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Interested
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 7:26 pm

namezero111111 wrote:
Interested wrote:
So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?


I'm sure they'd be willing to pay anyone a generous amount for a viable solution to that conundrum.


Come on guys. Someone on here must have a proposal?

How about they go 1.5 ie in the middle of 2.5 and 0.6

And promise to mention what they've done in the manual and train it from now on?

Could they get that one through the certification process?
 
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SheikhDjibouti
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 7:29 pm

Interested wrote:
So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?

There are well over 7,000 posts on these forums and that alone suggests that "simple" is definitely not an option.
I'm flattered that you think I am some sort of miracle worker who can sort this problem out. Sorry to disappoint.

For the time being, Boeing will need to sell 737NG at a discount.

But not too much of a discount because that would be dumping, and Boeing made it very clear in the C-series case that dumping is a v bad thing. :yes:

They are screwed.
Nothing to see here; move along please.
 
Amiga500
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 7:29 pm

Interested wrote:
So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?


Nothing easy IMO.

Choices boil down to

1. Get lucky with re-architecting and recording of MCAS with somehow getting buy off from FAA/EASA/TC/CAAC. Not very likely IMO.
2. Detail design changes to H-Stab/elevators. Uncertain of authority buy off that this is sufficient.
3. Resize H-stab & elevators. Most likely - guaranteed solution but with performance penalty.
4. Redesign nacelle. Difficult to be sure of success. Not likely.


But... if I were CEO of Boeing - my solution to this whole mess would solve an awful lot of Boeing's narrowbody problems.

Buy out the MC-21 program, or at least a license to build it and relocate it to the USA.
 
Interested
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 7:33 pm

Amiga500 wrote:
Interested wrote:
So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?


Nothing easy IMO.

Choices boil down to

1. Get lucky with re-architecting and recording of MCAS with somehow getting buy off from FAA/EASA/TC/CAAC. Not very likely IMO.
2. Detail design changes to H-Stab/elevators. Uncertain of authority buy off that this is sufficient.
3. Resize H-stab & elevators. Most likely - guaranteed solution but with performance penalty.
4. Redesign nacelle. Difficult to be sure of success. Not likely.


But... if I were CEO of Boeing - my solution to this whole mess would solve an awful lot of Boeing's narrowbody problems.

Buy out the MC-21 program, or at least a license to build it and relocate it to the USA.


Excuse my ignorance - are any of the above the possible software fix that Boeing says will be ready next week that can actually make the planes safe enough to get certified then?

In your opinion
 
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PixelPilot
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 7:47 pm

SheikhDjibouti wrote:
Interested wrote:
So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?

There are well over 7,000 posts on these forums and that alone suggests that "simple" is definitely not an option.
I'm flattered that you think I am some sort of miracle worker who can sort this problem out. Sorry to disappoint.

For the time being, Boeing will need to sell 737NG at a discount.

But not too much of a discount because that would be dumping, and Boeing made it very clear in the C-series case that dumping is a v bad thing. :yes:

They are screwed.


Oh boy you're so sure...
How much you want to bet Max gets back and is as strong as ever?
I like bets and will be the first to say when I'm wrong but you seem to figured out the case already by some magic carpet magic so I'm happy to go against the current :)
 
namezero111111
Posts: 139
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 8:08 pm

Amiga500 wrote:
Buy out the MC-21 program, or at least a license to build it and relocate it to the USA.


Not too shoddy an idea, talking about a black eye for Boeing, here goes the other...
 
mrbots
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 8:16 pm

Several are acting like refinement of MCAS and training of pilots and the Max will still just randomly fall out of the sky so just scrap the entire program, the fastest and highest selling program in Boeing history. The airframe is proven and (please correct me if I'm wrong) it looks like the changes from NG to Max are significantly less than Jurassic to Classic or even Classic to NG. Just some design bugs to be squashed though it's a shame over 300 people had to die in the process. So far it seems what they're doing will help address the issues from the Lion Air crash (we'll see what all the findings are from the Ethiopian crash).

To me it seems like Boeing downplayed MCAS not only externally, but internally as well. Like they just had a junior guy throw a minimum amount of code into the FCC using systems already in place (AoA sensors and trim jack screw) with little oversight. "Towards the end of AoA envelope, approaching a stall the nose starts to continue to lift up more than the NG, probably extra lift off the new engines, just get the intern to code in to trim down a little to offset that so it'll fly like the NG." Then got the other intern to put a PowerPoint together to for the training requirements but was in a silo and never learned about MCAS.

This has and will continue to hurt Boeing severely (as it should) but they have some of the top airplane and aerodynamic engineering minds in the world. Getting them back in the air will be their #1 priority now as the grounding is costing them millions a day and they can't afford NMA or NSA without the 737 cash flow. I believe that dispite this early and significant setback, due to their complacency, ignorance, and (possibly criminal) negligence the 737M will end up with a career rivalling it's predessessors and hopefully after all the dust, fines, and management and board shuffling they'll come back stronger than ever to release a fantastic 797 and whatever finally ends up replacing the 737.
 
Waterbomber2
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 8:26 pm

dakota123 wrote:
Waterbomber2 wrote:
seahawk wrote:

Ni it would not be broken.

First there is nothing fundamentally wrong with the MAX. Add an AoA disagree warning and correct the MCAS software and it is just fine. Secondly any competition still lacks the economy of scales advantage and product support to compete with the 2 big players.


Mmmm what are we going to do about the airspeed disagree and loss of altitide indication?
Weren't ET asking the tower for ground speed and altitude readouts?
Stick shaker + AoA disagree + airspeed disagree + altitude disagree.
Just make it a package checklist item and call it ADIRU FAIL.

So why is the ADIRU failing so often and in the same phase of flight?
This is not a sensor problem.
ET and Lion Air would do well to keep a copy ofnthe current hardware and software as evidence before the software patch also silently overwrites any bugs.

AF447 couldn't recover from an airspeed disagree situation at cruise altitude. ADIRU failure in the take-off phase without clear indication is a death trap on its own, MCAS or no MCAS.


The procedure is to crosscheck airspeed on takeoff run, which could have shown up an issue before V1 — and maybe it did, but after V1. If in flight, crosscheck against the standby instrumentation, which has its own pitot and static system, and decide which side is giving correct info. So doesn’t make much sense that they would be asking externally. It’s a commonly trained scenario, or it should be. Will certainly be interesting if there was a valid reason as to why.

I’m not sure too many conclusions can be drawn from AF447. Certainly not the first time, nor the last, that an airspeed disagree happened in cruise, or any phase.


You make it sound easy like peeling onions.
When 2 indicators are disagreeing with 3 indicators, and the former are warning of you a stall, how do you decide which ones to follow?
It wouldn't be the first time that an idiot in MX covers up the static port of the standby instrument and forgets to remove it. That would cause the airspeed indication to be inflated, wouldn't it?

A 8000 hour pilot would probably have been through airspeed disagree training like 10 times and know that he would need to compare against the standby instruments.
A 350 hour pilot who has just been through type training and line training would also have this reviewed very recently.
And yet they asked ATC for ground speed.

I think that I know why and it's nothing less than good airmanship.
On one side you have the stick shaker activated by AOA sensor, and a low speed indication which would be sensed by a different set of sensors, ie the pitot/static probe combination, on the other side everything is looking good. But it's rather weird that two different unrelated sensors are giving incoherent information.
So which one is giving the correct information? The standby and opposite side's instruments or your instruments? Did MX cover up some static ports?
As a pilot you have to assume the worst and that's that the aircraft is stalling. You just don't ignore a stick shaker. Ignoring a stick shaker is incredibly counter-intuitive.
That's when you ask ATC for a ground speed read-out. That's just plain good sense.


I once took off with a partially clogged pitot tube on a Cessna 150.
Speed is alive, then it keeps rising, but by the time that I realised that the airspeed is stagnating and checked my throttle position, engine RPM, a quick glipse that the flaps are indeed up, the aircraft is floating off the ground.
Flew the circuit with airspeed stuck below Vstall, which despite all training is terrifying, believe me.
After landing, pissed that someone didn't put the pitot covers before leaving it parked overnight, wrote it up in the techlog and put red tape all over the control column before an idiot takes it up and kills himself.
The mechanic then approached me and asked me why I wrote it up in the techlog, now he was going to have to fill an EASA CRS, which would cost money. I told him that I'm a mechanic on commerical aircraft and that what he was suggesting was criminal. Then he asked why I didn't abort the take-off. At that point I walked away as I was about to put a hole in his face.


The B737NG doesn't have this high of an instrument failure rate.
If you look at the B737NG ADIRS, it has two ADIRU completely separated. The only thing they have in common is the TAT probe.
I don't have any B737MAX manuals, but I assume this would be the same.

So either the TAT probe made both ADIRU go nuts, or there was something else.

The assumptions that the pilots were idiots can only be made as the last solution, once all other possibilities have been ruled out.
Starting with that assumption makes us idiots.
 
fabian9
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 8:35 pm

What many are forgetting is that MCAS (and its higher THS deflection angle) have been implemented for a reason. It wouldn’t have been introduced in the first place, or changed from 0.6 to 2.5deg deflection, if it wasn’t required to create a “stable” aircraft.

The fact that the system has had to exist in the first place also tells a story. This is an aircraft that has been artificially engineered beyond its architectural limits. As I said in a previous thread, the Max changes are lipstick on a pig.

If MCAS fails, and a stall is entered, will pilots be able to get the aircraft back into a stable configuration?
 
mrbots
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 8:53 pm

fabian9 wrote:
What many are forgetting is that MCAS (and its higher THS deflection angle) have been implemented for a reason. It wouldn’t have been introduced in the first place, or changed from 0.6 to 2.5deg deflection, if it wasn’t required to create a “stable” aircraft.

The fact that the system has had to exist in the first place also tells a story. This is an aircraft that has been artificially engineered beyond its architectural limits. As I said in a previous thread, the Max changes are lipstick on a pig.

If MCAS fails, and a stall is entered, will pilots be able to get the aircraft back into a stable configuration?


From what I've read, it's more to do with the Max wanting to keep pitching the nose up a lower angle than the NG as the back of the wing starts losing lift before the front and engines on the Max stick out a little further. Once an actual stall has occurred, it's already trained to both push the column down and trim down to recover from a stall.

Anyone know of any articles on the issues everyone had going from the 100/200 to the Classic? Longer fuselages and going from underhung low bypass turbofans to the much higher thrust, high bypass CFM56s mounted infront of the wing had to be a huge difference in handling!
 
rheinwaldner
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 9:12 pm

Amiga500 wrote:
At higher angles of attack, the engine nacelle is acting like another mini wing ahead of the main wing[1]

Basically the nacelles of the MAX are like little canards (!) and the horizontal stabilizer has not sufficient surface area to stabilize the aircraft in the way, stabilizers usually do.
Many things are difficult, all things are possible!
 
dakota123
Posts: 241
Joined: Wed Aug 30, 2006 11:03 pm

Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 9:16 pm

Waterbomber2 wrote:
dakota123 wrote:
Waterbomber2 wrote:

Mmmm what are we going to do about the airspeed disagree and loss of altitide indication?
Weren't ET asking the tower for ground speed and altitude readouts?
Stick shaker + AoA disagree + airspeed disagree + altitude disagree.
Just make it a package checklist item and call it ADIRU FAIL.

So why is the ADIRU failing so often and in the same phase of flight?
This is not a sensor problem.
ET and Lion Air would do well to keep a copy ofnthe current hardware and software as evidence before the software patch also silently overwrites any bugs.

AF447 couldn't recover from an airspeed disagree situation at cruise altitude. ADIRU failure in the take-off phase without clear indication is a death trap on its own, MCAS or no MCAS.


The procedure is to crosscheck airspeed on takeoff run, which could have shown up an issue before V1 — and maybe it did, but after V1. If in flight, crosscheck against the standby instrumentation, which has its own pitot and static system, and decide which side is giving correct info. So doesn’t make much sense that they would be asking externally. It’s a commonly trained scenario, or it should be. Will certainly be interesting if there was a valid reason as to why.

I’m not sure too many conclusions can be drawn from AF447. Certainly not the first time, nor the last, that an airspeed disagree happened in cruise, or any phase.


You make it sound easy like peeling onions.
When 2 indicators are disagreeing with 3 indicators, and the former are warning of you a stall, how do you decide which ones to follow?
It wouldn't be the first time that an idiot in MX covers up the static port of the standby instrument and forgets to remove it. That would cause the airspeed indication to be inflated, wouldn't it?

A 8000 hour pilot would probably have been through airspeed disagree training like 10 times and know that he would need to compare against the standby instruments.
A 350 hour pilot who has just been through type training and line training would also have this reviewed very recently.
And yet they asked ATC for ground speed.

I think that I know why and it's nothing less than good airmanship.
On one side you have the stick shaker activated by AOA sensor, and a low speed indication which would be sensed by a different set of sensors, ie the pitot/static probe combination, on the other side everything is looking good. But it's rather weird that two different unrelated sensors are giving incoherent information.
So which one is giving the correct information? The standby and opposite side's instruments or your instruments? Did MX cover up some static ports?
As a pilot you have to assume the worst and that's that the aircraft is stalling. You just don't ignore a stick shaker. Ignoring a stick shaker is incredibly counter-intuitive.
That's when you ask ATC for a ground speed read-out. That's just plain good sense.


I once took off with a partially clogged pitot tube on a Cessna 150.
Speed is alive, then it keeps rising, but by the time that I realised that the airspeed is stagnating and checked my throttle position, engine RPM, a quick glipse that the flaps are indeed up, the aircraft is floating off the ground.
Flew the circuit with airspeed stuck below Vstall, which despite all training is terrifying, believe me.
After landing, pissed that someone didn't put the pitot covers before leaving it parked overnight, wrote it up in the techlog and put red tape all over the control column before an idiot takes it up and kills himself.
The mechanic then approached me and asked me why I wrote it up in the techlog, now he was going to have to fill an EASA CRS, which would cost money. I told him that I'm a mechanic on commerical aircraft and that what he was suggesting was criminal. Then he asked why I didn't abort the take-off. At that point I walked away as I was about to put a hole in his face.


The B737NG doesn't have this high of an instrument failure rate.
If you look at the B737NG ADIRS, it has two ADIRU completely separated. The only thing they have in common is the TAT probe.
I don't have any B737MAX manuals, but I assume this would be the same.

So either the TAT probe made both ADIRU go nuts, or there was something else.

The assumptions that the pilots were idiots can only be made as the last solution, once all other possibilities have been ruled out.
Starting with that assumption makes us idiots.


I don’t disagree that it’s easy to kibitz when we’re sitting in our respective lounge chairs. And I never assume pilots are idiots (unless flying drunk or high). Often (usually?) there’s a reasonable explanation when performance is wanting. But it’s a valid question as to whether a proper crosscheck was performed, especially since it seems that 302 apparently transitioned from ground to flight at 93 knots. Just one of dozens of questions, but a question I personaly have nonetheless.
“And If I claim to be a wise man, well surely it means that I don’t know”
 
dakota123
Posts: 241
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 9:17 pm

rheinwaldner wrote:
Amiga500 wrote:
At higher angles of attack, the engine nacelle is acting like another mini wing ahead of the main wing[1]

Basically the nacelles of the MAX are like little canards (!) and the horizontal stabilizer has not sufficient surface area to stabilize the aircraft in the way, stabilizers usually do.


Not true. Stick force gradient decreases. It doesn’t go negative.
“And If I claim to be a wise man, well surely it means that I don’t know”
 
dakota123
Posts: 241
Joined: Wed Aug 30, 2006 11:03 pm

Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 9:22 pm

mrbots wrote:
fabian9 wrote:
What many are forgetting is that MCAS (and its higher THS deflection angle) have been implemented for a reason. It wouldn’t have been introduced in the first place, or changed from 0.6 to 2.5deg deflection, if it wasn’t required to create a “stable” aircraft.

The fact that the system has had to exist in the first place also tells a story. This is an aircraft that has been artificially engineered beyond its architectural limits. As I said in a previous thread, the Max changes are lipstick on a pig.

If MCAS fails, and a stall is entered, will pilots be able to get the aircraft back into a stable configuration?


From what I've read, it's more to do with the Max wanting to keep pitching the nose up a lower angle than the NG as the back of the wing starts losing lift before the front and engines on the Max stick out a little further. Once an actual stall has occurred, it's already trained to both push the column down and trim down to recover from a stall.

Anyone know of any articles on the issues everyone had going from the 100/200 to the Classic? Longer fuselages and going from underhung low bypass turbofans to the much higher thrust, high bypass CFM56s mounted infront of the wing had to be a huge difference in handling!


No. The new cowlings add additional lift ahead of the CG, which causes stick force gradient to decrease. It should take ever more backpressure to get into a stall. With the Max, it does increase (as I understand it), but it increases at a lower rate, which from a perception standpoint is not good, and is not allowable. The ND trim ensures that the gradient increases at the same rate, or an acceptable rate in any case.
“And If I claim to be a wise man, well surely it means that I don’t know”
 
marcelh
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 9:56 pm

freakyrat wrote:
What were seeing if I read the new articles correctly is that the final MAX product MCAS system did not comply with the original specs that limited the MCAS system to 0.6 % nose down trim. There was also no redundancy built into the system which now Boeing will build in. The software and some hardware updates will put the MCAS system back to the original specs which should make the aircraft very safe to operate.

There is a reason why Boeing choose to raise the MCAS limit to 2.5%. Just going back to 0.6 makes a safe plane safer....
IMO Boeing cut some corners and rushed the MAX into production to keep the shareholders happy.
Last edited by marcelh on Fri Mar 22, 2019 9:58 pm, edited 1 time in total.
 
asdf
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 9:56 pm

Interested wrote:
SheikhDjibouti wrote:
freakyrat wrote:
What were seeing if I read the new articles correctly is that the final MAX product MCAS system did not comply with the original specs that limited the MCAS system to 0.6 % nose down trim. There was also no redundancy built into the system which now Boeing will build in. The software and some hardware updates will put the MCAS system back to the original specs which should make the aircraft very safe to operate.

Er…. no.
That is the very definition of a "kludge"

Boeing did not increase MCAS limit from 0.6deg to 2.5deg simply because it was a nice number. They did it because (Boeing?) test pilots deemed more MCAS authority was necessary.

Now, in order to satisfy FAA documentation you propose they revert to the original 0.6deg, and somehow claim it "should make the aircraft very safe to operate". :banghead:

The tail should not be wagging the dog.

You do not invite a test pilot to check out your baby, and then ignore his recommendations because it will mess up your paperwork. :hissyfit:


So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?


actually not a lot
played high and lost everything
they are fu**ed

one poster here in the forum suggested moveable engines
kinda dynamic pylons
during landing and takeoff the engines are in the actual position
during the flight they get moved below the wings to be in the perfect position
maybe that squeeze oth a few more % of economics so they can overtake the A320NEO
sounds freaky but there have been done more insane solutions before
and hey ... they are americans ... yes, they can!
 
Planetalk
Posts: 470
Joined: Thu Aug 27, 2015 5:12 pm

Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 10:17 pm

fabian9 wrote:
What many are forgetting is that MCAS (and its higher THS deflection angle) have been implemented for a reason. It wouldn’t have been introduced in the first place, or changed from 0.6 to 2.5deg deflection, if it wasn’t required to create a “stable” aircraft.

The fact that the system has had to exist in the first place also tells a story. This is an aircraft that has been artificially engineered beyond its architectural limits. As I said in a previous thread, the Max changes are lipstick on a pig.

If MCAS fails, and a stall is entered, will pilots be able to get the aircraft back into a stable configuration?


A very good point seemingly being missed by a lot of people. 'Just switch it off' they say. The very facg. You need to switch it off means you are probably in a fairly critical situation already, and then you have to switch something off without which the plane may become uncontrollable at a certain AoA.

If inreliable airspeed means you have to switch it off, then what is the point of MCAS? In all sorts of situations it might be needed the pilots have probably already turned it off. Then of course when in an already heavy workload situation, be sure you're not switching it off at the wrong moment. And you've never been trained on the control forces involved in any of this. It really defies belief.
 
CO953
Posts: 523
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 10:29 pm

Planetalk wrote:
fabian9 wrote:
What many are forgetting is that MCAS (and its higher THS deflection angle) have been implemented for a reason. It wouldn’t have been introduced in the first place, or changed from 0.6 to 2.5deg deflection, if it wasn’t required to create a “stable” aircraft.

The fact that the system has had to exist in the first place also tells a story. This is an aircraft that has been artificially engineered beyond its architectural limits. As I said in a previous thread, the Max changes are lipstick on a pig.

If MCAS fails, and a stall is entered, will pilots be able to get the aircraft back into a stable configuration?


A very good point seemingly being missed by a lot of people. 'Just switch it off' they say. The very facg. You need to switch it off means you are probably in a fairly critical situation already, and then you have to switch something off without which the plane may become uncontrollable at a certain AoA.

If inreliable airspeed means you have to switch it off, then what is the point of MCAS? In all sorts of situations it might be needed the pilots have probably already turned it off. Then of course when in an already heavy workload situation, be sure you're not switching it off at the wrong moment. And you've never been trained on the control forces involved in any of this. It really defies belief.


Maybe a short way to describe it is that, to me, it seems that MCAS helps save the airplane if sensor data is good and the pilots are screwing up (stalling), but it can crash the airplane if the airplane is screwing up (bad sensor data).

Sort of a double-edged sword?
 
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flyingclrs727
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 10:33 pm

fabian9 wrote:
What many are forgetting is that MCAS (and its higher THS deflection angle) have been implemented for a reason. It wouldn’t have been introduced in the first place, or changed from 0.6 to 2.5deg deflection, if it wasn’t required to create a “stable” aircraft.

The fact that the system has had to exist in the first place also tells a story. This is an aircraft that has been artificially engineered beyond its architectural limits. As I said in a previous thread, the Max changes are lipstick on a pig.

If MCAS fails, and a stall is entered, will pilots be able to get the aircraft back into a stable configuration?


Sure the 737 Max does not have the aerodynamic stability to fly without the MCAS system, but using systems like that to create artificially stability that are not unprecedented on military aircraft like fighters. The problem was in having just one sensor in control of the whole system. Ideally there would be more than just 2 sensors. How do the pilots tell which sensor is correct if there is a disagreement between them?
Last edited by flyingclrs727 on Fri Mar 22, 2019 10:38 pm, edited 1 time in total.
 
WIederling
Posts: 9593
Joined: Sun Sep 13, 2015 2:15 pm

Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 10:37 pm

kelvin933 wrote:
......... and are mounted further in front of the wing creating CG issues.


forward CG will alleviate the observed issue but reduces efficiency as you need higher negative lift from the tail ( induced drag ).
( but Good Thing (TM) here ).
But that advantage is too small to iron out the nacelle drag ( with the wrong vector under higher AoA ) issue.
comes center stage :. MCAS

Desired is a CG more aft to minimize downward force on the tail. That negative lift on the tail costs twice in induced drag.
( once for the horizontal stab and once for the extra lift that has to be provided by the wing ( aircraft mass PLUS compensate downward force on the tail for overall lift equivalent to aircraft mass )

If that blowback can be observed/proven that explains the final ( now unrecoverable ) STUKA bombing run.
Murphy is an optimist
 
Waterbomber2
Posts: 1445
Joined: Mon Feb 04, 2019 3:44 am

Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 10:39 pm

asdf wrote:
Interested wrote:
SheikhDjibouti wrote:
Er…. no.
That is the very definition of a "kludge"

Boeing did not increase MCAS limit from 0.6deg to 2.5deg simply because it was a nice number. They did it because (Boeing?) test pilots deemed more MCAS authority was necessary.

Now, in order to satisfy FAA documentation you propose they revert to the original 0.6deg, and somehow claim it "should make the aircraft very safe to operate". :banghead:

The tail should not be wagging the dog.

You do not invite a test pilot to check out your baby, and then ignore his recommendations because it will mess up your paperwork. :hissyfit:


So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?


actually not a lot
played high and lost everything
they are fu**ed

one poster here in the forum suggested moveable engines
kinda dynamic pylons
during landing and takeoff the engines are in the actual position
during the flight they get moved below the wings to be in the perfect position
maybe that squeeze oth a few more % of economics so they can overtake the A320NEO
sounds freaky but there have been done more insane solutions before
and hey ... they are americans ... yes, they can!



That's a very complex solution.
The pylon may not look like more than a piece of metal holding the engines, but there is much much more to it.
If you open up the panels on the pylon, you can notice that there are a lot of things packed inside the pylon in a very compact way.
Bleed air ducts, electronic wires, electric wires, fuel pipes, hydraulic pipes, fire detection looms.
A movable pylon is thus a very complex and not very efficient solution.
 
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casinterest
Posts: 12440
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 10:44 pm

Excellent Video by Mentour_Pilot on the Runaway Stabilizer and MCAS

https://www.youtube.com/watch?v=xixM_cwSLcQ

Good discussions on Thrust, trim, memory items., auto pilot, cut off switches, and shows a demo in the simulator
Where ever you go, there you are.
 
CO953
Posts: 523
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 11:26 pm

Waterbomber2 wrote:
asdf wrote:
Interested wrote:

So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?


actually not a lot
played high and lost everything
they are fu**ed

one poster here in the forum suggested moveable engines
kinda dynamic pylons
during landing and takeoff the engines are in the actual position
during the flight they get moved below the wings to be in the perfect position
maybe that squeeze oth a few more % of economics so they can overtake the A320NEO
sounds freaky but there have been done more insane solutions before
and hey ... they are americans ... yes, they can!



That's a very complex solution.
The pylon may not look like more than a piece of metal holding the engines, but there is much much more to it.
If you open up the panels on the pylon, you can notice that there are a lot of things packed inside the pylon in a very compact way.
Bleed air ducts, electronic wires, electric wires, fuel pipes, hydraulic pipes, fire detection looms.
A movable pylon is thus a very complex and not very efficient solution.


I took it as sarcasm, myself.
 
MrBretz
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 11:45 pm

casinterest wrote:
Excellent Video by Mentour_Pilot on the Runaway Stabilizer and MCAS

https://www.youtube.com/watch?v=xixM_cwSLcQ

Good discussions on Thrust, trim, memory items., auto pilot, cut off switches, and shows a demo in the simulator


Thanks for this. It was an excellent video.
 
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Aesma
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Re: B737MAX Grounded Worldwide

Fri Mar 22, 2019 11:53 pm

Bradin wrote:
New York Times: Ethiopian Airlines Installed Max 8 Simulator, but Pilot on Doomed Flight Didn’t Get Training

Fair Use Excerpt:

Ethiopian Airlines surpassed many carriers by becoming one of the first to install a simulator to teach pilots how to fly the new Boeing 737 Max 8, but the captain of the doomed Flight 302 never trained on the simulator, according to people close to the airline’s operations. The people, who spoke on condition of anonymity because Ethiopian Airlines had not authorized disclosure of the information, said the carrier had the Max 8 simulator up and running in January, two months before Flight 302 crashed.

https://www.nytimes.com/2019/03/20/worl ... oeing.html


Does the simulator even simulates MCAS behaviour correctly, anyway ?
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
 
Babyshark
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 12:51 am

Waterbomber2 wrote:
asdf wrote:
Interested wrote:

So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?


actually not a lot
played high and lost everything
they are fu**ed

one poster here in the forum suggested moveable engines
kinda dynamic pylons
during landing and takeoff the engines are in the actual position
during the flight they get moved below the wings to be in the perfect position
maybe that squeeze oth a few more % of economics so they can overtake the A320NEO
sounds freaky but there have been done more insane solutions before
and hey ... they are americans ... yes, they can!



That's a very complex solution.
The pylon may not look like more than a piece of metal holding the engines, but there is much much more to it.
If you open up the panels on the pylon, you can notice that there are a lot of things packed inside the pylon in a very compact way.
Bleed air ducts, electronic wires, electric wires, fuel pipes, hydraulic pipes, fire detection looms.
A movable pylon is thus a very complex and not very efficient solution.


Having a movable pylon so that an old airplane can keep a type certificate and keep southwest's pilot costs downs is so amazingly... ... there's no words.

That said. I'm sure it could be done. But what happens when it fails to retract back?

Better to just scrap the design then go max nutso. I personally think the program will founder and in sure many would argue the opposite but they probably didnt think it needed to be grounded and here we are.
 
asdf
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 1:02 am

B knows how to build FBW planes
isnt the 787 full FBW ?

couldnt they transfer the complete electronic stuff from the 787 to the 737?

not a project to finish within a few weeks but well
i think nothing can fix that in a short amount of time
 
Bradin
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 1:04 am

Aesma wrote:
Bradin wrote:
New York Times: Ethiopian Airlines Installed Max 8 Simulator, but Pilot on Doomed Flight Didn’t Get Training

Fair Use Excerpt:

Ethiopian Airlines surpassed many carriers by becoming one of the first to install a simulator to teach pilots how to fly the new Boeing 737 Max 8, but the captain of the doomed Flight 302 never trained on the simulator, according to people close to the airline’s operations. The people, who spoke on condition of anonymity because Ethiopian Airlines had not authorized disclosure of the information, said the carrier had the Max 8 simulator up and running in January, two months before Flight 302 crashed.

https://www.nytimes.com/2019/03/20/worl ... oeing.html


Does the simulator even simulates MCAS behaviour correctly, anyway ?


Only those with simulators could answer that properly, however I have a good faith belief that the same indicators - minus a computer driven authority that commands the trim - could be devised in existing simulations correctly because all MCAS is doing is adjusting trim. It is inline with existing runaway trim processes.
 
Brucekn
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 1:15 am

asdf wrote:
B knows how to build FBW planes
isnt the 787 full FBW ?

couldnt they transfer the complete electronic stuff from the 787 to the 737?

not a project to finish within a few weeks but well
i think nothing can fix that in a short amount of time


If I was on Boeing’s board of directors (and I’m not but have served on other non-aviation company boards), my question would be- assuming the worst- “if the 737MAX never flies again, how long would it take to get back into the narrow body market again?”. True- Boeing are working on a patch and some crew training, and the 73MAX will probably fly again- but what if a similar accident occurs again? Even a non-related crash? I recall the DC-10 issues, where even in non-related accidents (even a human nav error at Mt. Erebus by NZ), the DC-10 was “to blame”. Going back another decade the Lockheed Electra issues which finished it off as a pax carrier.

Boeing would be crazy to not have a clean-sheet design now in process, even if that was just started in the past few weeks. They might keep it secret (if they could), although AB would no doubt assume this and start their own clean-sheet design- just in case.
 
tullamarine
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 1:24 am

asdf wrote:
B knows how to build FBW planes
isnt the 787 full FBW ?

couldnt they transfer the complete electronic stuff from the 787 to the 737?

not a project to finish within a few weeks but well
i think nothing can fix that in a short amount of time

NO, that is basically a new plane and would require massive engineering and complete re-certification. It is also likely that it would trigger the end of the grand-fathering which would probably mean the plane can't comply anyway.
717, 721/2, 732/3/4/5/7/8/9, 742/3/4, 752/3, 762/3, 772/E/W, 788/9, 300,310, 319,320/1, 332/3, 359, 388, DC9, DC10, F28, F100, 142,143, E75/90, CR2, D82/3/4, SF3, ATR
 
SkyGrunt
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 2:29 am

Sooner787 wrote:
Very intersting column by Bjorn Fehrm in Leeham newsletter this morning
regarding " Blowback" syndrome

https://leehamnews.com/2019/03/22/bjorn ... sh-part-2/
Woah. This is potentially big. Lots of random noise now on this thread but this is worth thinking about.

Sent from my BBD100-2 using Tapatalk
 
Aviation737
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 2:51 am

SheikhDjibouti wrote:
"Boeing won't have any aircraft to compete against the NEOs" is your reason for continuing with a flawed design? :banghead:

It is ridiculous that people are thinking the MAX is a flawed design. The only issue that I can see that Boeing screwed up on is the MCAS system which will be fix and the MAX WILL return to the skies. The MAX design is fine, it is aerodynamically stable in normal flight. But once the MAX is in a stall, due to its placement of its engine, it becomes harder in the MAX than the NG for the pilot to push the nose down and that is where the MCAS comes in. The MCAS is there to ensure that the pilot would be able to point the nose down as well as to prevent a secondary stall from happening. So the issue here is not the design or even the MCAS( even though the MCAS did play a role in the crash) but the thing that cause the MCAS to activate during normal flight operations. The MAX can fly without the MCAS just fine. Please watch this part of the video: https://www.youtube.com/watch?v=TlinocVHpzk&t=952s
SheikhDjibouti wrote:
"they" are presumably airlines that for some reason can only operate Boeing aircraft. What happens if they break that rule; does the CEO turn into a pumpkin at midnight? :roll:

I think you misunderstood me. I'm not saying that airlines can only operate Boeing aircraft, if they want to they can. But, I'm saying that it is more financially logical for airlines and Boeing to continue the MAX programme. I mean if you are the CEO of an airline like Southwest or Ryanair would you cancel your rather wait for the grounding of the MAX to be lifted in a few months or decide to go with Airbus or any other aircraft manufactures where you have to pay a cancellation fee to Boeing, pay to retrain all your pilots to the new aircraft and not to mention you still have to pay a cost for a new plane. It just doesn't make financial sense at all. So I'm not saying that Boeing is the best or that airlines can't survive without Boeing, I'm just telling those who thinks that the MAX will not fly again and how unlikely for that to happen.

SheikhDjibouti wrote:
Boeing doesn't have anything to compete in the RJ market, but they survive.
Boeing doesn't have anything to compete against the ATR72, but they survive.
And now for a while it looks as if they will only have the NG to compete against the A320. They will survive.

For years, Airbus didn't have anything to compete against numerous different offerings from Boeing.

And for decades nobody on the planet had anything to compete against the 747.

Get real! Life goes on.

Boeing will take a hit, regroup, redesign, and come out of this stronger and better.
Airlines will have to fly the NG for a few more years, and swallow any extra fuel costs. Or make Boeing cough up the difference.


Yes, Boeing can survive without having the MAX but if you can save it by making a few changes why throw the whole operations away? Especially after coming this far with over 5,000+ orders in the books. Why risk it in creating an entirely new aircraft if you can just fix your current one? I expect Boeing to receive more orders for the MAX after all this debacle is over.
 
Aviation737
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 3:13 am

Carlos01 wrote:
Aviation737 wrote:
I bet people would completely forget about this in 1 or 2 years. I mean if half the world's future narrowbody fleet in the future being the MAX, it would be pretty difficult to keep avoiding it in the future. If Boeing really goes for a new clean-sheet design they will be really shooting themselves in the foot. A new design would take at least years for it to roll out of the production lines and they basically won't have any aircraft to compete against the NEOs. Not to mention, it would also be a nightmare for airlines if Boeing stops production on the MAX since they basically won't have any next-gen aircraft to compete with their competitors that have newer aircraft. They basically can't turn to any other manufacturers to provide them with a replacement. The MAX is definately here to stay whether you like it or not.


Well, there's actually 2 things here, which should not be mixed.

1. What makes economically sense for Boeing

2. What Boeing has to do.


I don't get why you are trying to separate both of those points. Boeing has to do something no matter what.

Carlos01 wrote:
The second point has most likely nothing to do with what makes sense for Boeing. Boeing has f-d up so bad, that it's entirely possible that MAX is actually not here to stay, instead it could turn out to be the biggest single failure in all of industrial history to date.

Just read what I wrote to SheikhDjibouti on top.
 
Chemist
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 3:17 am

People tend to be binary with statements like "Boeing made no mistakes, it's all the pilots" or "The 737 MAX is a flawed kludge, it should be scrapped".
Unfortunately for binary thinkers, reality is almost always somewhere in the middle.

IMHO:
1 - Boeing royally F'd up MCAS, perhaps criminally, and they ought to be penalized. This is what happens when beancounters get too powerful in a company. Personally we don't see enough responsible managers in industry going to jail for negligent behavior. I could put the US banks and financial institutions on that list, too. Just like Volkswagen.
2 - FAA/certification basic processes need to be improved.
3 - I suspect MCAS can be fixed appropriately with software only, perhaps hardware will be needed
4 - The fundamental 737 airframe is excellent and safe. Bigger engines are put on aircraft all the time. There's no reason it can't be made safe, so forget about scrapping the program.
5 - Pilot training is probably deficient in a number of individuals and/or airlines. It seems a lot of pilots lack basic stick and rudder skills. If your airspeed is reading artificially low, you pitch for level flight and set power manually, ignoring airspeed and a perhaps erroneous stick shaker.
6 - If you have a ton of pressure on your control column, you adjust trim to remove those forces. If you are plunging and holding full rear yoke and your power is high then you trim up.
7 - If your trim system isn't auto-adjusting in the right direction, you have a malfunction and you should disconnect it.
 
maint123
Posts: 396
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 3:57 am

Just a thought - how many 737s in the last 10 or 20 years had to be flown fully manually with the handwheel, due to whatever reasons ? Anyone ?
 
Bradin
Posts: 379
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 5:16 am

Chemist wrote:
People tend to be binary with statements like "Boeing made no mistakes, it's all the pilots" or "The 737 MAX is a flawed kludge, it should be scrapped".
Unfortunately for binary thinkers, reality is almost always somewhere in the middle.

IMHO:
1 - Boeing royally F'd up MCAS, perhaps criminally, and they ought to be penalized. This is what happens when beancounters get too powerful in a company. Personally we don't see enough responsible managers in industry going to jail for negligent behavior. I could put the US banks and financial institutions on that list, too. Just like Volkswagen.
2 - FAA/certification basic processes need to be improved.
3 - I suspect MCAS can be fixed appropriately with software only, perhaps hardware will be needed
4 - The fundamental 737 airframe is excellent and safe. Bigger engines are put on aircraft all the time. There's no reason it can't be made safe, so forget about scrapping the program.
5 - Pilot training is probably deficient in a number of individuals and/or airlines. It seems a lot of pilots lack basic stick and rudder skills. If your airspeed is reading artificially low, you pitch for level flight and set power manually, ignoring airspeed and a perhaps erroneous stick shaker.
6 - If you have a ton of pressure on your control column, you adjust trim to remove those forces. If you are plunging and holding full rear yoke and your power is high then you trim up.
7 - If your trim system isn't auto-adjusting in the right direction, you have a malfunction and you should disconnect it.


I'm not quite as confident that Boeing messed up MCAS purposely. Testing for use cases is easy. Testing for abuse cases is much harder because you're trying to find as many possible combinations that would break its intended use case. When an abuse case is not identified, there are consequences, and sometimes they have dire results.
 
Chemist
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 5:21 am

Bradin wrote:
Chemist wrote:
People tend to be binary with statements like "Boeing made no mistakes, it's all the pilots" or "The 737 MAX is a flawed kludge, it should be scrapped".
Unfortunately for binary thinkers, reality is almost always somewhere in the middle.

IMHO:
1 - Boeing royally F'd up MCAS, perhaps criminally, and they ought to be penalized. This is what happens when beancounters get too powerful in a company. Personally we don't see enough responsible managers in industry going to jail for negligent behavior. I could put the US banks and financial institutions on that list, too. Just like Volkswagen.
2 - FAA/certification basic processes need to be improved.
3 - I suspect MCAS can be fixed appropriately with software only, perhaps hardware will be needed
4 - The fundamental 737 airframe is excellent and safe. Bigger engines are put on aircraft all the time. There's no reason it can't be made safe, so forget about scrapping the program.
5 - Pilot training is probably deficient in a number of individuals and/or airlines. It seems a lot of pilots lack basic stick and rudder skills. If your airspeed is reading artificially low, you pitch for level flight and set power manually, ignoring airspeed and a perhaps erroneous stick shaker.
6 - If you have a ton of pressure on your control column, you adjust trim to remove those forces. If you are plunging and holding full rear yoke and your power is high then you trim up.
7 - If your trim system isn't auto-adjusting in the right direction, you have a malfunction and you should disconnect it.


I'm not quite as confident that Boeing messed up MCAS purposely. Testing for use cases is easy. Testing for abuse cases is much harder because you're trying to find as many possible combinations that would break its intended use case. When an abuse case is not identified, there are consequences, and sometimes they have dire results.


I never said they did it purposefully. But clearly corners were cut. Whose fault and why? If due to schedule pressure, then criminal indictments should occur. But that is up to the authorities to determine. Certainly it could be either situation.
But I wonder how they could have even done basic scenario evaluation - "what if the AOA indicator fails?". What if a pilot doesn't disconnect trim? What would that look like to the pilots?
 
sgrow787
Posts: 450
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 5:29 am

freakyrat wrote:
The problem as I see it lies squarely with Boeing who probably never dreamed of a scenerio where a single Angle Of Attack sensor could fail and cause the MCAS system to interpret bad data.


But Boeing should have plenty of experience with sensor redundancy design. And according to the MAX system diagram presented by Youtube user "blancolirio":

https://youtu.be/9Ts_AjU89Qk?t=1120

the hardware connections are there to get both AOA sensor data to the FCC (through both ADIRU-L and ADIRU-R).

Is it possible a software bug was introduced during the two-sensor redundancy design that wasn't caught in the testing and certification phase because of the other half of the problem - the shortened time to market to compete with Airbus meant not enough time to perform all the development phases properly and with proper oversight.

Software bug could be a cut-n-paste error. Someone copies the same redundancy code used for air speed sensors, and in the process of changing 'computed_airspeed_1' and 'computed_airspeed_2' to 'angle_of_attack_1' and 'angle_of_attack_2', they copy 'angle_of_attack_1' to both locations, and forget to go back and change the second paste from a '1' to a '2'. They're behind in their schedule and maybe upper management decides there's no time to test the redundancy code. This would explain why they have a software patch so fast.
Just one sensor,
Oh just one se-en-sor,
Just one sensor,
Ooh ooh oo-ooh
Oo-oo-ooh.
 
impilot
Posts: 232
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 5:32 am

Chemist wrote:
People tend to be binary with statements like "Boeing made no mistakes, it's all the pilots" or "The 737 MAX is a flawed kludge, it should be scrapped".
Unfortunately for binary thinkers, reality is almost always somewhere in the middle.

IMHO:
1 - Boeing royally F'd up MCAS, perhaps criminally, and they ought to be penalized. This is what happens when beancounters get too powerful in a company. Personally we don't see enough responsible managers in industry going to jail for negligent behavior. I could put the US banks and financial institutions on that list, too. Just like Volkswagen.
2 - FAA/certification basic processes need to be improved.
3 - I suspect MCAS can be fixed appropriately with software only, perhaps hardware will be needed
4 - The fundamental 737 airframe is excellent and safe. Bigger engines are put on aircraft all the time. There's no reason it can't be made safe, so forget about scrapping the program.
5 - Pilot training is probably deficient in a number of individuals and/or airlines. It seems a lot of pilots lack basic stick and rudder skills. If your airspeed is reading artificially low, you pitch for level flight and set power manually, ignoring airspeed and a perhaps erroneous stick shaker.
6 - If you have a ton of pressure on your control column, you adjust trim to remove those forces. If you are plunging and holding full rear yoke and your power is high then you trim up.
7 - If your trim system isn't auto-adjusting in the right direction, you have a malfunction and you should disconnect it.


“6 - If you have a ton of pressure on your control column, you adjust trim to remove those forces. If you are plunging and holding full rear yoke and your power is high then you trim up.
7 - If your trim system isn't auto-adjusting in the right direction, you have a malfunction and you should disconnect it.”

I agree with most of what you said but you missed the mark on #6/7. Here’s (imo) why:

They were adjusting trim to remove the forces. Trim worked properly when they used it. Then they release trim...no nose down forces exist and all seems well (because MCAS has a few second delay until it kicks in again). They think all is well and go back to figuring out why their airspeed indications and AoA is wrong, why they have/had a shaker, or whatever else. Then it happens again. Rinse, repeat. If it was a simple pressure on their control column, that’s one thing. It wasn’t. Further, when hand flying, as they were doing, trim doesn’t auto adjust as you say. They have trim switches to control trim when hand flying, and as I said, it was working. What wasn’t working properly was a faulty AoA sensor that caused a system not related to the normal trimming and normal manual flying to kick in (MCAS), in a flight regime it shouldn’t have been engaged. And it was all unbeknownst to the crew, trimming the nose down when auto trim wasn’t supposed to be happening. But then when they used the main electric trim switches, it worked as advertised. This is why it was such a back and forth and why I can absolutely see how there was confusion...it wasn’t a simple trim runaway scenario.

Should they have flipped the stab cutoff switches? In hindsight yeah, I’d say so. But to armchair quarterback these accidents not knowing how exactly the accident unfolded and what exactly the pilots saw in the cockpit that caused confusion is premature, and I’m guessing enough info will come to light making the pilots’ inactions with the trim disconnect switches a lot more understandable.
 
art
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 5:37 am

Amiga500 wrote:
seahawk wrote:
First there is nothing fundamentally wrong with the MAX. Add an AoA disagree warning and correct the MCAS software and it is just fine. Secondly any competition still lacks the economy of scales advantage and product support to compete with the 2 big players.


The existence of MCAS would indicate there likely is something fundamentally wrong with the MAX.


If the aircraft has an aero centre that moves forward signficantly at high AoA to the point that it becomes unable to pitch down to recover from that AoA, or worse, prevent that AoA further increasing into a stall - then that is a pretty fundamental problem.

The correct answer would have been a resize of elevators (and horizontal stabiliser too). But if the aero centre is moving significantly it will need the elevators to be oversized, the actuators upsized and the pilots to get a new type certificate as the control responses would be very different.

That will take time and cost $$$.


I guess that the brief for the design engineers restricted them to changes that would avoid the need for a new type certificate and that, as a consequence, they were pushed into coming up with a sub-optimal solution.
 
Volaris320
Posts: 28
Joined: Wed Mar 13, 2019 3:07 pm

Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 6:24 am

Aviation737 wrote:
It is ridiculous that people are thinking the MAX is a flawed design. The only issue that I can see that Boeing screwed up on is the MCAS system which will be fix and the MAX WILL return to the skies. The MAX design is fine, it is aerodynamically stable in normal flight. But once the MAX is in a stall, due to its placement of its engine, it becomes harder in the MAX than the NG for the pilot to push the nose down and that is where the MCAS comes in. The MCAS is there to ensure that the pilot would be able to point the nose down as well as to prevent a secondary stall from happening. So the issue here is not the design or even the MCAS( even though the MCAS did play a role in the crash) but the thing that cause the MCAS to activate during normal flight operations. The MAX can fly without the MCAS just fine.


I saw another video on YouTube about the 737 MAX, and according to it, pitch instability was noticed during testing. As well as MCAS, Boeing also considered the possibility of having a larger redesigned horizontal stabilizer than on the 737 Original/Classic/Next Generation. My guess is had Boeing opted to redesign the horizontal stabilizer on the 737 MAX instead of implementing MCAS, then maybe those two crashes wouldn't have occurred (assuming there were glitches in the MCAS system). But then another possibility is that the pilots on both the Lion Air and Ethiopian planes that crashed weren't trained to deal with MCAS.

https://www.youtube.com/watch?v=mqUxmlwRqGU
 
majano
Posts: 287
Joined: Sun Oct 14, 2018 10:45 am

Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 7:14 am

Chemist wrote:
People tend to be binary with statements like "Boeing made no mistakes, it's all the pilots" or "The 737 MAX is a flawed kludge, it should be scrapped".
Unfortunately for binary thinkers, reality is almost always somewhere in the middle.

IMHO:
1 - Boeing royally F'd up MCAS, perhaps criminally, and they ought to be penalized. This is what happens when beancounters get too powerful in a company.

What do beancounters have to do with this? Isn't Muilenburg an engineer anyway?
 
usflyguy
Posts: 1757
Joined: Thu Jan 12, 2012 7:29 am

Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 7:44 am

Rumor is that WN is mothballing the MAX8 in the desert.
My post is my ideas and my opinions only, I do not represent the ideas or opinions of anyone else or company.
 
arfbool
Posts: 100
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 7:48 am

I’m having trouble understanding one thing... if the only true purpose of MCAS is to make the stick feel of the MAX match the NG to avoid pilot retraining, that only makes sense if MCAS never fails. In reality, it fails all the time due to bad design, and software cannot fix this. Yes, we can use software to avoid the catastrophic incorrect nose-down scenarios, but the system would be unavailable for its intended purpose of preventing stalls, in which case the MAX would start getting into actual stall accidents. So if retraining is necessary, then having MCAS at all seems unnecessary. Unless the plane would be extremely difficult to fly without, due to real underlying flaws, even with lots of training. Then it’s not just an issue of stick feel, but a very serious control problem. And now we should be asking, under what circumstances does a software fix make sense? None, that I can see. Either MCAS is disbanded completely and pilots must be properly MAX trained and rated, or the plane must redesigned with more AoA sensors so that MCAS failure is so remote it practically can never occur.
 
SurlyBonds
Posts: 412
Joined: Mon Nov 02, 2015 10:24 am

Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 7:53 am

mrbots wrote:
The airframe is proven and (please correct me if I'm wrong) it looks like the changes from NG to Max are significantly less than Jurassic to Classic or even Classic to NG.


The airframe is proven? In what universe? The whole point is that the 737MAX did not go through the full certification process because it is a derivative of the existing 737 design, not a clean-sheet design. Yet the classification as a derivative is dubious, because the engines were moved so far forward as to change the basic aerodynamics of the aircraft. And those changes did NOT occur with introduction of earlier 737 models.

mrbots wrote:
Just some design bugs to be squashed though it's a shame over 300 people had to die in the process.


Other than that, Mrs. Lincoln, how did you like the play?
 
Interested
Posts: 890
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 7:53 am

arfbool wrote:
I’m having trouble understanding one thing... if the only true purpose of MCAS is to make the stick feel of the MAX match the NG to avoid pilot retraining, that only makes sense if MCAS never fails. In reality, it fails all the time due to bad design, and software cannot fix this. Yes, we can use software to avoid the catastrophic incorrect nose-down scenarios, but the system would be unavailable for its intended purpose of preventing stalls, in which case the MAX would start getting into actual stall accidents. So if retraining is necessary, then having MCAS at all seems unnecessary. Unless the plane would be extremely difficult to fly without, due to real underlying flaws, even with lots of training. Then it’s not just an issue of stick feel, but a very serious control problem. And now we should be asking, under what circumstances does a software fix make sense? None, that I can see. Either MCAS is disbanded completely and pilots must be properly MAX trained and rated, or the plane must redesigned with more AoA sensors so that MCAS failure is so remote it practically can never occur.


Your last sentence answers the whole question doesn't it?

If something can still occur that is dangerous however few times it happens. That isn't needed on other planes

Then Boeing have created a plane that is less safe than the one it replaced

That's just inconceivable that they would do that.

Why should pilots and the public accept that?
 
art
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 8:33 am

Interested wrote:

If something can still occur that is dangerous however few times it happens. That isn't needed on other planes

Then Boeing have created a plane that is less safe than the one it replaced

That's just inconceivable that they would do that.

Why should pilots and the public accept that?


Not quite sure what you are asking but I would imagine that the designers of the original 737 were perfectly happy with the positioning of the engines. When the design was updated to use engines with bigger fans (NG), there was a problem - the bottom of the engine nacelles would be too close to the ground. They got round that without moving the engines by flattening the bottom of the nacelles. That was not possible with the still larger diameter CFM Leap engine. Originally the intention was to increase ground clearance by increasing the length of the undercarriage but that proved impractical (for cost reasons, I presume) so the decision was taken to move the engines from the optimum location to a location that was not. To me that made the aircraft less safe. I don;t think pilots would have approved, had they been consulted. The public, with no disrespect intended, would not have understood enough about aircraft design to be in a position to voice an informed opinion.
 
lowbank
Posts: 511
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 8:34 am

Interested wrote:
namezero111111 wrote:
Interested wrote:
So what can Boeing do that is simple to make these planes at least as safe as the 737s they are replacing?


I'm sure they'd be willing to pay anyone a generous amount for a viable solution to that conundrum.


Come on guys. Someone on here must have a proposal?

How about they go 1.5 ie in the middle of 2.5 and 0.6

And promise to mention what they've done in the manual and train it from now on?

Could they get that one through the certification process?


Having worked in the industry now for 38 years what I can safely say is it does not work like that at all. MCAS was developed and added to the MAX for a very good reason or it would not exist at all. It would have been axed on cost alone if it was a nice to have.

We have debated the situation at work and someone at Boeing who’s has signed off this system is looking at a jail term, it’s just who ends up being fall guy or girl or neutral gender to be PC.

Now put yourself in the position of the guy of the person who has to sign off the fix! That person is going to want to be 100% certain everything is correct.

What you find is you have to do ten times the amount of work to convince someone to put their name to it.

If anyone wants to know the detail these investigations go into, download the QF32 incident report where no one was hurt and it’s 300 pages long.
Every days a school day.
 
Interested
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 8:42 am

Aviation737 wrote:
SheikhDjibouti wrote:
"Boeing won't have any aircraft to compete against the NEOs" is your reason for continuing with a flawed design? :banghead:

It is ridiculous that people are thinking the MAX is a flawed design. The only issue that I can see that Boeing screwed up on is the MCAS system which will be fix and the MAX WILL return to the skies. The MAX design is fine, it is aerodynamically stable in normal flight. But once the MAX is in a stall, due to its placement of its engine, it becomes harder in the MAX than the NG for the pilot to push the nose down and that is where the MCAS comes in. The MCAS is there to ensure that the pilot would be able to point the nose down as well as to prevent a secondary stall from happening. So the issue here is not the design or even the MCAS( even though the MCAS did play a role in the crash) but the thing that cause the MCAS to activate during normal flight operations. The MAX can fly without the MCAS just fine. Please watch this part of the video: https://www.youtube.com/watch?v=TlinocVHpzk&t=952s
SheikhDjibouti wrote:
"they" are presumably airlines that for some reason can only operate Boeing aircraft. What happens if they break that rule; does the CEO turn into a pumpkin at midnight? :roll:

I think you misunderstood me. I'm not saying that airlines can only operate Boeing aircraft, if they want to they can. But, I'm saying that it is more financially logical for airlines and Boeing to continue the MAX programme. I mean if you are the CEO of an airline like Southwest or Ryanair would you cancel your rather wait for the grounding of the MAX to be lifted in a few months or decide to go with Airbus or any other aircraft manufactures where you have to pay a cancellation fee to Boeing, pay to retrain all your pilots to the new aircraft and not to mention you still have to pay a cost for a new plane. It just doesn't make financial sense at all. So I'm not saying that Boeing is the best or that airlines can't survive without Boeing, I'm just telling those who thinks that the MAX will not fly again and how unlikely for that to happen.

SheikhDjibouti wrote:
Boeing doesn't have anything to compete in the RJ market, but they survive.
Boeing doesn't have anything to compete against the ATR72, but they survive.
And now for a while it looks as if they will only have the NG to compete against the A320. They will survive.

For years, Airbus didn't have anything to compete against numerous different offerings from Boeing.

And for decades nobody on the planet had anything to compete against the 747.

Get real! Life goes on.

Boeing will take a hit, regroup, redesign, and come out of this stronger and better.
Airlines will have to fly the NG for a few more years, and swallow any extra fuel costs. Or make Boeing cough up the difference.


Yes, Boeing can survive without having the MAX but if you can save it by making a few changes why throw the whole operations away? Especially after coming this far with over 5,000+ orders in the books. Why risk it in creating an entirely new aircraft if you can just fix your current one? I expect Boeing to receive more orders for the MAX after all this debacle is over.


Depending on what happens next re grounding or certification if Boeing can't make the plane safe etc then surely all deposits have to be returned if requested?

Also at some stage Boeing may need to halt production full stop of the planes short term regardless. If they can't move them forwards in the production cycle

I already read they are halting production for 3 days next week

Theyve got a problem that this plane accounts for about 80 per cent of the planes they are currently building I believe. At what stage of the grounding do they have to stop producing full stop

Or do they just keep flying them on to somewhere temporarily?
Last edited by Interested on Sat Mar 23, 2019 8:57 am, edited 2 times in total.
 
Interested
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Re: B737MAX Grounded Worldwide

Sat Mar 23, 2019 8:48 am

art wrote:
Interested wrote:

If something can still occur that is dangerous however few times it happens. That isn't needed on other planes

Then Boeing have created a plane that is less safe than the one it replaced

That's just inconceivable that they would do that.

Why should pilots and the public accept that?


Not quite sure what you are asking but I would imagine that the designers of the original 737 were perfectly happy with the positioning of the engines. When the design was updated to use engines with bigger fans (NG), there was a problem - the bottom of the engine nacelles would be too close to the ground. They got round that without moving the engines by flattening the bottom of the nacelles. That was not possible with the still larger diameter CFM Leap engine. Originally the intention was to increase ground clearance by increasing the length of the undercarriage but that proved impractical (for cost reasons, I presume) so the decision was taken to move the engines from the optimum location to a location that was not. To me that made the aircraft less safe. I don;t think pilots would have approved, had they been consulted. The public, with no disrespect intended, would not have understood enough about aircraft design to be in a position to voice an informed opinion.


I'm saying why would anyone consider designing a plane that requires a new software system to be able to fly safely. When we know a new system ( by its nature will have a failure rate - no matter how low that failure rate is)

We should surely only be adding systems that can improve safety when they work compared to an old model and are a bonus safety feature. Not a feature that becomes necessary due to a step backwards in stability

We should never be adding systems that we NEED to work every time just to mirror previous stability safety

It's just crazy that this could be agreed and happen in the first place IMO

And I'm saying it shouldn't be accepted that we've made planes less safe

We may be talking just 0.001% less safe than before. But with the amount of flights and passengers involved that can add up to a problem weve created.

We should be going for 0.001% more safe with a new plane - not less safe shouldn't we

And shouldn't our authorities always focus on safety ahead of any other benefits?

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