What was found
DURING ANNUAL INSPECTION, COMPLY WITH 500 HR MAGNETO INTERNAL INSPECTION, WHICH INCLUDES THE IMPULSE COUPLING IAW MFG SB. ONE IMPULSE COUPLING WAS FOUND TO BE VERY LOOSE, DUE TO LOOSE RIVETS, WOULD HAVE FAILED SOON. FAILURE OF THIS TYPE CAN CAUSE EXTENSIVE DAMAGE TO MAGNETO AND ENGINE. MFG INSPECTION CHECKLIST DOES NOT CALL FOR DETAILED INSPECTION OF MAGNETO IMPULSE COUPLING OR OTHER MAGNETO INTERNAL PARTS OTHER THAN POINTS. REPLACED COUPLING WITH NEW PART. OLD PART ONLY HAD 529 HRS. LOOSE RIVETS AND WORN PAWLS. (K)