Rudder Trim & Y/D

[hais]

Question for those who replaced their KFC150 with GFC500. 

KFC150 didn't have a Y/D. The rudder trim was independent. GFC500 on the other hand does control the rudder. 

1. Did you remove the rudder trim switch? 

2. If you kept it, does it control the original servo or the GFC500 servo? 

3. If you kept it, does operating it result in a mis-trim situation similar to operating the elevator trim with A/P on?

[donkaye]

The rudder trim switch stays and works the same as it always has.  For takeoff full rudder trim.  At 800 ft YD on.  On level off, YD off, trim for cruise, then YD on.  At least that's the way I do it for minimum excess torque on the YD servo.

[hais]

47 minutes ago, donkaye said:

The rudder trim switch stays and works the same as it always has.  For takeoff full rudder trim.  At 800 ft YD on.  On level off, YD off, trim for cruise, then YD on.  At least that's the way I do it for minimum excess torque on the YD servo.

Thanks! Does that mean there are two servos with the GFC500 one acting on top of rudder trim's? 

[Marc_B]

Just went though this myself.  For later models the standard Mooney rudder trim attached to the bellcranks in a way that does not interfere with the Garmin GFC500 yaw damper. However there were models in the mid bodies that had YD/rudder trim modules (such as the S-Tec) that must be removed if you are using GFC500 YD.  I believe if you have the split rocker switch rudder trim, then you are fine to add GFC500 YD.  And, yes, in that case you will have a motor that controls the rudder trim (item #1 below, believe made by Globe Motors) and a Garmin GSA28 "smart" servo that controls yaw damper.

 

[carusoam]

7 hours ago, hais said:

Thanks! Does that mean there are two servos with the GFC500 one acting on top of rudder trim's? 

expect yes…

Similar to our elevator trim and the attitude servo…  

Essentially they are two different jobs being done…

one is coarse and dumb, the other is fine and smart…
 

kind of like flying manually… our arms would get tired without the trim adjusting the tale plane in range first…

PP thoughts only… neither a CFI nor a mechanic…

Best regards,

-a-

Edited February 8, 2023 by carusoam

[donkaye]

12 hours ago, hais said:

Thanks! Does that mean there are two servos with the GFC500 one acting on top of rudder trim's? 

No.  2 Motors, but only one feedback servo, the rudder YD.  The other motor is manual with no feedback.