Originally Posted by
gums
My examination of the FAR requirements do not reference stall prevention, just a requirement to have increased back stick force or actual elevator force as AoA increases. They could have done the trim kludge at a much lower AoA.
Gums,
to accept MCAS is there only to increase back stick force, we need to accept that Boeing engineers decided it was a good idea to repeatedly move the stab, probably one of the most critical control surfaces, just in oder to simulate increased stick force.
We need to accept that noone asked if this might by any chance be a bad idea. Like, you know, trimming all the way nose down in close proximity to the mother Earth. Noone remembered AF447 where pilot error resulted in full up trim, making stall unrecoverable - so nobody said "uhm guys, if something goes wrong and this system fails, it could mean trouble".
Again - all with the goal to produce some back stick force? I mean, for sure there must be better solutions for that alone?
What if there is another explanation? Perhaps the nacelles are so far out that it's a serious problem? Perhaps they act to some degree as canards when approaching stall? Imagine the wing stalls but the nacelles still produce lift... you'd be in big, big trouble.
Now this big big trouble would be something to justify MCAS. But due to competition and regulation requirements Boeing could not be open about it, or it would have meant entierly new certification. That's why it's half baked, hidden and relies on a single AoA.
Test flight data should show if this is indeed the case. Requirement for 2.5 units trim every 5s surely does seem like a smoking gun. Testimony from test pilot would be interesting. I'm sure we will hear about it in the coming years.
Then another question is, why were the cutout switches changed to prevent manual electric trim along with MCAS. There must be a reason. Without a reason it makes no sense. Did Boeing by any chance estimated that keeping the electric trim on without MCAS could easily put the airplane in the high AoA situation as described above? That could be another smoking gun. If that is not the reason to change the switches, then what was it? Any reasonably ideas?