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. Mitsubishi MU-2 Series Aeroplanes AD/MU-2/71 Wing Attachment Barrel Nuts and Bolts 3/2007 Applicability: Model MU-2B-10, -15, -20, -25, -26 aircraft, serial numbers 101 through 347, except serial numbers 313 and 321. Model MU-2B-30, -35, -36 aircraft, serial numbers 501 through 696, except serial numbers 652 and 661. Requirement: Action in accordance with Mitsubishi Service Bulletin No. 241A dated 21 November 2006 or later JCAB approved revisions. Note: JCAB AD TCD-7030-2006 refers. Compliance: Within 200 hours time in service or 12 months after 15 March 2007, whichever occurs first. This Airworthiness Directive becomes effective on 15 March 2007. Background: The manufacturer received a report of several fractured wing attachment barrel nuts that were detected during routine maintenance. During a subsequent field survey, no additional cracked barrel nuts were detected, but a significant number of aircraft were found to have incorrect torque values on the wing attachment bolts. David Villiers Delegate of the Civil Aviation Safety Authority 1 February 2007