STC's for GA Aircraft
If you have a Day VFR light aircraft that is fitted with traditional vacuum instruments (AI and DG) can you legally fit modern electronic instruments to replace them without an STC? All of the replacement candidates have STC's for most common GA types but not the aircraft that I would seek to install in.
Because these instruments are over and above what is required for Day VFR it seems ridiculous to even need an STC but that is what my avionics guy tells me is required plus an electrical load analysis (these instruments use absolutely minimal power).