Headings off and erronious winds aloft.

[britguy59]

Hope I can fix this before Oshkosh next week.
I am getting weird EFIS headings, way off, and winds aloft of 80-99 kts. Used to work fine. I mover the Mag sensor slightly, should be no worse. Rewired the GPS feed, which seems fine for all other instruments. Could I have the GPS data  wires switched? Would that cause it? or is the erronious DG the source of both? Thanks.

 

[mmarien]

Probably the magnetic compass needs to be re-calibrated. I think they subtract ground track (GPS) from magnetic bearing and air speed to get winds aloft.

 

[dynonsupport]

Which product? This does sound like a magnetometer issue. That would affect BOTH the heading itself, and the winds aloft (mmariens description of the winds aloft calculation is correct). If you moved the mag sensor, check and make sure it didn't get closer to power or ferrous metal. You also might simply start with recalibrating the heading per the installation manual procedure.