AIRWORTHINESS DIRECTIVE On the commencement date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below repeals Airworthiness Directive (AD) AD/LTS/13 and issues the following AD under subregulation 39.001 (1) of CASR and subsection 33 (3) of the Acts Interpretation Act 1901. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct an unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section. Honeywell International Turbine Engines - LTS 101 Series AD/LTS/13 Amdt 1 Improved Power Turbine Retention 16/2021 Applicability: Honeywell International (formerly AlliedSignal and Textron Lycoming) LTS101‑650B1, -750B1, -650C and -750C model turboshaft engines. Requirement: 1. To prevent a power turbine overspeed and an uncontained engine failure, install an improved power turbine retention system and improved power turbine rotor assembly in accordance with the following Honeywell International Service Bulletins (SBs): (a) LTS 101B-72-50-0122 Revision 4 as in force on the commencement date of this AD, or (b) LTS 101B-72-50-0116 Revision 6 as in force on the commencement date of this AD, or (c) LTS 101C-72-50-0119 Revision 2 as in force on the commencement date of this AD, as applicable, and 2. Install an improved electronic power turbine rotor overspeed controller in accordance with the following Honeywell International SBs: (a) LTS 101B-73-10-0127 Revision 2 as in force on the commencement date of this AD, or (b) LTS 101C-73-10-0129 Revision 3 as in force on the commencement date of this AD, as applicable. Note 1: United States of America Federal Aviation Administration (FAA) AD 95‑26‑01 is the basis for this AD. Note 2: CASA Airworthiness Directives AD/JBK 117/9, AD/GBK 117/7 and AD/BELL 222/19, as in force from time to time, address the airframe wiring requirements for the installation of an electronic power turbine overspeed controller. Compliance: Requirement 1. Before further flight after the commencement date of this AD, unless accomplished previously. Requirement 2. Concurrent with Airworthiness Directives AD/JBK 117/9, AD/GBK 117/7 and AD/BELL 222/19, as applicable, but before further flight after the commencement date of this AD, unless accomplished previously. This AD commences on 20 August 2021. Background: This Directive has been issued to require the installation of an improved power turbine rotor and an improved power turbine rotor overspeed controller. The requirements address reports of uncontained power turbine failure events. Amendment 1 removes obsolete references and makes minor editorial changes to reflect current requirements. David Punshon Delegate of the Civil Aviation Safety Authority 6 August 2021