View Full Version : Trutrak Vizion Torque

08-31-2018, 11:04 AM
We just completed the installation of a TruTrak Vizion into our RV-6 today, and the ground test didn't go too well. There's no Tech Support till Tuesday so I'm wondering if anyone can help out. We have not done a flight test yet.

First we had to switch the wires to the roll servo to make it reverse direction (we installed it on the right under the passenger seat so I think that's why). However once we did that, we found that the torque provided by the roll servo is not always sufficient to move the ailerons against the trim spring! I suppose this could be something to do with being on the ground, but it is very surprising. The pitch servo seemed a little better but still very weak. Both servos could be overcome with about 2.5 to 3 lbs of stick force, which seems ok if a little low. They also sound very "notchy" rather than smooth in their operation.

I know that the Vizion doesn't have a torque setting like the older TruTrak A/Ps did, and we tried adjusting a few other settings with no success (not surprising since they are mostly concerned with feedback of which there isn't any on the ground). We tried simulating 85 kts by blowing into the pitot tube but that didn't seem to change the behaviour.

If it wasn't a new installation I would wonder if the shear screw has broken, but since both axes seem to suffer from very low torque, and I know this is controlled by the header unit, I wonder if there is a setting issue or some issue with the header. It's very odd since it's hard to think of an aircraft with lower stick force required than an RV.

If anyone can shed any light or offer any suggestions we'd be very grateful.

08-31-2018, 11:38 AM
I can say one thing, on the ground test the trutrac does feel notchy, far from what we think it should move. But in the air it works flawlessly. As far as torque is just matter of number settings.

Bob Martin
08-31-2018, 12:25 PM
I just installed a Vizion in a RV6.
Used recommended settings in install manual. Seemed all good.
I have roll trim on alerion, so no springs on sticks.
There was some notchyness you mention but went away with normal operation.
Good luck

08-31-2018, 06:14 PM
Also... the reversal of the roll sense can be done through an on-screen setting rather than having to swap wires around. Yeah, I didn't discover this until I had swapped wired. DOH!

Bob Martin
08-31-2018, 07:08 PM
Also... the reversal of the roll sense can be done through an on-screen setting rather than having to swap wires around. Yeah, I didn't discover this until I had swapped wired. DOH!

Pretty sure the onscreen reversal is for pitch...not roll....

09-01-2018, 02:03 PM
Thanks for the replies. Glad to hear the notchiness goes away in flight. Did anyone notice low torque during the ground test? I'm wondering if that is a serious problem that will need to be fixed or something that will be ok in flight?

09-08-2018, 09:26 AM
After speaking with TruTrak, they said it was ok to go ahead and test fly and that the increased voltage provided by the alternator might be enough to make a difference in the torque. They also suggested checking for 5V on pin 6 of each servo (torque control line), but we haven't done that yet.

So I took off hopefully today for a short flight. The good news was that when the A/P was off, everything seemed normal and I could barely feel any drag from the servos in the control system. However the bad news was that although the A/P seemed to be doing everything right, picked up the GPS track, was trying to move the stick in sensible directions etc, it couldn't move the stick at all against the cruise speed airflow forces, either in pitch or roll. I didn't try at slow speed but I doubt whether anything would be different given that it didn't work on the ground.

Strangely enough, the servos did seem able to hold the stick firmly with reasonable breakout forces of about 3 lbs at the stick grip. I will call Trutrak Monday afternoon UK time, but in the meantime, does anyone have any ideas or experience?

10-09-2018, 03:42 AM
Just for completeness I thought I should finish off this thread by relating the resolution to the problem we were having.

It ultimately turned out to be a wiring problem where one of the 4 wires to each servo had snapped at the crimp pin in each servo connector. Entirely our fault, not TruTrak's. Indeed a shout out to TruTrak is due, since they were extremely helpful in the troubleshooting process, and even sent us a new header unit to try (despite I think believing themselves that it was unlikely to solve the problem). We had to eat humble pie after proving them 100% right! In our defence it was a bizarre coincidence to have two faults which had identical symptoms causing us to assume that the problem was somewhere common to both servos.

The performance of the autopilot is outstanding - we went up for two extensive flight tests yesterday in moderate turbulence and it handled everything we threw at it with no fuss, no over-controlling, no hunting and no unpleasant characteristics at all. The only problem we found was that we didn't get a trim annunciation, which is likely due to another broken wire from pitch servo back to the header unit. We'll fix that next time we have the baggage wall off for inspection I suppose.

Thanks TruTrak!