Boeing 737 Max8 Aircraft Crashes and Investigations [Part 8] 24

[Sparweb]

This post is the continuation from this series of previous threads:

thread815-445840
thread815-450258
thread815-452000
thread815-454283
thread815-457125
thread815-461989
thread815-466401

This topic is broken into multiple threads due to the length to be scrolled, and images to load, creating long load times for some users and devices.
If you are NEW to this discussion, please read the above threads prior to posting, to avoid rehashing old discussions.

Thank you everyone for your interest! I have learned a lot from the discussion, too.

Some key references:
Ethiopian CAA preliminary report (Link from Ethiopia is now broken. See link from NTSB Investigations below)

Indonesian National Transportation Safety Committee preliminary report

NTSB Investigations

NTSB Safety Recommendation Report: Assumptions Used in the Safety Assessment Process and the
Effects of Multiple Alerts and Indications on Pilot Performance

A Boeing 737 Technical Site

Washington Post: When Will Boeing 737 Max Fly Again and More Questions

BBC: Boeing to temporarily halt 737 Max production in January

Pulitzer Prize, For groundbreaking stories that exposed design flaws in the Boeing 737 MAX that led to two deadly crashes and revealed failures in government oversight.

http://www.sparweb.ca

 

[RedSnake]

Inherent in both the Flight Control Computer (FCC) and Stall Management Yaw Damper (SMYD) is the angle of attack sensor, or AOA sensor.
The AOA sensor data is used to determine airplane pitch attitude to set the stall warnings and to calculate performance data.
Amongst the many analog interfaces, the Stall Management Yaw Damper outputs discretes for stick shaker and to activate the elevator feel shift module.
Each Stall Management Yaw Damper activates its on-side stick shaker motor.
When airspeed is close to a stall, the Stall Management Yaw Dampers do the Elevator Feel Shift (ELF) function by operating the Elevator Feel Shift Module EFSM which provides 850 psi (58 bar) hydraulic system A pressure to the elevator feel computer and the dual feel actuator.
This causes the elevator feel force in the feel and centering unit to increase and to counteract or resist elevator up movement at the control column.
Activation of the Elevator Feel Shift Module occurs at an AoA of 8 to 11 degrees depending on flap position.
There are no other flight deck indications when this system operates.

And the reason why the FEEL DIFF PRESS lights up is that since it is only hydraulic system A that provides pressure to the elevator feel shift module and it also provides pressure to only one side (channel) of the elevator feel computer when the SMYD dual coil solenoid valve is turned on the pressure difference between channel A and B in the EFC:n becomes more then 25 bars and then the the FEEL DIFF PRESS lights up after 30 sec.

And one AoA was calibrated wrongly 21 degress the first crash.
And it is enough that one stick shaker motor activates for this to happen.. as I see it..

The only thing I am not shore of, is if both SMYD:s are always turned on or if it is only the one on the side witch is the captain "designated driver" ??

Best Regards A


“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

From Boeings standard with the rest of the design I suspect it will be only one in the loop with one in back up ready to take over mode. Or one does each side.

But as usual nothing to indicate its fired.... apart from a cryptic hydraulic pressure differential light. And its on the flight control panel which is on the ceiling right at the very back of the overhead panel behind the pilots heads and out of view.

 

[RedSnake]

No there is two one for each side left Aoa and SMYD 1 for captain and right AoA and SMYD 2 for O.P ??
What's the other side called ?
I an not shore if both is active all the time.
As fast as one of the stick shakers starts left or right regardless of reason both control columns are "looked" and the light goes on and all the other "Christmas tree lights" as well depending on the problem.
AISI..

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

Sounds about right but there is usually some logic which has 1 side the master and the other the backup or they run them solo and each side looks after itself with neither side backed up. Depends on the design philosophy. British aerospace always used to run them solo don't have a clue what Boeing does.

Just so you have a reference this is the max cockpit

And this is the flight control panel. Which is located in the top left of the photo above most of it out of shot I think.

 

[RedSnake]

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

you think that's bad here is the CB panel. The ones with the collars on them are the ones that need to be pulled in various checklists. I don't have clue where the stick shaker CB will be. But with all of them someone will have to get out of their seat to pull it.

Modern aircraft designs have electronic thermal circuit breakers which automatically alert you that they have tripped and tell you which system they are on and which checklist to run and what you loose all through the 5th screen in the cockpit.

 

[RedSnake]

Well I know that new people that come and work at the press shop feels like that when they are going to learn how to drive the presses but there isn't even 1/4 as many buttons on the presses ..

I cant really see anything on the pictures that looks like the SMYD.
I found a reference that says it is located in the E&E bay on the E3-2 shelf.
E&E bay ???
It seems it does not always look the same.

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

thing is some of those switch's on Boeings come down to turn on and some go up...

 

[RedSnake]

Sounds logical and consistent
Have you ever flown one?

BR A


“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

Not a max or other flavour in the actual aircraft but Boeing sims are probably the most common sims available, so there is usually open slots for low level course such as multi crew cooperation.

Because they are available when company's for other types are recruiting they tend to use them for doing check flights to makes sure you can fly a procedure and straight and level. So I have been in both a 737 classic and NG sim a few times.

Also sometimes you do someone a favour by being a the second pilot on a course that needs it done quickly but doesn't have a sim partner. But these course are not type specific so you don't need to know teh nitty gritty of the type as you don't go near the emergency procedures apart from knowing how to secure the engine after a failure.

What is noticeable though flying with ex 737 pilots is the amount of rule of thumb they use and additional procedures which they think everyone does on every type and are good airmanship. But in reality are just 737 specific. They absolutely poo themselves when you drop a wing while landing to control side slip in a xwind landing. Its because the 737 has a very small ground clearance from the bottom of the engine so they are petrified they are going to scrape a pod. BUt they try and apply the 737 limitation to other types which you can do 10 deg and then the machine starts bitching "bank angle" and even then you won't scrape the engine pods until 16 deg bank. But the ex 737 pilots will start screaming if you get anywhere near 5 deg.

 

[RedSnake]

Sounds a lot like the Pixar short movie Lifted
I think it is hilarious.

https://www.youtube.com/watch?v=LVLoc6FrLi0

Putting an even bigger motor on the 737 does not seems like a good idea then?

BR A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

The max is a Frankstien collection of 1960's and modern design. They have changed absolutely nothing over the years unless it was regulated that they had to. There is issues that have been running since the first one left the hanger and they are still present in the MAX.

 

[RedSnake]

I was trying to find out if there was any technical changes made to the Max8 before it was approved for flight again, but it's like looking for a needle in a haystack :-(
Someone who knows?
And was the function to increase and to counteract or resist elevator up movement at the control column when airspeed is close to a stall, via SMYD > ELF > EFSM something that came with the MCAS or it is an old function that all 737:s have?

And some "stupid" questions"
I so a video with some captain referring to the 737 Max8 as a she..
Is all airplanes female?
And if so is it because it is a "ship", since all boats also is "female"?
And I am not shore I would like to why.. if that is the case..

And do all commercial aircrafts have the captains seat on the right side?
Are air traffic "left traffic" ?
Is it due to the Romans or the Vikings?
Since most people are right handed it would be more natural to be sited to left since most controls are in the middle..

And finally..
I guess this one is mostly to Alistair, the guy in the video do you know of him and is he Swedish?

https://www.youtube.com/watch?v=ePDl1JNqjpM

Am quite shore he must be the way he speaks English.
Since cockpit door is always looked now a days I guess the knowledge conveyed in the video want come in handy but it was a bit educational anyways..

Best Regards A


“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[LittleInch]

Anna,

Go back in this post to the 18th nov and there are the links to the faa site where its all listed.

The force thing I would think was a standard 737 thing.

Planes and ships seem to be female. Don't know why.

Pretty sure Captain sits on the left, First Officer/ Co pilot on the right.


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RedSnake]

LittleInch
Thanks I will have a look at it.

Well the Feel Force Computer probable was, it was needed after making elevators mechanical.
But I not shore about this extra force prohibiting the pilots to counteract the systems when the stall warning comes if that is a old function on that plane or on any other plane?

Pretty sure Captain sits on the left, First Officer/ Co pilot on the right.
Me to but I just wonder why?
That is the same in cars when driving on the wrong side of the road.
Why that is so, in commercial aircrafts I do not know.
In small planes it is usually on the "right" right side.

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[zeusfaber]

Fixed wing, Captain sits in the left-hand seat. Rotary, it's the other way round. No idea why.

A.

 

[dik]

Where was the rotary generally developed? US or Europe/Asia?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[LittleInch]

https://www.airspacemag.com/need-to-know/why-do-helicopter-pilots-sit-in-the-right-seat-243212/

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dik]

thanks LI... great explanation...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Alistair_Heaton]

Fixed wing its due to the rules of the road and collision avoidance. Which came from the maritime world.

So the pilot always has the aircraft they are manoeuvring to avoid in view if sitting in the left seat. Don't have a clue in rotary but that article I can see the logic with having a hand that can come off but keep one hand on the cyclic.

In English speaking culture most things in aviation are taken from Maritime to do with naming and ships are always she. I think German its masculine and Russian they always call aircraft he as well.

The UK driving on the left side dates back to Napoleonic times and which hand your sword is in before that and jousting, I was told many years ago in school.

And yes Mentor pilot in that youtube is a Swedish pilot. I have chatted with him online but don't know him. He knows his stuff and has a good way of delivering information.

Back to Engineering though the feel system I believe is common through 737-300 through to the MAX it was one of the systems that missed getting reworked when they went to the NG and beat the new grandfathering rules. They more than likely wanted to use it to do the function of the MCAS. But if they touched it then they would open Pandora's box of it and the stall system which would have triggered additional training requirement and lengthy certification possible completely replacing the stall system.

There is something funny with the stall system with both the FAA and Boeing. They have always been extremely adverse to letting the pilots be able to cancel it. I suspect the original design team basically made it so that its impossible to rework the current system to the modern standards due to this clash of opinion. I am expecting that pulling the CB on the stick shaker like the Canadians and EASA have mandated is going to have a knock on effect which again is not documented. I believe the 737-10 will have some changes which should be retrofitted to the others but what I really don't know. And I suspect there will be huge arguments about them and lengthy delays certifying it.