What was found
PILOT REPORT OF FLUCTUATING RPM'S WHILE IN CRUISE FLIGHT, PLUS OR MINUS 400RPM. DURING GROUND RUN FOR TROUBLESHOOTING, RH MAGNETO MAG DROP WAS EXCESSIVE. FURTHER ATTEMPTS AT CLEARING PLUGS, ETC, TO THEN RECHECK RH MAGNETO DROP RESULTED IN COMPLETE ENGINE SHUT DOWN WHEN RH MAGNETO SELECTED ON IGNITION SWITCH. MAGNETO REMOVED AND SENT TO REPAIR FACILITY WHERE IT WAS DISCOVERED THAT THE RIVETS HOLDING THE PAWLS IN PLACE HAD LOOSENED, ALLOWING THE PAWLS MOVE IN AN OBLONG PATTERN, CONTACTING AND DAMAGING THE OIL SEAL, INTRODUCING OIL INTO THE MAGNETO HOUSING WHICH CAUSED A LACK OF SPARK.