{"id":"F2006B02667","name":"AD/B727/144 Amdt 1 - Wing Centre Section Front Spar Web","slug":"ad-b727-144-amdt-1-wing-centre-section-front-spar-web","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41983,"registerId":"commonwealth-F2006B02667-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/144 Amdt 1 - Wing Centre Section Front 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)  \n![](image.002.png)  \nBoeing 727 Series Aeroplanes\n\nAIRWORTHINESS 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 revokes Airworthiness Directive (AD) AD/B727/144 and issues the following 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.\n\nAD/B727/144\n\nAmdt 1\n\n  \nWing Centre Section Front Spar Web 4/2000\n\nApplicability: Model 727 series aircraft, as listed in Boeing Service Bulletin 727-57-0177, dated 22 December 1988.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 2000-02-19 Amdt 39-11537.\n\nCompliance: As specified in the Requirement document for the repetitive inspections and modification action, with a revised effective date of 20 April 2000.\n\nThis Amendment becomes effective on 20 April 2000.\n\nBackground: Fleet experience had shown that there was a possibility of cracks developing in the wing centre section front spar web, if not corrected could lead to fuel leakage or depressurisation of the cabin.\n\nAmendment 1 is issued in response to a new FAA AD which was prompted by a report indicating that the optional terminating modification in the existing FAA AD does not adequately address the identified unsafe condition. This amendment requires a new terminating modification for the repetitive inspections.\n\nThe original issue of this Airworthiness Directive became effective on 3 March 2000.\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 9 March 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 22 March 2000.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose: addressing structural cracks in the wing centre section front spar web of Boeing 727 aircraft. The amendment does not expand scope — it merely strengthens the existing safety requirement by replacing an inadequate terminating modification with a more robust one, in direct response to new safety data."},"complexity_factors":["Short, single-purpose directive (approximately 300 words)","Only 3 defined structural elements (Applicability, Requirement, Compliance)","Single cross-reference to external technical document (FAA AD 2000-02-19) — actual technical requirements are incorporated by reference rather than reproduced","No nested exceptions or conditional logic — straightforward mandate with single amendment purpose","Clear linear structure: Background → Applicability → Requirement → Compliance → Effective date"],"plain_english_summary":"The Civil Aviation Safety Authority (CASA) replaces its earlier Boeing 727 safety order with an amended directive requiring continued inspections of the wing centre section front spar web and mandating a more robust, permanent repair where needed.  \n\nThis affects owners and operators of specified Boeing 727 series aircraft because cracks found in that spar can lead to fuel leaks or loss of cabin pressure; compliance follows the FAA service instructions and became effective 20 April 2000."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment changes the remedy required by the original AD rather than expanding the set of aircraft or creating new subject matter. The original AD allowed an optional terminating modification; Amendment 1 removes reliance on that optional fix and mandates a different terminating modification (per FAA AD 2000-02-19). Mechanically, the scope of obligation on operators increased because the acceptable terminating option was narrowed/replaced, which raises compliance requirements (more prescriptive remedy) though the fleet applicability and core safety objective remain the same."},"complexity_factors":["Short instrument (single-page AD) with limited internal detail","Direct cross-reference to FAA AD 2000-02-19 Amdt 39-11537 for technical requirements (external dependency)","Cross-reference to Boeing Service Bulletin 727-57-0177 (applicability list) dated 22 Dec 1988","Repetitive inspections plus a terminating modification create conditional compliance paths (inspections until modification)","Amendment replaces previously optional terminating modification with a new terminating modification (change of remedy rather than broadening applicability)","Specific compliance effective date (20 April 2000) but the AD relies on external documents for intervals and procedures"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Revokes a previous Australian Airworthiness Directive (AD/B727/144) and replaces it with Amendment 1. (See heading and amendment language.)\n- Requires operators of certain Boeing 727 series aeroplanes (those listed in Boeing Service Bulletin 727-57-0177, dated 22 December 1988) to carry out the inspections and modification work described in FAA Airworthiness Directive 2000-02-19 (Amendment 39-11537). (Applicability; Requirement.)\n- Keeps the same pattern of repetitive inspections and a terminating modification, but replaces the previously optional terminating modification with a different (new) terminating modification. Compliance timing is fixed with an effective date of 20 April 2000. (Requirement; Compliance; Background.)\n\nWho this affects\n\n- Aircraft operators (airlines, charter operators, aircraft owners) who operate Boeing 727 series aeroplanes listed in the Boeing service bulletin referenced. (Applicability.)\n- Maintenance organisations and engineers who must carry out the repetitive inspections and the required modification work in accordance with the FAA AD and Boeing service instructions. (Requirement.)\n\nWhy it matters (stated purpose and mechanical effect)\n\n- Stated safety concern: in-service experience showed cracks may form in the wing centre section front spar web; if uncorrected, such cracks could lead to fuel leakage or cabin depressurisation. The AD requires inspections and a modification to correct that unsafe condition. (Background.)\n- Mechanically, the AD forces either repeated inspections on a defined schedule or (now) a specified terminating modification that ends the need for the repetitive inspections. The amendment changes which modification terminates the inspections because the previously optional terminating modification was judged inadequate. (Requirement; Background.)\n\nClaims about purpose and a brief assessment of trade-offs\n\n- Source claim: the amendment is required because the optional terminating modification previously allowed does not adequately address the unsafe condition (Background). If true, the change narrows operators' compliance choices toward a more robust fix.\n- Costs and incentives: operators pay for additional inspections, labour and materials, and for the terminating modification if they choose it. The terminating modification will likely be more costly upfront but may remove recurring inspection costs and aircraft downtime. (Requirement; Compliance.)\n- Implementation risk and compliance burden: CASA enforces the FAA AD requirements by reference; this creates dependency on the FAA AD text and the Boeing service bulletin for technical detail. That increases operational complexity because Australian operators must follow foreign AD instructions precisely. (Requirement; Applicability.)\n- Bureaucratic discretion: the CASA delegate exercised regulatory power under subregulation 39.1(1) of CAR 1998 to revoke and reissue the AD with a different terminating action. The AD ties the technical specification to the FAA AD and Boeing service bulletin rather than reproducing detailed steps in the Australian instrument. (Introductory paragraphs; Requirement.)\n\nPractical effects on private choice and markets\n\n- Who pays: aircraft operators bear the direct costs (inspection labour, parts, modification work, aircraft downtime). Maintenance providers receive work but must follow specific technical instructions.\n- Behaviour change: operators must either continue repetitive inspections until they perform the new terminating modification or perform that terminating modification to stop inspections. This reduces the option value of choosing the earlier, optional terminating modification (that option has been withdrawn). (Requirement; Background.)\n- Competition and productivity: compliance imposes a compliance cost that may be proportionally heavier on smaller operators with few affected aircraft. Larger operators may be able to spread costs across fleet and thus adopt the terminating modification sooner.\n\nWhere to find the technical detail\n\n- The AD requires compliance with FAA AD 2000-02-19 Amdt 39-11537 and the Boeing Service Bulletin 727-57-0177 dated 22 December 1988 for exact inspection intervals, procedures and modification steps. The Australian instrument does not replicate those technical steps; it mandates them by reference. (Applicability; Requirement.)\n\nNet mechanical summary\n\n- In short: if you operate one of the listed Boeing 727s, you must follow the FAA AD and Boeing service bulletin to inspect the wing centre-section front spar web repeatedly and perform the newly required terminating modification (which replaces the previously optional one). The change is intended to eliminate an unsafe condition (cracking), and shifts the compliance option set toward a mandated corrective modification.\n"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-144-amdt-1-wing-centre-section-front-spar-web","history":"/api/acts/ad-b727-144-amdt-1-wing-centre-section-front-spar-web/history","analysis":"/api/acts/ad-b727-144-amdt-1-wing-centre-section-front-spar-web/analysis","conflicts":"/api/acts/ad-b727-144-amdt-1-wing-centre-section-front-spar-web/conflicts","importantCases":"/api/acts/ad-b727-144-amdt-1-wing-centre-section-front-spar-web/important-cases","documents":"/api/acts/ad-b727-144-amdt-1-wing-centre-section-front-spar-web/documents"}}