Erratic rate of climb

[JamesTrike]

I have just finished installing my sv1000 and have an issue with an erratic rate of climb reading from the ADHARS. when powered up the rate of climb (VSI) bounces between -500fpm to +500fpm. The altitude corresponds to my mechanical altimeter although it fluctuates due to the rate of climb (VSI) issue. I should mention the engine is NOT running and the fluctuations are very rapid, + to - several times a second.
Any pointers/suggestions on how to diagnose/solve this would be welcome.

James

 

[Dynon]

Can you take a video of the screen and PM it to us?

 

[JamesTrike]

Will grab a video of it tonight...

 

[JamesTrike]

Video of VSI bounce attached.
Note the plane is on the ground, engine off.

 

[Dynon]

Do you have any other electronics or radios powered on (transponder, COM, etc)? If so, turn everything else off. Does it still happen then?

 

[JamesTrike]

I know the radio & autopilot servos are off. Transponder may be on.. I will check again with everything else off.

 

[JamesTrike]

I can confim the same thing happens will all other avoinics off (radio/transponder, fuel pump etc etc)

 

[Dynon]

What other modules do you have on your SkyView Network? Also, one display or two?

 

[JamesTrike]

My skyview setup is the Vans RV-12 avionics kit and consists of:

1 SV-D1000
1 SV-GPS-250 GPS
1 SV-ADAHRS-200
1 SV-EMS-220
1 SV-XPNDR-26
2 SV32 Autopilot servos
1 SV-BAT (backup battery)

 

[Dynon]

For troubleshooting's sake, see if it does it with the battery disconnected, same for the EMS module. Alternatively, take it all the way down to just the display and ADAHRS. Any difference. There's something electrical going on, either in the display, ADAHRS, or from something that's nearby. We want to get eliminate all of the "not display / ADAHRS" possibilities.

 

[cessnadriver850]

If it were me, I would look for some moisture in the pitot or static line. Could be check quickly by disconnecting the lines at the ADHARS.

 

[Dynon]

Looking at the video, we're pretty sure it's not moisture. We've actually seen this affect before, but we're trying to isolate the offending piece of equipment.

 

[JamesTrike]

Interestingly enough when I flew yesterday the bounce was only in the range of +- 150 fpm rather than 500fpm, If this was electrical wouldn't you see a more consistent affect?
I have tried just running the SV off of it's internal battery (master switch off) and the bounce is still there.. the only 2 things to disconnect now are the GPS & EMS.

 

[Dynon]

Well, if it does it when there's no possibility of actual air fluctuations possible - on the ground, in a hangar, no winds, then it's not pneumatic (well, unless your hangar has a REALLY kick-butt music system with the world's biggest sub-woofer)