As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON STARTING THE ENGINE THERE WAS ARCING AND SPARKS COMING FROM THE STARTER GROUND ATTACHMENT LOCATED UNDERNEATH THE COCKPIT. THE SPARKS CAME FROM THE GROUNDING ATTACHMENT BOLT ANCHOR NUT RIVET. RECOMMEND A BETTER GROUNDING LOCATION AND ATTACHMENT.