Pilot maintenance of avionics
The quoted regulation is not relevant to a certified aircraft. See EASA MA803(b) for the tasks an owner can do. The specifics are covered in part M appendix viii. In the case of avionics, tasks are limited to changing units that don't require the use of specialist test equipment to prove serviceability. For the posted example, how do you certify the VOR function if you can't check receiver sensitivity, bearing accuracy, single-tone failure on LOC etc without a NAV signal generator?