Trutrak EFIS AP problems on approach

Hi All,

I inherited an RV-8 with a nifty little Trutrak EFIS autopilot, coupled to a Garmin 530W. This summer I did a lot of work to the plane, including hunting down and installing an elusive Arinc converter so the nav side of the 530 would talk to the efis, as well as updating the efis software and GNS530W software.

For the most part, everything seems to work. The autopilot flies the plane nicely. When I put a waypoint into the 530, it flies the plane there no problem. When I load an approach with a few fixes it flies it fine, including the turns as plotted on the 530W (doesn't overshoot). It appears to be taking steering commands.

The problem comes when it gets lined up on final. For some reason, it won't fly the vertical portion of the approach. In fact, the autopilot doesn't even seem to recognize it's on approach. I doesn't give me any of the GPSS or GPSV flags. It doesn't pop up the glideslope bar either. The 530 appears to be in Approach mode, but the autopilot is continuing to just fly waypoints.

Am I missing something here? The trutrak manual available for download is vague at best. Does anybody have any better instructions on how to set this up?

Another issue that popped up came when I tried to fly an ILS. When I setup the ILS in the 530 the EFIS seemed to have trouble switching to VLOC navigation. I played with both a bit and finally got it to recognize the VLOC signal. It tracked the localizer nicely (you have to hand fly this, the autopilot won't), and when I hit the outer marker the glideslope bar popped up and worked as expected. However the problem came when I broke off and went around again for another LPV. The EFIS didn't seem to want to get out of VLOC nav. I could get the autopilot to fly the plane, but it would no longer track a GPS course. Even if I just put another airport in as the direct to waypoint on the GPS, the HSI needle would swing, but the autopilot wouldn't fly to the new heading. Finally I cycled the power and that got it to work again, but what the heck?

530's aren't rocket science, and the Trutrak efis strikes me as relatively simple. Which is why I'm a little concerned I may have a problem. I hope I'm just missing something. Thanks!

DEM

Don't know if this helps as I don't know much about the Trutrak EFIS but will give you some info on my Trutrak Didgiflight II vsgv. and Garmin 430W.

TruTrak Digiflight VSGV should displaying GPSS-GPSV(inflight, won't show unless there is a GPS signal)
EFIS should be set on GNAV until the 430W or 530W locks on to VLOC then on the EFIS switch to NAV and arm approach, Vertical A/P should be on auto on the EFIS. Good luck you may try to get info from trutrak but their EFIS isn't sold anymore.

Make sure you are in altitude hold before intercepting the GS. Alt Hold is the only mode from which GS Arm will appear.

Ben

Thanks guys. I am in Alt Hold mode when approaching the glideslope. I don't know how to get it into GPSS mode. My understanding of the instructions is that the GSPS and glideslope arm options only come up when it receives the appropriate signal from the GPS, unless I'm missing something.

I get the impression that the EFIS is not seeing the right info from the GPS. I.e. it doesn't know the GPS is flying an approach. I'm not sure if I'm not using the GPS properly, wiring mistake, EFIS operator error, or defective unit somewhere.

DEM

Which EFIS model?

DEM, Do you have the AP4 EFIS? I think that's the only one that is able to fly approaches? Once I'm established on the approach, the GPSS heading over the second button changes to GPSV. I select it and the autopilot flies the "glideslope". A vertical deviation indicator will pop up on the left side of the screen.

Mine is an AP4 connected to a Garmin 400W via RS232 wire. Trutrak upgraded my AP3 to an AP4. I don't know if they are still able to do that. John

jpowell13 said:

DEM, Do you have the AP4 EFIS? I think that's the only one that is able to fly approaches? Once I'm established on the approach, the GPSS heading over the second button changes to GPSV. I select it and the autopilot flies the "glideslope". A vertical deviation indicator will pop up on the left side of the screen.

Mine is an AP4 connected to a Garmin 400W via RS232 wire. Trutrak upgraded my AP3 to an AP4. I don't know if they are still able to do that. John

Click to expand...

Hi John,

I'm pretty sure it's an AP4. It just came back from mx at TruTrak, and was supposedly given all the latest upgrades.

I don't get any of the GPSS, GPSV, etc... annunciation options, at least not consistently. I did get the GPSV ARM to pop up once for a few seconds, but it went away before I could activate it and I was not able to replicate it.

DEM

I don?t know how your panel is set up but my panel was built by Aerotronics and the way it?s configured is there are two ways to provide navigation inputs to the TruTrak autopilot. Method 1 (EFIS) feeds the signal from my top Garmin 430 (gps #1) (Non WAAS) through a 429 Arinc attached to my GRT Horizon WS EFIS to the autopilot. Method 2 (FMS) feeds the bottom Garmin 430 signal (gps #2) directly to the autopilot. A two position Autopilot switch (EFIS / FMS) facilitates this election. Since my 430s are not WAAS, glidepath information is only available when an ILS approach is selected in the 430.

My independent CDI gets its approach and glide path information much the same way except there is a two position CDI selection switch (FMS 1 / FMS 2) with FMS 1 being 430 (top 430 - gps#1) and FMS 2 being the bottom 430 (gps #2). Often, when doing an ILS approach I?ll have the EFIS signal (EFIS / FMS switch) feeding the EFIS display and the coupled autopilot and the CDI source selection switch (FMS 1 / FMS 2) set to FMS 2 with the bottom 430 feeding the CDI. This gives me two independent gps sources to confirm localizer / glide path information.

Read your EFIS operations manual to ensure you know how to set up your EFIS for the approach. Also play around with your panel while sitting in the hanger with your avionics powered up to make sure you understand what each switch on your panel does. Since I was not the builder and frankly had never flown an EFIS equipped aircraft prior to buying my RV; it took.me over a year of playing with switches, trying different coupling techniques inflight, and rereading the manual numerous time to get my approach ?switchology? down.

I then made myself an ?Instrument Approach? checklist to ensure I correctly sequenced the ?switchology? of setting up a coupled instrument approach. This checklist ensures the approach I think I?m getting ready to fly is in fact the ?expected? approach event. Too many times I?ve surprised myself during an approach because I failed to set things up in the proper sequence.

However, if you?re not running any of your 530W inputs through an EFIS system then I strongly suspect you?ve either not wired glide slope information from the 530 to the 429 Airinc then to the autopilot or you haven?t configured the 530 correctly to send the information. If that?s the case, you need to review the 530 installation manual pin layout and configuration setup to make sure you?ve correctly wired things up.

Good luck. I HATE sparks (wiring) issues! But with so many different EFIS and autopilot systems out there today it?s difficult to know exactly where one should start in trouble shooting an issue like yours. But I recommend starting with a thorough review of your 530 pin layout, then checking your 429 Airinc wiring and then seeing out it feeds the autopilot.

Hi All,

Thanks for the help! Your posts got me thinking....at the same time I updated the EFIS I updated the software in the 530W so it would work with my new ADS-B installation. Did one of the settings somehow get screwed up with the new Garmin software? I cracked the manuals, and there is a RS232 connection between the GPS and the EFIS. I distinctly remember having to reset the 232 port settings when we upgraded the software, so I'm betting (hoping actually) that we didn't set that port correctly.

I'll head out to the hanger this weekend and see.

DEM

You may be on to something DEM. I think my SERIAL speed setting in my EFIS is at 9600 Baud for RS232 communication but you had the option to use 4800. And, I think Trutrak told me to set the ARINC setting in my Garmin 400W to GAMA 429. I believe there is a data format setting in your GPS also. I seem to remember selecting the AVIATION format in mine. It's all a bit fuzzy after four years. I would make note of your current settings before changing anything.

The guys at Trutrak were very helpful to me. Especially Zach. Hopefully there is someone there that can guide you. John

Well....that didn't work. I checked my RS232 port settings and the port was off. Set it to Aviation. However when I fired everything the EFIS is now receiving NO GPS from the 530. Reset the port back to what it was, and no joy. Tried a few other settings, and could not get the EFIS to recognize a GPS signal. Worked fine last flight.

Given the randomness of these issues, I really think there's something wrong internally with the EFIS. Will see what TruTrak has to say this week.

Supposed to get more snow tomorrow, which will strand the RV in the hanger...likely for the rest of winter. Bummer.

DEM

Well....that didn't work. I checked my RS232 port settings and the port was off. Set it to Aviation. However when I fired everything the EFIS is now receiving NO GPS from the 530. Reset the port back to what it was, and no joy. Tried a few other settings, and could not get the EFIS to recognize a GPS signal. Worked fine last flight.

Given the randomness of these issues, I really think there's something wrong internally with the EFIS. Will see what TruTrak has to say this week.

Supposed to get more snow tomorrow, which will strand the RV in the hanger...likely for the rest of winter. Bummer.

DEM