COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Navion Series Aeroplanes AD/NAV/2 Rudder Horn - Inspection NK Applicability: All models from Navion to Navion H fitted with Rudder Horn P/N 145-24401. Requirement: Inspect the rudder horn for corrosion and cracking. Compliance: Within 100 hours time in service after 28 November 1968, and thereafter at intervals not exceeding 12 months.