COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Aerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes AD/TB20/26 Amdt 3 Rudder Balance Weight 6/98 Applicability: Model TB20 and TB21 aircraft with serial numbers 1 through 1554, 1754 through 1757, and 1767 through 1821. Requirement: Action in accordance with Socata TB Service Bulletin 10-071-55 Revision 3. Note: DGAC AD 93-012 (A) R2 refers. Compliance: For aircraft serial numbers 1 through 1554: Before 31 August 1998. For aircraft serial numbers 1754 through 1757, and 1767 through 1821: Before 31 December 1998. This amendment becomes effective on 21 May 1998. Background: The DGAC requires certain measures to be taken to avoid development of galvanic corrosion between the balance weight and both rudder tip stiffeners. Amendment 1 reflected a requirement document revision which corrected text anomalies and material information. Amendment 2 reflected a requirement document revision which clarified applicability. Amendment 3 is issued in response to a revision of the related DGAC AD which reflects a revision of the Requirement document which expands applicability and compliance times. Amendment 2 to this airworthiness directive became effective on 26 May 1994. Amendment 1 to this airworthiness directive became effective on 22 July 1993. The original issue of this airworthiness directive became effective on 29 April 1993.