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When HX (now HXr) is driving TT AP it constantly wing rocks

Postby BillinDurham » Sun May 19, 2019 12:21 pm

(This is a new summary post of a thread in the HX forum with new information added. It seems more appropriate under autopilot)

At some point in the first 1,000 hours on this installation of (3) HX systems, a G430w, and a TruTrak AP in an RV10 this wing rocking began. I don't recall this being a problem in the first 500 hours. It's a constant problem in calm air.

After 1,100 hours and an upgrade of (1) of the (3) HX systems to an HXr, the problem continues.

When the HX, or now the HXr, is driving the TT AP it constantly rocks the wings left and right. It seems to be hunting for the exact track and ends up deviating a degree or 2 left and right for the duration of the flilght in calm air. This occurs whenever the TT is in LS or NAV mode. To mitigate the problem, I allow the HX to get the AP on course and at the right altitude, then switch the AP into 'native mode' where it navigates using its internal guidance. The immediately stops the banking.

I've played with some of the HX settings (e.g. steering gain) but with no noticeable change in the problem.

Regarding the various modes:
There is 'full function 2 axis HX driven mode' where the TT AP displays "EXT LS GS". It is ARINC driven and it is full GPSS steering mode. A G430w supplies the GRT with the GPSS data.

There is 'steering-only mode' where the TT AP displayd "NAV". The HX is still driving it but only lateral steering and not GPSS steering mode. That is, it flies to and over waypoints rather than anticipaing them. I'm guessing that it is a serial feed.

In both of the above modes, I get the wing rocking.

There is 'TT native mode" where the AP flies whatever track and climb/descent rate I select. No wing wagging here.

I had to step away from this issue due to some other electrical issues but the problem persists despite a recent HXr upgrade.

There is one more data point to be considered: I have a switch that changes the ARINC input between the HX/HXr and direct input from the G430w. When connected to the HXr, the wing rocks. When getting the GPSS signal directly from the G430w, steady as a rock. Obviously in that mode I lose the vertical navigation function and the ability to control the Trutrak with the EFIS.

Next flight, I will document this behaviour with a video camera where it is very easily viewed. I can do a demo recording as well. The question is what else can I do to document my installation and the behavior?

- Is there a way to view or printout the settings from a backup file?

- How can I return all relevant settings to the defaults without effecting other settings?

And does anyone have a TruTrak - HX/HXr - G400/G500 installation where there is no wing rocking in GPSS mode? If so, can you share the settings.

Any and all advice welcomed.

1100 hours and flying...
Bill Watson
8NC8 Durham, NC
RV10 HX, G430w, NavWorx, EIS
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby Bobturner » Sun May 19, 2019 10:37 pm

I have a TRIO - HX - G420W in an RV10. Works absolutely great.
If you want the settings I use I can go out to the airport and copy them. I have no idea how similar or different the settings should be for a TT.
Bob
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby GRT_Jeff » Tue May 21, 2019 2:04 am

The HXr and HX have the same autopilot software. Did you upgrade your AHRS at the same time? That could change the dynamics. The HXr may run slightly slower because it has a higher resolution and more complicated PFD page, but that shouldn't have a major effect on the autopilot.

Your settings are saved in a DEMO recording. There is no way to view or print settings from a backup or DEMO besides restoring the backup or playing the demo on a display unit.

There's no way to partially reset some settings. The autopilot settings for a non-GRT autopilot are mainly the gains in General Setup. All of the gains start at 100%. The Autopilot Control Profile should be Auto (or Other). The Autopilot Serial Output should be Normal.
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby BillinDurham » Fri May 24, 2019 1:35 pm

I’ve uploaded a video to YouTube showing the wing rocking in various AP modes here:
https://youtu.be/EU7qM2eBF8I

You’ll see that the only mode where the wings rock is when the TruTrak is getting GPSS and Vertical Guidance signals from the HXr (this corresponds to ‘NAV 1’ selected with ‘EXT LS VS’ displayed on the TruTrak head.

I think the key comparison is between that and when the TruTrak is getting GPSS signals directly from the G430w (this corresponds to ‘NAV 2’ selected with ‘EXT LS gs FLG’ displayed on the TruTrak head.

Same G430w source for the GPSS signal in both cases; processed by the HXr when NAV 1 selected, and direct from the G430w when NAV 2 selected. ARINC connection in both cases.

This rocking occurred exactly the same way when an older HX head was installed with exactly the same settings. There was no change in the AHRS unit except perhaps firmware upgrades. I have not noticed any slowness in the HXr - I only experience the wonderful resolution and screen real estate.

I should note that I am blown away every single flight by the performance of the GRT HX/HXr, G430w and TruTrak AP combination. That’s after 1100 hours of cross country flying complete with coupled approaches and everything. Just Amazing!! Nothing like flying a turbulent final in IMC using the Flight Path Marker (FPM) to either hand fly the plane to the threshold or just monitoring the needles on a coupled approach. I thought having a Flight Director would be heaven but I don’t even display it given the functionality of the FPM!
Bill Watson
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RV10 HX, G430w, NavWorx, EIS
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby BillinDurham » Tue May 28, 2019 4:35 pm

Here is a photo of the AP setting in the Main Menu.
5CEA8B64-5552-457E-A12F-F6B2729C4336.jpeg
Autopilot Settings in Main Menu
5CEA8B64-5552-457E-A12F-F6B2729C4336.jpeg (820.05 KiB) Viewed 1340 times

Jeff, based on your note, the only thing different than the defaults are 4 gain settiing set at 70%. I’ll change them to 100% for the next flight.

Any other suggestions?
Bill Watson
8NC8 Durham, NC
RV10 HX, G430w, NavWorx, EIS
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby BillinDurham » Sun Jun 16, 2019 2:16 pm

GRT Jeff, I now have a Demo file with multiple instances of the Trutrak being driven by the GPSS signals coming directly from GNS430w and from the same signal being passed through HXr.

There was an attempt to video the same period covered by Demo file so the actual switching could be viewed as it was in the earlier posted video, but my buttonology failed me. Those old GoPro cameras can be darn difficult to operate consistently.

But I also recorded times What I attempted to do was to switch at 30 seconds at 1 minute and at 2 minutes. The 1 minute switching seems muffed up a bit so I ask you to focus on the 30 second and the 2 minute portions as shown on the HXr screen as follows:

HXr Time Stamp--------Switch Position-------Flight Behavior
--------------------------------------------------------------------------------------
8:41:50 (start)----------HXr-----------------------Wing Rocking
8:42:20------------------GNS430w----------------No Rocking
8:44:50------------------HXr-----------------------Wing Rocking
8:46:50------------------GNX430w----------------No Rocking
8:48:50------------------HXr-----------------------Wing Rocking

(The file seems to be too large because when I try to upload here, it fails at the end of the upload so I'll try to email Demo file separately - File Name DEMO-20190604-084143)
Bill Watson
8NC8 Durham, NC
RV10 HX, G430w, NavWorx, EIS
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby BillinDurham » Mon Jul 08, 2019 9:32 pm

Bobturner wrote:I have a TRIO - HX - G420W in an RV10. Works absolutely great.
If you want the settings I use I can go out to the airport and copy them. I have no idea how similar or different the settings should be for a TT.
Bob

Bob, I would be interested in your settings for the TRIO. I've been thinking this is TT/HX/HXr specific problem but now I'd like to at least try to 'tune' the settings optimally for the HX/HXr driven TT modes.

If you have the chance, I would appreciate it. Thanks!
Bill Watson
8NC8 Durham, NC
RV10 HX, G430w, NavWorx, EIS
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby BillinDurham » Mon Jul 08, 2019 9:36 pm

A new observation: the wing rocking occurs when the HX/HXr is driving the TT either in GPSS Nav mode and Heading Mode. I didn't check that before.

This suggests to me that I should be able to 'tune' that out using the HX/HXr gain settings. I've played with them before and noticed little or no difference in it's operations but I haven't chased the wing rocking.

So, what are some good gain settings for the TT? I'll search this forum for related posts but I'd appreciate any suggestions anyone has.

Thanks.
Bill Watson
8NC8 Durham, NC
RV10 HX, G430w, NavWorx, EIS
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby Bobturner » Tue Jul 09, 2019 12:53 am

Bill, if you go to the VAF post you made today; look about 5 or 6 posts earlier in that thread; you’ll see my post with my HX settings for the Trio. Some are quite different than 100%.
Bob
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Re: When HX (now HXr) is driving TT AP it constantly wing ro

Postby BillinDurham » Tue Jul 09, 2019 11:35 am

Bobturner wrote:Bill, if you go to the VAF post you made today; look about 5 or 6 posts earlier in that thread; you’ll see my post with my HX settings for the Trio. Some are quite different than 100%.
Bob

Thanks Bob! I did just that and printed it off. (obviously you can ignore my post on the GRT board).

I'll change it to the settings you use and fly it next week. Will report back.
Bill Watson
8NC8 Durham, NC
RV10 HX, G430w, NavWorx, EIS
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