Originally Posted by
DType
Acme nuts and threaded rods CAN be reversible, especially in a vibrating environment, as has been realised too late too many times.
But probably irrelevant in this case.
True, but they can be designed to reliably lock if the conditions are known.
There is a discussion of this in the Lion Air thread, I remember that the consensus seemed to be that it is unlikely to happen in the 737 design, certainly not enough to cause a noticeable issue.
I recall that one point is that Boeing would have designed it to not drift with vibration to eliminate need for an independent brake.