COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Beechcraft 90 and 65-90 (King Air) Series Aeroplanes AD/BEECH 90/36 Amdt 1 Wing Structural Fatigue Limitation 5/79 Applicability: All Model E90 aircraft with centre-section and outer wing main spar lower caps exceeding 13000 hours' time in service. Requirement: Retire from service the centre-section and outer wing main spar lower caps including the centre-section to the outer wing attachment fittings. This life limitation assumes an average mean flight cruise weight of 9300 pounds and one landing per hour. Should the mean cruise weight, averaged over the life of the aircraft be greater than 9350 pounds or should landings occur on average at a greater frequency than one every 45 minutes, the Secretary must be advised. Note: On the basis of the currently available fatigue substantiation for the aircraft, only one spar cap replacement is permitted. Any proposal for a further extension in life incorporating a second spar change must be supported by a substantiation covering all the remaining primary structure including empennage, control surface hinge arms etc. This substantiation must incorporate a safe life assessment, or a sufficiently rigorous revised inspection schedule to ensure that any fatigue cracking which could occur in service will be detected before the aircraft is endangered. A third spar change will not be permitted. Effective: 30 April 1975.