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 12/23 Amdt 1 Main Rotor Blade, Anti Node Weight Retention - Inspection 5/80 Applicability: All models UH-12D, UH-12E and UH-12E(4 place) fitted with main rotor blades assembly "Parson" P/N 2253-1101-03. Requirement: To prevent failure of the anti node retention system of the main rotor blade of referenced P/N perform the following: 1. Remove the antinode bar assembly per para. 4.53 of UH-12E/ UH-12L series structural repair manual. 2. Clean the thread outboard of the antinode weight anchor nut. 3. Using a micrometer, measure the thread major diameter (a) If the rod thread major diameter is between .3678 and .3750 inches reassemble rod and return the blade to service. (b) If the rod thread major diameter is .3677 inches or less the antinode rod must be replaced before the blade is returned to service. Note. Hiller Aviation SB No. 51-4 refers. Compliance: Unless already accomplished, within 10 hours time in service after 16 October 1978. Background: The inspection requirements for Parsons P/N 2253-1101-04 blades are now promulgated in AD/HILLER 12/28.