COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 747 Series Aeroplanes AD/B747/197 Wing Centre Section Rear Spar Web 3/99 Applicability: Model 747 series aircraft, line positions 1 through 816. Requirement: Perform a detailed visual inspection to detect corrosion of the rear spar web of the wing centre section and adjacent bulkhead fittings at body station 1241, in accordance with Boeing Service Bulletin 747-57-2263, Revision 1, or Revision 2, including Appendix A. 1. If no corrosion is detected during the inspection, apply corrosion inhibitor in accordance with the Requirement Document. 2. If any corrosion is detected during the inspection, and the corrosion is within the limits specified by the Requirement document, accomplish the following actions: 1. Remove the corrosion in accordance with the Requirement document. b. Perform a high frequency eddy current inspection to detect cracking in the area of removed corrosion in accordance with the Requirement document. If any crack is detected, before further flight carry out a Boeing approved repair. c. Apply corrosion inhibitor in accordance with the Requirement document. 3. If any corrosion is detected during the inspection, and the corrosion exceeds the limits specified by the Requirement document, before further flight carry out a Boeing approved repair. Note: FAA AD 98-26-23 Amdt 39-10966 refers. Compliance: Before 2 August 2000 for the initial inspection, thereafter repeat the inspection at intervals not to exceed 2 years. This Airworthiness Directive becomes effective on 25 March 1999. Background: The FAA received reports of corrosion found on the wing centre section rear spar web and adjacent bulkhead fittings at body station 1241. Undetected corrosion could cause cracking of the rear spar web and result in fuel leakage.