COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Hiller UH-12 Series Helicopters AD/HILLER 12/17 Amdt 4 Applicability: All models. Control Rotor Blade Assemblies 3/87 Requirement: Action in accordance with Fairchild Hiller SB No 36-1 Rev 3. Compliance: At each scheduled inspection for Maintenance Release issue. Background: Amendment 4 to this Directive aligns the repetitive inspections with that for issue of Maintenance Release.