From AOPA



FAA MAY TAKE AWAY PANEL-MOUNT OPTION FOR PORTABLE GPS
Think your portable GPS would work great mounted to your old Cessna 172's
instrument panel? If the FAA has its way, you won't be able to mount it. The
parts-panel dock and connective wiring-needed to mount your portable GPS
would either no longer be available or be too expensive to buy. The FAA's
proposal would make it illegal for manufacturers to produce a replacement or
modification part if they know (or should know) the part would end up
installed in a certified aircraft-that is unless they obtain production
approval from the agency. But that costs tens of thousands of dollars,
something many companies can't afford. While AOPA agrees production approval
is necessary for critical parts like connecting rods and cylinders, it isn't
needed for non-critical parts like a portable GPS panel dock or traffic
detector that enhance pilot safety. See AOPA Online.