Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
Due to manufacturing problems of BR700-710 HP stage 1 and 2 turbine discs it was necessary to re-calculate the Declared Safe Cyclic Life (DSCL) for all BR700-710 HP turbine discs. The analysis concluded that it is required to reduce the approved life limits for the HP turbine disc part numbers that are listed in Table 1 and Table 2 of this AD (MCAI). Exceeding the revised approved life limits could potentially result in non-contained disc failure.
We are proposing this AD to prevent-failure of the high-pressure turbine (HPT) stage 1 and stage 2 discs, uncontained engine failure, and damage to the airplane.