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Sensor damaged by a foreign object on Ethiopian Airlines 737 MAX triggered fatal crash

Enviado há
 
The Ethiopian Airlines Boeing 737 MAX, which crashed in March and killed 157 people, suffered a damaged angle-of-attack sensor upon takeoff from a bird or foreign object, triggering erroneous data and the activation an anti-stall system -- called MCAS -- sending the pitch of the plane downward and ultimately crashing into the ground, two aviation sources familiar with the investigation told ABC News. As the jet was nose diving, the Boeing 737 MAX pilots did not try to electronically pull the… (www.yahoo.com) Mais...

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patpylot
patrick baker 8
boeing has much to answer for in this situation where they built systems and helped inspect and certify those systems wherein deficiencies commpounded upon each other resulting in fatalities and the destruction of two airliners. They can not talk their way out of this situation with legalistic mumbo-jumbos: deflecting blame on crews especially. Boeing is supposed to have an ethical partnership with the operators so as to guarantee predictable performance resulting in safe travel. This they did not do as of yet.
lecompte2
lecompte2 4
You people have to understand that the trim activates the horizontal stabilizer which is twice the size of the elevator controlled by the pilot so the pilot cannot overpower the trim when it is active. Now if the aircraft is in a high speed dive after the MCAS has run the trim to full nose down or close to it and is selected off by the pilot, the aerodynamic forces on the stabilizer (trim) are so strong that the pilot cannot override them in manual mode, this probably why they attempted to restart the electric trim in desperation to regain control in this short time event.
rapidwolve
rapidwolve 3
Not just the aerodynamic forces, but the forces on that jackscrew..this is what former Boeing flight control engineer Peter Lemme speculated "“The forces on the tail could have been too great,” Lemme said. “They couldn’t turn the manual trim wheel.”

Good write up includes 2 European 737 pilots using a simulator to demonstrate Lemme's hypothesis https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/
lecompte2
lecompte2 3
If this airplane cannot fly without the MCAS, it should not fly
jhakunti
Jayden Hakunti 0
Pilot_obet on instagram explains this in full detail in live action with the 747-8i on his page. Might I add what a fine work of engineering the 747-8i is, and what a shame no US passenger carrier uses this aircraft.
Highflyer1950
Highflyer1950 -1
Exactly, which is why early recognition and immediate deactivation of the MCAS/runaway trim using the Trim CutOut Switches is imperative.
rapidwolve
rapidwolve 1
Easy enough to say, Highflyer, but we don't know how fast or long that MCAS system takes to turn the stab trim jackscrew...is it fast or slow retention?
Highflyer1950
Highflyer1950 6
I don’t know any tranport category pilot who, when faced with a sudden nose down moment doesn’t pull back on the yoke/stick while trimming at the same time? Furthermore, if the nose down force re-occurs, trim cut outs are selected while one pilot starts manually trimming as fast as possible while the other continues to apply back pressure!
andyc852
Andy Cruickshank 5
Do not think you have to be a transport catagory pilot for that, just a trained pilot. There is more to this accident than that alone.
Highflyer1950
Highflyer1950 1
True, but I was referencing large aircraft drivers. Most GA aircraft with electric trim can be easily overridden or a cb easily pulled. I agree there is a lot more to this especially since two aircraft crashed. There is one thing still not explained, could the autopilot be engaged with an out of trim aircraft since this MCAS works only when manual flying, as far a I know?
punkrawk78
Silent Bob 2
No, the 737 autopilot is designed to not engage if there is force being applied to the yoke. Also, if you suspect a trim problem and run the appropriate checklist the first item is to disconnect the autopilot. We've been taught over and over through the years to not trust the automation, and if there's any doubt about what the airplane is doing to disconnect everything and fly manually until everything is back to normal.
jbqwik
jbqwik 2
but, here's the thing that keeps me insane: Why, after so much experience with faulty sensors interacting with and/or conflicting with software.. why, after allll these incidences and detailed forensics... why can't the dev team takes those scenarios into consideration and design truly fail safe software? You all know it's only going to get worse as AI is coming on strong and the dumbing-down of pilot muscle memory continues to creep. You only need to read in-depth WWII pilot interviews to fully appreciate how far we've come from hands-on flying. Those aircraft demanded to be flown, and in return the pilot developed a connection to his plane to such an extent that there were few surprises. I don't want to be old-school, and I understand the benefits of automated aircraft. So what's the solution?
BurntOut
BurntOut 1
There is no such thing "truly fail safe software" because you can ALWAYS make a scenario where some piece of hardware fails and there is nothing anybody can do to prevent the plane from falling out of the sky (example: Lockerbie). There is no such thing as "AI" -- True intelligence involves making the intuitive leap. Computer AI is merely backward/forward chaining of statistical information to come to the 'course of action most likely to get to the preapproved configuration/outcome'. The computer code will not 'create' anything on its own. If the programmer didn't think of it, the software won't create it.

I am not saying your comment(s) are not without merit. It may be the software should have auto-disengaged and flashed a message saying "I give up - Humans need to fly the plane."

Regarding your WW2 commment -- As an old SAC pilot told me before my first lesson: "A Driver walks up to the plane, gets in, and moves the plane from one airport to another. A PILOT walks up to the plane, straps it to his a$$, and tells everyone in earshot "Here's what we're gonna do today. . . .""

[This comment has been downvoted. Show anyway.]

rapidwolve
rapidwolve 3
Maybe, just maybe, you should read the whole damn prelim. report again instead of " Stupid pilots switched on and off the system controlling the auto trim and didn't use the correct procedures they were trained to do" What part of this "The Ethiopian Airlines crew commanding the aircraft followed all recommended procedures but couldn't regain control of the doomed flight" don't you understand??
JimG4170L
Jim Goldfuss 1
It has been determined (if you are following closely and with some understanding) that the Ethiopian crew initially followed the procedure and disconnected the STAB TRIM system. However, they reengaged the system which is NOT part of the process, which retriggered the MCAS system. The initial MCAS trigger moved the stabilizer to a nose down position. The crew did not trim it back up before disconnecting STAB Trim, so stabilator stayed in nose down position. The crew did not maintain speed control (they got too fast) and when they reengaged the STAB TRIM system, the MCAS started trimming nose down again, and at the speeds they allowed the aircraft to get to, made recovery impossible at the altitude they were at. The investigation continues, and more will come out. All the answers are not available yet, but hopefully this helps you understand. As for the other poster, there is no need for name calling.
rapidwolve
rapidwolve 1
I understand fully...and I have read a great deal of articles about it and now realize why they may have switched it back on...something Boeing failed to comprehend and has actually left out of the newer 737's manuals, not just MAX...remember, this "antiquated" flight control system minus the NCAS thrown into the mix, dates wayy back to the early 737's.
rapidwolve
rapidwolve 1
To me, this sentence within the prelim. report says a great deal "The Ethiopian Airlines crew commanding the aircraft followed all recommended procedures but couldn't regain control of the doomed flight" Remember, the officials have heard the CVR and read data from the FDR, where as we have not. As far as I am concerned, Boeing should have used it's head when asking for data from the AoA sensors...if they don't correlate, do not use this data and disconnect..that should have come about when realizing about the Lion Air accident and it's 1 faulty sensor.
Be like turning using cruise control and tapping the brake pedal to disengage it...if the cruise module got conflicting advice from various inputs, but didn't turn off, imagine the mess it could cause. Yes shutting off the cruise via the switch would disengage it, but it may be too late. (too close to the other traffic, brake failure due to trying to stop power train momentum that is not backing down etc)
JimG4170L
Jim Goldfuss 2
The crew did NOT follow the procedures. They re-engaged a system that was malfunctioning. To put it simply, if you engage the cruise control in your car and the car speeds up uncontrollably and you disconnect it - do you slow down afterwards? DO you turn the cruise control back on? Hopefully you answered YES to the first question and NO to the second. The Ethiopian crew did not. They did not retrim the aircraft and they reengaged the system - and that is not following procedures.
rapidwolve
rapidwolve 1
The crew DID follow procedure, BUT procedure did not work!
rapidwolve
rapidwolve 2
Just to add, they had no indication the MCAS system was malfunctioning, as there is no indication lights on the displays. I've been following this for a while in different forums, not just with the Ethiopian crash.
bbabis
Bill Babis 0
Congratulations Jim. It appears that you have been able to get across a point and likely accident scenario in your other comments that many others have made without triggering the wrath of down-voters. I salute you.
djjamar
Jamar Jackson 3
So one bad sensor can cause this much distrust and damage.
ADXbear
ADXbear 2
Pilots would not reenguage the trim system after cutting the power from the first upset. However if they did that would be a mistake.. pilots would naturally pull back on yoke and trim to relieve the pressure.. this system is a mess..
FrankHarvey
Frank Harvey 2
The AOA sensor on the nose doesn't measure "a stall", it measures the airflow past the nose, many feet away from the wing areas generating lift, or, in the case of a stalling wing, failing to generate lift. What is needed is a series of pressure sensors along the top and bottom of the wing sensing the pressure differential at each point. When the difference between the top and bottom sensor pair starts falling it indicates an incipient stall at that spot along the wing. You could call it a Bernoulli meter. These would cost a lot more than a metal triangle linked to a potentiometer, but almost every automobile has pressure sensors in the wheels today, so they can't be overly expensive.
Highflyer1950
Highflyer1950 2
I like your thinking but the chances of a faulty sensor goes up the more of them that are installed. Plus, the pressure differential is not linear along the surface of a swept wing airfoil makiing calibration a nightmare? AOA systems have been around for many years and I believe the New Icon 5 seaplane only has an AOA indicator for speed reference on takeoff and landing. For all the automation available today manufacturers still install a way to shut it off when it fails.
FrankHarvey
Frank Harvey 0
Hi Highflyer, thanks for taking my thought seriously, and responding in a like manner.

I did not intend this indicator/instrument to cause any computer action but just to indicate to the pilot(s) what was happening along the wing. It would be up to the pilot(s) whether to ignore it. In my mind there would be a light bar with tricolor LEDs in green (lift), orange (low lift), and red (no lift) and a large switch placarded "OFF". The device would not be linked to the computers controlling any a/c operation. Each LED would indicate the pressure differential at one pair of sensors. If one or more sensors were faulty it could be documented but it would not be on the Go/Nogo list. I want to emphasise this is only to indicate to the pilot what is happening, and for him to decide whether to take any action or not. It is not to be linked to any computerised or otherwise automated action.

If you know someone with a tandem sailplane, tape 4 inch lengths of wool every couple of feet along the top of the wings behind the main spar then take it up to about 4,000 and have them hold it in an incipient stall, just as the buffeting starts, while you look out along the wings. You'll see some of the yarn twisting along the parts of the wing which are stalling and it still flows straight on the parts still generating lift. Then (if they are very competent at spin recovery), tighten your straps and have them raise the nose till the ASI is just below the bottom of the green and then initiate a standard turn while you're looking quickly at the yarn on each wing. You'll see the yarns on the lower wing (inside the turn) start twisting around progressively from the outside towards the root while the high wing (outside of the turn) outer yarn flows strongly straight. Then you feel a massive force as you enter the spin.

I got the idea of the sensors and light bar from the seeders used by farm contractors in custom farming. Each nozzle across the equipment drops a seed every couple of inches and the bar shows them as green when they are working. When they get clogged the show up red and the computer automatically blows compressed air down them to clear clog. They almost always clear themselves and become green again. As you're driving along you see them clog and unclog and if there are ares of wet soil several can clog adjacent to each other while the remainder stay green. If we can afford this type of display on an $50,000 planter we should be able to afford it on a multi-million dollar a/c where lives and not the loss of a few square feet of unplanted acreage are at stake.

Its really just a thought which will never be implemented anyway.
Highflyer1950
Highflyer1950 1
An interesting thought process and well stated. Since my early days in a piston single up to heavy jets to all the corporate Gulfstreams they pretty much all fly the same. Most stall characteristics are comparable with the odd airframe like the Lear 20 Series being somewhat more demanding of stick & rudder skills. Stall recognition/recovery techniques haven’t changed that much, however, the display information has advanced tremendously ie; AOA Displays, Flight Director cues, better understanding of high altitude flight on low and high speed buffet boundary, H.U. D. units for both pilots, FLIR etc. What hasn’t kept up is system undestanding when it fails. It’s pretty easy to recover from a stall, even easier on departure......just lower the nose, but when the aircraft systems indicate a impending stall when there isn’t one, disabling that protective system in a timely manner has eluded two crews so far? Boeing probably didn’t do enough for the pilots, the airlines didn’t go far enough to fully equip their planes, not one crew asked what does MCAS stand for in the flight manual or QRH that we know of? QRH procedures are fairly straight forward with Auto Pilot disconnect usually in the first 5 items, but what about manual flying of the aircraft while it’s trying to fly itself as well? The pilot always has to win the fight for control, except in the case of AF-447? sorry, got long winded again!
FrankHarvey
Frank Harvey 1
Hi Highflyer
Your reply wasn't as long winded as many of my posts but it contains much to ponder. I agree that the pilot has to be given final overriding authority over any system under any condition. But I also want the pilot to understand the system(s) he is controlling as well as having basic stick and rudder skills, and understanding. That said I also am amazed at how complex commercial a/c systems now are. It also seems that on AF447 the PF and P2 (FO ?) were not communicating their intentions, something that is absolutely essential for any team. The crews on both Lion Air and Ethiopian had very few seconds to try to figure out, and remedy, the problems they faced in a very scary environment. Even experienced air force personnel need a lot of concentration to fly at 300+kn 400 feet above the terrain in a perfectly functioning a/c. Much more a transport pilot in the Lion or Ethiop situation. I feel that is not the time or place to be flipping through a QRH and running through what might be the correct checklist. But there is a lot I don't know, for example: the ergonomics of turning the 737 manual trim from 2.5 degrees nose down to neutral and what would be the difference for a left hander or right hander. And how would this be for someone who has almost always used a thumbswitch for trim adjustment ? Understanding this might explain why someone would turn back on the Stab Trim so they could use the thumbswitch. Anyway I'm in danger of rambling way beyond "long winded" and its 0415 so I'll say goodnight.
Highflyer1950
Highflyer1950 -1
Reference to the QRH was made only to show MCAS is shown in the abbreviations and most pilot’s would have asked, What is this? The trim Cut Out Switch (s) is a memory item for a runaway trim or uncommanded trim/stab movement. Since the pilot was hand flying the aircraft and the stab was moving on it’s own to nose down position, a quick response to shut off the Trim Cut Out Switches should have stopped all movement leaving the aircraft flyable. If action was delayed and the stab went full nose down, high airspeed and associated aerodynamic forces ( as stated by another poster) may have been too great for either brute force on the yoke or re-engaging the electric trim to bring the nose attitude up. I ref. AF447 only to emphasize neither pilot understood the side stick authority function, failed to assess their high altitude stall (coffin corner) properly, poor communication.
FrankHarvey
Frank Harvey 0
Thanks Highflyer, I completely missed your point, which I recognise is very important, that MCAS is actually mentioned in the abbreviation section of the QRH. I was not aware of it until reading your most recent post. Thanks for clarifying. As for AF447, I just feel sorry that the two kids up front were so overwhelmed by the situation that they weren't able to figure out, or to communicate with each other, what was going on and how they were trying to remedy it in time. I am also amazed that the authorities were able to retrieve and decipher the boxes after so long.
JimG4170L
Jim Goldfuss 1
AOA sensor measures angle of attack (hence AOA). A plane stalls at a definite Angle of Attack regardless of speed or attitude. It is not measuring the airflow, it is measuring the angle that the airflow is striking the leading edge of the wing.
airpound69
Enrique Silva 1
Correct.
FrankHarvey
Frank Harvey 1
Hi Jim and Enrique,

Thanks for responding to my post. I used the wrong terminology in trying to simplify a point regarding the stalling of a modern aircraft wing resulting in partial or complete loss of lift, actually a quite complex issue which I am going to try to simplify for brevity here.

Jim, I believe the AOA we are interested in is the angle that the air is flowing relative to the chord of the wing, not as you said, the angle that it is "striking the leading edge". The chord, very roughly, being the line extending from the leading edge to the trailing edge. This chord can vary along the wing from the root to the tip and can vary considerably with wing design and geometry.

What I meant was that the AOA sensor mounted close to the nose of an aircraft is indicating the direction in which the air is flowing past the AOA sensor mounted on the nose of the fuselage. It does not show the direction that the air is flowing over any part of the wing except possibly the wing root at its junction with the fuselage. The AOA we should be interested in is the AOA of the chord of the wing relative to the air flowing over the wing, thus generating lift.

Most modern commercial a/c can change the position of the leading edge of the wing relative to the AOA sensor on the fuselage by altering the geometry of the leading edge (eg extending "slats"). This usually alters the chord of the wing relative to the fuselage. Similarly the chord of a wing can be altered by extending the trailing edge. A stall which is of importance in this case occurs "somewheres" along the wing, not on the nose, when the airflow above the wing breaks up and the wing stops generating lift. Very approximately stalls commence at about 12 to 14 degree angles. Stalls can occur on one section of the wing while another is still generating lift.

We can know if a stall is occurring on a section of wing if that section stops generating lift. So instead of using the airflow at the nose of the fuselage to determine the onset of a stall why don't we try to determine when areas of the wing stop generating lift ? I contend that pressure sensors along the wing would indicate whether each section was generating lift or not, relative to the remainder of the wing, and therefore imply that a stall was occurring proximate to that section.

Thanks again for your response.
ianmcdonell
ian mcdonell 2
The report DISPUTES the FOD finding - says it found no evidence of damage - what's with the garbage headline
bbabis
Bill Babis 0
I see the headline was finally changed and there is finally more admittance that the crew while fighting to their capability just didn’t know what to do. By no means is Boeing off the hook but this was a perfect storm of events waiting for susceptible crews that lead to these accidents.
airpound69
Enrique Silva 2
Yes they are on this one. Sensor was damaged and caused a malfunction. Pilots cut off the stabs and then back on for whatever reason instead of using the alternate method.
bbabis
Bill Babis -1
There is a lot being lost in translation. We still don’t have the whole story and Ethiopia is covering for a woefully untrained crew to put even more liability on Boeing and off them. No one turns a malfunctioning system back on and rides it into the ground if they truly figured it out once and stopped the down force. My guess is they had the down force, correctly disengaged the electric trim, then found that the down force remained and their “manual trim switches on the wheel” weren’t working to help with the problem so they reengaged the electric stab and were ultimately overcome. I don’t think they ever moved the manual trim wheel as we know it or they would still be alive to tell us about the problem.
rapidwolve
rapidwolve 2
Ethiopia is not the only investigation team in the area, and your last sentence is pure speculation.
Highflyer1950
Highflyer1950 0
Actually I kind of agree with Bill on this one. However, the info being disseminated is piece meal at best. I suppose it is quite possible that the Ethiopian crew finally turned off the Trim Cut Out switches but didn’t realize that also disabled the electic trim switches on the yoke. So by turning the cut out switches back on gave them back electric trim but also powered up the MCAS as well? I’ll bet the manual trim handle was never deployed and manual trilm never used throughout the whole process? Speculation yes, but sometimes the simplest explanation is the correct one! The think Boeing mucked up by having the Trim Cut Out Switches control power to the electric trim and MCAS without some sort of highlighted reference in the QRH about both systems? (and that is pure speculation because I don’t have the QRH in front of me)
rapidwolve
rapidwolve 5
Sorry but when someone comes in and starts lambasting a crew, without knowing full situation, to try and defend another company, is not called for. Who is to say manual trim was never used, but used too late. Sometimes a craft gets into such a steep decline that it is impossible to recover from, no matter how much you try.
But to say "covering for a woefully untrained crew to put even more liability on Boeing and off them" when he doesn't know how trained they are is just wrong especially when they are not here to defend themselves!
jhakunti
Jayden Hakunti -1
Everyone in this forum was absent from the cockpits of Lionair and Ethiopia Air, absent from Boeing's development and design of the max 8 and absent from the investigations into the crashes. Thus every comment here is ignorant or naive, out of place and unworthy. But what we do know is that the plane had a design flaw patched with a software called mcas which without it, the max airplane is unflyable. I will never step into one as passenger or pilot, and I wil, pray that one does not come crashing down into my home or car if somehow this plane is foolishly allowed back into the air. Arrogance won't let certain people admit they failed which is why it is a positive thing Airbus was brought onto the investigation. The FAA and Boeing already failed everyone here. I cannot imagine the feeling of the captain who could not get control of his plane as it is travelling over 300mph. Unless we are on the decline we must acknowledge our laziness in Boeing not designing a better, newer aircraft, and the government's lackadaisical shutdown showdown politics and lack of due diligence in the certification of this aircraft. People need to wake up. Boeing is our number 1 GNP and something this reckless is a big deal.
rapidwolve
rapidwolve 0
Excuse me but every comment here is not ignorant or naive, out of place and unworthy. If that is the case then why did you comment? According to you, it's obviously ignorant or naive, out of place and unworthy.
jhakunti
Jayden Hakunti 0
Because when in Rome...sometimes you gotta speak the language of your audience.
Highflyer1950
Highflyer1950 0
True, but when you are Transmitting you are not Receiving!
jhakunti
Jayden Hakunti 0
But any VORTAC equipped aircraft can transmit and receive.
Highflyer1950
Highflyer1950 0
Except at 40 West?
airpound69
Enrique Silva 0
Lmao is your comment serious? The plane does not have any flaws, it’s a characteristic. As you stated, people here are not part of the team, so how can you affirm there’s a flaw? The reports from the investigators are very clear to show what happened there
bbabis
Bill Babis -2
I clearly stated that my last sentence is pure speculation but I have more faith in it than a report out of an Ethiopian government that has much to hide.
rapidwolve
rapidwolve 0
And you did not read my line that the Ethiopian government is not the only team investigating...sorry but I do have faith in the Canadian, US, and UK/European investigation team!
bbabis
Bill Babis -2
I do too. Maybe they will put out a report closer to the truth. The Ethiopian government is iron fisting what gets said right now. I’m glad the US investigator got a line in on the stab being reenergized. Not what Boeing would recommend if they followed the procedures as stated.
rapidwolve
rapidwolve 1
The Ethiopian government has no real say what is getting released as it is an international investigation NOT just an Ethiopian investigation, and it was an international prelim. report...BTW, how do you know it was a US investigator who made mention of the re-energized surfaces in the report?

And if a government wanted to chastise a company and cover things up, they sure as heck would not have mentioned " Based on the initial report, Ethiopian safety investigators recommend Boeing reviews the aircraft flight control system of its new 737 Max 8 model and that aviation authorities verify the flight control ability has been adequately addressed by the manufacturer before resuming operations of this jet, according to the transport minister."
airpound69
Enrique Silva 0
So, they activated the system back on when they shouldn’t instead of using the alternate trim, that explain some things. Again, it’s very convenient for the airlines to blame Boeing when they clearly played a role in this crap.
Also, wtf does “The data provided by the FDR (flight data recorder) doesn't indicate that there is an FOD” means? Lmao either the Ethiopian aircraft came with some really advanced sensors or the people working for them don’t have a clue about what they are doing.
jhakunti
Jayden Hakunti -1
Flawed airplane that should and will be scrapped. These days from a passenger standpoint all the worthwile boeings that arent the 777 and 787 are gradually being phased out of service. The 737ng is a terrible plane for 3hrs+ flight if you sit anywhere aft of comfort plus. Besides the crj900 and erj175 are more spacious and have fresher flight attendants. Its high time to follow Trump and get a private 757. Anyone interested in a fractional ownership for a 757?
FrankHarvey
Frank Harvey 1
I don't believe the Max "unflyable" with or without a functioning MCAS. I believe that almost all of the time it is flyable in either condition.

However I believe that MCAS was an attempt to make Max "the same" as the NG or some earlier 73xs and without MCAS it is not "the same". It also seems that MCAS has flaws under some conditions, especially in its use of a single source for activation and in its overriding the pilots.

It seems to me that without MCAS engine power can give Max a nose-up moment which makes it "different" to the NG or some other 73xs. MCAS is supposed to counteract this with trim and supposed to therefore make it "the same as" the NG etc. It seems to me the if the Max pilot was aware of this characteristic he could do the trimming himself and Boeing could eliminate MCAS.

Many a/c have different characteristics which have to be handled differently to other similar a/c. The pilot just has to be aware of them and to be expected to handle them when they occur. The way I see it is that in Max when you apply power you have to expect a nose up moment which you have to counteract with trim. However it appears to me from what I read that if you switch out MCAS you lose the thumbswitch trim and have to resort to the manual trimwheel. This is undesirable.

It also seems that if you remove MCAS you make the Max a "different a/c to the NG etc and need to comply with many different and costly certification and qualification requirements.

When you power up some prop jobs they swing across the runway while other different engined similar airframes do not. You just have to know what to expect and to anticipate the need to counteract it.
jhakunti
Jayden Hakunti 1
I dont see your point because the cessna 172 pitches nose up with increased power and it does not require an mcas type system. Also, are you trying to say that the FAA and Boeing were negligent in certifying this craft as the same type when in actuality it deserved a new type rating to fly? Either way...
FrankHarvey
Frank Harvey 2
Hi Jayden,

You are correct in that my point is that the Max, without software, appears to perform significantly differently in some aspects than the NG and other 73X series a/c and I strongly believe these differences should have been explicitly stated by Boeing.

Also, other than trying to eliminate one difference I don't see what MCAS buys you instead of telling the Max pilot to be aware of, and trim for, the nose-up pitch when adding power.

However I did not intend to say that, without MCAS, the Max definitely needed a different rating. I am not qualified to determine whether or not the difference(s) are so great as to require a different rating. But the fact that Boeing devised and installed MCAS implies to me that perhaps they thought it might have been an issue, and others appear to believe this to be the case. Even more so, after flight testing Boeing seem to have changed the MCAS program to a 2.5 degree maximum from the 0.6 degrees the designers originally calculated was required, but do not appear to have told anyone.

I did intend to say that without MCAS (whether set to 0.6 or 2.5) the Max "might" need to comply with many different and costly certification and qualification requirements.
jhakunti
Jayden Hakunti 1
Ok, well said across this entire thread. I agree about the pressure sensors on the wing that you name Bernouli sensors, but would de-icing fluid or precip. affect their performance in certain operations? Hypothetically pondering : If the nose up pitch is so great during increased thrust, is the a/c underpowered or is the thrust line so far off balance to require so much trim? Why and why not just design something new since so much certification? Did boeing hastily cut corners to meet the A320neo series?
FrankHarvey
Frank Harvey 1
Hi Jayden
Thanks for raising several questions which I hadn't fully thought through. I think if pressure sensors ("Bernoullis") were to be actually created the materials would need to be resistant to de-icing fluids and robust. I don't believe precip would affect their operation as their positions on the wing should not be affected by icing. Also I do not perceive these as activating any action by the a/c computers, they are intended to only to provide information to the crew and should only connect to a bar of lights showing the lift (green) or lack of (orange or red) at several sections along the wing. Also if they become a distraction there should be an on/off switch and they should not be on a go/nogo list.

As to your other questions, the thrust on the Max must be generating the pitch-up moment as if it was the nacelle acting as an aerofoil (providing lift ahead of the CofG) this would increase with relative airspeed and that does not appear to be the case. Your thrust line suggestion is interesting but if this were the case surely the designers would have altered the pylon design to counteract this ? The 0.6 to 2.5 degree change of maximum deflection after flight testing implies a serious divergence between design calculation and (presumably) wind tunnel tests and the full scale prototype and that some unexpected behavior was encountered in flight tests.

Boeing were months (well over a year ?) behind the Neo with the Max and American seemed to be opening the door to Airbus.
airpound69
Enrique Silva -1
I don’t want to disrespect you but your comment is just stupid. You clearly didn’t read the parts about the sensors being damaged during the take off roll by FOD and the pilots restarting the system when they should not. Even if there was/is a flaw, it can be easily foxed.
Whether the plane is comfortable or not has nothing to do with it being better or not - it has to do with the airline fitting as many seats as they can to make more money and be able to offer lower fares.
jhakunti
Jayden Hakunti 2
If the plane is unflyable without mcas and they turned off mcas because it was unflyable with the mcas malfunctioning, then yes the design is flawed and shall be scrapped. But i will acquiese that my argument about the lack of comfort in this aircraft cannot be absolutely attributed to boeing, but i still maintain that largely it can be attributed to boeing who is responsible for the size and performance of their design by which their customers are bound. Falls under same category of know your audience. And just for disclosure, i used to be a Aint boeing aint going guy until the max 8 series of crashes. Airbus has gained a lot of respect to me now. For the sake of humanity, the max 8 should be discontinued. I never want to be on an aircraft that cannot be controlled inflight because the craft itself violates the principles of flight.
jhakunti
Jayden Hakunti 1
Also i would like to add that bombardier and embraer have also built craft far superior to the 737ng series with respective ERJ175, CS Series, and CRJNG series aircraft. Just maybe Boeing has invested too much time and effort into the 737ng and perhaps these max8 crashes should result in the resignation of some of Boeing's C-level management.

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