IImorrow 2001 GPS IFR Cert

"MJC" wrote in :

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



The CDI needs to be seperate from the display on the GPS box. It can be
switched between GPS and VOR/ILS. Every IFR GPS installation that I have
ever seen in an airplane with an HSI switches the HSI between the GPS and
the VOR/ILS. Note: a while ago (I can't define "a while") there was a
requirement that if the HSI (or CDI) was displaying the GPS info, it
would automatically be switched to the NAV radio when the NAV was tuned
to a localizer frequency. This is no longer a requirement. My
installation is not set up that way.