{"id":"F2006B02634","name":"AD/B727/110 Amdt 2 - Wing Centre Section Front Spar Web","slug":"ad-b727-110-amdt-2-wing-centre-section-front-spar-web","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41950,"registerId":"commonwealth-F2006B02634-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B727/110 Amdt 2 - 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)  \nBoeing 727 Series Aeroplanes\n\nAD/B727/110\n\nAmdt 2\n\n  \nWing Centre Section Front Spar Web 2/93\n\nApplicability: Line Numbers 1 to 191.\n\nRequirement: Visually inspect the wing centre section front spar web in accordance with Boeing Service Bulletin 727-57-0107 Revision 6.\n\nNote: FAA AD 90-20-02 refers.\n\nCompliance: If back to back angles were installed before 20000 flights:\n\nInspect within 12000 flights after installation of the angles, or within 1000 flights since last inspected in accordance with the previous issue of this AD, or within 1000 flights after 4 February 1993, whichever is the latest.\n\nIf back to back angles have not been installed, or were installed after 20000 flights:\n\nInspect before 15000 flights, or within 1000 flights since last inspected in accordance with the previous issue of this AD, or within 1000 flights after 4 February 1993, whichever is the latest.\n\nRe-inspect at intervals not exceeding 1000 flights, until the doublers and straps have been installed per Boeing Drawing No 65-78836.\n\nBackground: Fatigue cracks caused by pressurisation cycling have been found in the subject area. Amendment 2 is issued to require further repeat inspections to aircraft that have been previously modified by installing additional angles back-to-back with existing stiffeners, as several of these installations have been subsequently found to crack.","sortOrder":0}],"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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The original directive (implied by 'Amendment 2' and 'previous issue of this AD') was narrower, targeting the basic fatigue cracking issue. Amendment 2 expands the scope to address a specific subset of aircraft that had already been modified with 'back-to-back angles' — a repair that was initially thought to solve the problem but was subsequently found to crack as well. The directive now maintains two parallel compliance tracks: one for pre-modified aircraft and one for unmodified or later-modified aircraft, effectively doubling the regulatory complexity to address an emergent safety issue with the 'fix' itself."},"complexity_factors":["Multiple conditional compliance pathways based on modification history (back-to-back angles installed before/after 20,000 flights)","Three alternative triggering events for initial inspection deadline ('whichever is the latest' logic)","Cross-reference to external technical document (Boeing Service Bulletin 727-57-0107 Revision 6)","Cross-reference to foreign regulatory document (FAA AD 90-20-02)","Specific technical drawing reference required for terminating action (Boeing Drawing No 65-78836)","Nested temporal conditions (flight cycles, installation dates, directive effective date of 4 February 1993)"],"plain_english_summary":"This CASA Airworthiness Directive mandates repeated visual inspections of the wing centre section front spar web on early-model Boeing 727s to detect fatigue cracks that could cause structural failure. \n\nIt affects operators of those 727s (including aircraft with an earlier back-to-back angle repair) and requires strict inspection intervals until a permanent modification is fitted—so affected operators must inspect on a defined schedule and complete the specified modification."},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Amendment 2 expands the AD’s inspection requirements by specifically imposing further repeat inspections on aircraft that were previously modified by installing additional back‑to‑back angles. The AD text states: 'Amendment 2 is issued to require further repeat inspections to aircraft that have been previously modified by installing additional angles back-to-back with existing stiffeners, as several of these installations have been subsequently found to crack.' This adds targeted obligations beyond the prior issue by focusing on modified installations and clarifying inspection intervals."},"complexity_factors":["Conditional compliance timings dependent on whether back‑to‑back angles were installed and on flight counts (different thresholds and multiple ‘whichever is the latest’ clauses).","Repeated, short re‑inspection interval (every 1,000 flights) until a terminating modification (doublers/straps per Boeing Drawing No 65‑78836) is installed.","References to external technical documents (Boeing Service Bulletin 727‑57‑0107 Revision 6; Boeing Drawing No 65‑78836) creating dependency on manufacturer's materials for procedures and standards.","Applicability limited to specific line numbers (1–191), requiring operators to determine applicability precisely.","Technical subject matter (wing centre front spar web fatigue and pressurisation cycling) requires specialised maintenance personnel and potential engineering assessments.","Cross‑reference to FAA AD 90‑20‑02 in the Note adds an additional regulatory reference to consider."],"plain_english_summary":"This Airworthiness Directive (AD) requires operators of Boeing 727 aeroplanes (line numbers 1–191) to carry out visual inspections of the wing centre section front spar web using Boeing Service Bulletin 727‑57‑0107 Rev 6, with staged initial inspection deadlines and 1,000‑flight repeat intervals until doublers and straps are fitted per Boeing Drawing No 65‑78836. Amendment 2 adds extra repeat inspections for aircraft that had back‑to‑back angles fitted because some of those installations have been found to crack; operators bear the inspection and compliance costs and must follow CASA’s mandated schedule."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-110-amdt-2-wing-centre-section-front-spar-web","history":"/api/acts/ad-b727-110-amdt-2-wing-centre-section-front-spar-web/history","analysis":"/api/acts/ad-b727-110-amdt-2-wing-centre-section-front-spar-web/analysis","conflicts":"/api/acts/ad-b727-110-amdt-2-wing-centre-section-front-spar-web/conflicts","importantCases":"/api/acts/ad-b727-110-amdt-2-wing-centre-section-front-spar-web/important-cases","documents":"/api/acts/ad-b727-110-amdt-2-wing-centre-section-front-spar-web/documents"}}