Action
Final rule; request for comments.
Summary
We are adopting a new airworthiness directive (AD) for certain Rolls-Royce Deutschland (RRD) Models Tay 611-8 and Tay 611-8C turbofan engines. This AD requires replacement of the high-pressure (HP) turbine spanner retaining nut. This AD was prompted by the discovery that certain HP turbine spanner retaining nuts were improperly heat treated after application of silver plating. We are issuing this AD to prevent failure of the HP turbine stage 2 disc, uncontained engine failure, and damage to the airplane.