Boeing 737 Max design error

[Lasse Langwadt Christense]

mandag den 6. maj 2019 kl. 21.06.02 UTC+2 skrev tra...@optonline.net:

On Monday, May 6, 2019 at 1:10:10 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 6. maj 2019 kl. 16.36.21 UTC+2 skrev Joe Chisolm:
On Mon, 06 May 2019 08:12:13 +0000, DecadentLinuxUserNumeroUno wrote:

omnilobe@gmail.com wrote in
news:c53fb380-eaac-4408-9422-959a9d1f8d3f@googlegroups.com:

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling? Without software it
stalls.

The software was for IF the plane stalled, which it did not. It was
a sensor error.

It is because the pilot does not always have a sense of a stall
situation, which the craft never get into anyway unless the pilot and
copilot are sleeping.

A stalling plane is pilot error, not airplane error.

The biggest issue to me is that there was no release switch to return
pilot control.

There is a procedure and it's a MEMORY item of what to do in a
run-away trim situation. There are 2 switches, just below the
throttle quadrant that cuts out the electric trim (and MCAS).
Once turned off the AFM says you do not turn it back on. It
stays off until you land.
Auto Pilot off
Auto Throttles off
Auto trim off.

A friend of mine with over 10K hours in the 737 variants explains
these are memory items drilled into your head and you practice
them every 6 months in the simulator check ride.

In the Ethiopian crash it seems they never disabled the auto throttles
and towards the end they re-engaged auto trim (and MCAS). The aircraft
was already red-line in speed.


yes it does seem strange what the pilots did, but they might have had a
reason for it, I guess we will learn eventually

I saw a 737 pilot show in a simulator that it is possible at high speed
to get so much nose down trim that is near impossible to move the trim nose
up because of the aero dynamic forces, the solution is to dive while trimming but with no altitude to spare that's not an option

In the case of the Ethiopian crash, the solution would have been to turn the
electric trim back on, while holding the trim up button in. It looks like
in the seconds before the crash, they did turn it back on and MCAS pushed nose
down again. No evidence if they were pushing the trim up button at the time.
Or what happens if the pilots are commanding trim up while MCAS is doing
trim down, ie who wins or if nothing happens. The even better procedure
would have been to use the up trim button to first get the trim back to
near neutral and only then turn off the trim switches.

everything I've read says that the MCAS with pause for 10 seconds
if the pilots command trim up, though it might be confusing that the
problem goes away only to come back 10 seconds later

Interesting that it's so difficult to manually trim with full trim and speed.
It also apparently takes some time winding the wheel, it's many turns.
I watched a video of it being done in a simulator. One pilot spent most
of his time adjusting the trim, as needed, while they did a return and
landed. Also interesting, with the LA flight the day before the crash,
when they had the same problem and the jump seat pilot had to tell the
actual pilots what to do, they then continued on to their destination,
using manual trim. Must be different standards over there, in
the US the plane would have returned to the airport, for a variety of
reasons, including that you're not sure what exactly is wrong or going on.

since you can override the electric trim by grabbing a trim wheel and
holding it I assume there must be some kind of clutch limiting the electric
trim force to less than you can hold by hand, which lead to the question;
if the force needed to trim up is so high you can hardly move the trim wheel won't the electric trim be useless as well?

I've asked on a few of the youtube videos done by pilots but never got
an answer

 

On Monday, May 6, 2019 at 1:44:26 PM UTC-4, Tom Gardner wrote:

On 06/05/19 13:55, trader4@optonline.net wrote:
On Sunday, May 5, 2019 at 11:25:13 PM UTC-4, omni...@gmail.com wrote:
Hello electronics design experts. I will never fly a 737 Max.
It is so flawed that board members at Boeing, like Caroline Kennedy and
Nikki Haley (Trump UN ambassador) should use their expertise to terminate
that death trap.

Electronics design sometimes used redundant sensors in case it is for
life support. Not Boeing. Kennedy and Haley approve of

Weight and Balance of the 737 Max.

I looked at photos of 737 and 737 Max. The 737 has the front of
the engine at the front of the wing. The Max has the rear of the engine at the front of the wing. That makes it stall easily.

It doesn't stall so easily. The problem only arises at very high levels
of angle of attack, that a plane would only experience in extreme, very
unusual situations. And then the problem is
that if you let go of the controls, instead of heading back toward a
lower angle of attack, the plane can nose up more, which would stall it.
The plane likely could not have been certified with that problem.
That's what MCAS was put in there to counteract. Granted it's not the
best design and a totally new plane design would have been better.
But then that costs a lot more, both in development and then you have
increased costs for the airlines due to training, type ratings, and now
you have a mixed fleet that adds to maintenance costs, etc.

False.

Well that's a lie. It doesn't cost more to develop a whole new plane
as opposed to modifying an existing design? Training and certification
on a new aircraft type doesn't cost money? Having some pilots that are
certified for one, but not the other, doesn't limit who's available to
fly a plane? Some airlines don't chose to limit the variants they fly
so that parts are the same, maintenance training is the same, etc?

The problem is that when approaching a stall, the SOP is to
increase engine power. In the 737 MAX (unlike all other 737s)
that causes a pitch up due to the changed engine position.
That pitch up increases angle of attack, thus driving further
into the stall.

MCAS was designed to sense that, and pitch down in a way
invisible to the pilot - so that no new training was required.

If that's the case, then why does MCAS force the nose down at high
angle of attack without regard to whether the throttles are advanced
or not?

Software cannot fix that
weights and balance mistake.

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling? Without software it stalls.

That's not true, except at very high angles of attack it behaves just like
any other 737.

False, or at least irrelevant.

Well, make up your mind. And it's not irrelevant because the other poster
claimed that

"Do you want to fly a plane that only software is used to prevent stalling? Without software it stalls."

So whether it really stalls without software under most conditions or the
software was only added for very high AOA conditions that a plane would
never experience except for some very rare, extreme conditions that it
should never see in passenger service, is relevant.

The MAX's changed aerodynamics make it more likely to encounter
high AoA, and if it does, the changed aerodynamics force it
into even higher AoA.

I would disagree. A 737 max is no more likely to wind up in that high
AOA position. It has to be some extreme flying, not a typical passenger
flight to get it there. And only then does the Max have a tendency
to stall easier.

MCAS was designed to detect and prevent the latter - without
the pilot being aware of any changes. "No new training
required, because it behaves the same".

That's true, but it's at the margins of operation, not what passenger
planes see every day.

 

On Monday, May 6, 2019 at 1:48:20 PM UTC-4, Tom Gardner wrote:

On 06/05/19 16:14, John Larkin wrote:
On Sun, 5 May 2019 20:25:09 -0700 (PDT), omnilobe@gmail.com wrote:

Hello electronics design experts. I will never fly a 737 Max.
It is so flawed that board members at Boeing, like Caroline Kennedy and
Nikki Haley (Trump UN ambassador) should use their expertise to terminate
that death trap.

Electronics design sometimes used redundant sensors in case it is for
life support. Not Boeing. Kennedy and Haley approve of

Weight and Balance of the 737 Max.

I looked at photos of 737 and 737 Max. The 737 has the front of
the engine at the front of the wing. The Max has the rear of the engine at the front of the wing. That makes it stall easily. Software cannot fix that
weights and balance mistake.

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling?

A jet plane is full of software that's critical to flight. The
throttles aren't mechanical any more, they send signals to the FADECs.
And on and on.

I don't think that your "looking at photos" is solid aerodynamic
analysis.

Boeing made some appalling choices with the AOA sensors. Absent those
mistakes, the 737 would be fine.

The Board of Directors didn't design the anti-stall system or decide
to only use one AOA sensor per flight.

Correct, but they did employ the people that set the company
ethos that allowed (and possibly encouraged) the corner cutting.

Marketing pushed for "no new training necessary, because it
behaves the same". We have no idea as to whether engineers
pushed back.

Why would engineers be expected to push back? This wasn't some after
thought. Boeing decided they wanted a plane based on the existing
737 for a variety of reasons, including that it was an obvious advantage
to it;s customers and in turn, to Boeing, because no new training would
be required. And for it's customers, it's a very similar plane to operate
and maintain. If they had come up with a new design, then the pilots
would not just need additional training, they would need a type rating
for the new aircraft. All that entails very real time and costs.
And with MCAS, by all indications it did behave the same way, unless
MCAS failed and even that is no different than a similar runaway trim
condition, which all pilots are supposed to have committed to memory.

This marketing push and corporate ethos thing is reminiscent
of the VolksWagen diesel fiasco.

Apples and Oranges. VW deliberately cheated and broke the law.
They designed a cheat around testing in the cars, something that was
not needed, was not used, except when the car detected that it was
being EPA tested. Boeing had a very reasonable design goal, one that
saved their customers money and time. It's just that somehow engineering
and safety turned to crap and failed badly. There is no reason to believe
that's anymore related to marketing than if some other fatal and bad
design flaw was found in any other aircraft. Presumably Boeing didn't
say to it's design team, come up with a poor, stupid MCAS design.
Now, if evidence emerges that there were internal discussions about it
being a bad design and marketing or management overrode it or it turns
out designers argued the AOA disagree light and display needed to be
standard equipment for safety and they were overridden, then it would
be different.

 

On Monday, May 6, 2019 at 4:12:21 PM UTC-4, Lasse Langwadt Christensen wrote:

mandag den 6. maj 2019 kl. 21.06.02 UTC+2 skrev tra...@optonline.net:
On Monday, May 6, 2019 at 1:10:10 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 6. maj 2019 kl. 16.36.21 UTC+2 skrev Joe Chisolm:
On Mon, 06 May 2019 08:12:13 +0000, DecadentLinuxUserNumeroUno wrote:

omnilobe@gmail.com wrote in
news:c53fb380-eaac-4408-9422-959a9d1f8d3f@googlegroups.com:

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling? Without software it
stalls.

The software was for IF the plane stalled, which it did not. It was
a sensor error.

It is because the pilot does not always have a sense of a stall
situation, which the craft never get into anyway unless the pilot and
copilot are sleeping.

A stalling plane is pilot error, not airplane error.

The biggest issue to me is that there was no release switch to return
pilot control.

There is a procedure and it's a MEMORY item of what to do in a
run-away trim situation. There are 2 switches, just below the
throttle quadrant that cuts out the electric trim (and MCAS).
Once turned off the AFM says you do not turn it back on. It
stays off until you land.
Auto Pilot off
Auto Throttles off
Auto trim off.

A friend of mine with over 10K hours in the 737 variants explains
these are memory items drilled into your head and you practice
them every 6 months in the simulator check ride.

In the Ethiopian crash it seems they never disabled the auto throttles
and towards the end they re-engaged auto trim (and MCAS). The aircraft
was already red-line in speed.


yes it does seem strange what the pilots did, but they might have had a
reason for it, I guess we will learn eventually

I saw a 737 pilot show in a simulator that it is possible at high speed
to get so much nose down trim that is near impossible to move the trim nose
up because of the aero dynamic forces, the solution is to dive while trimming but with no altitude to spare that's not an option

In the case of the Ethiopian crash, the solution would have been to turn the
electric trim back on, while holding the trim up button in. It looks like
in the seconds before the crash, they did turn it back on and MCAS pushed nose
down again. No evidence if they were pushing the trim up button at the time.
Or what happens if the pilots are commanding trim up while MCAS is doing
trim down, ie who wins or if nothing happens. The even better procedure
would have been to use the up trim button to first get the trim back to
near neutral and only then turn off the trim switches.


everything I've read says that the MCAS with pause for 10 seconds
if the pilots command trim up, though it might be confusing that the
problem goes away only to come back 10 seconds later

Agree. I'm not sure on the 10 secs, thought it might be 5, but you're
probably right and it's basically the same, MCAS comes back quickly.

Interesting that it's so difficult to manually trim with full trim and speed.
It also apparently takes some time winding the wheel, it's many turns.
I watched a video of it being done in a simulator. One pilot spent most
of his time adjusting the trim, as needed, while they did a return and
landed. Also interesting, with the LA flight the day before the crash,
when they had the same problem and the jump seat pilot had to tell the
actual pilots what to do, they then continued on to their destination,
using manual trim. Must be different standards over there, in
the US the plane would have returned to the airport, for a variety of
reasons, including that you're not sure what exactly is wrong or going on.

since you can override the electric trim by grabbing a trim wheel and
holding it I assume there must be some kind of clutch limiting the electric
trim force to less than you can hold by hand, which lead to the question;

IDK, but I had thought about the same thing, that part of the runaway
trim procedure is that you can hold the trim wheel to overcome it,
so how is that done?




> if the force needed to trim up is so high you can hardly move the trim wheel won't the electric trim be useless as well?

Very good question, but obviously the electric does still work, because
on these flights they were able to keep bringing trim back up and MCAS
was able to push it down. How you reconcile those, IDK. Also, if it
really was impossible for that Ethiopian co-pilot to turn the trim
wheel, seems there is more wrong there than just MCAS. It would imply
that on any 737, if you have a runaway trim and it goes to hard trim
in either direction, you may not be able to counter it by the stated
trim procedure.

Also, I think a step is missing in the runaway trim procedure. After
identifying runaway trim, the procedure should be to see if you can
use the trim button to get the trim back to near neutral and then
turn off the switches. If you can get it close to neutral that way,
that's going to be a lot faster than winding it by hand. That might have been
what the Ethiopian pilot was trying to do in the last seconds. But we
don't know much, they haven't released the voice recorder or anything
that shows what, if anything they were saying at that point. The
authorities only quoted the co-pilot saying he was going to trim
manually and that he couldn't, not that he couldn't turn the *wheel*
for example. It's even possible he was confused and was referring to
the trim buttons on the controls, which of course would not work
because the switches were off. Also quite surprising that from what
they released there was very little crew management and discussion.
Like the switches got turned back on, but apparently no words informing
the other pilot, etc.

I've asked on a few of the youtube videos done by pilots but never got
an answer

Someone must know the answer.

 

[Lasse Langwadt Christense]

mandag den 6. maj 2019 kl. 22.59.28 UTC+2 skrev tra...@optonline.net:

On Monday, May 6, 2019 at 4:12:21 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 6. maj 2019 kl. 21.06.02 UTC+2 skrev tra...@optonline.net:
On Monday, May 6, 2019 at 1:10:10 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 6. maj 2019 kl. 16.36.21 UTC+2 skrev Joe Chisolm:
On Mon, 06 May 2019 08:12:13 +0000, DecadentLinuxUserNumeroUno wrote:

omnilobe@gmail.com wrote in
news:c53fb380-eaac-4408-9422-959a9d1f8d3f@googlegroups.com:

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling? Without software it
stalls.

The software was for IF the plane stalled, which it did not. It was
a sensor error.

It is because the pilot does not always have a sense of a stall
situation, which the craft never get into anyway unless the pilot and
copilot are sleeping.

A stalling plane is pilot error, not airplane error.

The biggest issue to me is that there was no release switch to return
pilot control.

There is a procedure and it's a MEMORY item of what to do in a
run-away trim situation. There are 2 switches, just below the
throttle quadrant that cuts out the electric trim (and MCAS).
Once turned off the AFM says you do not turn it back on. It
stays off until you land.
Auto Pilot off
Auto Throttles off
Auto trim off.

A friend of mine with over 10K hours in the 737 variants explains
these are memory items drilled into your head and you practice
them every 6 months in the simulator check ride.

In the Ethiopian crash it seems they never disabled the auto throttles
and towards the end they re-engaged auto trim (and MCAS). The aircraft
was already red-line in speed.


yes it does seem strange what the pilots did, but they might have had a
reason for it, I guess we will learn eventually

I saw a 737 pilot show in a simulator that it is possible at high speed
to get so much nose down trim that is near impossible to move the trim nose
up because of the aero dynamic forces, the solution is to dive while trimming but with no altitude to spare that's not an option

In the case of the Ethiopian crash, the solution would have been to turn the
electric trim back on, while holding the trim up button in. It looks like
in the seconds before the crash, they did turn it back on and MCAS pushed nose
down again. No evidence if they were pushing the trim up button at the time.
Or what happens if the pilots are commanding trim up while MCAS is doing
trim down, ie who wins or if nothing happens. The even better procedure
would have been to use the up trim button to first get the trim back to
near neutral and only then turn off the trim switches.


everything I've read says that the MCAS with pause for 10 seconds
if the pilots command trim up, though it might be confusing that the
problem goes away only to come back 10 seconds later

Agree. I'm not sure on the 10 secs, thought it might be 5, but you're
probably right and it's basically the same, MCAS comes back quickly.






Interesting that it's so difficult to manually trim with full trim and speed.
It also apparently takes some time winding the wheel, it's many turns..
I watched a video of it being done in a simulator. One pilot spent most
of his time adjusting the trim, as needed, while they did a return and
landed. Also interesting, with the LA flight the day before the crash,
when they had the same problem and the jump seat pilot had to tell the
actual pilots what to do, they then continued on to their destination,
using manual trim. Must be different standards over there, in
the US the plane would have returned to the airport, for a variety of
reasons, including that you're not sure what exactly is wrong or going on.

since you can override the electric trim by grabbing a trim wheel and
holding it I assume there must be some kind of clutch limiting the electric
trim force to less than you can hold by hand, which lead to the question;

IDK, but I had thought about the same thing, that part of the runaway
trim procedure is that you can hold the trim wheel to overcome it,
so how is that done?




if the force needed to trim up is so high you can hardly move the trim wheel won't the electric trim be useless as well?

Very good question, but obviously the electric does still work, because
on these flights they were able to keep bringing trim back up and MCAS
was able to push it down. How you reconcile those, IDK. Also, if it
really was impossible for that Ethiopian co-pilot to turn the trim
wheel, seems there is more wrong there than just MCAS. It would imply
that on any 737, if you have a runaway trim and it goes to hard trim
in either direction, you may not be able to counter it by the stated
trim procedure.

I saw this snipped from the 737 Flight Crew Training Manual, chapter Non-Normal Operations/Flight Controls, sub heading Manual Stabilizer trim:

"Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually."

Also, I think a step is missing in the runaway trim procedure. After
identifying runaway trim, the procedure should be to see if you can
use the trim button to get the trim back to near neutral and then
turn off the switches.

I guess they expected a fault to be something like a short that would just keep trimming for as long as it was powered

 

[John Larkin]

On Mon, 6 May 2019 18:48:16 +0100, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

On 06/05/19 16:14, John Larkin wrote:
On Sun, 5 May 2019 20:25:09 -0700 (PDT), omnilobe@gmail.com wrote:

Hello electronics design experts. I will never fly a 737 Max.
It is so flawed that board members at Boeing, like Caroline Kennedy and
Nikki Haley (Trump UN ambassador) should use their expertise to terminate
that death trap.

Electronics design sometimes used redundant sensors in case it is for
life support. Not Boeing. Kennedy and Haley approve of

Weight and Balance of the 737 Max.

I looked at photos of 737 and 737 Max. The 737 has the front of
the engine at the front of the wing. The Max has the rear of the engine at the front of the wing. That makes it stall easily. Software cannot fix that
weights and balance mistake.

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling?

A jet plane is full of software that's critical to flight. The
throttles aren't mechanical any more, they send signals to the FADECs.
And on and on.

I don't think that your "looking at photos" is solid aerodynamic
analysis.

Boeing made some appalling choices with the AOA sensors. Absent those
mistakes, the 737 would be fine.

The Board of Directors didn't design the anti-stall system or decide
to only use one AOA sensor per flight.

Correct, but they did employ the people that set the company
ethos that allowed (and possibly encouraged) the corner cutting.

Marketing pushed for "no new training necessary, because it
behaves the same". We have no idea as to whether engineers
pushed back.

This marketing push and corporate ethos thing is reminiscent
of the VolksWagen diesel fiasco.

Not exactly. The VW people deliberately designed in specific cheats.
The Boeing thing was a mistake followed by some poor judgement.

Sounds like diesel sales are way down in Europe. Lots of big mistakes
were made.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

On Monday, May 6, 2019 at 5:23:24 PM UTC-4, Lasse Langwadt Christensen wrote:

mandag den 6. maj 2019 kl. 22.59.28 UTC+2 skrev tra...@optonline.net:
On Monday, May 6, 2019 at 4:12:21 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 6. maj 2019 kl. 21.06.02 UTC+2 skrev tra...@optonline.net:
On Monday, May 6, 2019 at 1:10:10 PM UTC-4, Lasse Langwadt Christensen wrote:
mandag den 6. maj 2019 kl. 16.36.21 UTC+2 skrev Joe Chisolm:
On Mon, 06 May 2019 08:12:13 +0000, DecadentLinuxUserNumeroUno wrote:

omnilobe@gmail.com wrote in
news:c53fb380-eaac-4408-9422-959a9d1f8d3f@googlegroups.com:

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling? Without software it
stalls.

The software was for IF the plane stalled, which it did not.. It was
a sensor error.

It is because the pilot does not always have a sense of a stall
situation, which the craft never get into anyway unless the pilot and
copilot are sleeping.

A stalling plane is pilot error, not airplane error.

The biggest issue to me is that there was no release switch to return
pilot control.

There is a procedure and it's a MEMORY item of what to do in a
run-away trim situation. There are 2 switches, just below the
throttle quadrant that cuts out the electric trim (and MCAS).
Once turned off the AFM says you do not turn it back on. It
stays off until you land.
Auto Pilot off
Auto Throttles off
Auto trim off.

A friend of mine with over 10K hours in the 737 variants explains
these are memory items drilled into your head and you practice
them every 6 months in the simulator check ride.

In the Ethiopian crash it seems they never disabled the auto throttles
and towards the end they re-engaged auto trim (and MCAS). The aircraft
was already red-line in speed.


yes it does seem strange what the pilots did, but they might have had a
reason for it, I guess we will learn eventually

I saw a 737 pilot show in a simulator that it is possible at high speed
to get so much nose down trim that is near impossible to move the trim nose
up because of the aero dynamic forces, the solution is to dive while trimming but with no altitude to spare that's not an option

In the case of the Ethiopian crash, the solution would have been to turn the
electric trim back on, while holding the trim up button in. It looks like
in the seconds before the crash, they did turn it back on and MCAS pushed nose
down again. No evidence if they were pushing the trim up button at the time.
Or what happens if the pilots are commanding trim up while MCAS is doing
trim down, ie who wins or if nothing happens. The even better procedure
would have been to use the up trim button to first get the trim back to
near neutral and only then turn off the trim switches.


everything I've read says that the MCAS with pause for 10 seconds
if the pilots command trim up, though it might be confusing that the
problem goes away only to come back 10 seconds later

Agree. I'm not sure on the 10 secs, thought it might be 5, but you're
probably right and it's basically the same, MCAS comes back quickly.






Interesting that it's so difficult to manually trim with full trim and speed.
It also apparently takes some time winding the wheel, it's many turns.
I watched a video of it being done in a simulator. One pilot spent most
of his time adjusting the trim, as needed, while they did a return and
landed. Also interesting, with the LA flight the day before the crash,
when they had the same problem and the jump seat pilot had to tell the
actual pilots what to do, they then continued on to their destination,
using manual trim. Must be different standards over there, in
the US the plane would have returned to the airport, for a variety of
reasons, including that you're not sure what exactly is wrong or going on.

since you can override the electric trim by grabbing a trim wheel and
holding it I assume there must be some kind of clutch limiting the electric
trim force to less than you can hold by hand, which lead to the question;

IDK, but I had thought about the same thing, that part of the runaway
trim procedure is that you can hold the trim wheel to overcome it,
so how is that done?




if the force needed to trim up is so high you can hardly move the trim wheel won't the electric trim be useless as well?

Very good question, but obviously the electric does still work, because
on these flights they were able to keep bringing trim back up and MCAS
was able to push it down. How you reconcile those, IDK. Also, if it
really was impossible for that Ethiopian co-pilot to turn the trim
wheel, seems there is more wrong there than just MCAS. It would imply
that on any 737, if you have a runaway trim and it goes to hard trim
in either direction, you may not be able to counter it by the stated
trim procedure.

I saw this snipped from the 737 Flight Crew Training Manual, chapter Non-Normal Operations/Flight Controls, sub heading Manual Stabilizer trim:

"Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually."

Well, that answers one question. Apparently it's known and accepted that
with enough trim and speed, you can't wind it by hand. Which makes the
MCAS design all the more worse. A weathervane blowing in the wind can
force the nose down hard, continually and if it's hard enough and
you just follow the runaway trim procedure, you might not be able
to recover period. Even worse, if the AOA is screwed, like the LA one
was, reading 20 deg on the ground, when does MCAS try to kill you?
Just as you're retracting the flaps, which means right after takeoff,
at low altitude, where there may not be enough time to figure it out
and recover.

Also, I think a step is missing in the runaway trim procedure. After
identifying runaway trim, the procedure should be to see if you can
use the trim button to get the trim back to near neutral and then
turn off the switches.

I guess they expected a fault to be something like a short that would just keep trimming for as long as it was powered

I think that's probably correct and it's also the more typical case.
An intermittent short could do similar, but probably not every ten seconds
and with such persistence. But if the common case is full runaway trim,
then the fact that you may not be able to recover by hand isn't very
good either. LEt's say it runs full amok, to the down limit, now the
plane is diving, picking up speed, it takes X seconds to figure out
what's going on and react. You turn it off and try to move the trim
wheel. Can you?

 

[Tom Gardner]

On 06/05/19 21:48, John Larkin wrote:

On Mon, 6 May 2019 18:48:16 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 06/05/19 16:14, John Larkin wrote:
On Sun, 5 May 2019 20:25:09 -0700 (PDT), omnilobe@gmail.com wrote:

Hello electronics design experts. I will never fly a 737 Max.
It is so flawed that board members at Boeing, like Caroline Kennedy and
Nikki Haley (Trump UN ambassador) should use their expertise to terminate
that death trap.

Electronics design sometimes used redundant sensors in case it is for
life support. Not Boeing. Kennedy and Haley approve of

Weight and Balance of the 737 Max.

I looked at photos of 737 and 737 Max. The 737 has the front of
the engine at the front of the wing. The Max has the rear of the engine at the front of the wing. That makes it stall easily. Software cannot fix that
weights and balance mistake.

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling?

A jet plane is full of software that's critical to flight. The
throttles aren't mechanical any more, they send signals to the FADECs.
And on and on.

I don't think that your "looking at photos" is solid aerodynamic
analysis.

Boeing made some appalling choices with the AOA sensors. Absent those
mistakes, the 737 would be fine.

The Board of Directors didn't design the anti-stall system or decide
to only use one AOA sensor per flight.

Correct, but they did employ the people that set the company
ethos that allowed (and possibly encouraged) the corner cutting.

Marketing pushed for "no new training necessary, because it
behaves the same". We have no idea as to whether engineers
pushed back.

This marketing push and corporate ethos thing is reminiscent
of the VolksWagen diesel fiasco.

Not exactly. The VW people deliberately designed in specific cheats.
The Boeing thing was a mistake followed by some poor judgement.

Agreed. But "reminiscant" implies there are differences.

Sounds like diesel sales are way down in Europe. Lots of big mistakes
were made.

Indeed. In both cases.

 

[Tom Gardner]

On 06/05/19 19:55, trader4@optonline.net wrote:
> What aircraft are (or have you been) qualified to fly?

 

[Tom Gardner]

On 06/05/19 23:15, Tom Gardner wrote:

On 06/05/19 19:55, trader4@optonline.net wrote:
What aircraft are (or have you been) qualified to fly?

Sorry for the mis-attribution.

What aircraft are or have you (i.e. trader4@optonline.net)
been qualified to fly?

 

[Sylvia Else]

On 7/05/2019 3:27 am, Tom Gardner wrote:

On 06/05/19 10:44, Sylvia Else wrote:
On 6/05/2019 7:37 pm, Tom Gardner wrote:
On 06/05/19 10:00, Sylvia Else wrote:
On 6/05/2019 1:25 pm, omnilobe@gmail.com wrote:
Hello electronics design experts. I will never fly a 737 Max. It is so
 flawed that board members at Boeing, like Caroline Kennedy and
Nikki Haley (Trump UN ambassador) should use their expertise to
terminate that death trap.

Electronics design sometimes used redundant sensors in case it is
for life support. Not Boeing. Kennedy and Haley approve of

Weight and Balance of the 737 Max.

I looked at photos of 737 and 737 Max. The 737 has the front of the
engine at the front of the wing. The Max has the rear of the engine at
 the front of the wing. That makes it stall easily. Software cannot
fix
 that weights and balance mistake.

Boeing is updating its software so the giant engines can unbalance
the airplane the same way as in the two crashes. Do you want to fly
a plane
that only software is used to prevent stalling? Without software it
stalls. With software it is low cost. Nikki Haley is a Trump liar. Do
not fly Trump-Boeing death traps. Don doesn't.

The Board at Boeing is packed with dunces and insurance agents who
know
nothing about Weights and Balances of aircraft.


The effect of the software behaviour, as was, was to trim the
aircraft forward for no good reason.

The MCAS software commanded a dive for a very *good* reason: the AoA
was dangerously high. Or so it was being told by a faulty sensor.


The pilots should have treated it as a runaway trim, and acted
accordingly. Then the crashes would not have occurred.

They were overridden by the MCAS.

The procedure for a runaway trim involves tripping two switches that
disconnect the electric trim. It prevents the MCAS, or anything else,
from moving the trim electrically.

In the Ethopian crash, they did trip those switches, and it did
prevent the MCAS from doing anything, but they also couldn't, or
didn't, rotate the trim
 wheels manually to get the aircraft back into trim. They then,
unaccountably, tripped the switches again, reenabling the electric
trim, and in the process letting the MCAS make the situation even worse.

You've snipped and avoided several key points from my previous post, so
here
they are again.....



Disabling the MCAS wasn't trivial.
I don't know why you're repeating that.

There are two switches. They've been there since the year dot - they're
not new to the 737 MAX. They're to be activated by the pilots in the
case of a runaway trim. A runaway trim is where the trim is moved
excessively for no valid reason. That's what was happening. The pilots
should have use the switches. They didn't need to know about MCAS to do
that.

If the switches are used, the MCAS cannot move the trim any more. The
pilots can adjust the trim by moving the wheels by hand.

Sylvia.

 

On Monday, May 6, 2019 at 1:27:09 PM UTC-4, Tom Gardner wrote:

On 06/05/19 10:44, Sylvia Else wrote:
On 6/05/2019 7:37 pm, Tom Gardner wrote:
On 06/05/19 10:00, Sylvia Else wrote:
On 6/05/2019 1:25 pm, omnilobe@gmail.com wrote:
Hello electronics design experts. I will never fly a 737 Max. It is so
flawed that board members at Boeing, like Caroline Kennedy and Nikki
Haley (Trump UN ambassador) should use their expertise to terminate
that death trap.

Electronics design sometimes used redundant sensors in case it is for
life support. Not Boeing. Kennedy and Haley approve of

Weight and Balance of the 737 Max.

I looked at photos of 737 and 737 Max. The 737 has the front of the
engine at the front of the wing. The Max has the rear of the engine at
the front of the wing. That makes it stall easily. Software cannot fix
that weights and balance mistake.

Boeing is updating its software so the giant engines can unbalance the
airplane the same way as in the two crashes. Do you want to fly a plane
that only software is used to prevent stalling? Without software it
stalls. With software it is low cost. Nikki Haley is a Trump liar. Do
not fly Trump-Boeing death traps. Don doesn't.

The Board at Boeing is packed with dunces and insurance agents who know
nothing about Weights and Balances of aircraft.


The effect of the software behaviour, as was, was to trim the aircraft
forward for no good reason.

The MCAS software commanded a dive for a very *good* reason: the AoA was
dangerously high. Or so it was being told by a faulty sensor.


The pilots should have treated it as a runaway trim, and acted
accordingly. Then the crashes would not have occurred.

They were overridden by the MCAS.

The procedure for a runaway trim involves tripping two switches that
disconnect the electric trim. It prevents the MCAS, or anything else, from
moving the trim electrically.

In the Ethopian crash, they did trip those switches, and it did prevent the
MCAS from doing anything, but they also couldn't, or didn't, rotate the trim
wheels manually to get the aircraft back into trim. They then,
unaccountably, tripped the switches again, reenabling the electric trim, and
in the process letting the MCAS make the situation even worse.

You've snipped and avoided several key points from my previous post, so here
they are again.....



Disabling the MCAS wasn't trivial.

They didn't even have to know that MCAS existed. Like other posters
have said, the planes were clearly exhibiting runaway trim. Runaway
trim is handled by turning it off using the clearly marked switches
for that purpose, right next to those pesky trim wheels that are
spinning rapidly back and forth, to extreme and totally improper
trim positions. Then
you trim manually. One mistake Boeing made was having too much
confidence in pilots remembering their very basic flight training
that they are supposed to have committed to memory. One pilot out
of 7 clearly got it right. He was the jump seat pilot on the LA
flight the previous day. He told the two dummies flying what to do.




Normally manually

operating the controls will disable the autopilot and
give control back to the pilots. But MCAS wasn't part
of the autopilot and was designed to prevent that.

Don't forget that the *purpose* of MCAS was to *pretend*
nothing had changed, i.e. pretend that MCAS didn't exist!



It seems likely that Boeing expected that that would happen in the event that
this> non-redundant computer system misbehaved.

Yet in both cases the pilots let the aircraft get itself seriously out of
trim. So much so, that in the case of the second crash, when the the pilots
did eventually disable the electric trim, the aircraft was so far out of
trim that the pilots were not strong enough to turn the trim wheels (or they
didn't try - it's rather unclear at the moment).

It was far more than "trim".

BS. That is all MCAS does, it uses the trim system to nose down the plane.

Serious questions need to be asked about the competence of the pilots. Would
a properly trained crew have had any difficulties, even in the absence of
details about MCAS? I rather think not.

Hiding behind "properly trained" is frequently an
inadequate figleaf. That's definitely the case here,
since the the whole purpose of MCAS is, *very explicitly*,
to *avoid* having to retrain pilots!

BS. The inability of the pilots to identify runaway trim and follow the
procedure that they are supposed to have committed to memory needs to be
examined just as much as what went on at Boeing and the FAA. We need
pilots who can handle basic emergencies or they should not be flying.

For a long time Boeing has trumpeted that they allow
their pilots full autonomy, unlike the Airbus fly-by-wire
system. MCAS is a complete change in that philosophy.

All they had to do was follow the procedure they were trained to follow.
Let's see these same pilots have been on how many flights where the
trim was at some normal modest value and the planes flew find. So now
you have one where *something* is forcing bizarre nose down trim.
Doesn't matter what it was, it could be a short, a stuck button or
MCAS. So, will the plane fly right with hard nose down trim?
No. So, what to do? Even without knowing the procedure, it's pretty
fucking obvious. The electric trim has to be turned off (what did
they think those switches were for?), and then the trim needs to get
to a reasonable value manually. Very basic stuff and if you can't
figure that out, you should not be flying airplanes.

 

On Monday, May 6, 2019 at 6:27:31 PM UTC-4, Tom Gardner wrote:

On 06/05/19 23:15, Tom Gardner wrote:
On 06/05/19 19:55, trader4@optonline.net wrote:
What aircraft are (or have you been) qualified to fly?


Sorry for the mis-attribution.

What aircraft are or have you (i.e. trader4@optonline.net)
been qualified to fly?

One doesn't have to be qualified to fly anything to be allowed to comment.
And if you look back at what I've posted, it's been absolutely right.
Yet here you are questioning my qualifications? Why don't you question
the qualification of the many posters here who have been WRONG.

One said that the AOAs only gave false readings in the air, not on the ground. That's wrong. Another said that when MCAS forces trim down,
that there is nothing the pilots can do to override it. That's wrong. Another one said that without software the 737 Max stalls. Another one posted this:

When Boeing's execs heard an Ethiopian plane had crashed they were like
"wtf? what are those monkeys doing running an airline with our planes,
anyway? Well we'll just patiently explain to low IQ Americans that the
reason it crashed is due to the even lower IQ of Africans. and well I
guess we gotta pay something what's a good payout for a shithole country
victim, like $25?"

Another one posted this:

"The Max has the rear of the engine at the front of the wing. That makes it stall easily."

Or this:

"My opinion is that such software should be written by pilots,
not by spaced out no flying experience people."


And then some dummy posted this:

"This marketing push and corporate ethos thing is reminiscent
of the VolksWagen diesel fiasco. "

And this LIE:

Other poster:

The pilots should have treated it as a runaway trim, and acted accordingly. Then
the crashes would not have occurred.

You:
They were overridden by the MCAS.

That's an outright lie, as proven by the Lion Air flight the day before
the crash. They had the same problem and the jump seat pilot told the
other two dummies what to do, follow the runaway trim procedure. Not
only did it not crash, it flew on to it's destination using manual trim.
What did they do? Turn off the two switches for the trim motor and trim
MANUALLY. Geez.

Or this gem:


"It was far more than "trim".

That's another lie. All MCAS can do is apply nose down trim. If you have
proof otherwise, present it to us, Mr. "Expert".

You're just sore because you think you know it all and can't deal with
someone who has the FACTS.

 

On Mon, 6 May 2019 13:42:35 -0400, bitrex <user@example.net> wrote:

On 5/6/19 1:34 PM, bitrex wrote:
On 5/6/19 12:02 PM, trader4@optonline.net wrote:
On Monday, May 6, 2019 at 11:02:30 AM UTC-4, bitrex wrote:
On 5/6/19 4:26 AM, DecadentLinuxUserNumeroUno@decadence.org wrote:
bitrex <user@example.net> wrote in news:c1RzE.535275$cD4.504076
@fx43.iad:

500-something people dead and Boeing seems to just shrug it off like
they're Microsoft and they're gonna patch a bug in Windows 10 at the
next update. "Sorry, our bad."

    You are so full of shit.  You have no clue what they are doing with
the families of the victims, etc.

I'd imagine they're hiring a lot more of the best legal teams money can
buy to fight all the negligence lawsuits heading their way and tie them
up in court until about the year 2045 would be my guess.

The lawsuits from the victims are the least of Boeing's problems.
They will wind up paying far more to all the airlines that have grounded
737 Maxs with no date in sight for that to end.  And they are losing
orders as some airlines move away from the Max.   And there could be
criminal charges too, depending on the investigation.


On the bright side the DC-10/MD-11 eventually became a well-regarded
aircraft and is still used by many cargo fleets today


incidentally the oldest bucket I've had the pleasure of flying on was a
DC-9, New York Air. It must have been 1985 or 1986 I was very young but
I still remember the plane with the apple on the tail. It was probably a
unit from the late 60s. What a bucket

DC-9s were OK planes. The Fairchild F-27 (Ozark Airlines, AKA
Ox-Cart) was a real bucket of bolts. They unbalanced the props so the
wings flapped harder to generate lift. Then there was the Short
SD3-30 (Command Airways, AKA Kamikaze Airlines). The doors fit so
loosely that you could see daylight around them. When it rained,
water came in through the door.

 

[Banders]

On 05/06/2019 11:55 AM, trader4@optonline.net wrote:

Mushing has nothing to do with what I stated. Explain to us how a 737
that's been going 300 MPH in level flight for 30 seconds can be stalling.
It can't.

Not during those 30 seconds perhaps, but wind shear can change things in
an instant.

 

[Riley Angel]

On 2019-05-06 06:46, trader4@optonline.net wrote:

The issue with the 737 Max is that at high levels of AOA, the plane has
a tendency to nose up even further. Part of the certification process
is that if you release the controls the plane is supposed to head in
a stable direction, not toward instability. That is why MCAS was added.

This is incorrect.

 

[Sylvia Else]

On 7/05/2019 12:01 am, trader4@optonline.net wrote:

It would seem most likely that he was trying to turn
the wheel, but could not. If so, that would be another huge problem,
one that could extend to all 737s. Is it possible with extreme trim
and enough airspeed that you can't turn the wheel?

There is some Boeing documentation on this. Mentour Pilot discusses this
in one of his videos - possibly this one.

https://www.youtube.com/watch?v=xixM_cwSLcQ&t=1217s

Certainly the load on the trim jackscrew increases as the aircraft is
further out of trim, and this can reach the level where the pilots are
not strong enough to turn the trim wheels. Boeing suggest briefly
unloading the control column to allow the trim wheels to be turned, and
then loading the control column again to recover the flight path, and do
this repeatedly, until the situation improves.

Of course, to get into that position the pilots have to fail to address
the deteriorating trim situation.

Sylvia.

 

[Riley Angel]

On 2019-05-06 06:42, Jan Panteltje wrote:

I have read lately it was, it is anyways in the sense that it did not detect the output to ever tilt the thing more and more.
Looks like the dumbest loop you can ever write.
It did not check angular position (I think they added that now, only takes a 1$ MEMS chip),
and it had no redundancy.

Swing a $1 MEMS chip round your head. Which angular position is which
now? An aircraft in flight is essentially a free body with only gravity
as a reference, which can be confused by any other sort of acceleration
force.

Angle-of-attack vane sensors actually measure the angle of passage of
air around the airframe relative to the inclination of the airframe and
consequently offer information which can't reliably be measured or
calculated otherwise, which is precisely why they use fragile external
sensors to measure it.

 

[Tom Gardner]

On 07/05/19 01:34, trader4@optonline.net wrote:

On Monday, May 6, 2019 at 6:27:31 PM UTC-4, Tom Gardner wrote:
On 06/05/19 23:15, Tom Gardner wrote:
On 06/05/19 19:55, trader4@optonline.net wrote:
What aircraft are (or have you been) qualified to fly?


Sorry for the mis-attribution.

What aircraft are or have you (i.e. trader4@optonline.net)
been qualified to fly?



One doesn't have to be qualified to fly anything to be allowed to comment.

Regrettably not, but after all this /is/ usenet.


> And if you look back at what I've posted, it's been absolutely right.

No, it hasn't.

Yet here you are questioning my qualifications? Why don't you question
the qualification of the many posters here who have been WRONG.

You haven't been paying attention!

Your descriptions of aerodynamics and how aircraft fly
(and fail to fly) have been "novel". Since that's central
to the points you have been asserting very confidently,
it is worth confirming and assessing your competence
in the topic.

 

[Jasen Betts]

On 2019-05-07, Riley Angel <4736angel@pm.me> wrote:

On 2019-05-06 06:42, Jan Panteltje wrote:
I have read lately it was, it is anyways in the sense that it did not detect the output to ever tilt the thing more and more.
Looks like the dumbest loop you can ever write.
It did not check angular position (I think they added that now, only takes a 1$ MEMS chip),
and it had no redundancy.

Swing a $1 MEMS chip round your head. Which angular position is which
now? An aircraft in flight is essentially a free body with only gravity
as a reference, which can be confused by any other sort of acceleration
force.

It's worse than that. An aircraft in flight does not have gravity as a
reference, what keeps you in your seat is the reaction to lift, and
lift is perpendicular to the wings, not the ground.

--
When I tried casting out nines I made a hash of it.