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 39.1 (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. McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters AD/HU 369/115 Fuselage Station 75 Control Support Bracket Assembly 1/2005 DM Applicability: Model 600N helicopters, serial numbers with a prefix of "RN" and numbers 025, 029, 032, 034 through 038, 040, 041, 045, 048, or 067; or, any Model 600N helicopter with a yaw stability augmentation system (YSAS) installed, and with a control support bracket assembly, part number 369N2608-11, installed. Requirement: 1. Replace the fuselage Station 75 control support bracket assembly, part number 369N2608-11, with a serviceable control support bracket assembly, part number 600N2608-1. Helicopter serial numbers and revised finite life (time in service) list: RN025 2556 hrs, RN029 2377 hrs, RN032 2498 hrs, RN034 2456 hrs, RN035 2243 hrs, RN036 2652 hrs, RN037 2544 hrs, RN038 2531 hrs, RN040 2562 hrs, RN041 2763 hrs, RN045 2015 hrs, RN048 2125 hrs, and RN067 1600 hrs. 2. For helicopters with a YSAS installed that are not listed in above serial number and revised finite life list, replace the control support bracket assembly part number 369N2608-11 with a serviceable control support bracket assembly, part number 600N2608-1. For helicopters with no YSAS installed, but with a control support bracket assembly part number 369N2608-11 installed, replace the control support bracket assembly part number 600N2608-1, before installation of a YSAS. This Directive revises the Limitations section of the applicable maintenance manual by reducing the life limit of the control support bracket assembly, part number 369N2608-11, to the life limits stated in the above serial number and revised finite life list or to 1,600 hours time in service, whichever occurs first. Note 1: MD Helicopters, Inc. Service Bulletin No. SB600N-040, dated 18 September 2003, refers. Note 2: FAA AD 2004-22-12 Amdt 39-13840 refers. McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters AD/HU 369/115 (continued) Compliance: 1. Before 1 December 2005 or upon accumulating the time listed in the serial number and revised finite life list in the Requirement part of this Directive; whichever occurs first. 2. Before 1 December 2005 or upon accumulating 1,600 hours time in service since installation of the YSAS, whichever occurs first. This Airworthiness Directive becomes effective on 8 December 2004. Background: This Directive is prompted by information received from the manufacturer indicating that the fatigue life of the control support bracket is shorter than the original analysis indicated. The actions required by this Directive are intended to prevent failure of the control support bracket and subsequent loss of control of the helicopter. David Villiers Delegate of the Civil Aviation Safety Authority 2 December 2004 The above AD is notified in the Commonwealth of Australia Gazette on 8 December 2004.