As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AS A RESULT OF PREVIOUS MAGNETO FAILURES, IMPLEMENTED A 100 HR INSPECTION OF ALL IMPULSE COUPLED MAGNETOS ON ALL ZLIN 242L AIRCRAFT. DURING ONE OF THESE INSPECTIONS ONE OF THE IMPULSE COUPLING PAWLS HAD A SPRING MISSING. THIS SPRING ALLOWS THE PAWL TO ENGAGE TO THE PIN ON THE MAGNETO HOUSING FOR STARTING. IN THIS CONDITION THE MAGNETO WOULD ONLY FIRE EVERY SECOND ROTATION DURING THE STARTING PROCESS.