AC 20-138A (Airworthiness of GPS systems) gives some guidance for avionics installations.
8-c(1)iii "...However, since GPS technology is now common and considerable experience has been obtained in the installation of GPS, approved data for every installation is no longer appropriate. Instead, installations that do not qualify as major alterations above should be accomplished as minor alterations." Our FSDO said no approval is needed for avionics upgrades except for IFR approved GPS and interface with an Autopilot (major alterations). And these only required FAA approval of IFR operation/test and the autopilot. Install NAV/Com/GS/MB as a minor installation. Transponder/encoder will need 24 month test. mitch - Learn2fly www.chickashawings.com 2+2=4! http://www.myspace.com/pianomitch
