What was found
LEFT MAG IMPULSE COUPLING BROKE, JAMMING THE MAGNETOS DRIVE SHAFT KEEPING IT FROM TURNING. THE MAG FAILURE ALSO CAUSED THE CRANKSHAFT ALIGNMENT PIN TO BREAK OFF AND BACK OUT HE CRANKSHAFT BOLT. THIS MAGNETO HAD AN AD 99-04-04 THAT WAS NEVER COMPLIED WITH EVERY 250 HRS. THE AD DOES NOT SHOW UP ON AIRFRAME AND ENGINE SEARCHES, BUT DOES SHOW UP ON A MAGNETO MODEL SEARCH. THIS IS BECAUSE THE ACFT ENGINE ORIGINALLY CAME WITH BENDIX MAGS AS NOTED IN THE TCDS. A SI 1443 ALLOWS THE INSTALLATION OF MAGNETOS A THOROUGH AD SEARCH OF ALL ACCESSORIES NEEDS TO BE CONDUCTED AT AN ANNUAL/100HR INSPECTION.