After software update, yesterday, the A/P flew about 1/2-1 mile left of the approach path on an LPV into Sarasota (KSRQ). I shot another approach with the same result. I tried an approach at Lakeland (KLAL) and got the same result. Today, to test without getting yelled at by ATC for being off course, I flew an RNAV into uncontrolled Wauchula (KCHN) and again the A/P flew consistently left of the correct approach path. It seems to fly an ILS fine and enroute GPS seems to be fine though it might be harder to notice a problem enroute. I’ve now heard that other people are experiencing the “parallel approach problem”. I’m in a RV10 with GNS530W. If this is is a fleet wide issue it could be a huge problem for Dynon as they move to certified. Are any of you experiencing this? If Dynon is listening, is there a fix? If not, is there a way to roll back to a version of the software that doesn’t have the problem?
Lateral tracking
- Thread starter tysonr
- Start date
airguy
Active Member
What Skyview hardware and software are you using?
Skyview touch, 15.4.7 I am using the GPS-250 which has a known problem supposedly corrected in 15.4.7, though I'm not sure why that would matter if the A/P is getting its input from the (IFR-certified) Garmin GNS-530W. I will re-apply the update tomorrow morning and see if that makes a difference. I learned later today that someone else at my airport discovered this same problem during his IPC.
We knew of an issue that only affected Avidyne GPSes, but that was fixed. Asking our dev team what they might think....
I reinstalled the latest version, after making sure that all components were up and running and able to accept firmware. I flew a GPS approach and the lateral alignment was spot on. Here's what I think I learned:
1) The latest version has a fix to the GPS-250 GPS module. This is what fixed the problem.
2) When I installed this version previously I just powered up each Skyview display which installed the update to the Skyviews but not to the GPS. Software updates need to be applied on ship power with all Dynon modules up and running (not just the screen).
3) The autopilot takes direction (turn left, turn right, ...) from the IFR certified GNS530W, but takes its staring position from the GPS-250. So the corrections were all correct but they were based on an incorrect starting point resulting in a laterally displaced approach course. I don't know why the A/P doesn't use the GNS for starting position.
Thanks to Dynon Support (Jeff) for helping me out.
1) The latest version has a fix to the GPS-250 GPS module. This is what fixed the problem.
2) When I installed this version previously I just powered up each Skyview display which installed the update to the Skyviews but not to the GPS. Software updates need to be applied on ship power with all Dynon modules up and running (not just the screen).
3) The autopilot takes direction (turn left, turn right, ...) from the IFR certified GNS530W, but takes its staring position from the GPS-250. So the corrections were all correct but they were based on an incorrect starting point resulting in a laterally displaced approach course. I don't know why the A/P doesn't use the GNS for starting position.
Thanks to Dynon Support (Jeff) for helping me out.
Seems unusual to have GPS-250 powered separately from Skyview screen. In any case, all Dynon peripherals should be powered before doing any firmware updates. GPS-250 is used for Skyview screen view primarily because it communicates with the screen at 5 times per second, while I believe the ARINC 429 communicates once per second...thus giving a smoother moving map.
Shouldn't make any difference. The screen would be useless on backup battery if GPS-250 wasn't powered from the screen. As I said, it would be unusual to wire it such that GPS-250 was powered separately.
jakej
Well-Known Member
As the OP said, why would you do it differently to the install manual? - it actually shows the tx/rx & Power/ground connections to the Dynon GPS serial port 5
Checking messages on startup it looks like the Dynon GPS does power up from the Skyview (even when Skyview is just on internal battery, so I don’t know why it didn’t update when the SV did (maybe not fully booted or some startup error that I’d didn’t notice). In any case a reinstall with ship power fixed the problem and the approach on autopilot tracks correctly (rather parallel displaced).