Autopilot disconnect

[rfazio1951]

I read through some previous posts on this subject. I'm not sure they had the same issue. My RV6 has two SV42 servos. Always worked great. Today on a long cross country 9.9 hours! It started cutting out on me. I get an err message and it disconnects. I still have the flight director. She says caution! And before the caution is finished I hear autopilot disconnect. The servos are shown off line. Funny thing the same network wire handles my ADAHRS and that is fine. Both servos went out.

I flew from Long a island NY to Manhattan Kansas for IFR training and I hope the auto pilot works for me!

    Could it have over heated? The screen was real hot. It was crazy hot today.

 

[coyote]

I have had a similar problem. AP worked great since installation a couple of years ago. Recently have had it disconnect intermittently for no reason. Usually I just re-engage. Yesterday, it dropped out. I then got a red "roll servo error" and pitch servo error message on the top bar. With AP offline message. Turned the power off and back on. Since then, the AP worked normal in the TRK mode but the HSI mode will not function. The map screen functions normally. It seems if were a hardware problem, the TRK function shouldn't be working. What would be the best way to troubleshoot?

 

[rfazio1951]

     So this happened to me yesterday on a long cross country and it was hot!!!

     Today it worked fine for me. It was hot but we flew early and it functioned perfectly. We stopped flying when it started getting too hot. Don't know, but I think mine was heat related.

     I bought some scat tubing and I'm going to blast air on the back of the unit.

     The other possibility I was thinking it could be is a problem with the power or ground to the servos. Both units are fed by one power and ground in my ship. If I had a bad connection on power or a faulty ground both units would drop out at the same time. Also if a bad connection say, once under load, it may show up, where when not powering the servos they may take a little power to stay on line and appear ok. Just a thought.

 

[kurtfly]

I have a Glasair with retractable landing gear. On occasion, the landing gear pump must kick on momentary to keep the landing gear up in the wing. If the battery is old and weak when this happens I get a power drop and it will kick off the servos. So, make sure something like that is not happening.

 

[Dynon]

I don't think we've seen any heat-related issues that are so specific. But a momentary grounding of the disconnect line would definitely cause this, and the disconnect wiring would be the first place to start here. If you export your user data logs to a USB stick, there is an alerts data log that might shed some light on what is happening there.

 

[Dynon]

On the HSI mode not working - HSI mode is only available if the HSI has a valid navigation direction. IE, a CDI from SkyView's flight plan, some other GPS, or a NAV radio. If both HSI and TRK are not available, that would likely mean that there's something up with your GPS position source(s).

 

[rfazio1951]

I exported the logs right after it happened. I will send you the logs once I retrieve the USB drive from the airport.

 

[rfazio1951]

I have the alert data log from the day I had the problem, Where should I email it?

 

[Dynon]

So first, those are text-based, so you may be able to do some sleuthing yourself to see if there are any hints. Beyond that, support at dynonavionics dot com.

 

[rfazio1951]

Texted based, but zipped up in a zip file that is password protected?

 

[dynonsupport]

Only the Dynon Diagnostic file is compressed and password protected. The alert log is exported as part of "User Data Logs" and is not protected.

 

[dougnlina]

Richard- This is my experience with an erratic autopilot disconnect issue, take it with a grain of salt.
We have two SV-52 servos on a Supercub replica that has fairly high control forces. The servos were located about 8 feet from the circuit breaker buss and wired using a Dynon Servo harness. We had issues with the servos going offline both during start and in flight. I checked the network/power wiring a dozen times, had the servos checked out at Dynon, replaced breakers, to no effect and it was driving us nuts. Finally I decided to rewire the power wires directly to the master contactor (which happened to be close by) using 18GA wire and inline fuses. We have not had a problem since. There may be some other explanation, but it is my belief that the 20 or 22GA wire coming out of the servo was inadequate for the demands of our servos. I do not know the threshold voltage at which the servos were dropping off, but if you have a long run of wire, and are starting to get frustrated as other solutions are not working, you may want to rewire the power input and ground wire to the servo with heavier gauge wire and see if it helps. Your mileage may vary......
DP

 

[rfazio1951]

DP,

     Thanks for your response. I thought power or ground could be an issue. I ran #20 wire from one breaker to the both servos along with the network wiring. I thought that if it was a power or ground issue it would effect both servos at the same time, which is what happened. I also did get an error on startup once. It has been perfect since then, no more errors of any kind. I was going check the wiring from the breaker and the ground block, just to see if I find anything loose.

 

[coyote]

dynon support,

I reported my problem to the tech line. I got a call and after a lengthy discussion, I was asked to send in my diag. file. I sent it in a couple of weeks ago and haven't heard anything back. I've sent requests a couple of times online but have not heard back to even acknowledge receipt of the file. could you please contact me.

 

[rfazio1951]

Same here, I think we have to call.