Interestingly: GPS RNAV systems may use an algorithm, which applies the local magnetic variation and may produce small differences in the displayed course. However, both methods of navigation should produce the same desired ground track when using approved, IFR navigation system.
This is quoted from AIM 1-1-19-k
You still cannot get a magnetic heading from GPS.
You could do it if you knew the wind vector but to get that you need to know TAS, GS, mag track, and the heading
So you cannot comply with ATC instructions to fly a heading.
If ATC asks for heading 150 and you fly a 150 track, they won’t complain, no
Well… that is true in practice but it will annoy them because if say they ask you to fly 220 and you fly what turns out to be a real hdg of 230, the man has to call you again and tell you to fly 210. The maths he is doing in his head isn’t going to work well.
IFR without a slaved compass system is strictly for masochists
If ATC asks for heading 150 and you fly a 150 track, they won’t complain, no ?
If there is noticeable wind they will certainly complain. Particularly if you are given a heading for separation.
With reference to this post reportedly a TB21 owner in the US is assisting Garmin with certifying the GFC500 for the TB20 and TB21.
So Garmin currently looks like the best option in the future for the TBs – unless you are happy with the “toy” autopilots previously mentioned (Trio and Trutrak) which don’t do pitch trim and don’t do ILS.
Any news on this? I find it very hard to believe nobody can offer a replacement AP for my old Stec 60-2 in a Socata TB20…
I have not heard of anything.
I guess the fleet size of TB20/TB21 is not big enough for one of the big names to finance the STC, and it was apparent (but could not be said openly) from the US Socata owners’ group that those wanting something new bought an SR22
There was a guy around here years ago saying Trio and/or Trutrak have EASA STC… here. Those are however not “normal” autopilots: no heading mode, no ILS, no pitch trim. Some of the posts around that topic were a frustrating farce.
EDIT: the other thing to remember is that any Garmin autopilot STC will only allow data from Garmin navigators, so if you have Avidyne IFD installed you will be out of luck.
Also it is rumoured that Garmin are working on a GFC500 TB STC. No more info.
Another update from the US for TB20 autopilot options; this time for the KFC230. This was posted on a US site by one of apparently two TB owners who had it installed
I am one of the 2 TB20’s that have the AeroCruz 230 installed. It does exist and it is STC’d for TB20 airplanes and I assume the rest of the TB line. I installed it because the KFC-150 was not working reliably. …
After an extended period of time and help from the factory rep my avionics shop got it working. I have a Garmin G500 which it couples with. The autopilot works very well…..BIG improvement over the KFC150. After all is said and done I am happy to have installed it. In spite of the advertising literature it IS NOT a drop in replacement but I believe a lot of the kinks were worked out on my install so future installs should be easier as the company learned where the bugs were.
The install time was given as 120hrs – for what is claimed to be a drop-in replacement – though the installer reckons it would take 60hrs to do another one.
One interesting thing is that it uses “GPS aiding” for flying ILS approaches. It receives the nav signals as normal but uses GPS data as an input to the feedback loop to improve tracking. If GPS reception is lost, it will disconnect and you have to continue to fly the ILS by hand, by reference to the usual indicators (and possibly the Flight Director; not sure about that). Same for VOR tracking. This is definitely a “novel idea” given that autopilots have been flying ILS and VOR approaches for many decades!
The 230 is not the only autopilot that does this; the Garmin GFC500/600/700 do it too, but the Garmin 600/700 don’t disconnect upon loss of GPS. The 500 will disconnect. This is relevant.
I am making too many posts on this thread
Can anyone guess how this would integrate into a TB20 with two Sandel SN3500 EHSIs and a GTN650+750 or 2×IFD540? AIUI, a GFC500 requires a G5, so an awful lot of good quality stuff would have to be ripped out.