Summary
We propose to supersede existing airworthiness directive (AD) 2012-26-14 that applies to all Rolls-Royce Deutschland Ltd & Co KG (RRD) BR700-715A1-30, BR700-715B1-30, and BR700-715C1-30 turbofan engines. AD 2012-26-14 currently requires removal from service of the high-pressure (HP) compressor stages 1 to 6 rotor disc assembly before exceeding certain thresholds. Since we issued AD 2012-26-14, RRD developed a new silver-free nut that, if installed with a new HP compressor stages 1 to 6 disc assembly, would correct the unsafe condition identified in AD 2012-26-14. Therefore, we propose to supersede AD 2012-26-14 to restrict the applicability to engines exposed to silver plated nuts. Additionally, we are removing the terminating action statement from AD 2012-26-14 based on a comment received. This proposed AD would require removal from service of certain HP compressor stages 1 to 6 rotor disc assemblies before exceeding certain thresholds. We are proposing this AD to prevent failure of the HP compressor stages 1 to 6 rotor disc assembly, which could lead to an uncontained engine failure and damage to the airplane.