COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Wright Piston Engines AD/WRI/1 Accessory Drive Gear - Modification NK Applicability: GR1820-200 series. Requirement: 1. Modify engines fitted with a two speed supercharger drive in accordance with either of the following sub-paragraphs: (a) Replace accessory drive gear P/N 62336 with modified gear P/N 62336J; or (b) Modify the supercharger drive for single speed operation only. 2. Modify engines fitted with a single speed supercharger drive in accordance with either of the following sub-paragraphs: (a) Replace accessory drive gear P/N 62336 with modified gear P/N 62336J; or (b) Replace existing gear P/N 62336 with a new gear P/N 62336 which has been reworked in accordance with paragraph 3 of this Order. 3. Rework gears P/N 62336 to remove all signs of grinding marks in the fillets at the roots of the gear teeth. Great care must be taken during the rework and the polishing operation must be confined to the radius of each fillet and must NOT extend up the flank of the tooth. The gear shall be checked with the aid of an approved crack detecting apparatus prior to installation in the engine. New gears only shall be reworked and unmodified gears which have been in service shall be rejected; or ANO 106.1.17.4.5.1 Compliance: Forthwith.