COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES DH 104 (Dove) Series Aeroplanes AD/DH 104/33 Nose Undercarriage Inner Casing - Inspection and Replacement 10/73 Applicability: All models. Document: Hawker Siddeley TNS CT(104) No. 232. Compliance: 1. Inspect casing in accordance with paras. 3.5 and 4.1 of TNS CT(104) No. 232 within 50 hours time in service after 29 October 1973 and thereafter at intervals not exceeding 600 hours time in service and after any reported heavy landings. 2. Replace casing in accordance with para. 3.2 of TNS CT(104) No. 232 before 17 March 1975.