AD FAA-2010-0452

We are superseding an existing airworthiness directive (AD) for the products listed above. That AD currently requires initial and repetitive torque inspections 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. That AD also requires replacing LPT-to-exhaust case bolts and nuts with bolts and nuts made of Tinidur material. This new AD requires the same torque inspection, blade, and Tinidur nut replacement actions, but requires replacement of the LPT- to-exhaust case bolts with longer bolts made of Tinidur material. This AD also requires installation of crushable sleeve spacers on the bolts. This AD was prompted by nine reports of failure of Tinidur material LPT-to-exhaust case bolts, as a result of blade failure, since AD 2005- 02-03 became effective. We are issuing this AD to prevent turbine blade failures that could result in uncontained engine debris and damage to the airplane.