TruTrak DF II VSGV upgrade pirep

We've been happily flying our TT DF II VSGV for almost 600 hours now in the -9A. The suite includes three GRT displays for EFIS and a GNS430W. We recently got "The Upgrade" with the new blue display and other inside guts.

The new display is a HUGE improvement. I can't count the number of times that we've looked down at the old display, only to not be able to see it at all in the sunlight. Very happy pilots on that improvement. Also, we're loving the higher roll angle for course changes and approaches. Big improvement. Ok, now that all the praise is in, the bad...

We HATE the loss of being able to fly coupled lateral nav while allowing the autopilot controller to deal with altitude hold. This is huge. I've been made aware that others feel the same. Previously, one could engage lateral navigation on the a/p and steering guidance would be driven from the efis. If you wanted the a/p to follow the efis altitude bug, you would also hit the vertical button on the right of the a/p head after the lateral was coupled. We found this valuable for many reasons. Sometimes things are happening quickly and the a/p is being used as a load shedding device. The lateral guidance is loaded usually (at least for us) long before the final altitude is dialed in. We've also gotten quite comfortable using separate altitude hold gains in the efis compared to the a/p controller for different turbulence needs, one set much more sensitive than the other for different conditions. Life was good. With the current software (v.2.34?), when the lateral nav is engaged on the a/p head, if there is ANY altitude input from the efis, the a/p automatically engages the vertical defined by the efis. This isn't ideal at all, at least in the current GRT efis world. Oh, well, we might get used to it, but we have certainly lost functionality on this detail. I would encourage Tru Trak to go back to the previous "buttonology". We're going to give it plenty of time before deciding if we want to go back to the previous version software.

Just two pilot's opinion.

So, it isn't a problem with the AP but rather the interface with certain EFIS units?

I got mine back and flew a bit with it, and was easily able to have it course coupled while "dialing in" a descent or climb on the TT control head, then just punching Alt hold to have it lock the current altitude.

Is that the VSGV, or the special model for GRT that you have?

As somebody getting ready to buy both GRT and TT products I want to understand your issues.

If I understand your concern is that you used to be able to have the EFIS provide your course information to the autopilot, then use the autopilot altitude hold feature to maintain the current altitude. Am I understanding your previous state accurately?

In the current state, with the new AP, you are stating that the EFIS provides not only the course information, but altitude as well. Am I understanding the current state accurately?

I guess the problem I'm having in understanding your concern is what is the difference from pressing the altitude hold on the AP, versus setting the altitude bug on the EFIS. I would have thought you would have wanted the EFIS to control this function. Am I missing something?

If it's just a sensitivity issue, can't that be adjusted in the TT unit?

bob

Scott, sounds like what you got is the new AFS AP Unwillingly...

My VSGV w/ 2.30 software does not do that.. it still has older behavior that you prefer... This one-button "fully engage EFIS guidance" is a feature of AFS AP.. and I suspect somehow that migrated to the "mainline" as well.

I don't (yet) have a strong preference either way, though I do see your point about vertical mode... since I've been known to forget to set altitude select (on my GRT) prior to engaging the autopilot.... so maybe the old behavior is indeed the better choice.. even if it requires pushing the button once or twice more..

Scott,

I agree 100% with you that the way you WANT it is better than what you have! And that is just how my unit is working (the way you want it). I just ran out to the hangar and powered it up to check the version - v.2.32. You might check with Lucas and see if you can "regress". I certainly don't like what you are describing - that really cuts down on the usefulness of the system.

Paul

rleffler said:

If I understand your concern is that you used to be able to have the EFIS provide your course information to the autopilot, then use the autopilot altitude hold feature to maintain the current altitude. Am I understanding your previous state accurately?
Yep
In the current state, with the new AP, you are stating that the EFIS provides not only the course information, but altitude as well. Am I understanding the current state accurately?
Yep
I guess the problem I'm having in understanding your concern is what is the difference from pressing the altitude hold on the AP, versus setting the altitude bug on the EFIS. I would have thought you would have wanted the EFIS to control this function. Am I missing something?
It is just the loss of functionality to engage guidance and 'hold what you've got' with respect to altitude, without having to Dial in a precise altitude to capture first.

If it's just a sensitivity issue, can't that be adjusted in the TT unit?
Our (mine) RVs are pretty pitch sensitive. It can be a little bit of a challenge to find a perfect pitch gain setting for both perfectly smooth and very turbulent air. Granted, not really a primary concern though.
bob

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Ironflight said:

Scott,

I agree 100% with you that the way you WANT it is better than what you have! And that is just how my unit is working (the way you want it). I just ran out to the hangar and powered it up to check the version - v.2.32. You might check with Lucas and see if you can "regress". I certainly don't like what you are describing - that really cuts down on the usefulness of the system.
Like I said, we're going to see if we can live with it until TruTrak sees the light. I haven't talked to Lucas yet since we're very happy with most of the improvements and it would pain me to go back to a previous version.
Paul

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I assume that the AFS interface has some functionality to engage nav with a simple Button for altitude hold without having to dial in a specific altitude?

It is amazing how quickly we identify little things like this that suck when bouncing along in turbulence, or IMC. My guess is that TruTrak will come around eventually. I know how a "feature" can sound really cool during development but be a real step backward in reality.

TruTrak

I had my VSGV updated in Feb to V2.34 and found the same issue, when autopilot is put in the GPSS mode, it also goes into the GPSV mode automatically because the GRT is sending a altitude command. This version also added a steeper bank angle which I do like because when making 90 deg turns on GPS approaches it no longer over shoots. The new display is also a nice improvement.

After flying with it for a few weeks, I called Lucas and returned mine to be reloaded with V2.32 with the steeper bank angle. I have made several flights now in the week we have had it back and am a happy flyer again. We flew up to Graham today and did approaches and am very pleased with the results. The GRT and Digiflight II VSGV are an amazing combo for IFR approaches.

Concerns noted

Hi all,

Thanks for voicing your concerns. It's impossible to make a product that people like if we don't know what it is that the people like. I am out of the country right now, but will talk with the software writers when return. The initial reason for the change in 2.34 was so that the AP didn't require an additional button push on an approach for say a 430W user. It was intended to reduce workload.

I will look into seeing what can be done when I get back to the office. If you have any questions, feel ree to PM me. Thanks!

I have the old software version and have thought about the upgrade to improve the display however the new version of sofware would make my the ALT HOLD and CLIMB functions of the autopilot unusable.
My AP is installed in a Cozy and which maybe even more pitch sensitive than a RV. At the moment the II VSVG AP will track the lateral commands from the GRT EFIS and (independently) climb, descend and ALT HOLD very well. However if I select the AP to follow the GRT EFIS vertical commands the aircraft starts to oscillate in pitch in ever larger and more aggressive motion until I disconnect it. In other words the AP in stand alone vertical mode performs well but once connected to the GRT EFIS vertical commands it is unstable and unuseable.

So to have a software version that automaticlly connects the AP to both the lateral and vertical commands of the EFIS would be a real problem for my self.

As an aside do any of you GRT EFIS users have the same problem I do. The vertical signals from the GRT EFIS appear to be sensitive. I have tried all possible LAG, SENSITIVITY etc combinations on the AP. I would really like to sort this out as being able to climb, descend and level off at a GRT preset alitutude would be real handy. By the way in perfectly still air the AP will follow the GRT vertical commands but the slightest bubble of turbulence upsets it.

Chris Byrne said:

As an aside do any of you GRT EFIS users have the same problem I do. The vertical signals from the GRT EFIS appear to be sensitive. I have tried all possible LAG, SENSITIVITY etc combinations on the AP. I would really like to sort this out as being able to climb, descend and level off at a GRT preset alitutude would be real handy. By the way in perfectly still air the AP will follow the GRT vertical commands but the slightest bubble of turbulence upsets it.

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It takes a fair amount of flight test tuning to get the right settings - I have found that I have a pretty stable set of gains for the RV-8 when I am flying solo, but am still playing with different combinations that will work with a passenegr and baggage. Tuning can be tedious - but that is what flight testing is all about!

Paul

VSGV change

I do not want the autopilot to automatically follow EFIS vertical steering upon selecting GPSS for three reasons.

1. Altitude control has always been stable with the TT, not so when driven by the GRT EFIS. When the EFIS begins causing pitch transients, I revert to TT control.
2. In a descent, I use the TT's knob to control vertical speed to finesse the green arc on the EFIS map display to stay over the point at which I want to be level. That is easier than changing vertical speed with the EFIS. Also works on a precision approach if not coupled.
3. On an approach with step-down altitudes; e.g. VOR, I can have the TT hold altitude while I set the next altitude in the EFIS. When I get to the point where I can descend, I then push the TT's ALT button to begin the descent to the next altitude and the EFIS will fly the descent and level off. Also works on an en route descent with an intermediate altitude restriction.

If TT wants to change something, it should add in-the-field firmware update capability.

John Nystrom
RV-7A, RV-3B

Just wondering how many have installed TT trim control unit and how do they feel about it. If I understand it correctly adding it to an already built RV is not much both in terms of the unit itself and wiring but just wondering how much of use it is and if really helps.
Heck, I took a friend on an IFR flight a couple of days ago and he accused me and IFR flying as just a computer game instead of flying an airplane. He said all I was doing was punching numbers and buttons on computer screens (A/P and EIFS)
BTW, my TT is working the same as the old ways which means I does not automatically go to VSGV when GPSS is selected and I like it that way.

I have the old software version and have thought about the upgrade to improve the display however the new version of sofware would make my the ALT HOLD and CLIMB functions of the autopilot unusable.
My AP is installed in a Cozy and which maybe even more pitch sensitive than a RV. At the moment the II VSVG AP will track the lateral commands from the GRT EFIS and (independently) climb, descend and ALT HOLD very well. However if I select the AP to follow the GRT EFIS vertical commands the aircraft starts to oscillate in pitch in ever larger and more aggressive motion until I disconnect it. In other words the AP in stand alone vertical mode performs well but once connected to the GRT EFIS vertical commands it is unstable and unuseable.

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I have the extact same issue with my RV4. I get little to no oscillation with the TT managing the altitude hold but tend to get some with the GRT in altitude hold mode. I am still trying various settings to see if I can remedy the situation but have not figured it out as of yet.

I do not want the autopilot to automatically follow EFIS vertical steering upon selecting GPSS for three reasons.

1. Altitude control has always been stable with the TT, not so when driven by the GRT EFIS. When the EFIS begins causing pitch transients, I revert to TT control.
2. In a descent, I use the TT's knob to control vertical speed to finesse the green arc on the EFIS map display to stay over the point at which I want to be level. That is easier than changing vertical speed with the EFIS. Also works on a precision approach if not coupled.
3. On an approach with step-down altitudes; e.g. VOR, I can have the TT hold altitude while I set the next altitude in the EFIS. When I get to the point where I can descend, I then push the TT's ALT button to begin the descent to the next altitude and the EFIS will fly the descent and level off. Also works on an en route descent with an intermediate altitude restriction.

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I agree whole heartedly with the above and would like the exact same functionality. I had been thinking of sending my relatively new unit in for the upgrade as I'm getting the lines across the display but I think it best to wait until TT has resolved this issue. I trust they will as they certainly have a well established track record in the support and customer service department.

BUT

the issue goes away if you request V2.32!!!! It will operate just the way it has with GPSS and GPSV requiring separate button pushes just like it has since I got the DF II VSGS 3 years ago. I believe if you want the steeper bank angle you need to ask for that also. In my opinion, there is no reason not to get your DF II VSGV repaired or updated.

Will TT do a sw downgrade to 2.2???

Suggestion for TT

In setup, include a choice whether or not to link VS to the mode button. That would allow TT to upgrade firmware and not leave behind those of us that do not want it linked.

John Nystrom

Vyking said:

In setup, include a choice whether or not to link VS to the mode button. That would allow TT to upgrade firmware and not leave behind those of us that do not want it linked.

John Nystrom

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This option has my vote