Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for Pratt & Whitney (PW) JT8D-209, -217, -217A, -217C, and -219 series turbofan engines. That AD currently requires torque inspection of the 3rd stage and 4th stage low pressure turbine (LPT) blades for shroud notch wear and replacement of the blade if wear limits are exceeded. This proposed AD would require torque inspections at shorter inspection intervals of the refurbished 3rd stage and 4th stage LPT blades, but the same or longer inspection intervals of the new 3rd stage and 4th stage LPT blades, for shroud notch wear and replacement of the blade if wear limits are exceeded. This proposed AD would also require replacing LPT-to-exhaust case bolts and nuts with bolts and nuts made of Tinidur material. This proposed AD results from reports of 194 blade fractures since 1991, with 37 of those blade fractures resulting in LPT case separation, and three reports of uncontained 3rd stage and 4th stage LPT bladefailures with cowl penetration. We are proposing this AD to prevent an uncontained blade failure that could result in damage to the airplane.