AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the 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. Boeing 767 Series Aeroplanes AD/B767/174 Thrust Reverser Modifications and Operational Checks 8/2002 Applicability: Model B767 series aeroplanes powered by Rolls-Royce RB 211-524 series engines. Requirement: 1. Install a second locking gearbox system on both left and right hand engine thrust reversers in accordance with Boeing Service Bulletin 767-78-0059, Revision 2, dated 10 June, 1993; or Revision 3, dated 20 January, 1994. Note 1: FAA AD 94-17-03, amendment 39-8998, specifies the appropriate revision levels for Rolls-Royce and Eldec Service Bulletins referred to in the Boeing Service Bulletins contained in Requirement 1. 2. Carry out operational checks of number 2 and 3 gearbox locks and airmotor brake in accordance with Appendix 1 (including figure 1) of FAA AD 94-17-03. 3. Repeat Requirement 2 operational checks. Terminating Action Compliance with this Directive terminates the actions required by paragraph (a) of FAA AD 91-22-02, amendment 39-8062. Note 2: FAA AD 94-17-03, amendment 39-8998.refers. Compliance: For Requirement 1: Prior to the issue of a Certificate of Airworthiness. For Requirement 2: Within 3,000 flight hours after accomplishment of Requirement 1, or within 1,000 flight hours after the effective date of this Directive, whichever occurs later. For Requirement 3: At intervals not exceeding 3,000 flight hours. This Airworthiness Directive becomes effective on 8 August 2002. Boeing 767 Series Aeroplanes AD/B767/174 (continued) Background: This Directive requires inspections, adjustments, functional checks, the installation of a modification and repetitive operational checks of the thrust reverser gearbox locks and the airmotor. These actions are intended to enhance the level of safety inherent in the original type design of the thrust reverser system to prevent possible discrepancies that exist in the current thrust reverser control system, that could result in an inadvertent deployment of a thrust reverser during flight. Eugene Paul Holzapfel Delegate of the Civil Aviation Safety Authority 28 June 2002 The above AD is notified in the Commonwealth of Australia Gazette on 17 July 2002.