COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron 212 Series Helicopters AD/BELL 212/46 Main Rotor Drag Brace Assembly 7/91 Applicability: All models. Requirement: Action in accordance with the Technical Requirements of FAA AD 90-26-11, Amendment 39-6840. Compliance: In accordance with the Requirement document with revised effective date 11 July 1991. Background: Eight reports of drag brace assembly cracking have been attributed to high cycle, low stress fatigue. The cracks had gone undetected at daily visual inspections and were not actually detected until after hub assembly overhaul.