COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pilatus Porter PC-6 Series Aeroplanes AD/PC-6/13 Elevator Attachment Bracket - Inspection 1/67 Applicability: All models prior to S/Nos. 621 not modified in accordance with SB No. 67. Document: Pilatus SB No. 67. Compliance: Inspect with the aid of dye penetrant at intervals not exceeding 100 hours time in service after 15 January 1967.