GRT Avionics

good morning
I have a dual HX system with Tru track auto pilot a couple things happened in the 2 hours of flight 1. It takes a bout 10 minutes for the dual AHARS , # one will level until the dual comes one line. One last flight when on ENAV with the Auto Pilot on GPSS the altitude tape became erratic by a 400 up and down place it on heading mode seemed to be better but it did same when auto pilot was off the second screen also went blank for about 2 minutes and then came back on line this happened before on a Lon flight in hot weather.

Help JIm Hannibal

Jim,
It is hard to trouble shoot on-line, but can you be more clear about the issues?
What takes ten minutes? For both ADHRS systems to boot up? Or for the problem to appear?
Are you saying the altitude display is erratic, quickly changing up and down by 400'? On both displays?
And in addition display #2 went blank for two minutes? Did you do anything to bring it back?
Can you run the autopilot in altitude hold independent of the HX? If it still wants to jump up and down then the issue is in the static line; if it holds altitude fine while the HX altitude jumps around then the problem is in the GRT system or associated wiring.