{"id":"F2006B03097","name":"AD/B747/197 - Wing Centre Section Rear Spar Web","slug":"ad-b747-197-wing-centre-section-rear-spar-web","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42469,"registerId":"commonwealth-F2006B03097-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/197 - Wing Centre Section Rear Spar Web","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBoeing 747 Series Aeroplanes\n\nAD/B747/197 Wing Centre Section Rear Spar Web 3/99\n\nApplicability: Model 747 series aircraft, line positions 1 through 816.\n\nRequirement: 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.\n\n    If no corrosion is detected during the inspection, apply corrosion inhibitor in accordance with the Requirement Document.\n\n    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:\n\n    Remove the corrosion in accordance with the Requirement document.\n\n    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.\n\n    c. Apply corrosion inhibitor in accordance with the Requirement document.\n\n    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.\n\nNote: FAA AD 98-26-23 Amdt 39-10966 refers.\n\nCompliance: Before 2 August 2000 for the initial inspection, thereafter repeat the inspection at intervals not to exceed 2 years.\n\nThis Airworthiness Directive becomes effective on 25 March 1999.\n\nBackground: 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.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope: addressing a specific corrosion issue in a specific aircraft model at a specific location. It has not expanded beyond its original safety purpose."},"complexity_factors":["Short, single-purpose directive (approximately 300 words)","Only 1 defined term implicitly used ('Requirement Document' referring to the Boeing Service Bulletin)","Simple conditional logic with 3 clear branches (no corrosion / corrosion within limits / corrosion exceeds limits)","Minimal cross-referencing (one FAA AD reference in a note, one Boeing Service Bulletin)","Clear compliance deadline and recurring interval","No nested exceptions or sub-subsections"],"plain_english_summary":"This safety order requires operators of early-production Boeing 747s (serial positions 1–816) to inspect the wing centre rear spar web and adjacent fittings for corrosion, with an initial visual check before 2 August 2000 and repeats every two years. Depending on findings, crews must treat, test, and protect affected areas or ground the aircraft until Boeing authorises repairs. It’s mandatory to prevent structural failure and fuel leaks."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive remains narrowly focused on detecting and remedying corrosion at a specific location (wing centre section rear spar web and adjacent bulkhead fittings at body station 1241). It prescribes inspections, conditional removal and HFEC checks, and Boeing‑approved repairs where required. Referencing revisions of the Boeing Service Bulletin does not materially broaden the AD's purpose; it retains the original safety‑limited scope of corrosion detection and repair rather than adding unrelated obligations or expanding the affected fleet beyond the specified line positions."},"complexity_factors":["Limited applicability (specific to Boeing 747 series, line positions 1–816)","Three conditional branches depending on inspection outcome (no corrosion; corrosion within limits; corrosion exceeding limits)","Dependency on an external technical document (Boeing Service Bulletin 747-57-2263, Revision 1 or 2, including Appendix A)","Requirement for an additional non-visual inspection method (HFEC) after corrosion removal","Specified compliance timing: initial deadline and a fixed repeat interval (2 years)","Mandate that repairs be \"Boeing‑approved\" introduces an approval dependency rather than detailed repair instructions in the AD"],"plain_english_summary":"**What this directive does (mechanics first)**\n\n- Applies to Boeing 747 series aeroplanes with line positions 1–816.  It requires operators to carry out a detailed visual inspection of the wing centre section rear spar web and the nearby bulkhead fittings at body station 1241, following the procedures in Boeing Service Bulletin 747-57-2263 (Revision 1 or 2, including Appendix A).\n\n- Timing: the initial inspection had to be done before 2 August 2000; after that, the inspection must be repeated at intervals not exceeding 2 years.\n\n- Actions depending on what the inspection finds:\n  - If no corrosion is found: apply a corrosion inhibitor as described in the Boeing document.\n  - If corrosion is found but is within the limits set in the Boeing document:\n    - Remove the corrosion per the Boeing document.\n    - Perform a high frequency eddy current (HFEC) inspection of the area where corrosion was removed to check for cracking.\n    - If any crack is found, perform a Boeing‑approved repair before the aeroplane flies again.\n    - Then apply the corrosion inhibitor per the Boeing document.\n  - If corrosion is found and it exceeds the limits in the Boeing document: carry out a Boeing‑approved repair before further flight.\n\n- Who decides and who pays:\n  - The operator (or the maintenance organisation they hire) must carry out the inspections, removals and inhibitor applications. Repairs that are required because of cracking or excessive corrosion must be Boeing‑approved repairs; that approval process and the repair work impose time and repair‑cost obligations on the operator.\n  - The civil aviation authority (the Airworthiness Directive) enforces compliance; the Service Bulletin specifies the technical steps.\n\n**Why the directive was issued (official rationale and testing that claim)**\n\n- The stated reason is that the FAA received reports of corrosion on the rear spar web and adjacent bulkhead fittings at body station 1241. The AD says undetected corrosion could lead to cracking of the rear spar web and consequent fuel leakage.\n\n- Practical implications of that rationale:\n  - Benefit to safety: detecting and removing corrosion, checking for cracks, and repairing before flight is targeted at preventing structural crack growth and fuel leaks.\n  - Costs and incentives: operators bear the inspection, removal and repair costs and aircraft downtime. Those costs create an incentive to ensure inspections are done efficiently and, where possible, to schedule work into routine maintenance checks to lower disruption.\n  - Dependence on manufacturer material: the AD requires compliance with a Boeing Service Bulletin. That means the exact limits, removal procedures, inspection detail (HFEC technique) and inhibitor specification are set by Boeing's documented procedures rather than written out in the AD itself. Compliance therefore depends on the content of the Service Bulletin (and its revisions), and operators must follow that manufacturer document to meet the AD.\n\n**Implementation, compliance risk and trade‑offs**\n\n- Inspection effectiveness depends on the quality of the visual inspection and the HFEC inspection that follows corrosion removal. Both require appropriately trained maintenance personnel and calibrated inspection equipment.\n\n- Downtime and repair lead times are the main economic costs to operators: if corrosion exceeds limits or cracking is found, the aircraft cannot fly until a Boeing‑approved repair is completed. That can affect airline scheduling and revenue.\n\n- The requirement to use a Boeing‑approved repair concentrates decision authority over major repairs (repair method and approval) with Boeing or an approved design authority; operators have limited freedom to use alternative repair designs unless approved.\n\n- Enforcement is straightforward (inspection records, repair approvals), but the practical burden falls on operators and their maintenance organisations.\n\n**Concrete distribution of effects**\n\n- Who benefits: passengers, crew and fleet operators benefit from reduced risk of structural failure or fuel leakage; regulators benefit from a clear, enforceable safety action.\n- Who bears the cost: aircraft operators (and their maintenance providers) pay for inspections, materials (corrosion inhibitor), removal work, HFEC inspections and any repairs, including downtime costs.\n\n**Reference to official material**\n\n- The AD references Boeing Service Bulletin 747‑57‑2263 (Rev 1 or 2, incl. Appendix A) for the technical steps, and notes FAA AD 98‑26‑23 for related action.\n\n(Sections referenced: Applicability; Requirement steps 1–3; Compliance interval; Background.)"},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-197-wing-centre-section-rear-spar-web","history":"/api/acts/ad-b747-197-wing-centre-section-rear-spar-web/history","analysis":"/api/acts/ad-b747-197-wing-centre-section-rear-spar-web/analysis","conflicts":"/api/acts/ad-b747-197-wing-centre-section-rear-spar-web/conflicts","importantCases":"/api/acts/ad-b747-197-wing-centre-section-rear-spar-web/important-cases","documents":"/api/acts/ad-b747-197-wing-centre-section-rear-spar-web/documents"}}