Airworthiness Directives; Teledyne Continental Motors (Formerly Bendix) S-20, S-1200, D-2000, and D-3000 Series Magnetos

The FAA is superseding 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 coupling assemblies. That AD currently requires replacing riveted-impulse coupling assemblies and snap-ring coupling assemblies, which are worn beyond limits, with serviceable riveted-impulse coupling assemblies or snap-ring impulse coupling assemblies. This ad requires a reduced inspection interval for magnetos with riveted-impulse coupling assemblies installed on certain Lycoming engine models. This AD does not lower the inspection interval for magnetos with snap-ring impulse coupling assemblies. This AD also limits the applicability to certain Lycoming engine models. This AD results from data provided by the manufacturer that shows a need to reduce the inspection intervals for riveted-impulse coupling assemblies used on certain Lycoming engine models. We are issuing this AD to prevent failure of the magneto impulse coupling assembly and possible engine failure.