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Bayou Bert
03-20-2019, 11:32 AM
I have the TruTrak Vision 385 in my 9A. I have the GRT HXr EFIS.
Today I was climbing out, had the destination loaded and activated
in the GTN 650 and turned on the AP at 2K with a 3K target at 500fpm.
I was at full power, had EFIS in GNAV and AP in GPSS VS and it went
right on through 3K and I finally reined it in at 3.5K. Reduced power
and trimmed down etc.
I have the recommended settings in the TruTrak AP for the 9A and all
the settings in the EFIS are at 100%. The lateral control is great but
vertical I can't depend on to be correct.
I don't have auto trim but not sure that would help.
The servos are 2008 blue motor style.
Any suggestions or help would be greatly appreciated.
I am working on my instrument and not being able to trust the AP
is really making things way more difficult than needed.
Any help/suggestions Greatly Appreciated.

Mike S
03-20-2019, 11:42 AM
I have the TruTrak Vision 385 in my 9A. I have the GRT HXr EFIS.
Today I was climbing out, had the destination loaded and activated
in the GTN 650 and turned on the AP at 2K with a 3K target at 500fpm.


You turned on the AP, or engaged it??

Bayou Bert
03-20-2019, 11:53 AM
The last action I usually do when going to AP
is hit the mode button on AP and make sure it shows
GPSS VS in the window.

BobTurner
03-20-2019, 12:10 PM
A typical wiring connection will have the autopilot?s ARINC lines going either directly to the 650, or to the HXr, with a dpdt switch choosing which.
1. Is the switch in the HXr position? If ?yes?, then
2. Have you set the final altitude (3000) in the HXr?
3. I have the Trio, which auto-defaults to arinc commands when present. But I *think* the TruTrak does not. Check the TruTrak manual, see what buttons you need to push to put it into the ?accept arinc commands? mode.

If your switch is in the ?650? position, you need to enter 3000 directly in the TruTrak.

Bayou Bert
03-20-2019, 12:38 PM
Thanks Bob, but I keep the switch on the HXr. I like the bigger numbers and
dealing with EFIS instead of the little AP head and little green numbers.
I was wondering if I need to just try letting the 650 feed the AP directly.
I assume an approach could be flown in that configuration?

BobTurner
03-20-2019, 12:54 PM
Thanks Bob, but I keep the switch on the HXr. I like the bigger numbers and
dealing with EFIS instead of the little AP head and little green numbers.
I was wondering if I need to just try letting the 650 feed the AP directly.
I assume an approach could be flown in that configuration?

Yes, but only a gps approach. Going thru the efis gives you vor and ils approaches in addition to gps. Also you can do heading (not ground track) mode if you want, like if you?re getting vectors (controllers try to build in wind correction). And as you say, the efis presentation is much easier to read.
But try a direct connection 650 to autopilot gps approach. (You should know how to do this anyway, in case the efis dies. That?s the only reason for the switch.)
However, I still suspect you want something other than VS set in the autopilot, something like ?use arinc?. But I?ve only used a TT once, so my memory is fuzzy.

BobTurner
03-20-2019, 01:08 PM
Reading page 33 of the 385 manual suggests that you need to set the autopilot vertical speed to zero prior to engaging it, in order for it to accept the ARINC commands. Try that?

Bavafa
03-20-2019, 01:19 PM
Bob is right on with his suggestions. One other thing, set the EIFS to ENAV, it will flip to GNAV automatically when/if it needs.

Tankerpilot75
03-20-2019, 01:19 PM
I assume you?re setting your desired altitude and rate of climb on your HXr EFIS and then engaging your autopilot for both heading/route and climbout. This doesn?t work.

If you?ll review your TruTrak operations manual section 6.4 I believe you?ll read that you have to sync the SVS mode (vertical speed) to less than 100 feet BEFORE the autopilot will enter GPSS mode. Once synced the EFIS and autopilot display GPSS indicating your EFIS and autopilot are truly communicating with each other.

When you initially engage your autopilot on climbout it will show an SVS rate equal to your actual rate of climb. You accomplish syncing by turning the autopilot knob until SVS indicates less than 100. The EFIS?s rate of climb you?ve entered will then continue your climb to your desired altitude. Failure to synchronize your autopilot rate of climb to your EFIS will result in the autopilot continuing to climb through your desired EFIS altitude.

Admittedly the TruTrak operating manual is poorly written. In fact it sucks! Like you, I struggled with this issue and couldn?t figure out why sometimes it would level off at the EFIS entered altitude and sometimes fly through it. I swore it was a intermittent system malfunction but eventually reread the operations manual and watched the GRT Jerry Morris videos enough times to figure out it was just operator error. The reason why it worked as advertised a few times but not always was simply because I accidentally had less than a hundred feet rate of climb at time of engagement.

I have the old WS EFIS system but the autopilot interface is the same. They are great systems but getting them to truly communicate is key. In fact I got so frustrated with my Garmin 430, GRT WS EFIS and autopilot not playing together as ?expected? I developed an ?Instrument Approach Procedures? checklist that I religiously use when flying a GPS or ILS approach. Starting an approach and engaging the autopilot only to have it take me a different direction than anticipated really frustrated me. I highly recommend you create one for yourself using the Jerry ?Widget? Morris videos available on the GRT support training website to assist you.

BobTurner
03-20-2019, 04:25 PM
Yep. My one and so far only RV10 instrument student failed his check ride when his TT took him off in some unexpected direction (failed to capture the final approach course) and he was too slow to catch it. So, the alternative: This is just one reason why I went with a Trio Pro rather than the TT autopilot (although not my major reason). It auto-defaults to the ARINC inputs if there's data there, so all I do is set what I want in the HX, then push the horizontal and vertical servo engage buttons on the Trio. No other knob twirling or button pushing needed. Only real problem is staying current on the "no-efis" operation of the autopilot, should the need ever arise.

Bayou Bert
03-20-2019, 04:40 PM
Thanks Jim and Bob, appreciate the help. Jim that is exactly what I did
this morning. Take off climb about 1400fpm, already had the destination
in the 650, put EFIS in GNAV, set 3K at 500 fpm, then tapped the TT mode
button until I saw GPSS VS and thought all was good, until 3K.
So if I understand right, this morning I was good except I should have moved
the TT cursor to the VS and dialed in 100 or less then hit mode to GPSS and
all would have been good?
I was to the point I was thinking, like you Jim, that something was wrong, but
not knowledgeable enough on the subject to decide what area, Me..EFIS..AP?
I was thinking my pitch servo was not strong enough. I just swapped servos
last month. I was not getting the trim bars on the TT head. The fellow I
bought the project from had the pitch servo in the wing. At least now I
know when it wants trim and in what direction. But find it very sensitive
and get pre occupied chasing trim.
Jim would you have a problem sending me a copy of your checklist?
If not I understand.
If you don't mind I will pm my email.

BobTurner
03-20-2019, 05:01 PM
"I should have moved
the TT cursor to the VS and dialed in 100 or less then hit mode to GPSS and
all would have been good?"

That's my understanding.

On the other subject: Do you have electric trim in your airplane, and do you anticipate using the TT for approaches? If the answer is yes, you might call TT and see what it costs to retrofit your autopilot for auto-trim. Again, different boxes, not sure about the TT, but my Trio has auto trim. It is programable for speed (fine trim movements for high airspeed, coarser movements at low speeds) and I can and do use it even when hand flying (autopilot powered on but servos not engaged). I can start a coupled approach at 130 kias (or more) and, as I come down the GS, slowly retard the throttle until the speed is down to 75 kias, add flaps, etc. At DH, runway in sight, when I disengage the autopilot, the plane is in perfect trim. Not as important in a -9 as in a -10, but a very nice-to-have.

pa38112
03-20-2019, 06:15 PM
How old is your Vision? When I first installed mine I would get the same thing part way into my climb. It turned out to be a pinched hose internal to the unit.

Bayou Bert
03-20-2019, 07:02 PM
I received the Vision in late 2014.

BobTurner
03-20-2019, 07:06 PM
How old is your Vision? When I first installed mine I would get the same thing part way into my climb. It turned out to be a pinched hose internal to the unit.

Not sure this is an issue here. When under control of the GRT, the GRT is sending all the pitch commands based on its data, not the autopilot's data.

Canadian_JOY
03-20-2019, 07:39 PM
A contrarian thought here, perhaps...

So far almost all of my Vizion 385 use has been with it being fed directly by a GNS480 and via manipulating the autopilot's front panel controls. Admittedly I haven't had an opportunity yet to shoot an ILS but for RNAV/GPS approaches it has been exceedingly easy to use and pretty much infallible if I've programmed the GPS correctly.

I love flying the assigned altitude and watching the autopilot transition from altitude hold to "GS Armed" to "GS Captured" as we work our way through the approach. Yes, I get the moving trim bars when I deploy flaps and the trim movement they command corresponds to the amount of trim I apply when hand-flying the airplane. It's a pretty slick system.

I have done VOR tracking with the HX feeding the Vizion and that seems to work as expected. Having the navigation data in an HSI format superimposed over the moving map data is a huge help in improving situational awareness. Still, for enroute navigation, climbs to altitude etc, the autopilot user interface is not difficult to master and provides for quick and easy access to the autopilot functions, albeit that set of functionality is substantially improved when the HX is driving the autopilot.

Isaac
03-20-2019, 08:01 PM
I have GRT Hx and the TruTrak 385 in my RV6. What you are describing about when the TruTrak AP transitions from its internal vertical speed mode (SVS) to GPVS mode and uses the ARINC 429 data from the GRT Hx is very confusing until you are familiar with how TruTrak designed it to work. I had the same experience initially that you are describing, sometimes it seemed to work fine and other times just blew thru the selected altitude?

The TruTrak will use GPSS steering any time it is valid and available from the GRT but it won't transition to GPVS vertical mode steering unless the TruTrak is in ALT HOLD or the aircraft's vertical speed is 0 FPM or you have pressed the knob to move the TruTrak cursor to the SVS position and dialed the vertical speed to 0 FPM. (reference section 6.4.5 of the Vizion 385 manual).

I find it easier to initially set the Altitude target that I want to climb to on takeoff in the TruTrak. Press the ALT button and turn the knob on the TruTrak to set the desired altitude i.e. Altitude Preselect Mode. After takeoff, engage the TruTrak AP and after the TruTrak has captured the initial altitude and transitioned to ALT HOLD mode, if you are already in GPSS mode, the TruTrak will automatically transition to GPVS at the same time. From then on as long as the AP is engaged, the GRT can be used to set the Altitude target and control the vertical AP mode, etc.

If you are going to track a GPS course it is usually more convenient to engage the AP by pressing the TruTrak knob and then use the TruTrak knob to steer the aircraft to the GPS course you want to fly. Once the nav steering signal is close to zero, press the MODE button to engage GPSS. That will minimize banking and maneuvering by the AP to get the aircraft on the GPS course.

If you disengage the AP, then you have to remember the gotcha that the TruTrak has to be in ALT HOLD or the aircraft's vertical speed is 0 FPM or the SVS has been set to zero before the TruTrak will go into GPVS mode again.

Tankerpilot75
03-20-2019, 08:02 PM
Jim would you have a problem sending me a copy of your checklist?
If not I understand.
If you don't mind I will pm my email.

Bert,
I?ll be glad to send you a Word document copy of my Quick Reference checklist which includes the ?Instrument Approach Procedures? checklist. But here?s the problem, I?m traveling right now and cannot access my desktop computer where the Word file is stored. Email me at Tankerpilot75@cox.net and next week I?ll send it to you. It?s customized for my RV7A and panel so you?ll have to modify it. It does not address the climbout problem you?ve encountered but maybe my next revision will.

I print the Quick Reference Checklist document front to back and have Office Depot laminate it so I have everything routinely needed immediately available on one hard plastic letter size document laying on my dash. I keep my POH in a storage case between the seats (the EZ Out Console Caddy sold by Aircraftextras.com - a very useful storage space). It is much more detailed as you would expect a good POH to be.

Since you have the HXr EFIS I strongly recommend watching the Jerry ?Widget? Morris videos available on the GRTAvionics website. They?re a great training tool for your system.

Typically I will setup my EFIS prior to takeoff by entering my desired/cleared altitude, climb rate and initial heading to my planned first coordinate and ensure my EFIS is set for ?heading? not ?Nav.? Since I normally fly out of an untowered airport my turn is towards my first gps entry. After establishing climb power and heading towards that point I will push both knobs to update the EFIS heading to actual heading and THEN engage the autopilot. I then turn the A/P knob to bring the SVS climb rate towards zero until I see GPSS VS in both the TT head and EFIS. I then know the two are talking to each other vertically and will switch to NAV mode on the EFIS when I?m ready to intercept my gps course.

Learning your systems quirks is at least have the battle of learning to fly the RV you purchased. I know, it took me about two plus years - but I am a bit old and slow.

Jim

Bayou Bert
03-20-2019, 08:58 PM
I want to thank everyone for taking the time to reply with the solution
to the problem of me not understanding the VS to less than 100.
I am anxious to go try it out and see.
I will post when I complete the flight on Friday.
Thanks again to everyone. That's what makes this such a good
place to be.

BobTurner
03-21-2019, 01:35 AM
A contrarian thought here, perhaps...

So far almost all of my Vizion 385 use has been with it being fed directly by a GNS480 and via manipulating the autopilot's front panel controls. Admittedly I haven't had an opportunity yet to shoot an ILS but ......

Mark,
Figure out how to get the TT controlled by your HX, and you?ll never go back. You need to go that way anyway for an ILS. And for vectors.

BobTurner
03-21-2019, 01:52 AM
One other thing, set the EIFS to ENAV, it will flip to GNAV automatically when/if it needs.

I think this is backwards. Start out on GNAV. You need this if you want turn anticipation or holding. Once inside the FAF, the GRT will auto-switch to ENAV and use the HX or HXr data for left-right control. If you push ?missed? it will go back to GNAV unless you?ve set it to go to a different mode.

rleffler
03-21-2019, 07:04 AM
I upgraded my Digiflight to a Vizion soon after they were available. It worked for awhile, they issues similar to what you described started to happen. I was getting the "we've not experienced any issues with the Vizion, so it's got to be the wiring or other vendor's gear" excuse.

I can't count the hours I spent chasing this down without much support from Trutrak. The support person I was dealing with is no longer employed at Trutrak.

Rob Hickman (AFS) reminded me that on the my GTN650, there is an ARINC diagnostic page. You can watch each of the ARINC labels and the data associated with each label. You don't need to really understand them to troubleshoot. Although the label names are not easily decipherable to a function. I was fortunate that Ken Chard (AFS) provide a cheat sheet of the label names for me to use in my dialogue with Trutrak. The data is either all 0's or a combination of 0's and 1's (binary). If a label is all 0's then the GPSS input for that function on your AP isn't going to work.

There are a couple ARINC labels that can't be tested in the hangar, i.e. glideslope. However, just about everything else can. The GPS should be sending up/down, left/right instructions as you change the heading and altitude bugs on your efis. You will see the data change real time on the ARINC diagnostic page as you make the bug changes.

The end result was that I was able to validate that the EFIS and GPS were working as designed. The issue was that the GPSS receiver board in the Vizion was defective. Once that was replaced, everything worked fine.

Before anyone asks, I've misplaced the ARINC label cheat sheet and no longer have it anymore. Your EFIS vendor should be able to assist with that translation as well as your autopilot vendor (although I know one support person that didn't know what they meant at Trutrak.)