COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES American Champion (Aeronca, Bellanca) Series Aeroplanes AD/CHA/15 Wing Front Strut Aerobatic Fatigue Life Limitation 4/76 Applicability: All model 8KCAB aircraft. Requirement: Retire the wing front strut assembly, including the aluminium end fittings, from service. Compliance: Before achieving 1100 aerobatic flying hours. Note: The hours are those actually spent in aerobatic flight and do not include positioning time.