Hot take: Those digital autopilot retrofits aren't always worth the hype

I was at a shop last month and overheard two guys raving about how a Garmin GFC 500 is the only way to go for any GA panel. I get that it's smooth and fancy, but I've seen three installs where the servo mounting was a nightmare and caused more snags than my old King KAP 140 ever did. For a simple VFR flyer on a budget, a properly maintained legacy system still gets the job done without breaking the bank. Anyone else sticking with older analog stuff for certain airframes?

3 comments

3 Comments

jason_lewis328d ago

Honestly, I had a buddy who swore by his old Cessna 172 that still had the original Century 1 autopilot. We were flying back from Oshkosh a few years ago and the thing just started doing this weird oscillation, like a drunk person trying to walk a straight line. Ended up hand-flying the last hour and a half because we didn't trust it to hold altitude. He finally ripped it out and put in a used S-TEC 30 and it's been solid ever since. Sometimes the old stuff is fine until it suddenly isn't, but those digital retrofits can have their own quirks too. Ngl, I'd rather have a simple wing leveler that works every time than a fancy box that needs a software update.

reed.elliot28d ago

Oh I gotta push back on that a little. I flew behind a Century 1 for almost 800 hours in an old 150 and that thing was rock solid until the day I sold the plane. The trick is knowing its limits and not asking it to do stuff it wasn't designed for, like holding altitude in moderate chop or tracking a GPS course. Half the time when those old units start oscillating, it's because nobody has bothered to check the rigging or clean the rate gyro filters in fifteen years. I've seen plenty of S-TEC failures too, especially the 30s that had the grey connector harnesses that crack and give you random roll upsets.

ryan_shah3827d ago

Wait, hold on - I gotta say something about the S-TEC 30 thing. Actually, the S-TEC 30 used the same grey Molex connectors as the early 50 and 60 models, and those were notorious for cracking and causing random roll axis failures. I've seen two failed S-TEC 30s in person where the whole system just quit mid-flight because of a bad pin connection in that harness, not even an oscillation, just straight up no autopilot anymore. So it's not always the old analog stuff that's unreliable, sometimes the "newer" used gear like a 30 from the 90s has its own specific failure modes people forget about.