COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 737 Series Aeroplanes AD/B737/105 Rudder Trim Switch 6/97 Applicability: All Boeing Model 737 -300, -400, -500 aeroplanes identified in Boeing Service Bulletin 737-27A1198 dated 6 June 1996. Requirement: Unless previously incorporated, replace the Aileron/Rudder trim control module in accordance with Service Bulletin 737-27A1198. Note: FAA AD 97-06-09 Amdt 39-9966 refers. Compliance: Prior to 22 May 1999. This Airworthiness Directive becomes effective on the 22 May 1997. Background: Operators have reported unwanted rudder trim motion occurring with the rudder trim actuator after the pilot had adjusted the trim and released the trim switch. This AD mandates the replacement of the module to provide a more reliable module and switch to help prevent the identified condition.