Originally Posted by
ARealTimTuffy
Wording from manual.
it differentiates between a column jam and a elevator jam in the aft elevator control mechanism.
My quote is from the original system, still in place. Yours is from the new EJLA system wording. Both deal with jammed control column (jammed somewhere in the entire cable run from Control Column to Elevator), at least as I have always understood the original system. I was told, at some point (probably 1986) that the breakout mechanism was under the cockpit floor, and that there were two separate controls runs from there to each elevator...that the Captain's control column worked the left elevator, and so on. If the elevator jams, you will feel it in the control column. Hopefully, I haven't been mistaken all this time...but, other than in a sim, it has never come up.
Here we go:
And just a few more inches down the page, a diagram of the breakout mechanism:
(Both from satcom guru, here:
https://www.satcom.guru/2018/11/stabilizer-trim.html
But since the final part of my quote continues...
If the jam exists during the landing phase, higher forces are required to generate sufficient elevator control to flare during landing. Stabilizer trim is available to counteract the sustained control column force; maybe Boeing thought it was just a good idea to improve it with the addition of a DLC type system. My guess, though, is that it (so far) takes input from only one pitot tube.