Uncommanded turns

[dynonsupport]

Hi Wilbar,

If your torque is set to 100%, we'll need to get you talking to tech support too.

Hello Dynon

I have been following this thread as over the past month or so i have the occasional uncommanded turn severly to the left.
On saturday of this week on a 3 hour flight the aircraft made 4 violent turns to the left whilst on altitude hold and track mode at various times thro the flight.
No slip indicator just immediate turns to the left and when the angle of bank went by 60 degrees it was a case of hitting the AP disconnect to restore normality and then turn the ap back on and it would operate normally then after a while left uncroled turn again.
The GPS is a Garmin 495 with up to date software and your AP 74
On the return leg the AP behavied itself.

 

[gteldp71i0]

Hello Dynon

I am pretty sure the torque is not set at 100 will check the setting of the torque next time up at the aircraft and set to 100 and report back thanks

 

[Jerrylane]

I have the D-10A, AP74, Roll and Pitch Capstan Servos, D-10 and HS34 Installed, using Garmin GNS 480, Servos are 42 Series. The system has been working perfectly for over 40 flight hours and the Autopilot was absolutely perfect. Settings for Roll are 100% Torque, 15 Sensitivity, Max roll angle 25 Degrees, Rate 2.0 Suddenly during a VFR Flight the Roll servo shows the yellow background indicating that it is slipping. It does not matter if I am in Heading, Track or Nav Mode, it goes in and out constantly and will hold for only a 1/2 second or so. I am updating my software and the Beta but I think the servo has failed, it worked perfectly for a long time even in moderate turbulence and I have flown approaches to minimums(VFR) to test the system. Please advise if I need to return the servo. When I run the test and calibration sequences it test out with no issues on the ground.
Thanks Jerry

 

[Jerrylane]

Hi Again, as promised I have updated the software to the 5.5 version and this morning I flew to Ft. Lauderdale in near perfectly smooth conditions and the roll servo will not stay locked in on Hdg, Track, or Nav.  In each mode it intially engages and then a slipping indicator (yellow background) pops up behind the mode indicator on the D10A.  The software made no difference whatsoever.  I have check grounds, and physically checked the servo.  The calibration and ground test have been performed and the results are excellent, the condition only exists during flight.  Physical inspection reveals no issues, and the servo shear pin is intact.  My guess at this point is that the servo is defective and will need to be replaced.  Please advise soonest if you agree.

Thank you,
Jerry

 

[dynonsupport]

If you're seeing that slip indicator all of the time, there is something up with the servo. Give our support team a calla t 425-402-0433 or an email at support at dynonavionics.com

 

[Jerrylane]

Hi Dyon Forum Members,
After speaking with Tech Support it was determined that since my roll servo worked perfectly for over 40 hours of use in flight that the issue is with the servo and a replacement has been shipped, if this does in fact solve the problem I will post an update.

Cheers,
Jerry

 

[Jerrylane]

Hi Folks,
I installed the New SV 42 Capstan Servo and all the problems are solved, Roll and Pitch Servos coupled to Nav-GPS, VOR, ILS are working great.  Even in moderate turbulence the servos stay engaged unless a parameter is exceeded.  Thanks again to the Dynon Customer Service Folks for getting the new servo to me right away.  If you are having problems make sure you give them a call, Steve is excellent and knows the systems. 
Cheers,
Jerry

 

[bryan]

Good morning, we have a skyview 7" and Dynon autopilot installed in our beech and recently on a 20 hour trip over 6 days the autopilot let go with a steep left hand uncommanded turn on at least 4 different occasions, whilst operating on both the Nav and Hdg source from the Skyview GPS. 3 times on the Nav and once on the hdg.
We also have a Garmin 430 coupled and when using that as the Nav source we did not appear to have the same problem.
Any thoughts as to what may be the cause. We have the latest software version installed.
This is a very dangerous thing for the Dynon to be doing and certainly reduces our confidence to use the unit.

 

[dynonsupport]

There's a bunch more data here that we'll need to get to the bottom of what's going on here. Working directly with our tech support staff at 425-402-0433 will be the best way for us to help you troubleshoot this.

 

[mmarien]

I had a problem where my plane would pitch up unexpectedly. It turned out the servo was fried. I upgraded to a bigger servo.

However, I do get uncommanded turns all the time, but in my case there are several causes.
[list bull-blacksq][*]It happens when I engage the AP at a different point then the DTO. The AP makes a uncommanded turn to get on course and then another when on course.[/list][list bull-blacksq][*]It also happens when the AP mode is not what I expected when I engage the AP. The TRK or HDG bugs can be different than the NAV direction so I get what appears to be an uncommanded turn.[/list][list bull-blacksq][*]In addition, I have two NAV sources and have been known to be confused as to which is the current source.[/list]Could this be the behavior that you are experiencing. For me the problem is eventually resolved by checking the AP mode and NAV source. It's a good thing if you want to get more air time. Not so good if you just want to get there and you're miles off course when you figure it out.  :-?

 

[bryanflood]

This has happened to me too 5 times in the last 100 hours and it scares the crap out of me every time b/c the roll is so abrupt.  The plane has always rolled to the right and I can usually catch it by about a 60 degree bank angle.  The first couple times it happened the roll rate was so great I thought possibly my passanger was accidentally pressing on the stick with their leg.  The third time it happened I was was able to look over at the passenger stick quickly and noticed that in fact the stick was deflected and the turn was being commanded by the AP, the passenger was clear of the stick. The autopilot mostly seems to work well otherwise but unfortunately this problem really lowers my confidence level quite a bit, I think if this was resolved it could be a pretty fabulous AP. I have never had any problems with the altitude hold only the roll.

I have an RV-9A with the recommended servos, a D-100 and an AP-74. Has a solution for this problem been identified by any chance? 

Thanks,

Bryan

 

[Foxflier]

I experienced this odd roll behavior (and once in pitch) early on with my D100 and servos last year. I found that it was due to the roll and pitch servos going into slip and the EFIS not being able to correct quickly enough. After changing my pushrod positions and relieving some of the mechanical stress on the servos I've never had a problem again. I'd recommend all who experience this issue to take a look at their setup to see if it's possible to either free up the surfaces or improve the mechanical leverage of the servos.

 

[dynonsupport]

So Bryan, the first thing to take note is whether or not you're getting servo slips or not. On the D100, that's annunciated by the axis in question's engagement notification in the lower left turning yellow. If the servo is slipping, the AP isn't in control at that moment.

Beyond that, we'd love for you to get in touch with us directly at 425-402-0433 or support at dynonavionics dot com so that we can help you through the issue. If you don't already have datalogging enabled, start by enabling it and using the 1/sec update rate. Getting a data log of the event happening could possibly help us diagnose your issue further.

 

[DBRV10]

BLUE TOOTH

I ahve only ever had two instances, while in NAV mode on an ARINC 429 connected GNS530W

Both times it was a passenger with a Samsung phone turning Blutooth on/off, linking to the Lighspeed Zulu's. I have never had this problem with the iPhones that are often connected.

The instances were directly associated with the Samsung bultooth mode changes.

Weird??

Maybe something to consider.

Ohh and I have Shielded Twisted Pairs...... :-/

 

[jakej]

BLUE TOOTH

I ahve only ever had two instances, while in NAV mode on an ARINC 429 connected GNS530W

Both times it was a passenger with a Samsung phone turning Blutooth on/off, linking to the Lighspeed Zulu's. I have never had this problem with the iPhones that are often connected.

The instances were directly associated with the Samsung bultooth mode changes.

Weird??

Maybe something to consider.

Ohh and I have Shielded Twisted Pairs......  :-/

Grounded both ends ??

Jake J

Ps - BTW well done at NRM

 

[DBRV10]

Don't remember that far back  But it would only be one end, and all at the common point. Given the short runs, it should not need the shield at all taken to ground.

AUSFLY was great thanks Jake. And thanks to DYNON and Horsham Aviation too, there generosity went to a good cause including the RFDS.

 

[jakej]

David

FYI - the 'industry' convention, & it's in most install manuals, is to have Arinc wire shielding grounded at both ends. Shieled Audio wiring is grounded at one end

Jake J

 

[DBRV10]

Was not referring to the ARINC, but I agree both ends and ours are.... DSAB was my thoughts as some folk see this with RS232 GPS and I have had it from ARINC 429, just a mystery with BT :-?

 

[jakej]

those sneaky electrons - gotta love (hate) them  :

Jake J 

 

[johnsteichen]

The uncommanded turns that occurred early on with my Skyview have ceased and have Not occurred in over a year now. I suspected it was something I was doing rather than a problem with Skyview