COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pilatus Britten-Norman BN-2 Series Aeroplanes AD/BN-2/50 Tailplane Skin and Structure - Inspection and Rectification 7/85 DM Applicability: All models. Document: Pilatus Britten-Norman S.B. BN-2/SB.131 Issue 2. Compliance: Within 100 hours time in service after 31 July 1985 or at the next scheduled inspection for Maintenance Release issue after 31 July 1985 whichever is the later, and thereafter at intervals not exceeding 500 hours time in service. Background: The manufacturer has received reports of some instances of deterioration of tailplane riveting and internal rib structure.