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. Learjet 45 Series Aeroplanes AD/LJ45/12 Airworthiness Limitations 3/2008 Applicability: Model 45 aircraft, serial numbers 45-002 through 45-302, and 45-2001 through 45-2049. Requirement: Action in accordance with the technical requirements of FAA AD 2008-01-03 Amdt 39-15328. Note: Learjet 45 Maintenance Manual Chapter 4, Revision 38, dated 24 April 2006, and Learjet 40 Maintenance Manual Chapter 4, Revision 6, dated 24 April 2006, refer. Compliance: As specified in the Requirement document, with a revised effective date of 13 March 2008. This Airworthiness Directive becomes effective on 13 March 2008. Background: This Directive requires revising the Airworthiness Limitations section of the Aircraft Maintenance Manual to incorporate certain inspections and compliance times to detect fatigue cracking of certain Principal Structural Elements (PSEs). The Requirement document of this Directive results from new and more restrictive life limits and inspection intervals for certain PSEs. This Directive is intended to ensure that fatigue cracking of various PSEs is detected and corrected, as such cracking can adversely affect the structural integrity of the aircraft. David Villiers Delegate of the Civil Aviation Safety Authority 30 January 2008