"No GPS" message

[TrueAirSpeed]

The Bad News: I have had my TruTrak Sorcerer autopilot installed for over a year and have never been able to use it. I get a "No GPS" message every time I turn it on and power it up.

Where does it get its GPS signal? Through the AFS 4500 installed by Aerotronics, the G430W, or does it require a independent antenna?

The Good News: In that year, I've taught my wife to hold heading and altitude.

Could of saved $10,000.00.

[TrutrakTech]

NO GPS means it is not receiving the RS232 signal from your GPS, whether that is the 430 or the AFS internal navigator, I do not know. That depends on how it's wired. The Sorcerer can receive Garmin Aviation or NMEA 0183 formats. The baud rate for both of the GPS's should be 9600, you'll need to make sure the Sorcerer is set to that.

Even without the GPS, the altitude hold function still works. If it doesn't, then there's a problem there that we need to address. If you can give me some more details (including aircraft type) we'll get it all working. Thanks!

And my apologies for not replying sooner, I have been in Florida at the U.S. Sport Aviation Expo.

[TrueAirSpeed]

I have an RV-7 with a Garmin 430W GPS and AFS 4500. I have been in touch with Aerotronics, the builder of my panel and found out a couple of things. (1) The panel has a switch that allows the Sorcerer to work slaved to the 4500 (EFIS position) or as a stand alone autopilot (FMS position). At present it doesn't slave to the 4500 and indicated "NO GPS Acquired," and only works in the stand alone autopilot (FMS position) and I do get "GPS Acquired." Apparently the autopilot or the 4500 are not communicating via the RS 232 or the ARINC 429. I have made plans to fly the plane to Billings in a month or two and Aerotronics' techs will take a look at it. HOWEVER, even in the autopilot stand alone position (FMS position) the ALT HOLD doesn't work. The airplane continues a climb past the pre-selected altitude. Any ideas on a fix for this?

[TrutrakTech]

Can you walk me through your steps to set up the autopilot? Also, if you have the list of your vertical settings handy that would help too. Thanks!

[TrueAirSpeed]

I initially had all the settings according to the installation/user manual. I've re-set the vertical since then, trying to remedy the problem. Here are the vertical settings as of yesterday: Vertical Activity - 1; Vertical Torque - 7; Min. Airspeed - 110; MAX Airspeed 165; Norm Climb airspeed - 125; Static Lag - 2; Micro Activity - 0; Half Step - N. I reduced the vertical activity to eliminate fore and aft control stick jerking.

I've tried several different ways to get the ALT HOLD to work. One, by putting in a predetermined altitude, prior to takeoff and the other by arriving at an altitude and engaging ALT Hold. In both cases the airplane continues to climb past the selected altitude.

Terry Small

[TrutrakTech]

With a vertical torque setting of 7 that's very likely, 7 is not really high enough to fly the aircraft. Try 12.

Next, your min airspeed is pretty high. If you hit 110, the autopilot will push the nose down to maintain that setting.

Do you have one of our autotrim systems on this plane as well?

[TrueAirSpeed]

I haven't installed the auto trim system yet. I'll increase the vertical torque to 12 and change the minimum airspeed. It'll be a week or so before I get back to you.

[TrueAirSpeed]

Flew the airplane today, after setting the vertical torque to 12, and the auto pilot still climbs. And as a side note, the auto pilot even shut down and when I tried to re-engage it would power up and then go dead. I finally shut it off. I'm at the point where I need someone to take a look at it.

Terry A. Small

[TrutrakTech]

PM me the serial number and I'll get you an RMA number. Thanks!