S-TEC 55X in a Cherokee 235. ATC audio is booming.

Q I have an S-TEC 55X in my Cherokee 235 coupled with dual Aspen and 430W. It’s a great autopilot but it is very sensitive to being out of trim. As such, when the trim up/down alarm comes on it is very loud. I understand it’s important to not overwork the servo, but the audio often booms over ATC giving instructions while descending on approach before I can trim things perfectly. Anyone know how to decrease the volume coming from the autopilot relative to the comm audio?

Stephen Hanff

S-TEC 55X Autopilot Audio Answers

A I have a 55X autopilot without autotrim, too. I’m using a Sonalert for sound generation. Is that what you’re using? If you do have a Sonalert, you can put a piece of masking tape over the hole on the front and that will cut some of the sound down, or you can put a resister or potentiometer in series with the Sonalert to cut the voltage down and reduce the volume.

Scott Sherer, Piper Owner Society Aviation Director

A You can turn the sound way down by removing the unit and then there is an adjustment option. There are two holes when you remove the unit — do your research online to make sure you choose the right one. I had to turn mine down three full turns I believe. It was louder than front row at a rock concert through my headphones. I changed audio panels and that caused my issue — it was low with the old audio panel. You don’t need to touch any wires or the audio panel to make this happen and it takes 10 seconds once removed! My problem was I did not have the right screwdriver to remove it

Michael Schwartz