Does every Safety–of–Flight Test (SOFT) include full testing of each and every equipment with the full EMC or is it just a basic quality test for some of the affected systems?
Safety of Flight (SOF) Testing is a sample, a subset, of a more exhaustive set of tests.1 It evaluates critical functions that "assures basic" levels of safety for critical components of the system.
The FAA further defines "critical" in this way: Usually a function whose loss would prevent the continued safe flight and landing of the airplane.2
Though the definition is somewhat circular, it is usually clear when a function is not critical, not required for safety of flight. For example, a Terrain Awareness and Warning System (TAWS) is not required to be installed, therefore, it's function would not be part of the SOF testing. However, attitude display, engine instruments, and airspeed are all defined in 2 as critical and would be part of SOF testing.