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. BAe Systems (Operations) Jetstream 4100 Series Aeroplanes AD/J4100/19 Vertical and Horizontal Stabiliser Attachment Fittings 4/2008 DM Applicability: All Model Jetstream Series 4100 aircraft. Requirement: Action in accordance with BAE Systems Mandatory Service Bulletin J41-55-012 Revision 1, or later CAA/EASA approved revision. Note: UK CAA AD 005-10-2002 refers. Compliance: Unless the initial inspection is already accomplished, within 30 days after 20 February 2008. If J41-55-011 Part 1 was complied with then the initial inspection requirements have been satisfied. If operators have removed the horizontal stabiliser and have carried out detail visual inspections of the attachment fitting lugs and eye bolt shanks, then the initial inspection requirements have been satisfied. Inspect thereafter at intervals not to exceed 8 years. This Airworthiness Directive becomes effective on 20 February 2008. Background: Fretting corrosion has been found during inspection of the horizontal and vertical stabiliser attachment fittings on aircraft in service. This fretting corrosion has been found on the horizontal and vertical stabiliser forward and rear attachment fitting lug contact faces. Corrosion has also been found on the eye bolt shanks. A dedicated inspection is required to maintain structural integrity. David Villiers Delegate of the Civil Aviation Safety Authority 15 February 2008