COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 320 Series Aeroplanes AD/CESSNA 320/19 Amdt 1 Wing and Airframe 10/95 Applicability: All Cessna Model 320 Series aircraft. Requirement: 1. Retire the wing main spar lower cap and wing upper and lower attachment fittings from service. Note: The centre section spar caps and attachment fittings are not affected by this Requirement. 2. Retire the remainder of the airframe from service. Compliance: 1. Retire components, in accordance with Requirement 1, before exceeding 19 200 hours time in service or 29 500 flights, whichever occurs first. 2. Retire airframe, in accordance with Requirement 2, before exceeding 38 400 hours time in service or before 59 000 flights, whichever occurs first. Note 1: For aircraft with an unknown number of flights an estimate shall be made by dividing the number of hours flown by an average flight time of 0.5 hours. Note 2: The available fatigue data covers wing main spars only. The durability of other parts of the airframe has not been evaluated, and is therefore unknown. Based on experience, the Authority is prepared to credit unevaluated structure with a retirement life equal to double the life for the wing spar (Requirement 2). An extension beyond this may be available, but any application must be supported by a fatigue substantiation covering all the remaining primary structure. This should include empennage, wing centre section, wing rear spar, control surfaces, fuselage, etc. The substantiation may take the form of 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. Background: Results of full scale fatigue testing of the wing, flight load data analysis and fleet usage have been used to extend the model 320 wing and attachment fitting fatigue life. The remainder of the airframe is allowed two wing spar lives without further substantiation.