traumamed
Pre-takeoff checklist
I figured I would write a review of the Trio autopilot, and my rationale for choosing it, after a little over a year and a half with it. Hopefully this helps someone facing a similar autopilot decision.
I currently fly a Turbo Arrow III. I started looking at AP replacement in late 2024 when my Autocontrol IIIB (basically a Century IIB) started experiencing issues. I didn't want to invest any resources into troubleshooting an obsolete legacy AP. The panel I inherited when I bought the plane was an Aspen MAX system // GTN 750 with integrated audio panel // GTX345 // G5 // EDM900. The GTN 750 fed the Aspen PFD, which could subsequently provide GPSS to the old Autocontrol IIIB unit via a DAC. Autopilot pitch axis was limited to an STEC-30 alt hold unit.
Given my AspeGarmin Frankenpanel, I had a tough decision. No option was ideal.
-- GFC500: Plausible, but would have had to fly off the G5 and render my Aspens essentially nothing more than unintegrated monitors. ~$20K installed quote. Alternatively, rip out the Aspens and go all-Garmin... to do it right with a full big-screen Garmin EFIS would have been $60-70K out the door.
-- Genesys/S-TEC: I thought with an S-TEC pitch servo already in the plane that I could put in a 3100 or old 55x for a reasonable price. Nope. $43K quote.
-- Aerocruze 100: Only certified for en route IFR, no approaches. Non-starter for me. (Yes, it's technically capable, but that doesn't make it legal.)
-- Trio: The most promising option. Certified for GPS-based approaches down to 500' AGL, new (at the time) Aspen partnership and integration, installed price $11K. So I went the Trio route.
Autopilot was installed Jan 2025. Very - and I mean very - difficult to dial in initially. Pitch axis was fine, but even after extensive attempts at calibrating, the best the roll axis would dial in was hunting across a ~5 degree arc every 10-15 seconds. Trio was very responsive with troubleshooting, but despite not one but two rigging checks, a control head replacement, and a roll servo clutch adjustment, the hunting just wouldn't resolve. I also had an early pitch servo failure. By Oct 2025, I was very close to ripping the thing out and resigning myself to one of the less-good (or significantly more expen$ive) options. Again, to Trio's credit, they were willing to refund the parts cost if I went that route.
As a last ditch effort, I decided to fly the plane all the way from FL to Trio's hangar in SoCal and let Trio themselves look at it. They were able to find a few things to clean up on the installation, but ultimately they determined there was an issue with the way the new Aspen integration was working. The temp fix was to put in an older control head fed directly by the GTN until they could develop and STC a new firmware. This meant no vertical coupling for awhile, but at least when I flew home from SoCal, the hunting on the roll axis was improved (although not fully resolved).
By Apr 2026, they had new approved firmware and sent me a new control head. I've been flying that control head for nearly four months and it has been excellent. Hunting is nearly resolved, it's about as good as one can expect from any autopilot, maybe 2 degrees total arc every 25-30 seconds. Aspen integration is seamless. Vertical coupling works great. I am at a point where my XC flights have become take off, hand fly to 500', engage AP, set power and retrim at cruise, and basically don't touch the yoke again until 500' AGL on final. The Aspens can drive it via the heading and alt bugs if you're on vectors or stepping up/down altitudes, and of course also via GPSS. The AP can also be driven directly off the GTN via a toggle switch, but that then requires manually setting altitudes on the AP control head itself. It's a nice backup feature to have though in the event something happened to the Aspens. As far as approaches go, it reliably flies fully coupled GPS approaches. It will also fly ground-based approaches via GPS overlay, but I'm not sure if that is strictly FAA-legal.
Overall, I am happy with the autopilot, but the journey to get it working right definitely had frustration and dragged on for 16 months before the permanent fix was installed. A lot of that seems to have been driven by being an early adopter of the Trio-Aspen integration system, with my plane helping them to sort out some of the initial bugs. The Trio is worth considering if you are in a similar position that I was: needing an IFR-capable autopilot and dealing with an Aspen-based PFD/MFD stack. It's not a GFC500, but it gets the job done. For me, I'd rather have a fully integrated panel than a GFC500 that leaves half of my panel nothing more than pretty read-only monitors. Of course, YMMV.
I currently fly a Turbo Arrow III. I started looking at AP replacement in late 2024 when my Autocontrol IIIB (basically a Century IIB) started experiencing issues. I didn't want to invest any resources into troubleshooting an obsolete legacy AP. The panel I inherited when I bought the plane was an Aspen MAX system // GTN 750 with integrated audio panel // GTX345 // G5 // EDM900. The GTN 750 fed the Aspen PFD, which could subsequently provide GPSS to the old Autocontrol IIIB unit via a DAC. Autopilot pitch axis was limited to an STEC-30 alt hold unit.
Given my AspeGarmin Frankenpanel, I had a tough decision. No option was ideal.
-- GFC500: Plausible, but would have had to fly off the G5 and render my Aspens essentially nothing more than unintegrated monitors. ~$20K installed quote. Alternatively, rip out the Aspens and go all-Garmin... to do it right with a full big-screen Garmin EFIS would have been $60-70K out the door.
-- Genesys/S-TEC: I thought with an S-TEC pitch servo already in the plane that I could put in a 3100 or old 55x for a reasonable price. Nope. $43K quote.
-- Aerocruze 100: Only certified for en route IFR, no approaches. Non-starter for me. (Yes, it's technically capable, but that doesn't make it legal.)
-- Trio: The most promising option. Certified for GPS-based approaches down to 500' AGL, new (at the time) Aspen partnership and integration, installed price $11K. So I went the Trio route.
Autopilot was installed Jan 2025. Very - and I mean very - difficult to dial in initially. Pitch axis was fine, but even after extensive attempts at calibrating, the best the roll axis would dial in was hunting across a ~5 degree arc every 10-15 seconds. Trio was very responsive with troubleshooting, but despite not one but two rigging checks, a control head replacement, and a roll servo clutch adjustment, the hunting just wouldn't resolve. I also had an early pitch servo failure. By Oct 2025, I was very close to ripping the thing out and resigning myself to one of the less-good (or significantly more expen$ive) options. Again, to Trio's credit, they were willing to refund the parts cost if I went that route.
As a last ditch effort, I decided to fly the plane all the way from FL to Trio's hangar in SoCal and let Trio themselves look at it. They were able to find a few things to clean up on the installation, but ultimately they determined there was an issue with the way the new Aspen integration was working. The temp fix was to put in an older control head fed directly by the GTN until they could develop and STC a new firmware. This meant no vertical coupling for awhile, but at least when I flew home from SoCal, the hunting on the roll axis was improved (although not fully resolved).
By Apr 2026, they had new approved firmware and sent me a new control head. I've been flying that control head for nearly four months and it has been excellent. Hunting is nearly resolved, it's about as good as one can expect from any autopilot, maybe 2 degrees total arc every 25-30 seconds. Aspen integration is seamless. Vertical coupling works great. I am at a point where my XC flights have become take off, hand fly to 500', engage AP, set power and retrim at cruise, and basically don't touch the yoke again until 500' AGL on final. The Aspens can drive it via the heading and alt bugs if you're on vectors or stepping up/down altitudes, and of course also via GPSS. The AP can also be driven directly off the GTN via a toggle switch, but that then requires manually setting altitudes on the AP control head itself. It's a nice backup feature to have though in the event something happened to the Aspens. As far as approaches go, it reliably flies fully coupled GPS approaches. It will also fly ground-based approaches via GPS overlay, but I'm not sure if that is strictly FAA-legal.
Overall, I am happy with the autopilot, but the journey to get it working right definitely had frustration and dragged on for 16 months before the permanent fix was installed. A lot of that seems to have been driven by being an early adopter of the Trio-Aspen integration system, with my plane helping them to sort out some of the initial bugs. The Trio is worth considering if you are in a similar position that I was: needing an IFR-capable autopilot and dealing with an Aspen-based PFD/MFD stack. It's not a GFC500, but it gets the job done. For me, I'd rather have a fully integrated panel than a GFC500 that leaves half of my panel nothing more than pretty read-only monitors. Of course, YMMV.
