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. Boeing 737 Series Aeroplanes AD/B737/266 Upper and Lower Skins of 13/2005 the Fuselage Lap Joint Applicability: Model 737-100, -200, and -200C series aircraft, line numbers 1 through 291. Requirement: Action in accordance with the technical requirements of FAA AD 2003-23-03 Amdt 39-13367. Note: Boeing Alert Service Bulletins 737-53A1224 original issue, and Revision 1, or later FAA approved revisions, refer. Compliance: As specified in the Requirement document. This Airworthiness Directive becomes effective on 22 December 2005. Background: The FAA received a report of an in-flight rapid decompression of a Model 737 series aircraft. Investigation revealed that the skin above the forward entry door was separated at the stringer S-4R lap joint, with a 28-inch tear running along the lap joint. Further investigation revealed that numerous scratches on the skin of the lap joint had initiated fatigue cracks and subsequent tearing of the skin. Fatigue cracking and corrosion was also detected in other lap joints at various locations. Such discrepancies, if not corrected, could result in sudden fracture and failure of a lap joint and rapid decompression of the aircraft fuselage. David Villiers Delegate of the Civil Aviation Safety Authority 11 November 2005