Airworthiness Directives; Pratt & Whitney Canada Corp. Turboprop Engines

We are adopting a new airworthiness directive (AD) for certain Pratt & Whitney Canada Corp. (P&WC) turboprop engines. This AD requires installing a reinforcement liner to the power turbine (PT) containment ring and, for certain PT containment rings, adding scallops. This AD was prompted by in-service events involving the perforation of engine cases as a result of the liberation of PT blades and the fracture/ displacement of the PT containment ring. We are issuing this AD to prevent uncontained engine failure and damage to the airplane.