Originally Posted by
FGD135
Not difficult to rotate the trim wheels under certain circumstances, but impossible.
IMPOSSIBLE.
Picture the stab, angled leading-edge up (trimmed for nose down) - then picture the elevator, attached to the rear of the stab, deflected up (to achieve nose up pitch).that
The down force at the rear of the stab (due to the elevator deflection) makes stab movement IMPOSSIBLE above a certain speed.
IMPOSSIBLE.
Hard to imagine that Boeing didn't include a WARNING in the flight manual advising that above certain speeds manual trimming of the stab would be extremely difficult, if not impossible. Surely they must have encountered this situation during flight testing. In their efforts to hide the MCAS system, they failed to make operators aware of a potentially deadly scenario.