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> a fundamental overhaul to an automated system that would ultimately play a role in two crashes Are they STILL blaming the computer instead of the unstable a

by tus87 7y ago

> a fundamental overhaul to an automated system that would ultimately play a role in two crashes Are they STILL blaming the computer instead of the unstable air-frame after the engines were moved?

Pxtl 7y ago
Because they can fix the computer and the sensors but if they have to toss out the whole airframe they're going to be out billions.
Obi_Juan_Kenobi 7y ago
The redesign did not make the aircraft unstable. I don't know how this became such a meme, but it's trivial to see that it's not true. Commercial passenger aircraft must be aerodynamically stable by FAA regulation: https://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.11#se14.1.25_1171 https://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.11#se1... The engine change really wasn't a big deal. The net effect is "flight stick feels lighter at high AoA with high thrust." That's it. My understanding is that the 737-MAX flys more like a 757 in this regard. Nothing crazy, just a difference. Now, that's enough to require re-certification by FAA standards, because it's enough of a difference that it could cause problems of pilot error. But going on like the aircraft wants to fall out of the sky isn't helping anyone here. MCAS was intended to be a small tweak that avoids the re-cert. And it would have been fine if they had neutered the system such that it couldn't input such extreme trim angles, or else has more reliability as needed in a system that could have such dramatic effects when malfunctioning.
- salawat 7y ago
  The meme comes from the fact that according to the technical definition of aerodynamic stability, the MAX has pitch instability at high AoA. FAA certification regulations appear to be willing to accept minor deviance in regard to them so long as they can be convinced there are sufficient technological controls in place to manage the instability. This is the danger of self-certification by the way. The company signs off that everything is fine, and the regulator is blissfully unaware they've been rused until after people have already died.

by tus87 7y ago

> a fundamental overhaul to an automated system that would ultimately play a role in two crashes Are they STILL blaming the computer instead of the unstable air-frame after the engines were moved?

Pxtl 7y ago

Because they can fix the computer and the sensors but if they have to toss out the whole airframe they're going to be out billions.

Obi_Juan_Kenobi 7y ago

The redesign did not make the aircraft unstable. I don't know how this became such a meme, but it's trivial to see that it's not true. Commercial passenger aircraft must be aerodynamically stable by FAA regulation: https://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.11#se14.1.25_1171 https://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.11#se1... The engine change really wasn't a big deal. The net effect is "flight stick feels lighter at high AoA with high thrust." That's it. My understanding is that the 737-MAX flys more like a 757 in this regard. Nothing crazy, just a difference. Now, that's enough to require re-certification by FAA standards, because it's enough of a difference that it could cause problems of pilot error. But going on like the aircraft wants to fall out of the sky isn't helping anyone here. MCAS was intended to be a small tweak that avoids the re-cert. And it would have been fine if they had neutered the system such that it couldn't input such extreme trim angles, or else has more reliability as needed in a system that could have such dramatic effects when malfunctioning.

salawat 7y ago
The meme comes from the fact that according to the technical definition of aerodynamic stability, the MAX has pitch instability at high AoA. FAA certification regulations appear to be willing to accept minor deviance in regard to them so long as they can be convinced there are sufficient technological controls in place to manage the instability. This is the danger of self-certification by the way. The company signs off that everything is fine, and the regulator is blissfully unaware they've been rused until after people have already died.