What was found
DURING A PREFLIGHT RUN-UP, THE LEFT ENGINE WAS OBSERVED TO ONLY PRODUCE ABOUT 2000 RPM. INSPECTION OF THE LEFT MAGNETO REVEALED THE BRONZE BEARING HAD BECOME LOOSE IN THE DISTRIBUTOR BLOCK ALLOWING THE DISTRIBUTOR GEAR ELECTRODE TO STRIKE AND DAMAGE SEVERAL OF THE DISTRIBUTOR BLOCK ELECTRODES. THIS IS THE THIRD INSTANCE OF A BENDIX 1200 SERIES MAGNETO TO FAIL IN THIS CONDITION AT ABOUT THE SAME TIME OF AROUND 1300 HOURS. THESE MAGNETOS HAVE BEEN INSPECTED IN ACCORDANCE WITH THE 500 HOUR REQUIREMENTS OF THE TCM 1200 SERIES MAINTENANCE MANUAL AT THE REQUIRED INTERVALS. ALL THESE FAILURES HAVE OCCURRED WITHIN A 6 WEEK TIME FRAME. TCM HAS BEEN CONTACTED AND THEY ARE AWARE OF 2 OTHER SIMILAR FAILURES AND THEY ARE PERFORMING AN ANALYTICAL INSPECTION ON THE RETURNED UNITS.