As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAGNETO WAS REMOVED FROM THE AIRCRAFT AFTER MAGNETO TIMING CHECK INDICATED MAGNETO INTERNAL TIMING WAS OFF BY 10 DEGREES. MAGNETO DISASSEMBLY INSPECTION REVEALED EXCESSIVE CAM FOLLOWER WEAR. CAM FOLLOWER ALSO APPEARED MELTED. CONTINUED OPERATION WOULD HAVE CAUSED MAGNETO TO BECOME INOPERATIVE.