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-6/28 Amdt 1 Wing Strut Attachment - Inspection 12/80 Applicability: All models with S/Nos. 338 to 701. Document: Pilatus SB No. 93. Compliance: At intervals not exceeding 100 hours time in service. Background: Service experience indicates that the inspection for corrosion in the wing strut attachment can be extended to 100 hourly intervals.