For non-commercially used D-reg aircraft the mandatory annual IFR avionics check has been lifted by NfL 2-382-17 in December 2017. With this publication by the LBA, I attach a copy of it but it is in German only, the previous NfLs which mandated the annual avionics check have been revoked and replaced by a mandatory pitot/static and transponder check every 2 years.
For all other avionics the operator of the aircraft can create an individual maintenance programme which has to detail what is being done to ensure the continued airworthiness of the avionics installed. For newer avionics, e.g. a Garmin GTN650, this is rather straightforward as the Instructions for Continued Airworthiness as per the installation manual state the the unit checks itself and nothing is to be done unless the unit reports a fault.
wbardorf wrote:
AFAIK, the DA20 is such an aircraft
Indeed. I have always thought of the DA20 as a VLA though, but I guess it isn’t.
The Bölkow 208 (most of them) and 209 were also type certified by the German LBA for day and night VFR only, with a mandatory placard on the panel to prove it. Obviously this was long before the VLA category existed, long before mass produced composite power planes and also long before FAA had any thoughts of special type certification requirements for IFR.
One can imagine the LBA in 1970 or whenever not understanding that just because the plane was originally sold without instrumentation for IFR, that it should not logically preclude the type from IFR for the next 100 years regardless of equipment later installed.
