ATA 27

Rudder Trim
Several new Westwind operators have called us asking why their aircraft “wing walks”. We have heard this same question for years, so we thought we would offer a few suggestions to help correct the problem. First, though, the pilot and mechanic need to understand the difference between wing walk and “Dutch roll”. The first is a roll axis problem and the second is a yaw axis problem—two different controls with very similar characteristics. Almost every Westwind we have worked this problem on has turned out to have a very slight Dutch roll. In almost every case, we were able to either eliminate the problem or lessen it to a greater degree by doing the following:

1. Run the rudder trim to the right stop and hold the trim switch in that position for 2-3 seconds. (DO NOT depend on the trim indicator for any of this.)
2. Run the trim to the left stop and again hold the switch.
3. Center the trim and go fly.

The trim actuators are not connected and will run at slightly different speeds. Over a period of time, they will position themselves out of rig and will bend the tab out of shape—causing a Dutch roll. Synchronizing the actuators again will straighten the tab. Don’t worry, it doesn’t hurt the tab at all.