I just had a Century NSD1000(slaved) HSI installed in my PA24-260C. I have a Garmin 430W, STEC30 Autopilot and STEC GPSS System . Everything worked fine before I replaced the DG with the HSI but now I am experiencing Autopilot problems. The HSI seems to work fine on it's own and the Autopilot works fine on heading mode. The problem occurs when the autopilot is in track mode, the aircraft is vey sluggish to intercept (even in Hi mode) and will fly through the track and very slowly tries unsuccesfully to re-intercept the track. On smart teer mode, the problem is worse: With the autopilot in heading mode, as soon as I switch the GPSS switch from "HDG" to "GPSS", the aircraft circles to the left. The avionics tech says the wiring has been checked and is correct. I'm tendin towards the setup is not configured right or an interface is missing.

Anyone out there with any ideas?

Bill

The STEC 30 does not haveNAV or course feedback to the autopilot. Therefore setting the course with your HSI has no real affect other than to orient you to the nav Tracking. The autopilot simply turns to the left when the needle is deviated to the left and similarity to the right. If read your manual, you will recall that you need to be on course and on heading when the NAV is turned on and you are trying to track a course. With Approach, the procedure is the same. GPSS is another deal and that made the 30 a great autopilot. Set in a course with the 430, set the AP in HDG and then press GPSS. You will now track and intercept.

jvb