Summary
We propose to adopt a new airworthiness directive (AD) for all Rolls-Royce Deutschland Ltd & Co KG (RRD) BR700-710A1-10 and BR700- 710A2-20 turbofan engines, and certain BR700-710C4-11 model engines. This proposed AD was prompted by RRD performing an evaluation that determined that certain high-pressure turbine (HPT) stage 1 and stage 2 discs from a specific supplier may contain steel inclusions that may cause the discs to fail before they reach their current life limits. This proposed AD would require reducing the life limits for certain HPT stage 1 and stage 2 discs. We are proposing this AD to prevent failure of the HPT stage 1 and stage 2 discs, which could result in uncontained failure of the engine and damage to the airplane.