COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F50 (F27 Mk 50) Series Aeroplanes 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 CAR 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. AD/F50/81 TCAS Antenna Structural Provisions 2/2001 Applicability: Model F.27 Mk. 050 aircraft, serial numbers 20168, 20171, 20177, 20180, 20181, 20185 through 20188, 20193 through 20195, 20198, 20199, 20207 through 20209, 20215 through 20219, 20221, 20233, and 20271. Requirement: Reinforce the affected structure in accordance with the Accomplishment Instructions of Fokker SB F50-53-054, dated May 1 2000. Note: RLD AD 2000-152 refers. Compliance: Within the next 12,000 flight cycles after installation of the TCAS antenna. This Airworthiness Directive becomes effective on 22 February 2001. Background: During a product review, Fokker Services discovered that the structural provisions for the installation of the Traffic Collision Avoidance System (TCAS) top antenna do not meet the pertinent requirements. This condition, if not corrected, could result in reduced service life of the affected structure. This Directive requires installation of an external doubler under the antenna. David Alan Villiers Delegate of the Civil Aviation Safety Authority 12 January 2001 The above AD is notified in the Commonwealth of Australia Gazette on 24 January 2001.