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-6/38 Horizontal Stabiliser Inspection 7/93 Applicability: All Pilatus Porter PC-6 series aircraft. Requirement: Retire the horizontal stabiliser; or Modify the horizontal stabiliser and inspect for cracks in accordance with a scheme approved by the Authority. Note: Aeronautical Designs Australia Pty Ltd EO-934 is an approved scheme for the purpose of this Directive. Compliance: Retire before 10000 hours component time in service; or Modify and inspect before 10000 hours component time in service. Re-inspect at intervals not exceeding 100 hours. Background: The Pilatus Porter horizontal stabiliser has a history of fatigue cracking in service. Inspection access to some cracking sites is very restricted. This AD gives two options: retire before cracks are likely to start; or improve access and inspect.