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

Abstract

This notice revises an earlier proposed airworthiness directive (AD), applicable to Teledyne Continental Motors (TCM) (formerly Bendix) S-20, S-1200, D-2000, and D-3000 series magnetos equipped with impulse couplings, that would have superseded an AD that currently requires inspections for wear, and replacement, if necessary, of the impulse coupling assemblies. The proposed rule would have retained the repetitive inspections for wear required by the current AD, but would have also required replacement, if necessary, of riveted impulse coupling assemblies with newly designed, improved, snap ring impulse coupling assemblies. In addition, the proposed AD would have required marking the magneto data plate to indicate installation of a snap ring impulse coupling assembly. Installation of snap ring impulse coupling assemblies would have constituted terminating action to the inspection requirements of the AD. That proposal was prompted by availability of an improved design for the impulse coupling assembly. This action revises the proposed rule by retaining the 500 hour repetitive inspections for wear required by the current AD but makes them effective for the snap ring couplings as well. The actions specified by this proposed AD are intended to prevent magneto failure and subsequent engine failure.