COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Airtractor AT-300, 400 and 500 Series Aeroplanes AD/AT/6 Amdt 1 Fuselage Fittings - Vertical Fin Front Spar Attachments - Inspection and Modification 11/83 Applicability: All models AT-300, AT-301, AT-302 with S/Nos. 0001 to 0240. Document: 1. Snow Engineering Co. Service Letter No. 26 and 2. Snow Engineering Co. Service Letter No. 47. Note: FAA AD 83-18-01 refers. Compliance: 1. Within 100 hours time in service after 31st July 1983 and thereafter at intervals not exceeding 100 hours time in service. 2. Modification - prior to 2000 hours time in service. Background: The manufacturer reports that service history indicates cracking of attachment fittings. Amendment 1 of this AD details Snow Engineering Co. Service Letter No. 26 for the repetitive inspection and notes the issue of FAA AD 83-18-01.