{"id":"F2006L00208","name":"AD/B737/274 - Wing Centre Tank Wire Bundles","slug":"ad-b737-274-wing-centre-tank-wire-bundles","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":58155,"registerId":"commonwealth-F2006L00208-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/274 | Wing Centre Tank Wire Bundles | 2/2006 |\n| ----------- | ----------------------------- | ------ |\n\n| Applicability: | Model 737-600, -700, -700C, -800 and -900 series aeroplanes, as identified in Boeing Service Bulletin (SB) 737-28-1209, dated 17 February 2005.                                                                                                                                                                                                     |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Modify the wire bundles located below the passenger compartment, above the centre fuel tank, aft of station (STA) 540 through STA 601 inclusive, at right buttock line and left buttock line 24.82 in accordance with the Accomplishment Instructions of SB 737-28-1209, as amended by Information Notice (IN) 737-28-1209 IN 01 dated28 July 2005. |\n|                | Later revisions of the above SB, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2005-23-16, are considered acceptable for compliance with the equivalent Requirements of this Directive.                                                                                 |\n|                | Note: FAA AD 2005-23-16 Amdt 39-14374 refers.                                                                                                                                                                                                                                                                                                       |\n| Compliance:    | Within 60 months after the effective date of this Directive.                                                                                                                                                                                                                                                                                        |\n|                | This Airworthiness Directive becomes effective on 16 February 2006.                                                                                                                                                                                                                                                                                 |\n| Background:    | This Directive requires modification of wire bundles located above the centre fuel tank and is issued to prevent chafed wire bundles near the centre fuel tank, which could cause electrical arcing through the tank wall and ignition of fuel vapour in the fuel tank together with the possibility of a fuel tank explosion.                      |\n\n![](image.001.png)  \nCharles Lenarcic  \nDelegate of the Civil Aviation Safety Authority\n\n15 December 2005","sortOrder":0},{"sectionNumber":"AD/B737/274","sectionType":"part","heading":"AD/B737/274","content":"## AD/B737/274","sortOrder":1},{"sectionNumber":"Wing Centre Tank Wire Bundles","sectionType":"part","heading":"Wing Centre Tank Wire Bundles","content":"## Wing Centre Tank Wire Bundles","sortOrder":2},{"sectionNumber":"2/2006","sectionType":"part","heading":"2/2006","content":"## 2/2006","sortOrder":3}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains a narrow, targeted scope focused specifically on wiring modifications above the centre fuel tank for identified Boeing 737 models. It does not expand beyond its original safety purpose of preventing fuel tank explosions."},"complexity_factors":["Technical aviation terminology requiring specialised knowledge (station numbers, buttock lines, service bulletins)","Cross-references to external documents (Boeing Service Bulletin 737-28-1209 and FAA AD 2005-23-16)","Conditional compliance pathway allowing later revisions if FAA-approved as Alternate Method of Compliance (AMOC)","Precise spatial definitions for applicability (STA 540 through STA 601, specific buttock lines)"],"plain_english_summary":"This CASA Airworthiness Directive mandated modification of electrical wire bundles above the centre fuel tank on Boeing 737-600/-700/-700C/-800/-900 series aircraft, following Boeing Service Bulletin 737-28-1209 (or later FAA-approved instructions). It affected owners/operators of those models in Australia because chafed wires near fuel tanks can spark and ignite vapours, risking catastrophic explosion. The work had to be completed within 60 months of 16 February 2006 (by February 2011)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD remains narrowly focused on the original safety purpose: preventing chafing-induced arcing into the centre fuel tank by modifying specific wire bundles. It does not expand the regulated subject matter beyond that original intent; the instrument merely prescribes the technical fix, cites the applicable service bulletin, sets a compliance window, and recognises FAA-approved alternative methods. There is no substantive scope expansion in this version."},"complexity_factors":["Short, single-issue AD focused on one modification (wire bundles above centre fuel tank).","Applicability tied to specific Boeing models identified by a service bulletin rather than a long list of serial numbers (moderate cross-reference).","Cross-reference to Boeing Service Bulletin 737-28-1209 and its Information Notice IN 01 (external documents required to implement).","Acceptance of later SB revisions only if approved by the FAA as an AMOC (conditional acceptance adds one layer of procedural complexity).","Specific spatial routing requirements (STA 540 through STA 601 inclusive; buttock line 24.82 in) — technical precision but few legal branches.","Reference to FAA AD 2005-23-16 (regulatory harmonisation cross-reference).","Single compliance deadline (60 months) reduces branching in timing rules."],"plain_english_summary":"**What this instrument does, simply**\n\n- This Airworthiness Directive (AD) requires operators of certain Boeing 737 models to modify specified wire bundles routed above the centre fuel tank so the wires cannot chafe against structure and potentially cause an electrical arcing event into the tank. (Requirement — see “Requirement” and “Background.”)\n\n**Which aeroplanes are affected**\n\n- The AD applies to Model 737-600, -700, -700C, -800 and -900 series aeroplanes identified in Boeing Service Bulletin (SB) 737-28-1209 dated 17 February 2005. (Applicability)\n\n**What exactly must be done**\n\n- The mechanical action required is to modify the wire bundles located below the passenger compartment and above the centre fuel tank, aft of fuselage station (STA) 540 through STA 601 inclusive, at the right and left buttock lines 24.82 in, by following the Accomplishment Instructions of SB 737-28-1209 as amended by Information Notice IN 01 dated 28 July 2005. (Requirement)\n\n- Later revisions of that SB are acceptable for compliance if they have been approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2005-23-16. (Requirement)\n\n**When it must be done**\n\n- Operators must complete the modification within 60 months after the AD’s effective date. The AD’s effective date noted in the instrument is 16 February 2006. (Compliance)\n\n**Why this was imposed (stated purpose)**\n\n- The stated safety reason is to prevent chafing of wire bundles near the centre fuel tank, which could lead to electrical arcing through the tank wall and ignition of fuel vapour — a hazard that could result in a fuel tank explosion. (Background)\n\n**Who pays and who decides**\n\n- Who pays: aircraft operators (airlines, leasing companies) bear the direct costs — parts, labour, and any aircraft downtime required to perform the modification. (Requirement / Compliance)\n\n- Who decides: the AD is mandatory; compliance is achieved by following the Boeing SB instructions or a later SB revision accepted as an AMOC by the FAA. That means the FAA’s AMOC approvals are recognised for compliance with this AD; the issuing authority enforces the AD. (Requirement)\n\n**Practical effects and implementation trade-offs**\n\n- Compliance imposes direct maintenance costs and scheduling/daytime-out-of-service costs on operators. The modification must be done within a five-year window, which allows time for scheduling but delays the safety improvement.\n\n- Operators must either use approved service bulletin procedures or obtain an AMOC accepted by the FAA; this produces a constrained set of technical solutions (low flexibility) unless an approved AMOC exists. (Requirement)\n\n- Small operators or operators with fewer affected aircraft will carry the same mandatory fix but cannot spread fixed costs as widely as large carriers; thus per-aircraft cost is higher for smaller fleets.\n\n- The AD harmonises with FAA AD 2005-23-16 and accepts FAA-approved AMOCs, which reduces the risk of divergent technical solutions across jurisdictions but transfers some discretion to the FAA regarding acceptable alternative procedures. (Requirement)\n\n**Risks, opportunity costs and compliance burden**\n\n- Operational risk: if not done, the stated safety hazard remains (risk of arcing and fuel vapour ignition). If done, there is the usual execution risk — availability of qualified maintenance personnel and parts; incorrect implementation would undermine the safety intent. (Background / Requirement)\n\n- Opportunity cost: maintenance man-hours and shop capacity used for this modification cannot be used for other maintenance or upgrades during the same period.\n\n- Enforcement/compliance burden: an AD is mandatory; the burden is administrative (recordkeeping, scheduling) plus technical. Acceptance of FAA AMOCs narrows technical dispute but requires coordination with the FAA if an operator seeks an alternative method. (Requirement)\n\n**Concentrated benefits vs diffuse costs**\n\n- Benefits (reduced catastrophic risk) are concentrated in the sense that they directly protect operators, passengers and insurers of the specific affected aircraft. Costs (modification expense, downtime) are borne by the operators and are more concentrated on those with affected models; taxpayers are not directly charged by the AD itself. (Applicability / Requirement)\n\n**Net mechanical effect**\n\n- Practically, affected operators must schedule and carry out the specified wire-bundle modification within five years using the SB instructions or an FAA-approved AMOC. Once performed and documented, the aircraft will be in compliance with this AD. (Requirement / Compliance)\n\n(References: Applicability; Requirement; Compliance; Background sections of the AD.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-274-wing-centre-tank-wire-bundles","history":"/api/acts/ad-b737-274-wing-centre-tank-wire-bundles/history","analysis":"/api/acts/ad-b737-274-wing-centre-tank-wire-bundles/analysis","conflicts":"/api/acts/ad-b737-274-wing-centre-tank-wire-bundles/conflicts","importantCases":"/api/acts/ad-b737-274-wing-centre-tank-wire-bundles/important-cases","documents":"/api/acts/ad-b737-274-wing-centre-tank-wire-bundles/documents"}}