Another 737 MAX-8 down

originally posted by: Zaphod58
A little more detail is being revealed. The left AoA vane separated from the aircraft just after the weight on wheels switch showed the aircraft becoming airborne. The crew followed the procedure, but didn't follow them correctly, and became task saturated attempting to deal with the aircraft.

Aviation Week.

So is the story changing? It seems like it's changing (again). And seems like they keep putting out teasers that the pilots are to blame.

a reply to: KansasGirl

The narrative always changes until the final report is released. Data gets refined as it's gone over and more people look at it, more information is found as wreckage is examined. That's why it takes over a year to produce a final report.

The crew was not blameless here. Yes, MCAS began the chain, but the crew made mistakes too. They aren't fully to blame, but remove one of their mistakes, and the accident chain breaks and they don't hit the ground.

a reply to: KansasGirl

No, the story isn't changing...the 'official' story has always been the same...

It's NOT Boeing!! Some sensor blew off, got hit by a mysterious UFO or something or other, the pilots were untrained idiots, a black cat ran across the runway...anything, absolutely ANYTHING, but a Boeing DESIGN problem! Mitigate the liability, distract anything, elephants, lions and tigers...oh my...but NOT Boeing!!! No, there's another "contributing cause", a "chain of errors"...it's NOT Boeing...can't be them!! The root cause CANNOT be Boeing!!

Just because it ... can't!

Deflect, shuck, jive...anything...it simply CAN-NOT be a Boeing root cause!! it's someone else's fault, or some other limiting factor (for Boeing).

Bottom line...they will never admit it was their "DESIGN FAULT"...NEVER!

I've said it from day one...and look what's happened since then.

originally posted by: Zaphod58
a reply to: KansasGirl

The narrative always changes until the final report is released. Data gets refined as it's gone over and more people look at it, more information is found as wreckage is examined. That's why it takes over a year to produce a final report.

The crew was not blameless here. Yes, MCAS began the chain, but the crew made mistakes too. They aren't fully to blame, but remove one of their mistakes, and the accident chain breaks and they don't hit the ground.

What were the crew mistakes?

a reply to: KansasGirl

They only input enough trim to compensate for some of the MCAS trim, so the aircraft was never trimmed back to level or nose up. They never pulled the throttle back from takeoff power, which was 94%, so the entire time they were fighting the aircraft, it was accelerating. The closer it got to the maximum operating speed, the less effective the electric trim became. Once they exceeded that speed, it stopped working altogether.

It all comes back to the accident chain that was mentioned before. Losing the left AoA sensor started the chain, but wasn't the entire cause. Each action that occurred led to the next link in the chain, and the next. If any one link had been broken, the accident never occurs and they land. Boeing and MCAS are the ultimate cause, because of a bad design, but without the crew contribution, the accident wouldn't have happened.

a reply to: Zaphod58

spectrum.ieee.org...

great article. I agree with him that mcas be removed in its entirerity
a reply to: anzha

originally posted by: anzha
a reply to: Zaphod58

spectrum.ieee.org...

That is certainly the best article I've read about the MCAS fiasco.

Boeing really screwed up.

originally posted by: Zaphod58
A little more detail is being revealed. The left AoA vane separated from the aircraft just after the weight on wheels switch showed the aircraft becoming airborne. The crew followed the procedure, but didn't follow them correctly, and became task saturated attempting to deal with the aircraft.

Aviation Week.

That would seem to explain why the autopilot and MCAS systems kept on reacting as if the aircraft was near stall al the time.

Just prior to rotation on the takeoff run, the AOA should be essentially zero. As soon as rotation occurs, the true AOA will go to near its maximum value. Moments after rotation, the aircraft lifts off and the weight on wheels goes to zero. As the climb out proceeds and flight speed increases, the true AOA should steadily decrease from its max value. In this case, however, the left AOA sensor vane rotated all the way to the maximum position and then snapped off, leaving the AOA signal going into the flight omputer pegged at its max value. So the flight computer kept trying to drive the nose down but the AOA signal kept saying that the nose was high.

I would look for mechanical failure of the AOA sensor mechanism.

a reply to: Salander

Yes, yes they did!!

And then they tried to cover it up (or minimally make it seem like less of an issue).

That's where they really screwed the pooch!

originally posted by: Zaphod58
a reply to: KansasGirl

They only input enough trim to compensate for some of the MCAS trim, so the aircraft was never trimmed back to level or nose up. They never pulled the throttle back from takeoff power, which was 94%, so the entire time they were fighting the aircraft, it was accelerating. The closer it got to the maximum operating speed, the less effective the electric trim became. Once they exceeded that speed, it stopped working altogether.

It all comes back to the accident chain that was mentioned before. Losing the left AoA sensor started the chain, but wasn't the entire cause. Each action that occurred led to the next link in the chain, and the next. If any one link had been broken, the accident never occurs and they land. Boeing and MCAS are the ultimate cause, because of a bad design, but without the crew contribution, the accident wouldn't have happened.

Thank you for that explanation!

www.businessinsider.com...

originally posted by: anzha
www.businessinsider.com...

from the link [q]MCAS can never command more stabilizer input than can be counteracted by the flight crew pulling back on the column. The pilots will continue to always have the ability to override MCAS and manually control the airplane.[/q]So in both the cases pilots were not able to override the mcas by muscle power. clearly something else was wrong and is still wrong.

Why Boeing didn't tell airlines a safety alert didn't work

Boeing yesterday (May 5) said that it initially designed the AoA disagree alert as “a standard, standalone feature,” but later realized it was effectively optional. The Max’s software would only allow the disagree alert to work on airlines that had purchased an optional AoA indicator as well. After a review, Boeing decided it could fix the issue later:

That review, which involved multiple company subject matter experts, determined that the absence of the AOA Disagree alert did not adversely impact airplane safety or operation. Accordingly, the review concluded, the existing functionality was acceptable until the alert and the indicator could be delinked in the next planned display system software update. Senior company leadership was not involved in the review and first became aware of this issue in the aftermath of the Lion Air accident.

Airbus is completely bankrupt, it will have to be overtaken by Boeing or the Chinese.
No chances for French aircraft manufacturing survival after the Concorde get discontinued in 2001 ...

a reply to: Flanker86

Didn't know Concorde was being built still in 2001

from a few years ago.
A330 Qf72 incident

Boeing plans to issue a Safety Bulletin, followed by an AD from the FAA, requiring slat track assembly inspections on the Max and NG aircraft. During a meeting with the supplier late last week it was noticed that some of the tracks weren't heat treated. This could lead to premature failure or cracking.

www.cnn.com...

WOW imagine the galling on the tracks without heat treatment!!!!
How the hell did they pass QC?

a reply to: Blackfinger

The same way they always do. Someone trying to save money, or not doing their job. They've identified 21 aircraft that are affected.