On the recent two crashes of Boeings 737 Max

[Skybird]

https://www.zerohedge.com/news/2019-...tware-engineer

Nevertheless its a big damage for Boeing and could lead to punitive measures in the legal verdicts, whioch would effectively tripüle the costs thery would need to pay out.

In the early 90s, the aircraft company Piper went bancrupt due to such a punitive measure, which is a special characteristic in American law.

The close relation between Boeing and the Us government and its authorities, the closeness of producer and controlling authorities, even the political laziness of letting producers "control" themselves (pharmaceutical industry...) , is a general problem, no matter what the causes for the crashes are.

The competition between the 737 Max and the Airbus 320 Neo is tough, Airbus currently is in the clear lead in number of orders. Pilots of other nations and carriers have complained about inadequate documentation provided by Boeing and inadequate or non- existent training on the Max's characteristic features. Thats why I think the above linked explanation chain is only one aspect of the total picture.

If Boeing hoped to gain any form of lead or avantage due to the A 380 project ending in a disastrous economic failure (the German subsidies will not be paid back, its lost money for the German tax payers), this hope now has collapsed. The 737 affair has the ingredients to be really crippling . If politics do not interfere of course, which they likely will do.

This is focussing on the possibility of inadequte cetification due to time pressure and Boeing wanting to react to the challenge by Airbus'S A320.

https://www.seattletimes.com/busines...ion-air-crash/

[Catfish]

Both good links. It also shows it is dangerous to circumvent or give up certain approved procedures or designs.
I can only guess how those pilots must have felt when they tried to switch off the system when it switched on again and again, with the trimming wheel turning.
Politics, well.. someone will be sacrificed to say "i take responsibility", and this will be all.

[Aktungbby]

between Boeing and the ’ kissin cousin' FAA's 'apparent lack of impartial integrity in approving the craft and it's faulty MCAS, a universal truth of aviation holds true: profits first...sardine packed expendible passengers second...small wonder the Ethiopian investigators have turned over the flight recorder data to the French to avoid a FAA cover-up!

[Jimbuna]

Originally Posted by Catfish

Both good links.

Indeed, great

[Rockin Robbins]

To make matters even worse, it appears that there are two angle of attack sensors, one on either side of the fuselage and only one of them was hooked up to the MCAS system, with no warning that the sensor didn't agree with other autopilot systems. In addition MCAS was much too powerful, able to overpower pilot input and set stabilizer trim to FULL down.

However there is a stabilizer trim cutout switch in the same position it has been for more than 30 years of 737 production. The proper procedure for an MCAS malfunction is just to throw that switch, which every 737 pilot in the world, regardless of airframe series, knows where it is. That's easy to say sitting behind a computer.

Here's the perspective for why confusion in the pilot seat (actually hyper-focusing and blocking out "irrelevant" things that busily kill) you is sometimes a fatal affliction and why having a jump pilot (one saved the flight previous to the fatal crash!) is a great idea. This is the absolute best source of info on this lousy situation and also shows that Airbus isn't immune from pilot tunnel vision either. Subscribing to this guy's You Tube channel is a great connection to the developing situation.

[Skybird]

Latest theory is about blowback, meaning that the plane gained so much speed that the airstream hitting the ailerons defeated the hydraulic pressure of the system trying to move them - the plane than practically is uncontrollable and cannot be saved by pilot input if it does not by lucky events loose speed again before the hydraulic system suffered unrepairable damage already.



That speed could have been accumulated due to chnaged geometry due to bigger engine size - with the whole design not having been properly tested and the MCAS having been an improper attempt to fix it with - a not properly tested software solutionb that additionally was not properly advertised to avoid cetifcaiton delays and so was not properly included in pilot instructions.


A report in Der Spoiegel today said a former Boeing engineer said that the pressure was immense and worse than ever before when some years ago Americna airlines planned to buy Airbus A320 Neos. Boeing needed a quick reply to counter that threat and the result weas that they did this re-engineering project, but in less than half of th etime that itr would have needed if all internal security rpoutines by Boeing would have been followed. In other words: Boeing broke its own standards and security orutines, and lied about it to the authorities. Also, cockpit modernisation steps that would have been in demand were left out, due to time pressure.



When I red about it it reminded me of the problems of fighter pilots in WWII vintage aircraft who may have dived so fast unto their targets that they could not pull in time anymore since they had left the speed envelope inside which they could still move the flaps and ailerons with the stick. Battle of Britain 2 was a simultaion simulating this effect - it was terrifying at times.



When the blowback thing is true, the whole design of the aiframe is in question , and just some addings to the code of the MCAS most likely cannot fix it. And after 300+ people dead and two planes lost under identical conditions of malfunctioning.


It looks very much as if Boeing made a big, huge pile of self-made poo on its doorstep. It could turn out to become much more hurting for Boeing than the A380 that led Airbus into a dead end. First airlines have called for cancellation of their orders - and its no big guess that they will go with the A320Neo instead.

[Rockin Robbins]

Originally Posted by Skybird

Latest theory is about blowback, meaning that the plane gained so much speed that the airstream hitting the ailerons defeated the hydraulic pressure of the system trying to move them - the plane than practically is uncontrollable and cannot be saved by pilot input if it does not by lucky events loose speed again before the hydraulic system suffered unrepairable damage already.

What caused the pilot not to be able to be recovered was the trim system being too powerful, exerting forces too great for pilots to overcome, even at normal flying speeds. This has been a possibility during the entire 737 series manufacture, over 30 years.

In the event of a trim overrun, the stabilizer trim cutout switch is and has been in the same exact location all that time. Throwing that switch results in immediate recovery of the pilot's ability to fly the plane, as shown in the flight previous to the fatal crash, where a third pilot in the jump seat evaluated the problem and knew what to do. As blancolirio said in the video I posted, it was the addition of the pilot in the jump seat that made the difference.

The plane can be flown safely. Now it's up to Boeing to ensure that it always is. Pilot error can crash any plane. This was clear pilot error. The question is "was the pilot error a predictable consequence of Boeing's or the airline's procedures, and what must be changed to keep this from happening again?"

From Boeing's standpoint, the trim system is too powerful. The trim system is more powerful than any possible pilot input. A pilot should be able to overcome the trim by using stick position only, thereby buying the time to analyze the problem in a stress-free mindset.

Secondly, with two angle of attack sensors outside the fuselage, hooking only one of them to the MCAS system just makes no sense. Error handling is absolutely essential to the functioning of any system and unquestioningly accepting the word of a malfunctioning sensor with no backup is an obvious failing.

Then the decision to have two systems, the light indicating autopilot/angle of attack sensor disagreement and the cockpit angle of attack display as optional equipment is also obviously faulty.

The kicker is that Boeing already advised pilots that MCAS malfunctions should be treated as a trim overrun situation and the stabilizer trim cutout switch should be switched off. Simple simulator runs should have revealed the fact that in an MCAS malfunction, the pilot is simply too busy trying to save his and his passengers' lives to think clearly.

The information you need to know to understand this situation is in the video I provided. It is self-validating, from a professional pilot who knows his business.