As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING INSPECTION OF THE RT MAGNETO, AFTER FAILURE OF THE MAGNETO, FOUND THE DISTRIBUTOR GEAR ARM TO BE LOOSE. INSPECTION OF THE DISTRIBUTOR GEAR SHOWED THE METHOD OF ATTACHING THE ARM TO THE GEAR HAD BEEN CHANGED. THE PREVIOUS METHOD IS OBVIOUSLY STRONGER. THE DISTRIBUTOR ARM WAS NEAR COMPLETE SEPARATION FROM THE DISTRIBUTOR GEAR WHICH WOULD HAVE CAUSED FAILURE OF THE MAGNETO. RECOMMEND THE 500HR MAGNETO INSPECTION BE CHANGED TO 400HRS UNTIL THIS PROBLEM IS CORRECTED.