Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Honeywell International Inc. TPE331 series turboprop, and TSE331-3U model turboshaft engines. This proposed AD would require 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 would require determining total equivalent cycles accrued. This proposed AD results from several reports of uncontained turbine rotor separation on engines used in special-use operations. We are proposing this AD to prevent uncontained failure of the turbine rotor due to low-cycle-fatigue (LCF), and damage to the aircraft.