COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES DH114 (Heron) Series Aeroplanes AD/DH114/17 Landing Gear Actuator Piston - Inspection NK and Replacement Applicability: All models fitted with Dunlop actuators P/N AC 11130 in which pistons P/N AHO 19742 are installed. Requirement: 1. Remove the piston from the jack and inspect the piston crown for signs of cracking. 2. Remove from service Dunlop piston Part Number AHO 19742. Compliance: For Para. 1 - At intervals not exceeding 200 landings after 15 June 1966. For Para. 2 - Whenever a cracked piston crown is detected or at intervals not exceeding 5000 landings whichever occurs first. Note: Incorporation of Heron Mod. No. 1161 cancels these requirements. DH114 (HERON).