Airworthiness Directives; Honeywell International Inc. TPE331 Series Turboprop, and TSE331-3U Model Turboshaft Engines

The FAA is adopting a new airworthiness directive (AD) for certain Honeywell International Inc. TPE331 series turboprop, and TSE331-3U model turboshaft engines. This AD requires implementing a new flight cycle counting method for first, second, and third-stage turbine rotors used in aircraft that make multiple takeoffs and landings without an engine shutdown, and removing turbine rotors from service that have reached or exceeded their cycle life limits. This new flight cycle counting method requires determining total equivalent cycles accrued. This AD results from several reports of uncontained turbine rotor separation on engines used in special-use operations. We are issuing this AD to prevent uncontained failure of the turbine rotor due to low-cycle-fatigue (LCF), and damage to the aircraft.