Originally Posted by
safetypee
The reports / FDR did indicate that the crew attempted to use elect trim at larger tail angles, but without movement. Unfortunately there is no indication of this being relative to any elect trim inhibition, not known (or trim direction?), nor if this was due to high mechanical loading or purely elect inhibition.
I assume you are talking about the ET302 Preliminary Report. Where does it "indicate that the the crew attempted to use MET at larger tail angles, but without movement"?
The second MCAS activation at 05:40:20 moved the stab trim down to 0.4 units, its lowest point of the flight. Airspeed was just below VMO. The crew responded with MET and raised the stab trim back up to 2.3 units. The two MET blips at the end of the flight (05:43:11) raised the stab trim position from 2.1 to 2.3 units. The switch wasn't held long enough to affect more movement, but that doesn't mean it was "without" movement.
As for the question whether MET can trim up after the stabilizer is beyond the nose-down limit, or trim down after the stabilizer is beyond the nose-up limit, the schematics posted by Yoko1 on June 28 suggest they can (sorry, but I don't seem to be able to reproduce them here b/c I'm still new). The MET trim up signal goes through the stab nose up limit switch, but not the nose down limit switch. Likewise, the MET trim down signal goes through the stab nose down limit switch, but not the nose up limit switch. So, for example, the stabilizer being beyond the nose down limit should have no effect on MET trim up signals.