Posted on 06/26/2019 3:13:21 PM PDT by CondoleezzaProtege
While the crashes remain under investigation, preliminary reports showed that a new stabilization system pushed both planes into steep nosedives from which the pilots could not recover. The issue is known in aviation vernacular as runaway stabilizer trim.
In simulator tests, government pilots discovered that a microprocessor failure could push the nose of the plane toward the ground. It is not known whether the microprocessor played a role in either crash. When testing the potential failure of the microprocessor in the simulators, "it was difficult for the test pilots to recover in a matter of seconds," one of the sources said. "And if you can't recover in a matter of seconds, that's an unreasonable risk."
Boeing engineers are now trying to address the issue, which has led to another delay in recertifying the 737 Max.
"The safety of our airplanes is Boeing's highest priority. We are working closely with the FAA to safely return the MAX to service," Boeing said in a statement. The sources say Boeing engineers are trying to determine if the microprocessor issue can be fixed by reprogramming software or if replacing the physical microprocessors on each 737 Max aircraft may be required.
(Excerpt) Read more at -m.cnn.com ...
Why not just get rid of the system? Or just take it offline physically?
The crashes will probably cost Boeing billions. Overall, though, still a drop in the bucket compared to designing a new plane from scratch. Sad for the victims, but true.
Oxymoron?
It’s supposed to be an extra add-on feature. From what I gather from crew is they don’t want to fly it or be on it. I wouldn’t.
A stablized runaway. Perfect.
Terrific.
Also the yaw damper problem years back; they only had one when safety mandated two. You’d get un-commanded rudder action to full extreme flipping the plane on its back.
Is this Boeing’s first “fly by wire” aircraft?
In simulator tests, government pilots discovered that a microprocessor failure could push the nose of the plane toward the ground. It is not known whether the microprocessor played a role in either crash. When testing the potential failure of the microprocessor in the simulators, “it was difficult for the test pilots to recover in a matter of seconds,” one of the sources said. “And if you can’t recover in a matter of seconds, that’s an unreasonable risk.”
...
The reports on both crashes indicate the pilots had much longer than a few seconds to recover.
Why does this sound like they completely failed in safety design? You’re supposed to do tests where components fail to show your safety concept working. HARA/FMEA/MC-DC etc.
Where’s the redundancy?
This plane is a bow-wow. Sad to say. Doesn’t come close to replacing the best ever, the rocket, the 757.
The Max doesn’t have the power to take off in hot, high altitude scenarios.
So unlikely to be used for ‘heavy’ loads out of minimum runway locations. The 757 could.
Re-engine the 757, add some new electronics.
This is bull$hit! I trained pilot knows how to deal with a “runaway trim situation.” You turn off the automatic system, and resort to what most non-commercial pilots do, manually trim the plane. My next door neighbor is a Southwest Captain. SW flles ONLY the 737. He tells me that there are two switches at hand that disable tne motors that drive the stabilizer trim system, and there is a manual crank to speed up the trim process if needed. He told me that only a seriously training deficient pilot would have crashed either of those planes. A/C are not video games, they need to have pilots who know the basics of flying, wherein when the bells and whistles are inoperative you have the abilty to resort to basics.
Just give them to Iran as a gesture of peace.
What would you replace the microprocessors with?
A different type of microprocessor should be tested first and would be time consuming.- -Tom
It does have an “off” switch, and from reports the more experienced pilots were able to turn it off and regain control.
CC
Have you heard about the recall on Ford’s electronic automatic transmission? It downshifts all the way to low in one step whereupon the truck may be uncontrollable. The software fix resulted in even worse behavior and Ferd went back to the original programming.
Solid state works until it fails, computer programs work until some unexpected condition causes them to do something odd.
I can hardly wait for autonomous cars and trucks to hit the highways in big numbers.
Isn’t this the purpose of testing? Find the problems and fix them? Personally, I am happy to learn they found problems. Every one they find is one less to encounter outside the simulator.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.