The FAA is proposing to adopt a new airworthiness directive (AD) for certain Pratt & Whitney Canada PT6A engines. The proposed AD was prompted by in-service events involving the perforation of engine cases as a result of the liberation of power-turbine blades and the fracture/displacement of the power-turbine containment ring. This proposed AD would require installing a reinforcement liner to the power-turbine containment ring and, for certain power-turbine containment rings, adding scallops. The FAA is proposing this AD to prevent uncontained engine failure and damage to the airplane. The agency is taking comments on the proposed AD until March 10.