COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Aermacchi - Lockheed AL 60 Series Aeroplanes AD/AL 60/8 Rudder Torque Tube - Modification 6/64 Applicability: Models AL 60 and AL 60B. Requirement: Modify the rudder torque tube by drilling a 3/16 in. hole in the lower portion of the torque tube 3/8 in. above the lower bearing as shown in Figure 1 of Aeronautica Macchi Modification Bulletin No. 19. Compliance: Before 1 September 1971.