As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE 500 HOUR INSPECTION OF MAGNETOS, DISCOVERED THAT ALL FOUR MAGNETOS HAD CRACKED IMPULSE COUPLING FLYWEIGHT PLATES. CRACKS WERE DISCOVERED DURING NDT MAGNETIC PARTICLE INSPECTION OF IMPULSE COUPLINGS. SUSPECT THE SHARP-CORNERED FEATURE OF THE FLYWEIGHT PLATE THAT FORMS THE FULL ADVANCE STOP IS DEVELOPING CRACKS DUE TO STRESS RISERS AT THE CORNER.