Navaid won't use correct course

Hi ya'll,

So I'm helping an RV owner friend (Mike C) who is trying to figure out why his 'new' navaid that is in his RV won't follow a GPS course.

Here's the clues:

• Wing leveler works fine - though the trim knob has to be set almost all the way to the right to keep wings level.
• The 'turn' knob on the navaid works correct to turn left or right.
• The smart-coupler is getting valid GPS data as confirmed by the LED blinking correctly when engaging course or heading mode.
• When you flip the navaid switch to the left to have it start following the smart coupler, the left wing briefly drops and then it turns to a course and holds on that couse. Just never the right course ;-)

Anyone have any advice? I've never played with one of these units (I have a trutrak AP in my plane)

Are you holding the course switch for 1/2 second before flipping the mode switch to the left? Its at that point that it determines how far off course it is and how much of a correction to make.

rocketbob said:

Are you holding the course switch for 1/2 second before flipping the mode switch to the left? Its at that point that it determines how far off course it is and how much of a correction to make.

Click to expand...

Yep. Thanks for the idea though...

Recommend you adjust/calibrate the head/servo combination so that you can fly the plane level without needing to have the trim knob set almost all the way to the right to keep wings level. I believe that in "track mode" (toggle switch to the left) the trim knob will command the plane to fly an offset to the desired track. Is that possibly what you are seeing. I'm not sure just how well this unit will track when the adjustment/calibration is out of range as you describe.

If you don't have the manual, I can scan relevant pages for you and e-mail.

First try to get the plane to fly straight in wing leveler mode (toggle switch to the right) by using a small screw driver to adjust the "trim range" trimpot. If you don't have enough adjustment in the trimpot to bring the plane level, you'll need to open up the servo and reset the null point (no big deal).

You need to be reasonably close to the desired course before engaging track mode. Once engaged and tracking, the trim knob can be used to remove any undesired offset, or add some offset if you need it.

Good luck and hope this helps,

Hi Dave,

My friend does have the manual. Thanks for the advice - we'll follow it (and I'll post an update for future searchers...)