AIRWORTHINESS DIRECTIVE On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CESSNA 180/15 Amdt 3 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section. Cessna 180, 182 and Wren 460 Series Aeroplanes AD/CESSNA 180/15 Amdt 4 Rear Spar 8/2004 Applicability: All models except those with rear spars P/Nos. 0523400-90 L.H. and -91 R.H.; 0523400-111 L.H. and -112 R.H.; 0726014-1 L.H. and 0726014-2 R.H. Note 1: Restart series Cessna 182s have rear spars part numbers 0726014-1 L.H. and 0726014-2 R.H. Requirement: 1. Modify the rear spar root, of the left and right mainplanes on all aeroplanes engaged in agricultural operations in accordance with Rex Aviation Drawing RA- 491 or an alternative scheme approved by the Secretary. 2. Inspect the mainplane rear spar web for fatigue cracks in the root area. These cracks originate in the radius which is located under the attachment fittings. This inspection shall be carried out using a magnifying glass of at least 4X' magnification or alternatively a device such as the "Syte Ade" may be employed. 3. Inspect the upper flange of the rear spar channel at the outer end of the attachment fitting. This can be done via the flap bay inner inspection panel. Since the trailing edge root end fits closely to the spar, it may be difficult to detect possible cracks, therefore when doubt exists the trailing edge root end rib shall be removed for more detailed inspection. Note 2: The affected area is illustrated in Rex Aviation Technical Memorandum No. 12 dated 10 May 1960. Compliance: Para. 1 - Unless already accomplished, before further flight after the effective date of this Airworthiness Directive. Paras. 2 and 3 - Aeroplanes modified to Rex Aviation Drawing RA-491 - at intervals not exceeding 500 hours time in service. For all other aeroplanes: at intervals not exceeding 100 hours time in service. This Amendment becomes effective on 5 August 2004. Cessna 180, 182 and Wren 460 Series Aeroplanes AD/CESSNA 180/15 Amdt 4 (continued) Background: Amendment 4 has been issued to remove the requirement for Restart series Cessna 182 aircraft to comply with this directive. Restart series C182s have a different part number rear spar to the original models. David Villiers Delegate of the Civil Aviation Safety Authority 21 June 2004 The above AD is notified in the Commonwealth of Australia Gazette on 14 July 2004.