As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TCM/BENDIX MAGNETO IMPULSE COUPLING SPRING. P/N 10-51324, PART TSN 11.6 HOURS INSTALLED ON: MAGNETO P/N 10-349350-5. S/N E189909FR M/N S6RN-1225 MAGNETO TSN 11.6 HOURS. THIS SPRING BROKE APPROXIMATELY 6 INCHES FROM THE OUTER DIAMETER END. THE MECHANIC REMOVED THE MAG BECAUSE HE HEARD NO COUPLING ENGAGEMENT. I DO NOT KNOW THE RESULTS OF THE MAG DROP TEST, PERHAPS THEY NEVER GOT THAT FAR. I WOULD GUESS IT WAS ROUGH. THE BREAK IN THE SPRING LOOKS LIKE A METALLURGY PROBLEM. IT IS A CLEAN BREAK WITH A BIT OF A FLASHING ON ONE SIDE.