Problems with DG overshooting

[Frankh]

Morning

Took the EFIS for its first IFR checkout and my CFI noticed the DG is swinging beyond the assigned heading by 20 degrees or so before settling back....Almost like a regular compass would.

Also noticed that when transmitting on Comm 1 the DG would pull away from the heading by 30 or 40 degrees and then return when the PTT was realeased.

The EDC is behind the seats at the top of the fuse, the Comm1 antenna is under the pilots seat below the airplane (metal RV7a). I believe all the RG58 sheilding is properly grounded and I made a point of keeping the coax seperated from the EDC cable runs (except behind the panel) and the EDC uses sheilded cable, also grounded.

This last problem is not the end of the world but is presented as data that might help diagnose the real problem, i.e the DG swinging about.

Any ideas??

Frank

 

[Frankh]

Took the EFIS for its first IFR checkout and my CFI noticed the DG is swinging beyond the assigned heading by 20 degrees or so before settling back....Almost like a regular compass would.

I mean when moving to a new assigned heading by say 90 degress ...the DG would overshoot then come back.

Frank

 

[Frankh]

From MY CFI, Who was clearly paying more attention than I was..


The heading seems to be the worst when flying 270 and making a right turn to 360. We rolled out on 360 and the heading continued to go to around 020-030. This is exactly how I would expect a real compass to work in this quadrant. The error didn't seem to occur when turning to east, west, or southerly headings. I can't say for sure, but I don't beleive the error was there while making a left turn from 090-360. Perhaps this will make sense to the Dynon folks as they actually know what the box is programmed to do.



Does that help??

Frank

 

[Thomas_Schaad]

My COM 1 was also disturbing the heading for quite a while, mostly on frequencies of 124.00 and above. After quite a search and close to get crazy,  ............    we finally found out, that the disturbing signal was coming trough the OAT probe.

The cable of my OAT probe is now routed compeltely different and the cable is shielded twice. Still, the problem persists some times, so the plan is to look for an even better place for the cable of the OAT probe. The antenna I use, that causes the problem is a Comant one. COM 2 is hooked to an antenna that is laminated in the structure and does not cause any problem at all.

Question to Dynon: If we route the OAT probe trough the EMS instead the ADC do we still get the full benefits on the EFIS, as DSAB shares the infromation? I have big hopes, that this could finally kill the bug.

Cheers

Thomas

 

[Frankh]

Hmm...maybe not. If indeed that is the problem, my OAT is wired to the EMS, both on the bottom of the airplane but about 5 feet apart.

Frank

 

[dynonsupport]

Thomas: We wouldn't really expect an OAT to affect heading, but in any case, if you connect the OAT to the EMS, and have DSAB connected, you will indeed have full OAT functionality.

Frank: Did you go through the calibration process AFTER inputing the magnetic inclination for your geographic location into the EFIS? If yes, what was the number you used for inclination, and what is your zip code?

 

[Frankh]

yes and yes...sort of..

Zipcode is 97330...I put in 67 as the inclination angle...Then calibrated the DG on the compass rose at the airport...all in that order.

Then the screen went black and I returned it to your goodselves where you fixed it and uploaded firmware version 1.08.

When I got the D100 back i reinstalled it, checked to see the 67 number was still there (yes) and went flying.

I.e I did not recheck the calibration on the compass rose after the upgrade or repair.

We also noted the unit appeared to be calibrated to True North as it was about 20 degrees off, we assumed this was maybe due to the compass rose being setup to true rather than magnetic.

Frank

 

[dynonsupport]

Ah - if your compass didn't come back with your EFIS and we updated your EFIS's firmware, you'll need to reapply the latest firmware update to your EFIS with the compass connected. Then, if it still isn't working after the update, try recalibrating with the latest firmware.

 

[Frankh]

Oh yes of course that makes sense...In fact it says in the manual that the EDC has to be connected when doing a firmware upgrade...

Excellent...Thanks

Frank