COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 737 Series Aeroplanes AD/B737/84 Main Rudder Power Control Unit (PCU) 5/95 Applicability: All Boeing 737 series aircraft fitted with Part Number/Serial Number PCU's as Listed in the Requirement Document which have been modified and/or tested by Aerocontrols Inc. in Auburn, Washington. Requirement: Action in accordance with the technical requirements of FAA Telegraphic AD T95-06-53. Note: CAO 105 AD/B737/79 makes reference to Boeing SB 737-27-1185 and FAA AD 94-01-07 which are called up as Ref B and E, respectively, in the Requirement document. Compliance: As specified in the Requirement Document. Background: The FAA has advised that two reports of in-service malfunctions of certain rudder PCU's has been reported. The PCU's were removed from the aircraft and subsequently failed their functional tests. Subsequent investigation confirmed that during modification of the PCU the proper tooling may not have been used to torque the spring retainer.