean government's secrecy in the early days of the investigation suggest that they are not in the mood for sharing. International law entitles them to run the investigation. Does it also allow them to hide the data?

YYZjim
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Old 1st May 2019, 17:01
  #4699 (permalink)  
 
Join Date: May 2019
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Not a 737 driver so I have no vested interest in defending my plane/livelihood. Also neither American nor European, so I could not care less about defending my "team". What I am is a frequent traveller who would prefer not to become a smoldering crater in the ground -- preferably not even if I am flying on a plane flown by the most poorly trained, least-skilled and most sleep-deprived (but properly licensed) pilot.

I've read this whole thread and then some, and thus far my reading of the facts of these incidents is as follows:

1. (Fact) Boeing was caught with their pants down by the A320neo and needed to come up with a quick 737 update with better fuel economy (i.e. with minimal engineering changes).

2. (Fact) Rather than produce a clean-sheet design or update the 737 undercarriage/wings to incorporate an extended main landing gear, Boeing extended the nose gear and bolted on larger engines by moving the engines forward relative to COG, in spite of the negative impact that this had on aircraft stability/handling.

3. (Fact) The 737 stabilizer has much greater vertical authority than the elevator (I have seen estimates of about 3x as much)

4. (Fact) Due to the enlarged and forward-positioned engines, the Max exhibits poor aerodynamic/flight handling characteristics (tendency to pitch up) at high AOA when approaching stall. As communicated by at least one purported Boeing engineer much further up this thread (post 1000 or thereabouts?), this tendency to pitch up is so extreme that elevator input alone would not have been sufficient to make the aircraft adequately controllable, hence why a stick pusher was considered and rejected.

5. (Speculated) For the same reason, once in a stall, the 737 Max is quite likely to be extremely difficult to bring back under control through normal control surface inputs, without the rapid application of an extreme amount of stab trim (i.e. by MCAS). (Has anyone flown a Max into a stall at MTOW/rear COG and would they be able to provide input on whether it is possible to bring it back under control without trim input/MCAS?)

6. (Fact) The FAA/other authorities require positive elevator feel at high AOA to provide stall protection.

7. (Fact) MCAS is designed to provide positive elevator feel at high AOA to meet regulator requirements.

8. (Fact, deduced from 6 and 7) MCAS provides stall protection.

9. (Fact) The certified limit of MCAS authority (one burst of 0.6 deg) was also not sufficient to make the aircraft adequately controllable at high AOA. Boeing increased MCAS authority to 2.5 degrees per cycle, with an unlimited number of allowed cycles, without informing regulators/obtaining certification.

10. (Fact) The FAA was so understaffed/feckless that they did not discover/were not made aware of this severe deviation from certification.

11. (Fact) Based on various pilot reports and according to archaic 737 manuals and flight training, past a certain limit that is inversely related to airspeed, manual authority over trim is impossible for pilots of less than super-human strength, so e trim is the only option available.

12. (Fact) Boeing shrunk the size of the Max trim wheel, reducing leverage and further increasing strength required to manually trim. They failed to inform regulators of this change.

13. (Fact, deduced from numbers 10 and 3) Under certain portions of the flight envelope, pilots lose all vertical authority without electric trim.

14. (Opinion) Based on its essentiality to maintaining vertical authority under all allowed portions of the flight envelope, electric trim should be considered a safety-critical component and should be subject to all of the requirements thereof (e.g. redundant computers, motors, etc.)

15. (Fact) Boeing redesigned the cutoff switches to make it impossible to disable MCAS without also disabling e trim. They then failed to describe these changes in the manual or provide this information to pilots.

16. (Unverified, but extremely likely) Based on the inconsistent application of upward electric trim by the pilots during the two accidents, something was likely preventing the pilots from continuously applying upward trim. If your life is flashing before your eyes and you are battling to get your aircraft to climb, your thumb is going to be glued to the trim switch, not making the bare minimum in small (and inconsistent) blip applications. As far as I know it has not been conclusively reported, but it appears that based on the trim traces that MCAS is in fact capable of overriding thumb trim and not the other way around, despite claims to the contrary.

17. (Speculation) Many have speculated that the electric trim motor is also incapable of controlling the stabilizer under certain portions of the flight envelope (e.g. high speed, extreme trim, opposing elevator). If this is true, then there are actually portions of the flight envelope in which pilots lose all vertical authority even if electric trim is operational.

18. (Opinion) If there are regions of the 737 flight envelope (e.g. extreme trim, opposing elevator) under which pilots lose vertical authority, the whole 737 fleet, both maxs and NGs (assuming that they are also affected by the same issue), should be grounded until such a time as trim deflection is mechanically limited to prevent entry into these uncontrollable regions of the flight envelope.

19. (Fact) Boeing did not advise pilots of the limits of manual trim authority or the need to e trim to neutral before cutting the trim switches.

20. (Fact) Boeing decided to base the activation of MCAS on a single AOA sensor (rather than making use of the two installed sensors) and a single computer, without even basic sanity checking.

21. (Fact) A large number of recent reports have identified safety-critical manufacturing defects and foreign object debris in recently-constructed Boeing aircraft as a result of lax manufacturing standards, and articles from yesterday indicate that a whistleblower reported to the FAA on April 5th that FOD had resulted in damage to Max AOA wiring in at least one instance.

22. (Fact) Boeing did not inform airlines or pilots about MCAS, did not include it in the manual, and did not provide any MCAS related training.

23. (Fact) Boeing chose not to provide an aural/visual MCAS activation warning.

24. (Fact) Boeing opted to sell the AOA indicator display as an optional extra rather than a built-in safety feature.

25. (Fact) Boeing disabled the AOA disagree warning for customers who did not purchase the optional AOA indicator display. Previous 737 models had functional AOA disagree warnings. As reported recently by the SWA pilots assoc, Boeing did not inform airlines/pilots of this change.

26. (Fact) Boeing did not make or arrange for the production of an adequate number of Max simulators, hence the extreme resistance to any changes that would require sim training.

27. (Fact) Pilots did not receive any information about MCAS or sim/flight training for dealing with a possible MCAS activation prior to these incidents (they did not even know that the system existed).

28. (Inferred based on events) The incident pilots were inadequately trained to handle and responded very poorly to MCAS activation incidents. (Note: is it the pilots' fault that they were inadequately trained on a system that they did not know existed on simulators that were not available?)

29. (Fact) After the Lion air accident, Boeing provided only the bare minimum in information regarding MCAS and refused to acknowledge any problem with the plane, placing the blame entirely on the dead pilots.

30. (Fact) After the Ethiopian accident, Boeing resisted efforts to ground the aircraft and refused to acknowledge any problem with the plane, again placing the blame entirely on the dead pilots.

31. (Fact) After the Ethiopian incident and following a meeting between Muilenburg and Trump, Trump's FAA stooge resisted requests to ground the Max.

32. (Fact) Only after foreign regulators began grounding the Max en masse did the FAA also follow suit and ground the Max.

33. (Fact) Boeing, as evidenced by Muilenburg's recent press conference, still refuses to acknowledge any problem with the plane, and continues to place blame solely on the dead pilots. Meanwhile they are working on a software "improvement" for MCAS, without any reports of hardware fixes in the works.

Conclusion:

In my opinion, Boeing has acted disgracefully in this situation and should be prosecuted criminally for manslaughter (perhaps this is an opportunity for Barr to prove that he is not a Trump stooge). Meanwhile the FAA has been completely compromised and corrupted by the kleptocracy that is taking over America. These are systemic failings rather than a one-off incident, and they raise the question of how many other similar failures remain lurking in the shadows due to negligent management practices and oversight in a country that is rapidly losing any respect for the rule of law. No outcome short of a complete (and transparent) overhaul of Boeing's safety culture, prosecution and incarceration of senior management, and possibly even a break-up of the company (e.g. splitting off commercial aviation from defense) will make me comfortable flying on any recently-produced Boeing metal. I'll be putting my money where my mouth is by exclusively booking Airbus until these changes are made. I'm not holding my breath, so it looks like I'll be flying Airbus for some time to come.
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Old 1st May 2019, 17:06
  #4700 (permalink)  
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Edit - Gums (and also Bill Fly) - just seen your Post 4706 when I Posted - but as I've written this forgive me for Posting anyway. Exactly! You and I are together I think on this! (If I may be so bold as to assume that?)

Originally Posted by AAKEE View Post
...........

There is a pitch up moment from the engine nacell’s at high alfa but it is allways less than the pitch down coming from the CG being forward of the centre of pressure center. The nacelles pitch up moment ease the elevator work to pitch up /decrease speed, making the stick force gradient to low.
Never flown (or fixed) Boeings but, given the above which is what I think we all agree is the issue – not enough stick force at higher AoA to meet Certification due to the pitch-up moment generated by the donks homes - then surely this Thread (B737 Feel And Centering Unit) describes where the solution should have been implemented to “reprofile” Elevator Feel but for Speed and AoA rather than just for Speed – in other words, add in a bit more "aft" stick Q-resistance at high AoA.

While, ideally using a dual AoA system, if Boeing insisted on just one AoA feed, all you would have is a slightly erroneous “feel profile” at higher AoAs with a U/S AoA system (auto cured when the AoA system is fixed). This would seem far more manageable (tho it would be out of Certification limits in purist terms on AoA fail) than the MCAS erroneously trimming AND which materially affects the flightpath (and I’m deffo going to avoid any discussions on whether or not that was handleable by an “average crew” - whatever one of those is – but we do have 2 jets down with awful consequences for 100’s of people so the complete system (incl aircrew and bits and software) fell over twice).

Is that assessment correct and did MCAS seem to provide Boeing with a simpler/cheaper solution to “emulate” a change in Q rather than make changes to the Elevator Feel Computer (EFC) in it’s role as described by IFixPlanes? I can’t really recall this discussion of the EFC anywhere. Or, since that Thread was wayyy back in 2010, does the EFC no longer exist – but since Q-feel has been around for ever really - something still does that job surely. Boeing seems to be trying to keep the aircraft away from high AoA so that we don't get uncertifiable Q issues rather than sorting Q so it's certified at all AoAs. I can’t recall where the schematics appear in this thread re an EFC but just a thought … and happy to crawl back into my box if talking utter tosh! Won’t be the first time for me!

Originally Posted by AAKEE View Post
...........

Gums, you have my respect for many excellent posts and a very good carreer! Thumbs up :-)
And “Here, here!” - always good to see Gums chipping in for the reasons above!

Last edited by Hot 'n' High; 1st May 2019 at 17:25.
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