wrote in message ...
In addition to the frequency tests mention, the GPS has to display on an
external CDI, there has to be a switch and annunicator to change that
external CDI from VOR/LOC to GPS, and some installations require an
external
annunicator for Approach Mode.



I apologize if this changes the subject a little, but I'm wondering
about something related to your comment.
I'm planning a panel for my Experimental (RV7), and it will have the
Grand Rapids EFIS/AHRS display. For radios, there will be both the GNS-430
GPS and the SL-30 Nav/Com.
The interesting part about the setup is that both radios can be switched
to display and drive the HITS on the EFIS (if I understand the specs
correctly).
So, the question is: Is a HITS display driven by either a certified GPS
or a certified NAV signal a "legal" equivilant for a separate CDI
instrument?

MJC