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mxhossai
05-31-2020, 06:24 PM
All,

Went out flying my RV12 today, only thing changed from my last fight few days ago is that this time I had the latest software build loaded into Skyview Touch. The autopilot wasn't following the roll-> Nav command, or the HDG or TRK command.

Could the new s/w upload had something to do with it? What can I do to troubleshoot?

Thank you,
Monir

mturnerb
05-31-2020, 06:41 PM
If your autopilot is on a separate circuit from your Skyview displays, is it possible the servos needed an update but didn't get it because that circuit wasn't turned on during the upgrade?

Speaking from G3X experience, so not sure if this is relevant to you.

mxhossai
05-31-2020, 06:44 PM
Turner,

Worth looking into it and may be do another update? But thought I was pretty sure autopilot was 'on'.

This is the first time I updated the s/w, so may be I didn't do something right, but thought I kept everything on: avionics switch, autopilot and of course the Skyview.

Thank you,
Monir

RFSchaller
05-31-2020, 09:41 PM
I have the D180. My roll was tracking but altitude hold was erratic. Turned out to be a broken shear pin. Sometimes what seems the obvious issue is not. Easy to check so it is a good starting point for troubleshooting.

mxhossai
06-01-2020, 08:39 AM
Broken shear pin?

DHeal
06-01-2020, 10:58 AM
If a shear pin is broken, you can feel and hear it when doing an on-ground preflight inspection -- the AP does not have to be ON. There is a very slight "rumbly/vibratory" sensation that you will feel/hear when you move the control stick -- lateral stick movement for the roll servo and fore/aft stick movement for the pitch servo. This sensation tells you that the shear pin is in place and is connecting the control arm to the servo. BTW, replacing a sheared pin on the Dynon is relatively simple once you have accessed the servo -- contact Dynon.

https://www.dynonavionics.com/includes/guides/Servo_Shear_Screw_Replacement_Instructions_Rev_E.p df

mxhossai
06-01-2020, 01:55 PM
Will look for it and report back. Thank you

RFSchaller
06-01-2020, 10:21 PM
Dave,

What you said should be the case, but mine failed in a really unanticipated way. The pin did not shear cleanly. It left a nub sticking up through the hole in the capstan. The servo would turn trying to maintain altitude, but it had to travel through a number of degrees of rotation until the nub came in contact with the other side of the hole. This resulted in a dead band. On the ground I could move the elevator through some range of travel without hearing the servo before the servo started turning.

Rich

mxhossai
06-02-2020, 07:57 PM
Just wanted to give you guys an update, from today's flight:

The good man Jeff Fox from Dynon (as always) had returned my call regarding autopilot malfunction. He said, to make sure that Source was selected to HSI (I only have a GPS that came with aircraft).

So that was the first thing to try today: HSI was selected correctly as before. While on ground, I turned the Dynon, avionics and autopilot on and selected Roll->HDG. What I was after is to see if I change heading bug, if the survos followed and they did. So I thought may be its fixed and went flying. Well, it wasn't. Kept being erratic. Vertical nav seemed to track much better. One thing, however, is that servos moved much slower (may be it does that always, not sure as the turns should be standard rate), unless its weak and under airpressure, its not able to overcome

When arrived at a destination airport, thought, I try reloading the software from the USB stick I had, which I did (while having autopilot, avionics and Dynon on) and everything seemed to update OK. However, no improvement, when flying back to home airport.

So anyway, that's where I am and not really sure what to do.

Thanks for all your thoughts, some of which I believe I addressed.
Monir

RFSchaller
06-02-2020, 09:31 PM
Have you tried adjusting the AP settings like sensitivity, pull rate, g-limit, etc?

mxhossai
06-02-2020, 09:52 PM
Rich,

I remember doing that the first time, when the Skyview came back from Dynon and had to set it up the first time. Not sure where that menu is, worth a try, to get it calibrated.

Monir

mxhossai
06-06-2020, 10:04 PM
Rich,

Just following on this thread:

I reloaded the software, with everything on then recalibrated the AP. It seems to follow the roll in the direction in the ROLL->HDG, while on the ground, but does it slow. Not sure if somehow the motor doesn't have enough power to overcome air when in flight?

AP ROLL in any mode is not following / working properly. I haven't checked the shear pin yet, but may be I need to open the back access door and get access to roll servo and check it?

Anyway, no worries if no idea at this time. But thought I report back and thanks for everyone (and you of course) on this forum for being so helpful!

Monir

RFSchaller
06-06-2020, 10:07 PM
You could swap the roll and pitch gyros and reconfigure. I believe you said the pitch was working. If the problem persists and pitch works you could eliminate the servo as the problem. I know it?s a PITA, but nobody said life was easy!😝

mxhossai
06-07-2020, 01:56 PM
Somehow that smile of your's worry me: saying something like 'welcome newbie' and a evil smile ;-)

Ok anyway, I plan to open the back panel and see if something looks out of place in the servo. Curious, your AP deflects the Ailerons fully (or just a little).

Thanks a lot anyway!
Monir

Tony_T
06-07-2020, 03:15 PM
Do you have your autopilot on "Expert" mode? Lots of "what's it doing now" (WIDN) happens in that mode if you are not actually expert with it.

The Dynon In-flight Tuning guide starts you off in "simplified" mode to confirm it will Track properly.

Your problem would be hard to diagnose if you have not done the Dynon In-Flight tuning of the autopilot. The document can be found on their website:

https://www.dynonavionics.com/includes/guides/SkyView_Autopilot_In-Flight_Tuning_Guide-Rev_C.pdf

You need a co-pilot to look outside while you are doing the steps in the guide. Write notes including starting settings and any changes you make so you can debrief after the flight(s).

I would hold off pulling off the baggage panel to look at the servo until you have some better data.

If you already have done all this then disregard.

mxhossai
06-07-2020, 07:06 PM
Tony,

Thanks a ton. I was definitely not looking forward to opening up that baggage door so happily willing to look through this try the tuning method and go back to simplified mode.

This all started after I had software update. So after a software update, may be it wants to be in simplified mode then do expert mode. Anyway, thanks for your thoughts and worth a try.

Will report back any finding to you guys.

Post-edit: looking through that document you sent, it definitely seems carries some merit to try!

Monir

mxhossai
06-08-2020, 09:38 PM
If a shear pin is broken, you can feel and hear it when doing an on-ground preflight inspection -- the AP does not have to be ON. There is a very slight "rumbly/vibratory" sensation that you will feel/hear when you move the control stick -- lateral stick movement for the roll servo and fore/aft stick movement for the pitch servo. This sensation tells you that the shear pin is in place and is connecting the control arm to the servo. BTW, replacing a sheared pin on the Dynon is relatively simple once you have accessed the servo -- contact Dynon.

https://www.dynonavionics.com/includes/guides/Servo_Shear_Screw_Replacement_Instructions_Rev_E.p df

First of all, thank you all for the different thoughts on AP malfunction. I did try the Roll sensitivity gain adjustment on a quick flight today, but didn't seem to help.

So, David, the gold medal at least this time around, goes to you..

Opened the back panel, looked in to the roll servo and sure enough it was the shear pin that was loose. Tried tigthtening it but didn't help. So was able to unscrew and bring it home. Will be doing what Dynon suggested so thanks for the link. Matter of fact without that document, I could be looking at the servo and not even think to check the shear pin, as it looked perfectly normal unless you tried turning it.

Anyway, thanks to each of you for taking the time to respond. What a great community.

Regards,
Monir

Pdtofly
06-08-2020, 09:53 PM
When I upgrade to Version 16 Beta, my settings blindly changed big time, and my pitch was all over the place. I reloaded my AP settings and it was much better.

Try these settings and see if the AP improves. These might not be perfect for your aircraft, but will be a place to start.

Trim speeds:
100% trim speed at or below 100 knots
40% speed at 135 knots.

The pitch numbers:
Torque 100%
Sensitivity 16
Pitch Gain 1.5
Alt Gain 0.9
Pull rate 1.0
VSI gain 1.5
G Error Gain 1.0
G Error limit 0.25

Brian

mxhossai
06-11-2020, 09:17 PM
Brian,

Thanks for you reply. So as I noted, it was indeed the shear pin of the roll servo that broke off. Dynon sent me a new shear pin along with instructions. I replaced it and installed it back on the airplane and took it for a ride today. The autopilot worked great and I am a happy RV12 owner again (until next time anyway..)

Thanks,
Monir

Pilot135pd
06-11-2020, 10:03 PM
The good man Jeff Fox from Dynon (as always) had returned my call regarding autopilot malfunction.

Wow, you got an answer quick !! I guess I?ll have to sell my D180 and buy an expensive Skyview to get quicker support. I contacted them wanting to spend $2,200 on some new Dynon equipment to add to my current setup on June 2 and they just answered this afternoon on June 11.

RV8JD
06-11-2020, 10:03 PM
I also had a Dynon shear screw fail about a year and a half ago, on the SV-32 pitch servo in my RV-8.

Per Dynon, they adopted a stronger shear screw beginning late in the 1st quarter of 2017. It was adopted due to premature fatigue failures of the previous spec'd screw during normal use.

Dynon quickly sent replacement shear screw kits gratis. The kit includes the shear screw, an Allen wrench, a cotter pin, thread locker, and instructions for replacement.

mxhossai
06-12-2020, 09:01 AM
I also had a Dynon shear screw fail about a year and a half ago, on the SV-32 pitch servo in my RV-8.

Per Dynon, they adopted a stronger shear screw beginning late in the 1st quarter of 2017. It was adopted due to premature fatigue failures of the previous spec'd screw during normal use.

Dynon quickly sent replacement shear screw kits gratis. The kit includes the shear screw, an Allen wrench, a cotter pin, thread locker, and instructions for replacement.

Interesting good to know. That's exactly what they sent me in the kit and sounds like they may have sent a better/stronger shear pin.

Pilot135pd
06-12-2020, 12:07 PM
Is there a way to inspect that pin and determine if I have the old one or the new style?

mxhossai
06-14-2020, 10:09 AM
It looks exactly the same. May be you could call Dynon and give them the SN for the servo as ask.