As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PREFLIGHT RUN-UP, FOUND RIGHT MAGNETO INOPERATIVE. REMOVED AND DISASSEMBLED MAG. FOUND DISTRIBUTOR BLOCK CENTER BUSHING LOOSE. THIS CAUSED TIMING GEAR TO SHIFT POSITION AND CHANGE INTERNAL TIMING. OTHER DAMAGE NOTED WAS DEFORMED TIMING GEAR. TIMING GEAR SPARK FINGER SHEARED SPARK TOWERS FROM DISTRIBUTOR BLOCK AND CONTAMINATED MAG WITH BRONZE SHAVINGS.