COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AlliedSignal (Lycoming) Turbine Engines - T53 Series AD/T53/19 N2 Accessory Drive 8/97 Applicability: AlliedSignal (formerly Textron Lycoming) T5311, T5313, T5317, T53-L-11, T53-L- 13 and T53-L-703 series engines. Requirement: To prevent possible uncommanded engine acceleration resulting from N2 accessory drive assembly disengagement, remove from service N2 spur gear nut retainers (lock cups) part number (P/N) 1-070-066-01 in accordance with the following AlliedSignal Aerospace Service Bulletins (SB): 1: T5311 and T53-L-11 series engines: 2: T5313B and T5317 series engines: 3: T53-L-13B/SSA/SSB series engines: 4: T53-L-13B/SSD series engines: 5: T53-L-703 series engines: SB No. T5311/T53-L-11-0080. SB No. T5313B/T5317-0081 Revision 1. SB T53-L-13B-0082 Revision 1 SB T53-L-13B/D-0083. SB T53-L-703-0084 Revision 1. Note: FAA Airworthiness Directive 97-07-05 refers. Compliance: Within 300 hours time in service or prior to 17 July 1999, whichever occurs first. This airworthiness directive becomes effective on 17 July 1997. Background: This directive has been issued to require the removal from service of certain part number N2 spur gear nut retainers in response to reports of N2 spur gear retainer separation. Separation of the retainer could result in N2 accessory drive disengagement and uncommanded engine acceleration.