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 39.001(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. Pacific Aerospace Corporation Cresco Series Aeroplanes AD/CRESCO/12 Fin Leading Edge - Inspection 2/2008 DM Applicability: Cresco 08-600 series aircraft, all serial numbers. Requirement: 1. Remove the dorsal fin extension and carry out a detailed visual inspection of the leading edge skin in accordance with Pacific Aerospace Ltd Service Bulletin PACSB/CR/043. Repair any defects before further flight. Report any or nil damage to CASA through the Service Difficulty Reporting System. 2. Inspect the entire exterior skin of the fin from the leading edge to the rear spar for defects such as cracking, corrosion, working rivets or previous repair doublers. Repair any damage and indicate the position of defects, including previous repairs, on the diagram attached at Appendix A. Note: New Zealand Airworthiness Directive (AD) DCA/CRESCO/13 refers. Compliance: 1. Within 5 hours TIS, and thereafter at intervals not to exceed 300 hours TIS. 2. Before 5 January 2008 This Airworthiness Directive becomes effective on 14 December 2007. Background: Three occurrence of serious cracking in the leading edge skin underneath the dorsal fin extension have been reported. There have also been reports of chafing and corrosion. Cracking of the leading edge skin can lead to failure of the vertical fin and loss of control of the aircraft. David Villiers Delegate of the Civil Aviation Safety Authority 12 December 2007 AD/CRESCO/12 Fin Leading Edge - Inspection 2/2008 DM Appendix A The attached diagram should be used to annotate the location and type of damage. Tip Fairing Internal Ribs Lap Joints Starboard Port Figure 1 - Damage and Repair Location Diagram Indicate extent of defects, including repair doublers on the appropriate diagram. This information is necessary for the CASA and the NZ CAA to assess the overall condition of the vertical fin against its time in service.