Uncommanded turns

[johnsteichen]

Every once in a while when naving on autopilot I will get an uncommanded turn out of the blue. It is substantial enough for me to hit the disconnect button when the turn progresses 60 to 90 degrees. When I reset the autopilot, everything is normal again. This has happened maybe 5 times in the last 20 hrs
Has anyone elsemhad this experience?  

 

[DBRV10]

no

What aircraft, what mode were you in and what nav device are you using to feed the A/P?

What size servo are you using?

Were you in turbulence?

 

[dynonsupport]

You might be experiencing a temporary loss of the GPS, which is something that we're going to keep improving until it's not an issue anymore. When this happens, the AP will "fail down" to either TRK or HDG mode, in which case it will follow the bugs.

What Dynon system do you have? If you pull your datalog after a flight that this happens, we can help you figure out what you're seeing.

 

[Camillo]

I also experienced this issue. After approx. 1 hour of flight, the airplane turns right with a steady bank and continue the turn until I disengage the autopilot. Last times I let it bank until at 60° before disengaging. After that, I engage it again and the issue starts again after a shorter period (say 15'/20'). I thaught this was dued to the heating of the SV CPU.

How can it be a GPS signal loss if I set the heading bug via magnetic input? Is there an upgrade that stops this issue? I would not like to experience it while, for instance, in the clouds... This could be very dangerous.

I have a SV system connected to a Garmin GNS430W. I never used to link the autopilot to the GPS input or to the NAV. I always set heading on magnetic.

Thanks.
Camillo

 

[dynonsupport]

If the aircraft banks beyond the limit set in the roll menu then the servo is unable to move the ailerons.   Are you seeing the SLIP indication in the AP status bar? 

 

[Camillo]

I will check it as soon as possibile.
Thanks.
Camillo

 

[dynonsupport]

If you were experiencing the following problem, we have an update on this issue, and a solution for you to try out:

To recap, some customers have been experiencing momentary GPS data dropouts from 3rd party GPS devices that can feed a D10/D100 series-based autopilot. When this happens, and the autopilot is following the GPS through either the NAV or TRK modes, the autopilot decides that the GPS has gone away. This, in turn causes the autopilot to revert to heading mode. Some customers experience this routinely, as often as every few minutes.

We've had a hard time characterizing the exact nature of the problem, and getting a smoking gun of the problem happening in action is pretty difficult for affected customers to do. So, while we aren't 100% sure that this attempted fix will work, we're fairly confident in it.

Below is a "beta" version of D10/D100 series firmware that is exactly the same as 5.4.3, except for that it includes an attempt to fix the above undesirable behavior. It has no new features, and it does not fix any other problems. This software is not considered an official release. Though it is considered stable, it has not received the full set of release testing that would normally be performed on a firmware release.

PLEASE tell us if this firmware fixes the dropout issue for you. We'd love to get both positive and negative confirmations from everyone that installs it. A post here or an email to support at dynonavionics dot com are the best ways to let us know how it works for you.


Download Link: D10/D100 series beta firmware

 

[Camillo]

Dynon, yesterday I engaged the autopilot and after a few minutes it turned right again. On the top bar, the "SLIP" yellow indication appeared.

I simply engaged the autopilot setting the heading. Does the beta version fix my problem also?

Thanks.
Camillo

 

[DBRV10]

I think you are getting a thermal upset, or some turbulence induced wing drop, the servo is asked to oppose it but the torque is insufficient and thinks you are overriding it, so it sits there in slip.

You need to check the following.

Torque set to 100%

Aileron linkage is fixed to the inner most hole on the servo arm, without going over centre.

Recalibrate it just to be sure.

And what servo is fitted to what plane?

Cheers!

DB

 

[dynonsupport]

Camillo - the update would not change that behavior. The SLIP indication fundamentally means that the torque of the servo is not enough to command the aircraft in the way that the servo is trying to at that moment. In other words, the servo is not in positive control of the control surface. Momentarily seeing this indication in turbulence is expected. If it stays on, that can indicate a problem with the sizing of the servo to the aircraft, the physical interface (too much friction impeding movement), or it could indicate that the servo is faulty if it happens all of the time, even when the AP isn't trying to command active movement of the aircraft.

 

[Camillo]

Thanks.
Airplane is a Van's RV9A. Servo is the smallest one, but I checked before buying and as far as I can remember it is OK for my airplane.
Problem happens also when in level flight and without turbulence.
Simply, all of a sudden, airplane turns and doesn't stop turning unless I disable it.
Commands are very smooth. It really take a few grams of force on the stick to make the airplane turn.
Turns are always right side.
So, I guess it should be the servo.

 

[dynonsupport]

It may well be. You might want to get in touch with our tech support staff directly at either 425-402-0433 or support at dynonavionics dot com so they can work with you on diagnosing the issue in depth.

 

[igor113]

I have the same problem. After some time after turn-on autopilot, he goes into deep right turn. More than 100 hours before had no problems. All this began to happen after updating software and the onset of heat. What exactly is the reason I can not figure out. Autopilot by height works good. For ailerons autopilot works at different times, then begins to burn label slip and after even a short time turn. Airplane beech musketeer , dynon sky view 7"

 

[DBRV10]

Take your turn rate to ZERO. 0.0

Trust me

 

[dynonsupport]

If the roll servo is slipping at 100% torque, there may be excess mechanical friction in your installation, or there may be a servo problem.

A continuously slipping servo means that the autopilot cannot control the airplane, leaving you in a hands-off condition.

Please contact our tech support at:
support@dynonavionics.com
425-402-0433, 7am-5pm M-F Pacific

 

[gteldp71i0]

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.

 

[igor113]

Take your turn rate to ZERO. 0.0 This is can not help me. I have uncommanded turn!!!

 

[igor113]

If the roll servo is slipping at 100% torque, there may be excess mechanical friction in your installation, or there may be a servo problem.

A continuously slipping servo means that the autopilot cannot control the airplane, leaving you in a hands-off condition.


We tested the roll, we tested the possible friction in the system. He is not. The next flight showed that at a height of 700-800 meters in the relaxed atmosphere of the autopilot manages and operates smoothly. It should appear turbulence as the plane begins to rotate uncommanded, it was on the way back. Back in the fall to update the operating system, the autopilot in such a situation, when the lights are constantly slip, just flying straight. Maybe the problem is still in software? All appeared after the update!

 

[gteldp71i0]

Hello Dynon

Meant to say the unit is a D100

 

[dynonsupport]

It sounds like a servo problem; please contact tech support at:

support@dynonavionics.com
425-402-0433, 7am-5pm M-F Pacific
Reference case number: 98486

If the roll servo is slipping at 100% torque, there may be excess mechanical friction in your installation, or there may be a servo problem.

A continuously slipping servo means that the autopilot cannot control the airplane, leaving you in a hands-off condition.


We tested the roll, we tested the possible friction in the system. He is not. The next flight showed that at a height of 700-800 meters in the relaxed atmosphere of the autopilot manages and operates smoothly. It should appear turbulence as the plane begins to rotate uncommanded, it was on the way back. Back in the fall to update the operating system, the autopilot in such a situation, when the lights are constantly slip, just flying straight. Maybe the problem is still in software? All appeared after the update!