As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A ROUTINE 500 HR MAGNETO AND IMPULSE COUPLING INSPECTION, THE LT MAGNETO IMPULSE COUPLING PAWL WAS FOUND CRACKED FROM THE RIVET HOLE TO OUTER EDGE OF PAWL. A NEW IMPULSE COUPLING WAS INSTALLED AND ACFT RETURNED TO SERVICE. CAUSE OF CRACK MAY BE IMPROPER HEAT TREAT AT MFG.