COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AlliedSignal (Garrett/AiResearch) Turbine Engines - TPE 331 Series AD/TPE 331/53 Third Stage Replacement 6/98 Applicability: TPE331-1, -2, -2UA, -3U, -3UW, -3U, -5, -5A, -5AB, -5B, -6, -6A engines incorporating a part number (P/N) 868379-3 third stage turbine stator not inspected in accordance with National Flight Services Alert Service Bulletin (ASB) Number NF- A72-10961. Requirement: Replace applicable third stage turbine stator P/N 868379-3 in accordance with AlliedSignal Service Bulletin TPE331-A72-0861 Revision 2. Note 1: FAA Airworthiness Directive 98-04-15 refers. Note 2: The requirements of this directive do not supersede the in-service inspection requirements of Airworthiness Directive AD/TPE331/41 Amdt. 2. Compliance: As detailed in the requirement document. This Airworthiness Directive becomes effective on 21 May 1998. Background: This directive has been issued to require the replacement of certain third stage turbine stators. The requirement reflects advice of fatigue cracking may result in the stator moving aft and contacting the third stage turbine wheel. If uncorrected, this could result in uncontained failure of the third stage turbine wheel.