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: Following a review of operational data of the Tay 651-54 engine, it has been found that the actual stress levels in the Tay 651- 54 engine High Pressure Compressor (HPC) stages 1, 3, 6, 7 and 12 discs were higher than those originally assumed and therefore the approved lives needed to be reduced. We are proposing this AD to prevent HPC stages 1, 3, 6, 7, and 12 discs from exceeding the approved reduced life limits, which could result in an uncontained failure of a disc and damage to the airplane.