Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for Teledyne Continental Motors (TCM) (formerly Bendix) S-20, S-1200, D-2000, and D-3000 series magnetos equipped with impulse couplings. That AD currently requires replacing riveted-impulse coupling assemblies, which are worn beyond limits, with serviceable riveted-impulse couplings or snap-ring impulse couplings. This proposed AD would require a reduced inspection interval for magnetos with riveted-impulse couplings installed on certain Lycoming engine models. The proposed AD would not lower the inspection interval for magnetos with snap-ring impulse couplings. This proposed AD would also limit the Applicability to certain Lycoming engine models. This proposed AD results from data provided by the manufacturer that shows a need to reduce the inspection intervals for riveted-impulse couplings used on certain Lycoming engine models. We are proposing this AD to prevent failure of the magneto impulse couplingand possible engine failure.