As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAGNETO REMOVED FROM ENGINE FOR 500 HOUR INSPECTION IN ACCORDANCE WITH THE MM. REMOVED THE REAR COVER OF MAGNETO AND FOUND A GRAY COLOR POWDER ON THE CAP AND AROUND THE COIL. THIS WAS FOUND ON THE MAGNETOS THAT HAD FAILED IN FLIGHT WITH ABOUT THE SAME FLIGHT TIME ON THEM. MFG WAS INFORMED OF FAILURES.