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. Airtractor 600 Series Aeroplanes AD/AT 600/3 Horizontal Stabiliser Attachment Eyebolts 9/2005 Applicability: Model AT-602 aircraft, with serial numbers up to and including 602-0695 that have any 7/16-inch eyebolt (part number AN47-22A) installed; aircraft with serial number 602-0703 and subsequent; and all aircraft that have any 9/16-inch eyebolt (part number 30774-1) installed. Requirement: 1. Tighten the four eyebolts that attach the front and rear spar of the horizontal stabiliser to the respective stabiliser strut using the torque values referenced in Snow Engineering Co. Service Letter (SL) No. 129, revised 21 October 2004. 2. Replace eyebolts that attach the front and rear spar of the horizontal stabiliser to the respective stabiliser strut, in accordance with SL No. 129, Issued 26 September 1994, Revised 21 October 2004. 3. For aircraft with serial numbers up to and including 602-0695: As an alternative in order to use the increased replacement compliance times in Requirement 2 of this Directive, replace the steel brace assembly inside the stabiliser with a new steel brace assembly with larger bushings, and replace any 7/16-inch eyebolt with the 9/16-inch eyebolt part number 30774-1; in accordance with SL 129A, dated 7 August 2004. Do not install any 5/16-inch eyebolt (part number AN44-17A or AN44-21A), 7/16-inch eyebolt (AN47-22A or AN-47-30A), or 9/16-inch eyebolt (part number 30774-1 or 30775-1) that exceeds the corresponding cumulative hours time in service specified in Requirement 2 or 3 of this Directive. Note: FAA AD 2005-13-12 Amdt 39-14149 refers. Compliance: 1. Within 100 hours time in service or 12 calendar months after 1 September 2005, whichever occurs first, unless already accomplished. Tighten thereafter at intervals not to exceed 12 calendar months. 2. Replace initially upon accumulating the applicable number of hours time in service specified in SL No. 129, revised 21 October 2004, or within 50 hours time in service after 1 September 2005, whichever occurs later. Replace thereafter at the intervals specified in SL No. 129, revised 21 October 2004. 3. At any time after 1 September 2005. Use the applicable time in SL 129A, dated 7 August 2004. The repetitive replacement of Requirement 2 is still required. This Airworthiness Directive becomes effective on 1 September 2005. Background: The FAA has received numerous reports of failures of horizontal stabiliser attachment eyebolts on AT-301, AT-400, and AT-602 aircraft. Engineering analysis concluded that the eyebolts failed as a result of high cycle, low-nominal stress; and most likely due to the loss of torque during service. Failure of an eyebolt could lead to an abrupt change or complete loss of pitch control and/or aircraft departure from controlled flight. David Villiers Delegate of the Civil Aviation Safety Authority 20 July 2005