What is wrong with the old autopilots?

This is my experience personally. A GNS530W + GI275 coupled to a Century IIB gives solid roll axis control and is plenty usable for IFR flying. The only thing I worry about is maintenance and repairs. I had it overhauled at Straubing two years ago for practically nothing though.

The force of garmin proposal is indeed to interface these GI275 with older autopilots, and being certified, which wasn’t the case of G5.
G5 can drive these same APs but are not certified the same way; G5 can only replace 1 of the 6 pack gauge, although GI275 will replace AI and ASI.
I have to say that, looking at solution to run an eventual KAP150 with older avionics, it is not that cheaper.

dutch_flyer
This is my experience personally. A GNS530W + GI275 coupled to a Century IIB gives solid roll axis control and is plenty usable for IFR flying. The only thing I worry about is maintenance and repairs

This was my own initial plan/hope for my Century IIB which had given me wonderful good service for nearly 50 years.
It was though the lack of maintenance in the U.K., the lack of guarantee + threat of limited spares which has finally forced my hand.
Hence I have gone down the GNS530W + (two) GI275 coupled to Garmin GFC 500 route.

Am curating a Bendix King KFC200 at some expense using a UK avionics shop, albeit under FAA rules. I sent the pitch servo to the USA and it was rejected for OH so purchased a new one. The mode controller computer also got overhauled. I don’t have WAAS/EGNOS so no GPSS roll steering, and the KFC200 I have has altitude hold but not capture. Basically smooth attitude control in HDG/ALT/VS/VOR/ILS APPR modes. I still have considerable change from a new digital autopilot install cost.

Am using my maintenance budget on airframe priority items, with avionics on a secondary budget spend, and hoping the 530/430/KFC200 combo chugs on. The punch and judy FD wings on a stick have a time capsule charm, redolent of analogue Lear Jets.

With hindsight perhaps I should have requested any units needing rectification to go to Straubing before being shipped to the USA?

The electronics in old autopilots isn’t too complex, but you need test sets to diagnose them, and these are hard to find and specific to each model or family, so a good shop needs to have many of these.

Pontoise Aero Maintenance have told me that they can recertified old avionics, I think they’re doing it through a thrid party, there must be a Bendix-King office near by, that can test and potentially overhaul them.
Installation is of course another story.

RobertL18C wrote:

I don’t have WAAS/EGNOS so no GPSS roll steering

Is that specific for KFC200? Generally speaking you don’t need SBAS for GPSS.

Peter wrote:

A lot of planes have one of the old autopilots approved on the factory Type Certificate and these can be easily installed. You just need to find a working one

Are we talking about retrofitting an old AP or is this about mx?

Regarding mx and overhaul I’d agree that there’s nothing wrong with old AP and when properly set up they work nicely. So an old AP that’s not working on the spot might be worth being overhauled rather than exchanged. However, I can also understand that it’s not so tempting to overhaul. Because we all like new stuff.

Mine, an original 1970ies Piper AP, has recently been overhauled and it gets GPSS. It flies very well and for the moment I’m fine with what it can do. Of course it has no functionality by itself whatsoever. It is “on” or “off”, and the “wings level” option. But due to the GPS coupling it will follow anything up to missed approach procedures, because that is output from the GTN650 navigator. It also flies happily any GPS, NDB or ILS approach, however anything on GPS data only. So the game is to double check the analog (ILS) signals that are displayed on the instruments, but still it’s a lot easier to monitor (what I’d do anyhow) than to fly.

I was following the way of retrofitting a used S-TEC 55x into my plane, where I got a very attractive offer for the parts, but this path got destroyed by the holder of the STC. S-TEC wouldn’t accept several of the parts and required them new, and would have to have all of the other parts recalibrated by them, where the bill for all this was more or less equal to buying completely new from them. The GFC500 together with two glass instruments would have come cheaper, and that says it all, because the installation work seems to also be even less for the GFC500. So retrofitting a used device seems not to be a viable option.

Regarding the typical total costs for installation of a new autopilot being in the ballpark of at least 25.000 Euros, and including to this the amount of time still required for debugging the new system, maintaining the old AP is in fact a good option.