Originally Posted by bobg56
I believe that Cap is for noise filtering. Rotax require one for radio interference.
That's correct. I had one fail in the air just after takeoff on climb out. There was a bang and the cabin filled with smoke. I declared an emergency, turned the master switch off and landed. This was in my Kitfox IV with a rotax 912 ULS. There wasn't much left of the capacitor. I replaced the capacitor and placed the new one forward of the firewall. The original one was aft of the firewall per the kit instructions.
I bought the replacement from ACS and it was much better quality than the one that came with the kit.