LR40/45 yawdamper
I flew the Learjet 40/45 and am aware of the issue that has been raised. Both Bombardier and Flight Safety train the pilots to turn the Yaw damper off. As stated above, the reason is that the yaw damper will fight the pilots rudder pedal inputs during a crosswing landing and during the landing roll. This is true on the early premod models and the latter models with the mod integrated at manufacture.
All the SB 45-55-6 does is stops the rudder boost and the yaw damper fighting with each other and does not stop the yaw damper working.
This is in complete alignment with my personal experience. I was once operating the 40/45 with a strong crosswing, maybe 15 to 20 knots and we missed the yaw damper off final check before landing. Needless to say that the rudder work was more than a handfull (or is that foot full??).
Some larger Bombardier bizjets, stipulate that the Yaw damper should be turned on on stand and turned off once you arrived on stand. What the system does in reality was keep the yaw damper off until some pre-determined criteria and then turns it on, and on landing, turns it off when close to the ground.
I hope this helps.