What Autopilot for PA28 Arrow III when upgrading

This video here might be really useful for you, as he was in the same situation and also wanted to keep and interface an Aspen…

Darkfixer wrote:

I got a quote on a S-Tec 55X and are there any other solutions ?

I have exactly that setup:

- Aspen EFD1000
- STEC-55x AP with autotrim and flight director.
- GNS430W
- Avionic Straubing Altitude Capture

At the time I installed this system, it was pretty much the only one available. I also said to myself then, that I could possibly upgrade to the Avidyne DFC90 (which is plug and play with an existing STEC-55x installation) later, but the Avidyne never got certified for the Mooney, but LOTS of Cirrus installations got upgraded this way.

Am I happy with it? Yes. Would I install an 55x system today? Most probably not.

For what it is and for what I use it in a non-de-iced light IFR and VFR platform, it has shown to be pretty reliable and working well enough. My previous experience was with the KFC150 system, and it is pretty close to it in terms of what it can do, even though the King system was more stable.

What do I like about the setup in no particular order?
- GPSS: It can do GPSS in two different ways: 1st directly from the Garmin GNS/GTN series. 2nd: Via the Aspen and it’s GPSS Steering emulation, which I’ve never actually used so far. This is a really cool feature and works fine.
- It is a pretty good system when it comes to being able to work on it’s own. It does not rely on any external device for the basic HDG/ALT/VS modes, so you will have an AP if there is no GPS reception, if the Aspen decides to pack up and so on. The only thing it does rely on is the old S-Tec turn-coordinator, which quite a few people have installed out of sight.
- Autotrim is a really cool feature. I would not remotely consider an S-tec 55x or 3100 without it.
- It has a quite funny CWS mode which can prove darn useful if you fly VFR and are told to do 360ties over a reporting point at a specific altitude. You can even change the altitude while letting the AP continue to fly the 360 turns.
- It works quite ok for me in benign flying conditions and is WAY better than any of the smaller S-Tec systems or the old Piper Systems.

What do I not like about it?
- While it works fine in good conditions, it will chase badly in turbulence or crosswind.
- It takes a good avionic shop who really knows how to calibrate them properly to get them to fly ILS’s well. Once it is calibrated, it does ok though.
- It is missing the IAS/LVL-CHG mode which is a pitch mode which holds a specific IAS vs the thrust applied.
- It needs (needed?) a separate remote display for implementation of Flight Director. (As far as I know you can now couple it directly to the Aspen by use of a (costly) unlock key for the Aspen).

So far, I have had one computer fail on me 2 years after warranty ran out. S-Tec was really good about it given the flight hours we could prove and replaced it for free. I’ve had one servo freeze up, which got repaired locally. Otherwise, so far, the system has been performing well.

Would I install this system today, given what is available on the market now? The answer would be most probably not and for the same reasons the video quotes. The only reason I could imagine installing an S-TEC 55X today would be:
- There is no STC for any alternative (which was pretty much the case then)
- All the alternatives are so far out of budget that I have no choice.

So if you look at the excellent video above, there are really 3 choices for you.

1.If you want to keep the Aspen (and I would too if at all possible) you can actually go the Avidyne DCF90 route without actually having to buy a full S-tec system (as opposed to what the video sais). How? Talk to your avionic shop. Quite a few have full S-tec systems minus computer in stock, which today don’t sell very well or which were removed by people who upgraded to the G500s. Some avionic shops will install the 55x basic installation without the computer and then directly put the DCF90 into the empty slot. I was told of at least one case where this was offered to somebody in Europe by a big shop, but he eventually opted for a Garmin system.

I know quite a few people who have gone the DCF90 route and which are happy. Mostly cirrus people who upgraded plug and play.

2. You can go for the S-tec 3100. It will work well with your Aspen and is definitely better in functionality than the 55×. I looked at it and have to say I was totally put off by the many negative comments I found online about it. For me, the upgrade would have been the same price than the upgrade to an Avidyne (which however is not certified for my plane) and also the 3100 did not get certified for the Mooney (but is for the Arrow) but frankly, I would not have done it reading the user feedback. However, if I for some reason would HAVE to go the S-TEC / Genisys route, I would definitly NOT install the 55x but the 3100 instead, for the simple fact that it is much better connected to the Aspen and has a lot of functionality which I would want in comparison to the 55x which is hopelessly outdated. In any case, if you do go the Genisys route, do get the autotrim system with it.

3. You can either bite the bullet and get a G5 (in addition to the Aspen quite possibly) and a G500 or you can get the G600, which again will work with the Aspen and it will work perfectly with the GTN navigator you have. While IMHO it is the best AP you can get, it is also quite expensive. But given all, it may well be worth the effort.

One thing I would like to add: Don’t let the purchase cost of any of those systems be the driver but also consider installation cost. They are in any case a massive part of the upgrade but some AP’s are easier to install and come with less “need to have” options which drive the price up. E.g. in my case, I got a great deal on my S-tec 55x system at the Aero, when it was offered to me for the price of the S-TEC 30 I orginally looked at for budget reasons. And that is what I paid for the basic system too, only to find out I needed the autotrim separately and the remote display to get the Flight Director capability e.t.c. so make sure you know really well what you need.

I am sure you will get tons of opinions here, but in the end the decision will be yours.

I think 2x 275i costs not much less than G5 + G500 TXi…
Another option is G3X? Although there would be no DME or NDB on PFD.

Darkfixer wrote:

So for the moment I can get a S-Tec 55X + Autotrim for around EUR ~30K + VAT (including installation)

You’d have to ask about the option to couple it with the Aspen directly too. Last time i talked to them, they said there now is a way to directly connect the 55x and 3100 with the Aspen PFD in order to have the mode announcement and I believe altitude capturing and Flight Director enabled without the use of the remote display. Absolutely make sure that this works, otherwise you need the remote display to get the flight director going. Which you definitly will want.

Also, I am not sure if the coupling of the 55x and the Aspen directly now will enable the Altitude selected to be captured by the 55×. If it is not, make sure you get the little gadget of Avionic Straubing which does exactly that. It’s worth every penny.

If you are in Friedrichshafen at the Aero, make sure you visit Genesys and Aspen both. That is how I got my 55x massively reduced.

Still, I would consider if going the Garmin way is not better in the end, even if that means you’d be ditching the Aspen.

Get an additional G5 and a GFC500. Spending that kind of money today on a rate based STEC system vs. a state of the art digital GFC system would be a waste (imho it would be insane).

The way to do this is to centrally place a GMC507 for the AP inputs. GMC507 → G5 → GFC500. The Aspen can stay and will show the same nav info. You’ll only have to set the altimeter on the G5.

The Aspen can stay and will show the same nav info. You’ll only have to set the altimeter on the G5.

Is there a way to connect the Aspen to the GFC500 at all?

Otherwise get rid of the Aspen in exchange for a full Garmin setup.

GFC500 and G5’s or GI275 or G3X, no other so cost effective and awesome competitor on the market.

Is there a way to connect the Aspen to the GFC500 at all?

I believe not.

Otherwise get rid of the Aspen in exchange for a full Garmin setup.

Or keep the Aspen and just get a G5 + GMC507 + GFC500. The Aspen will still show everything from the Nav Sources.