Ethiopian ET302 Crash.

[MolaKule]

Originally Posted by Lapham3
I was at Honeywell for 25+ years and the bean counters always wanted to get in the act to run some 'value engineering'. That was taking something that worked and making something a little less so as to obtain more profit. More often than not, the result was something that just wasn't as reliable from the start or failed before it should. We ended up with a grumpy customer and ultimately had to do another redesign or go back to the original that worked. Of course, engineering folk always want to have the best and would want to work endlessly towards that goal='shoot the engineers and go to production'!


And that's where management needs to fight for the engineers.

In our case, our management would call a meeting with all parties to clarify the goals, the costs, and the reliability and risks of using alternative components if and when the bean counters wanted to get involved.

We would often ask the bean counters this question: "What engineering facts and data would you like to present to show that alternative components would increase reliability and reduce operational risk?" With no viable answers the meeting was terminated.

 

[ZeeOSix]

Originally Posted by MolaKule
We would often ask the bean counters this question: "What engineering facts and data would you like to present to show that alternative components would increase reliability and reduce operational risk?" With no viable answers the meeting was terminated.


Yep, pretty easy to shutdown the bean counters with that tactic. Bean counters show just count the beans in and out, and not worry about controlling how many beans are going in and out.

 

[john_pifer]

Originally Posted by Lapham3
I was at Honeywell for 25+ years and the bean counters always wanted to get in the act to run some 'value engineering'. That was taking something that worked and making something a little less so as to obtain more profit. More often than not, the result was something that just wasn't as reliable from the start or failed before it should. We ended up with a grumpy customer and ultimately had to do another redesign or go back to the original that worked. Of course, engineering folk always want to have the best and would want to work endlessly towards that goal='shoot the engineers and go to production'!


And average everyday folks were the victims of this, starting in the 70s & 80s with planned depreciation of American autos and the cheapening of everyday items like home appliances that, today, for the most part, have become "throwaway, disposable" items.

 

[fdcg27]

Originally Posted by MolaKule
Originally Posted by Lapham3
I was at Honeywell for 25+ years and the bean counters always wanted to get in the act to run some 'value engineering'. That was taking something that worked and making something a little less so as to obtain more profit. More often than not, the result was something that just wasn't as reliable from the start or failed before it should. We ended up with a grumpy customer and ultimately had to do another redesign or go back to the original that worked. Of course, engineering folk always want to have the best and would want to work endlessly towards that goal='shoot the engineers and go to production'!


And that's where management needs to fight for the engineers.

In our case, our management would call a meeting with all parties to clarify the goals, the costs, and the reliability and risks of using alternative components if and when the bean counters wanted to get involved.

We would often ask the bean counters this question: "What engineering facts and data would you like to present to show that alternative components would increase
reliability and reduce operational risk?" With no viable answers the meeting was terminated.



The irony is that doing it right the first time is often cheaper than having to pay compensation to customers when a cheapened design fails to perform in a satisfactory manner in service.
In the case of an airframe OEM, the risks and the costs are enormous, especially if aircraft crash and people die.
Boeing is headed for a severe epiphany whatever the accident investigations reveal.

 

[PandaBear]

Originally Posted by MolaKule
A bit of History as to why MCAS was implemented (2 reasons):

1) For the 737-MAX(7,8,9), Boeing chose a new, more powerful engine, the new CFM LEAP-1B engine which has Carbon fiber fan blades with a titanium leading edge, noise reduction chevrons at the rear of the engine casing, and higher thrust and fuel efficiency.

This engine is larger than previous ones so two major design changes were needed, the addition of 8" of landing gear length and placing the engine forward and higher for increased ground clearance.

The net result was that because of the engines' position, the more powerful engines produced a net "pitch up" moment. Too much pitch up moment and the aircraft will stall under certain conditions.

2) In addition, operators of the older 737 fleets complained that stall characteristics and stall warnings needed to be improved.

The MCAS system is actually a software module that was added within both FCC's (Flight Control Computers) that is supposed to correct for any pitch up movements that might cause a stall.

The problem I see is that the active FCC (only one of the two FCC systems is active at any one time) is only monitoring one of the two Angle of Attack sensor vanes. If the active AOA is sending false data to the one active FCC, then MCAS kicks in and attempts to correct what may have been a non-pitch up (stall) situation.

In my opinion, even if only one FCC was active, sensor data from both AOA's should have been compared and any conflicts should have been resolved. A conflict should result in say a warning that there is an AOA conflict and the MCAS should disconnect the autopilot and an audio warning that might say, "Manual Control, Manual Control."

False sensor data has been the result of many air crashes in recently Automated Airplanes.

The Airworthiness Directive (AD) that was issued by the FAA last year gave a very detailed procedure in case of Trim Stab runaway.

737 MAX AD (Page 6)

Most pilots that I know of who sense a problem will kill any automation by quickly hitting the Cutoff Switches so they gain control of the airplane, and only afterwords will they attempt to resolve any automation conflicts. I.e., Fly first and then resolve.


Thanks for the explanation. This seems to be the same cause for most self driving car fatality (sensor data / its interpretation).

Also when you automate driving / flying you will see drivers and pilots start to get rusty and too depended on automation, thus losing emergency response reflex.

 

[DeepFriar]

Also when you automate driving / flying you will see drivers and pilots start to get rusty and too depended on automation, thus losing emergency response reflex.

Ah, you mean like the usual European airline *pilot*, an ab initio trained systems manager flying an Airbus of one sort or another. ...±

 

[BusyLittleShop]

Skills are perishable... one needs to hone their skill set at every opportunity... at least thats what I say to Mr.CHP...

 

[George Bynum]

Very good IEEE Spectrum article on the 737Max and implementation of MCAS ... https://spectrum.ieee.org/aerospace...Ib8ptNMvICxiT6ZQaQG3F2FKYQARktosrQmx7-dA

 

[SonofJoe]

I haven't read the preceding 23 pages (so apologies if this had already been done to death) but I just found this article which I thought was an interesting read...

https://moneymaven.io/mishtalk/api/...oftware-designer-ed5jwi2s8kCuGTAgFXR0GA/

What struck me were the superficial similarities between aircraft approvals & engine oil approvals. You do the first big program & get a load of 'proper', comprehensive approvals. Then as new requirements come along, you start doing changes under the so-called 'minor mod' & 'read-across' rules which allows you to change an oil with minimum test expenditure.

However you can reach a point where the oil is so heavily modified & the application of the read-across rules so heavily stretched that the link back to the original program starts to breaks down. This bad situation is further exacerbated when old tests are 'grandfathered' into modern use & inappropriate Level I & II support data used and the idea that an oil still meets a given approval becomes unsustainable.

TBH, all modern engine oils are so over-specified relative to 'normal' use that abuse of the rules doesn't usually result in catastrophic failure. However I can see how the same philosophical principles applied to aircraft might go horribly awry...

 

[SZR48207]

 

[Jcountry]

Boeing REALLY hosed this up!

In my opinion, they attempted to sneak this MCAS thing through. Few regulators seemed to notice it was on the plane, and no pilots I know had any useful description of the MCAS system in their manuals.....

Here's a good description of how the system works, and why it was created:
http://www.b737.org.uk/mcas.htm

And here's a bot of insight into the mgmt which led to this clown show:
https://www.seattletimes.com/busine...system-implicated-in-the-lion-air-crash/

Some politicians, a bunch of boeing managers, and a bunch of FAA people need to go to prison over this one. There wasa comparator available to alert pilots of a mismatch in AOA inputs, but it was an extra 80k per airplane. All US airlines I know of got it, but neither of the accident airlines did.

Boeing simply changed when they moved to Chicago. They used to be a great example of US strength in engineering and manufacturing. They made fine products. But this new crap show company has been putting out horrible products for years.

MCAS was an extremely dangerous idea..... "Let's create this system to counteract dangerous qualities no airplane should have..... Oh, and let's hide it from everyone" is pretty much what it boiled down to.

 

[BusyLittleShop]

Across the globe there are 5,000 737 operating... there is a 737 taking
off or landing every 3 to 4 seconds minutes in the world...

We may think MCAS is dangerous but we don't know how many times MCAS has
saved lives over the years operating like your friendly CFI...

 

[Jcountry]

I think you might misunderstand MCAS.....

It was only included on the MAX, and it operates very differently from the traditional trim system.

Check out the links in my post above if you want a good description of it.

 

[BusyLittleShop]

Check all of my MCAS post...

 

[Jcountry]

This really isn't a question of skills..... It's a question of installing a very poorly designed system on a plane, and not telling any pilots it was even onboard.

I don't fly the 737, but every single pilot I know who does did not know this system was onboard, or at least didn't have any useful explanation of what it was or how it worked.

Boeing flat out killed those people with greed.

Boeing very purposefully hid that system from airlines and operators worldwide....

And the story gets worse every day:

https://www.usatoday.com/story/trav...y-deactivation-not-disclosed/3615169002/

Every VP and higher level boeing exec should be fired, and every manager and exec who had any active involvement in MCAS should go to prison. This was flat out criminal.

 

[ZeeOSix]

 

[Jcountry]

Originally Posted by ZeeOSix


I disagree with this guy's conclusion.

This site clearly describes the non-linear stick forces as the aircraft approaches higher and higher AOAs.

http://www.b737.org.uk/mcas.htm

By definition, that stick force gradient issue is a stability problem.

This system was a poorly designed kludge to try and weasel through some real issues which should have been addressed.

I'm not saying that there is no way this can be certified, but this was definitely not the way to do it.

And yes, any aircraft which does this stuff (a huge center of lift shift) has stability issues.

I do think this plane may require a separate type rating. It's behavior appears significantly different from previous models.

 

[BusyLittleShop]

Miss match AOA inputs may cause a emergency but its up to pilots to prevent a crash...

 

[fdcg27]

There is a now 239 page thread on pprune about this very accident.
Posts range from seemingly well qualified ATPs who scoff at the abilities of the crew involved in this accident to those who lay blame entirely at the feet of Boeing and the FAA.
It is a bit shocking just how limited the hand-flying skills and experience many of the younger pilots flying the world's airliners exhibit, but it also needs to be considered that the number of airliners flying worldwide has nearly doubled over the past twenty years.
Has the number of experienced pilots with significant military or civil experience ready to move to the airlines also doubled over the past couple of decades?
I think we all know the answer to that.
As a consequence, we have many relatively lightly trained pilots flying at many of the world's airlines. Everything works just fine as long as it does, and then something that would have been no more than a trim runaway for a crew with plenty of hours flying by hand becomes a catastrophe.
As I posted above, it's impossible to believe that Boeing and the FAA together approved what's really a feel augmentation system knowing that some pilots would be caught out, regardless of the suits having moved to Chicago.
Rather, I suspect that Boeing figured that if there were ever a problem, a crew would have enough actual flying time, as opposed to system monitoring time, to react quickly and correctly.
Trimming is one of the first things you learn flying a Cessna. The pilots of the accident aircraft didn't seem to have acquired that skill.
For the future, we're going to see more crews trained to operate systems and not to really fly airplanes and deal with emergencies.
Take a look at A and B's order books and deliveries and consider how many really well qualified crews will be available to fly these nice new airliners, especially since each fleet addition will need to operate enough hours with enough margin to cover those lease costs, which means six or seven crews per aircraft with reserves.

 

[Jcountry]

One thing I think you misunderstand is how little stick and rudder skills matter in airliners these days. They are designed to take finesse and touch out of the equation. You don't need to be good at that stuff.. BUT you do need to be good at managing the machine. And highly "automated" planes actually make that more difficult in some ways. Stick and rudder stuff is way in the past. Flying an airliner feels like driving a dump truck. Flying a light aircraft well takes only a couple of fingertips.

The main issue I have with MCAS is that the [censored] at boeing HID the system. And yes, the FAA didn't seem to notice. [censored], they even let boeing "self-certify". The [censored] plane. And MCAS is much more than just a "feel" system. It has aggressive trim rate inputs which can reset an unlimited number of times. I believe it runs its full authority in only about 3 or 4 seconds..... And with it turning on/off and behaving very strangely, I can certainly imagine why those pilots were confused-especially considering how there was nothing in any of the manuals about the system even being installed.

Really read that UK technical site link closely. It has an excellent explanation. Far more than a feel system.