As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING A ROUTINE 500 HOUR INSPECTION OF THE MAGNETO, SMALL CRACKS (1/4 INCH OR SHORTER) WERE FOUND IN THE ROTOR HOUSING WHERE THE MAGNET PROTRUDES THRU AT THE CORNERS (8 LOCATIONS). WERE ADVISED THIS WAS NOT RARE AND IS COMMON TO THE O-540 ENGINE SERIES AND PREDOMINENTLY TO THE O-540 INSTALLED IN R44 AIRCRAFT.