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 12/28 Main Rotor Blade Anti-Node Bar - Inspection 5/80 Applicability: All models UH-12D, UH-12E, UH-12E4, H-23F, OH-23G and all models converted by STC178WE or STC177WE, equipped with main rotor blades Parsons P/N 2253- 1101-04. Document: Hiller Aviation SB No. UH-12-51-5. Compliance: As per requirement document. Background: The manufacturer states that anti-node bars with machine cut threads may be installed on certain main rotor blades of the subject P/N 2253-1101-04. Note: The requirement for inspection of these blades has been removed from AD/HILLER 12/23 to this Directive.