I messed up bad

Our first color TV in 1967 was a Heathkit. It was the start of my electronics career. Magnetos produce a wild output on a O'scope. They need to be grounded on both sides to prevent arcing. In the aircraft world, we have no proper "ground". Everything is grounded to the airframe. It's complicated by the fact that 28 volts DC is hard enough, but the AC is 400 hertz, not 60 hertz like your house outlet. It's more efficient over short distances, but the bite is way more than 60 cycle. Ask me how I know.....