{"id":"F2006B03124","name":"AD/B747/223 - Diagonal Brace Underwing Fitting Bolts","slug":"ad-b747-223-diagonal-brace-underwing-fitting-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42496,"registerId":"commonwealth-F2006B03124-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 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.","sortOrder":0},{"sectionNumber":"AD/B747/223 Diagonal Brace Underwing Fit","sectionType":"part","heading":"AD/B747/223 Diagonal Brace Underwing Fitting Bolts 5/2000","content":"# AD/B747/223 Diagonal Brace Underwing Fitting Bolts 5/2000\n\nApplicability: Model 747-100, \\-200, and 747SP series aircraft, with line numbers 1 through 567, and equipped with aluminium diagonal brace underwing fittings.\n\nRequirement: Inspect in accordance with the technical requirements of FAA AD 2000-03-22 Amdt 39-11582.\n\nNote: Boeing Service Bulletins 747-53A2308 and 747-57-2288 Revision 1 refer.\n\nCompliance: As specified in the Requirement document for the initial and repetitive inspections and eventual bolt replacement, with a revised effective date of 18 May 2000.\n\nThis Airworthiness Directive becomes effective on 18 May 2000.\n\nBackground: The FAA received reports of damaged, broken, and corroded taperlock bolts of the engine strut diagonal brace underwing fittings on the outboard strut due to stress corrosion cracking. Loss of the underwing fitting load path due to missing, damaged, or broken taperlock bolts, could result in separation of the engine and strut from the aircraft.\n\n![Signature of Bernard Malcolm Hole, Delegate of the Civil Aviation Safety Authority.](image.003.png)  \n\nBernard Malcolm Hole\n\nDelegate of the Civil Aviation Safety Authority 31 March 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 19 April 2000.","sortOrder":1}],"analysis":{"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD remains tightly focused on a single technical unsafe condition: stress corrosion cracking of taperlock bolts at the diagonal brace underwing fittings on early-model 747s. It does not expand the regulatory reach beyond that original safety purpose. The AD accomplishes that purpose by mandating inspections and replacement per the referenced FAA AD and Boeing service bulletins, rather than adding new unrelated obligations or broader regulatory programs."},"complexity_factors":["Short standalone AD text (single-page length)","Single, focused technical issue (taperlock bolts on diagonal brace underwing fittings)","Limited number of affected models and line numbers specified (Models 747-100, -200, 747SP; line numbers 1–567)","Primary reliance on external documents (cross-reference to FAA AD 2000-03-22 and two Boeing Service Bulletins)","Compliance logic delegated to the referenced FAA AD and manufacturer service bulletins rather than embedded detailed procedures","One clear compliance timeline (effective date 18 May 2000) with initial and repetitive inspections plus eventual replacement"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA). It requires specific inspections and, where necessary, replacement of taperlock bolts that secure the diagonal brace underwing fittings on certain Boeing 747 aircraft. (See \"Requirement\" and \"Applicability\".)\n- The AD directs operators to carry out those inspections and any follow-up work in accordance with the technical requirements of FAA AD 2000-03-22 and the Boeing Service Bulletins it cites (Boeing SBs 747-53A2308 and 747-57-2288 Revision 1). (See \"Requirement\" and the Note.)\n- The AD sets the compliance regime (initial inspections, repeat inspections, and eventual bolt replacement) and has an effective date of 18 May 2000. (See \"Compliance\" and the effective date statement.)\n\n**Who is affected**\n\n- Owners and operators of Boeing Model 747-100, -200 and 747SP series aircraft with line numbers 1–567 that are equipped with aluminium diagonal brace underwing fittings. (See \"Applicability\".)\n- Maintenance organisations and mechanics who perform inspections and bolt replacements to meet the AD.\n- Potentially airlines’ operational planners and parts suppliers because of inspection scheduling, bolt procurement and aircraft downtime.\n\n**Why the AD was issued (stated safety problem)**\n\n- The FAA reported damaged, broken and corroded taperlock bolts in the engine strut diagonal brace underwing fittings due to stress corrosion cracking. Loss of those bolts could remove the underwing fitting load path and risk separation of the engine and strut from the aircraft. The AD is directed at correcting that unsafe condition. (See \"Background\".)\n\n**How it works in practice**\n\n- CASA requires the inspections and corrective actions specified in FAA AD 2000-03-22; operators must follow the inspection schedule, repeat intervals and replacement instructions that document prescribes. (See \"Requirement\" and \"Compliance\".)\n- The AD cross‑references Boeing service bulletins for technical details and procedures. Operators will typically use those service bulletins and approved maintenance data to perform the work. (See Note.)\n- The safety regulator (CASA) has imposed a legally binding requirement; failure to comply can affect the aircraft’s legal ability to fly and may expose operators to enforcement action.\n\n**Costs, incentives and trade-offs (practical effects to watch for)**\n\n- Who pays: aircraft operators bear the direct costs — labour for inspections, parts for bolt replacement, and the opportunity cost of aircraft downtime. (See \"Compliance\" and \"Requirement\".)\n- Concentrated benefit / diffuse cost: the safety benefit is concentrated (reduced risk of engine/strut separation) while the cost is concentrated on the specific operators of affected 747s; third parties (passengers, the public) receive the safety benefit but do not pay directly.\n- Implementation and compliance burden: the AD relies on an FAA AD and manufacturer service bulletins (cross‑jurisdictional and technical documents). That creates administrative work to obtain, interpret and apply the referenced documents, and may impose supply and scheduling challenges when many operators require replacement bolts or maintenance slots.\n- Behavioural effects and substitution: operators may increase inspection frequency, accelerate bolt replacement, or consider retiring/recertifying older aircraft to avoid ongoing maintenance costs. Those choices affect fleet availability, leasing decisions, and secondary‑market values.\n- Risk of unintended consequences: concentrated maintenance demand could strain parts availability or maintenance capacity; increased downtime can raise costs or force schedule changes. These are operational risks rather than changes to the regulatory requirement itself.\n\n**Who decides and how discretion is used**\n\n- CASA (acting through the delegate who signed the AD) sets the mandatory requirement and effective date under the Aviation Regulations cited in the AD. (See the opening paragraph and the signed delegate statement.)\n- The AD delegates technical execution to operators and their approved maintenance organisations, who must follow the FAA AD and Boeing SBs for the specific inspection and replacement procedures.\n\n**What to check if you operate an affected aircraft**\n\n- Confirm whether your aircraft falls in the applicability set (Model 747-100, -200, 747SP, line numbers 1–567, aluminium diagonal brace underwing fittings). (See \"Applicability\".)\n- Obtain and follow FAA AD 2000-03-22 and the Boeing service bulletins cited for the exact inspection intervals, methods and replacement parts. (See \"Requirement\" and Note.)\n- Plan for inspections, recurring inspection costs and timing for eventual bolt replacement as specified in the compliance document. (See \"Compliance\".)\n\n(Sections cited: Applicability; Requirement; Compliance; Background; Note.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific mechanical failure mode (stress corrosion cracking in taperlock bolts) on a defined subset of Boeing 747 aircraft. It does not expand beyond this safety-critical maintenance requirement."},"complexity_factors":["Short, single-purpose directive (approximately 300 words)","Only 4 defined applicability criteria (aircraft models, line numbers, fitting material)","Single requirement that cross-references external technical documents (FAA AD and Boeing Service Bulletins) rather than reproducing them inline","No nested exceptions or conditional logic — straightforward 'inspect and replace' mandate","Minimal legislative cross-referencing (only cites CAR 1998 subregulation 39.1(1) as enabling power)"],"plain_english_summary":"This AD mandates inspections and eventual replacement of the bolts attaching the diagonal brace underwing fittings on Boeing 747‑100, 747‑200 and 747SP (line numbers 1–567) with aluminium fittings, due to stress‑corrosion cracking that could lead to bolt failure and engine/strut separation. Operators must follow FAA AD 2000‑03‑22 and Boeing Service Bulletins 747‑53A2308 and 747‑57‑2288 Rev 1. Effective 18 May 2000."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-223-diagonal-brace-underwing-fitting-bolts","history":"/api/acts/ad-b747-223-diagonal-brace-underwing-fitting-bolts/history","analysis":"/api/acts/ad-b747-223-diagonal-brace-underwing-fitting-bolts/analysis","conflicts":"/api/acts/ad-b747-223-diagonal-brace-underwing-fitting-bolts/conflicts","importantCases":"/api/acts/ad-b747-223-diagonal-brace-underwing-fitting-bolts/important-cases","documents":"/api/acts/ad-b747-223-diagonal-brace-underwing-fitting-bolts/documents"}}