Originally Posted by
SteinarN
Maybe this is not the tail plane jack screw.... It seems small? Could it be a gear actuator?
Hope a 767 mechanic can chime in on this.
I haven't spent much time in the forward stabilizer compartment, but your image seems to match the maintenance manual.
There is no mention of total jackscrew length or diameter in the manual, so it will be difficult to create scale diagrams of the assembly. The trim only moves the assembly 21.51 inches during control column trimming (less if the flaps are less than 5 units). i.e. from 0.25 units (full nose down) to 12.8 units (full nose up) with column switches. Maximum range of the stabilizer is 0~14.2 units. 2 units is neutral.
At full nose down (0.25 units), the top of the moving part (ballnut) is within an inch of the upper stop.