AIRWORTHINESS DIRECTIVE On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/B747/294 Amdt 1 and issues the following AD under subregulation 39.001(1) of CASR 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 747 Series Aeroplanes AD/B747/294 Amdt 2 Horizontal Stabiliser Outboard Centre Sections Upper Skin and Rear Spar Structure 2/2009 Applicability: All Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, -400, -400D, -400F, 747SR, and 747SP series aircraft. Requirement: Action in accordance with the technical requirements of FAA AD 2006-10-16 Amdt 39-14600. Note: Boeing Alert Service Bulletins 747-55A2050 and 747-55A2050 Revision 1, or later FAA approved revision, refer. Corrective actions (repairs or repeat inspections) that are approved on an FAA form 8100-9 and approved by the Manager, Seattle Aircraft Certification Office or delegate as an Alternative Method of Compliance (AMOC) to the requirements of FAA AD 2006-10-16, may be carried out without the need to obtain an exclusion from CASA from this airworthiness directive. Compliance: As specified in the Requirement document. This Amendment becomes effective on 12 February 2009. Background: The FAA has received numerous reports of cracking from two operators of six 747 series aircraft. Of the 22 reports of cracking received, 20 of the reports were in an area not covered by the Zone A inspections required by FAA AD 2002-06-02 (AD/B747/271). This Directive requires certain inspections to detect such cracking, which if undetected, could lead to reduced structural capability of the outboard and centre sections of the horizontal stabiliser, and result in loss of controllability of the aircraft. This amendment allows the use of an FAA approved Alternative Method of Compliance (AMOC) to the requirements of this AD, without the need for the operator to continually apply for an exclusion for repairs that are already approved on a form 8100-9 as an AMOC by an FAA delegate. Amendment 1 of this AD became effective on 6 July 2006. David Punshon Delegate of the Civil Aviation Safety Authority 18 December 2008