Originally Posted by
PEI_3721
I think this may be right, but that it may also or instead be referring to the "stabilizer trim limit switches", note that "
There are different limits for manual, autopilot, and for flaps up and flaps down." - well at least for the NG.
The trim wheels in contrast will run the jack screw to the physical stops, I believe (if you can get there against the aero loads, which the other thread covers). MCAS may also be only limited by the physical stop (singular, since it only runs one way, well
should only run one way).
However, this is very relevant to the accident discussion because of the accumulated incremental trim change due to MCAS malfunction can result in the same trim condition.
To my mind it also blows a hole in the reported design assumptions for the MCAS "reset". MCAS design apparently assumed that if the pilots touched the trim switches, they would get the aircraft back in trim and therefore the total mis-trim due to MCAS was limited. This assumption was clearly wrong on pilot behaviour, but it seems possible it was also more fundamentally wrong in that (as I read it) there are known areas of the flight envelope where it is not possible to get the a/c in-trim with the switches. This means the "reset" assumption was never valid, even before it was tested with real pilots.