Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for Rolls-Royce Deutschland Ltd & Co KG (RRD) Tay 650-15 turbofan engines. That AD currently establishes cyclic life limits for certain part number (P/N) stage 1 high pressure turbine (HPT) discs and stage 1 (LPT) discs operating under certain flight plan profiles. This proposed AD would add Tay 651-54 turbofan engines to the applicability. This proposed AD would also require removing certain stage 1 HPT discs and stage 1 LPT discs at reduced cyclic life limits using a drawdown schedule. This proposed AD results from RRD updating their low-cycle- fatigue (LCF) analysis for stage 1 HPT discs and stage 1 LPT discs and reducing their cyclic life limits. We are proposing this AD to prevent cracks leading to turbine disc failure, which could result in an uncontained engine failure and damage to the airplane.