Boeing CEO Dennis Muilenburg Addresses the Ethiopian Airlines Flight 302 Report • Hacker News Board

Re: Boeing CEO Dennis Muilenburg Addresses the Ethiopian Airlines Flight 302 Report

#341

Post by dredmorbius » Sat, Apr 06, 2019, 5:41 PM UTC

bitreality wrote: post #154

ndespres wrote: post #55

I know better than to read between the lines on a press release like this, but can't help but notice that it falls far short of accepting responsibility for the problem. He admits that MCAS "activated in response to erroneous angle of attack information" but doesn't admit that this alone directly resulted in the crashes. Rather, he implies that this sets off a chain of events which the pilots are unable to deal with…

With the way litigation works, corporations will never admit blame for anything, since it greatly increases their legal risk. It's unfortunate, but their responsibilities lie with their shareholders, not the people who lost their lives on their planes.

"Sharehlder value" as sole or even primary obligation is a myth.

https://scholarship.law.cornell.edu/cgi/viewcontent.cgi?arti...

Re: Boeing CEO Dennis Muilenburg Addresses the Ethiopian Airlines Flight 302 Report

#342

Post by dredmorbius » Sat, Apr 06, 2019, 5:44 PM UTC

BurningFrog wrote: post #110

cyberferret wrote: post #92

Earlier quoted context omitted.

> The FAA also lost a lot of trust, for rubber-stamping this. From documents I've seen (which I cannot find the links to now), it appears that the FAA let Boeing themselves do some of the certification work and sign offs. Putting the foxes in charge of the hen house, so to speak.

It's called Regulatory Capture, and it happens to all regulatory agencies sooner or later. They become primarily concerned with the interests of the companies they're regulating, rather than the public interest they're in theory tasked with working for. Unfortunately, that is just how a regulated society works.

Regulatoy capture is a prblem, but not an inevitable one.

Private enterprise has an analogue: principle-agent problem.

Re: Boeing CEO Dennis Muilenburg Addresses the Ethiopian Airlines Flight 302 Report

#343

Post by slavak » Sat, Apr 06, 2019, 8:05 PM UTC

EngineerDude wrote: post #208

As a few posters mentioned, an interesting question is why the plane needs MCAS in the first place. I read somewhere that the max 8 got new engines which were bigger than engines on previous 737 series, and that makes the plane nose up. Any kid who ever made a model plane understands the idea of CG - if it pitches up you change something, maybe move the wings back. Is it possible that an industry leader shipped a pla…

The new, more economical engines are physically bigger, so in order to maintain the required ground clearance the engines were moved forward and up. This gave the plane a tendency to nose-up in certain extreme circumstances. MCAS was supposed to make the plane behave more like previous 737 models, in order to fulfill the "common type" requirement that would allow 737 pilots to fly it without getting qualified for a new aircraft type.

The plane _is_ balanced; it's not like Boeing built an aircraft that falls out of the sky if you slightly nudge the yoke wrong. (Which wouldn't even be unusual; plenty of modern aircraft are completely uncontrollable without computer assistance.) Yes, the problem could've been solved with a re-design of the aircraft- lengthening the landing gear struts, modifying the wings, etc. - but that would negate the point of using an existing and well-tested design.

There's A LOT of guilt to go around in this story, but no one can actually be casting doubt on the abilities of Boeing engineers in the fundamentals of aircraft design.

Re: Boeing CEO Dennis Muilenburg Addresses the Ethiopian Airlines Flight 302 Report

#344

Post by salawat » Sun, Apr 07, 2019, 2:15 AM UTC

salawat wrote: post #338

salawat wrote: post #316

Earlier quoted context omitted.

Wing Load https://www.engineeringtoolbox.com/wind-load-d_1775.html Screw Jack and effort force https://www.engineeringtoolbox.com/screw-jack-d_1308.html Gearing: https://www.engineeringtoolbox.com/gears-d_1307.html Here's some 737-800 dimensional analysis as a starting point. https://holdingpoint.wordpress.com/2011/04/04/boeing-737-800... Knock yourself out. Or if you stick around long enough I may do it for gits and…

Okay, let's start with wind load. 737-800 has a 32.776m^2 horizontal stabilizer area. Let's double that to 65.556 to accomodate both airfoils. Wing load is 1/2p(v^2)A Where A=65.556m^2 (352.8 ft^2) v=180.556m/s (350 knots) And we'll guess our air density around .95ish kg/m^3 given our altitude of 2334m (7625 ft plus change) asl Barring any flawed fundamental assumptions, that gives us a wind load of 1015087 N (228200…

Okay. So after a bit of chewing on the screw jack equations, I settled on using an M24 screw as the basis just for convenience. Eyeballed a video of jackscrew of a 737NG, and figured a 6 inch lever arm. In the form of a pulley of some sort as the input for the screw jack from the trim wheel in the cockpit.

Dropping in the previously calculated wind load of 1015087 N, we end up with an effort force of 3182 N, which through a 6 in pulley would be 485Nm (357 ft-lbs) of torque,

Note, we're in automobile engine levels of torque output to actuate this screw jack against the wind load on the horizontal stabilizer.

Give me a bit to come up with some estimates on the trim wheel and play around with some gear trains to see if I can come up with an arrangement that does the trick.

It should be doable, but with the gear ratios I'm thinking will be required to generate the requisite torque, the actual rate of actuation is going to be pretty slow.

Re: Boeing CEO Dennis Muilenburg Addresses the Ethiopian Airlines Flight 302 Report

#345

Post by FabHK » Mon, Apr 08, 2019, 3:42 PM UTC

jefftk wrote: post #271

FabHK wrote: post #265

Earlier quoted context omitted.

> European agency EASA. FWIW, the Brazilian regulator (whose name I don't remember...) did not rubber-stamp the FAA's type certification of the 737 MAX, and required some differences training for MCAS, IIRC.

Very curious whether the additional Brazilian MCAS training would have helped, given how strange its behavior appears in practice.

Good question. Would be interesting to hear what (if any) additional training pilots there got.

And, yes, the Ethiopian Air pilots apparently did follow the procedures initially, flipping the Stab Trim Cutout switches, but did not manage to recenter the trim manually (via the trim wheel), so apparently re-enabled electric trim, and then let MCAS drive the trim even further down to their doom. :-/

Re: Boeing CEO Dennis Muilenburg Addresses the Ethiopian Airlines Flight 302 Report

#346

Post by ddalex » Tue, Apr 09, 2019, 11:45 AM UTC

treis wrote: post #332

ddalex wrote: post #329

Earlier quoted context omitted.

I wouldn't feed the troll, but I don't want your misinformation to spread. > They weren't They just took off, max height of the airplane was 1000 feet above the ground. That's a definely low altitude. > Runaway trim should be a recoverable situation. The trim pointed the nose down. The aerodynamic forces were so high on the elevator that the trim wheels could not be moved by a single person. This was confirmed in 737…

>They just took off, max height of the airplane was 1000 feet above the ground. That's a definely low altitude. People thought that based on Flightaware data. But if you actually read the report you will see that it is incorrect and they reached about 7,000 feet. >The trim pointed the nose down. Incorrect. The plane was steadily gaining altitude until they re-enabled electric trim. >I wouldn't feed the troll, but I d…

we must not be reading the same report. I'm speaking specifically about this one: https://avherald.com/h?article=4c534c4a/0023&opt=0

which points clearly to MCAS applying maximum nose down, based on incorrect data from the left alpha sensor, both pilots pulling on their control sticks, and the aircraft failing to gain altitude even before final MCAS activation because the trim could not be manually reset by the F/O.

this report contradicts every element that you're pushing (plane reached altitude, pilots didn't pull on the column, the electric trim was not needed, MCAS did not intervene). did I missing anything ?

Re: Boeing CEO Dennis Muilenburg Addresses the Ethiopian Airlines Flight 302 Report

#347

Post by drstewart » Tue, Apr 09, 2019, 5:20 PM UTC

ddalex wrote: post #327

drstewart wrote: post #28

Earlier quoted context omitted.

>The integrity of engineering excellence should never be sacrificed for profit and/or conveniency in places where it involves human lives. That's just unrealistic. Unless you want plane and car rides to cost as much as a trip to space, after all, since everything would need to be engineered to that level of quality.

Or you could fly Airbus.

https://en.wikipedia.org/wiki/List_of_accidents_and_incident...