Airworthiness Directives; Pratt & Whitney Canada PT6A Series Turboprop Engines

This amendment adopts a new airworthiness directive (AD), that is applicable to Pratt & Whitney Canada PT6A series turboprop engines that have certain turbine exhaust ducts that were modified by a number of different companies. This amendment requires inspections for low- quality welds and cracks of a large population of turbine exhaust ducts. This amendment is prompted by reports of cracks along the weld seams of certain turbine exhaust ducts. The actions specified by this AD are intended to prevent failure of the turbine exhaust duct due to cracking that could result in possible separation of the reduction gearbox and propeller from the engine, and possible loss of control of the airplane.