COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Piper PA-18 and 19 (Super Cub) Series Aeroplanes AD/PA-18/3 Fuel Selector Lever - Guard Installation NK Applicability: All models. Requirement: Install a suitable guard to prevent the possibility of inadvertent operation of the fuel selector lever. A wooden block at least 1 inch thick, shaped to clear the arc of the lever, and attach to the existing indicator plate, would be suitable for the purpose. Compliance: Forthwith.