{"id":"F2006B02922","name":"AD/B737/226 - Main Fuel Tank Aft Fuel Boost Pump Wiring","slug":"ad-b737-226-main-fuel-tank-aft-fuel-boost-pump-wiring","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42264,"registerId":"commonwealth-F2006B02922-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\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 CASR 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\n![](image.001.png)  \n\nBoeing 737 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B737/226 Main Fuel Tank Aft Fuel Boos","sectionType":"part","heading":"AD/B737/226 Main Fuel Tank Aft Fuel Boost Pump Wiring 8/2004","content":"# AD/B737/226 Main Fuel Tank Aft Fuel Boost Pump Wiring 8/2004\n\nApplicability: Model 737-600, 737-700, 737-700C, 737-800 and 737-900 series aeroplanes, as listed in Boeing Alert Service Bulletin (ASB) 737-28A1148, Revision 2, dated 18 December 2003.\n\nNote 1: The term ‘service bulletin’, as used in this Directive, means the Accomplishment Instructions of Boeing Alert Service Bulletin 737-28A1148, Revision 2, dated 18 December 2003.\n\nRequirement 1. For aeroplanes listed in the service bulletin as Groups 1, 2, 3 and 4 on which Boeing ASB 737-28A1148, dated 14 September 2000, has been accomplished and for aeroplanes listed in the service bulletin as Groups 5, 6 and 7 - Install screws and spacers to secure the applicable wire bundles for the aft fuel boost pumps of the main fuel tanks in accordance with the service bulletin.\n\n    2. For aeroplanes listed in the service bulletin as Groups 1 and 2 on which Boeing ASB 737-28A1148, dated 14 September 2000, has not been accomplished - Perform a general visual inspection of the applicable wire bundles for the aft fuel boost pumps of the main fuel tanks for chafing or other damage in accordance with the service bulletin.\n\n    3. If any discrepancies were noted during the Requirement 2 visual inspection, perform any applicable corrective action together with installing a new bracket, clamp and spacers to secure the wire bundles in accordance with the service bulletin.\n\n    4. For aeroplanes listed in the service bulletin as Groups 3 and 4 on which ASB 737-28A1148, dated 14 September 2000, has not been accomplished \\- Perform, in accordance with the service bulletin, a general visual inspection of the applicable wire bundles for the aft fuel boost pumps of the main fuel tanks to determine if the wire bundle is secured with a clamp, if the bundles are clamped no further action is necessary.\n\n    5. If, the Requirement 4 inspection reveals that the wire bundles are not clamped, in accordance with the service bulletin, repair the wire bundle if chaffing has occurred and install a new bracket, clamp and spacers to ensure sufficient clearance between the rear spar and structure and the wire bundles.","sortOrder":1}],"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":4,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a focused, single-purpose scope: addressing a specific unsafe wiring condition in Boeing 737 main fuel tanks. The document does not show evidence of scope creep — it targets one technical issue with tailored requirements for different aircraft configurations."},"complexity_factors":["Multiple conditional requirements based on aircraft 'Groups' (1-7) that are defined in an external document (Boeing Service Bulletin) rather than in the directive itself","Cross-references to specific dated versions of Boeing Alert Service Bulletin 737-28A1148 (September 2000 and December 2003 revisions)","Nested logic: Requirement 3 only applies if Requirement 2 inspection finds problems; Requirement 5 only applies if Requirement 4 reveals missing clamps","Technical aviation terminology requiring external knowledge (e.g., 'aft fuel boost pumps', 'rear spar', 'general visual inspection', 'chafing')","Dependency on prior compliance status (whether ASB 737-28A1148 dated 14 September 2000 was previously accomplished)"],"plain_english_summary":"This CASA safety order requires operators of certain Boeing 737 variants to inspect and fix wiring in the main fuel tanks where chafing can expose conductors and create a spark/ignition risk. Depending on aircraft history, the work ranges from securing wiring to visual inspections and repairs; aircraft cannot legally fly until required fixes are completed."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This AD expands or clarifies the remedy compared with the earlier Boeing ASB regime by requiring hardware installation (screws, spacers, brackets, clamps) in cases where an older ASB (14 September 2000) may already have been accomplished (Requirement 1). It also sets mandatory inspection-and-repair steps for aeroplanes that did not have the earlier SB done (Requirements 2–5). Concretely, the AD ties mandatory compliance to Boeing ASB 737-28A1148 Revision 2 and applies to Groups 1–7 listed in that ASB, which increases the regulatory reach beyond relying solely on the earlier 2000 SB: some aircraft that previously complied under the older bulletin may now require additional hardware fitting or further corrective actions. The change is focused and technical (hardware install and inspections) and does not broaden the subject matter beyond the original safety concern (aft fuel boost pump wiring), but it does widen the set of mandatory actions for aircraft that had earlier work completed."},"complexity_factors":["Short document but depends on an external technical document: Boeing ASB 737-28A1148, Revision 2 (the AD defers detailed steps to the ASB).","Reference to an earlier service bulletin (Boeing ASB dated 14 September 2000) creating conditional paths depending on whether that SB was previously accomplished.","Applicability divided into Groups 1–7 in the ASB (grouping definition is external to the AD), requiring cross-checking each aeroplane against the ASB group list.","Five numbered Requirements with branching logic (install hardware; inspect if earlier SB not done; repair and install if damage found; different actions for different groups).","Conditional corrective actions (inspection leads to repair only if discrepancies found), introducing possibility of follow-on work and parts ordering.","Regulatory enforcement via CASA delegate but technical execution controlled by the manufacturer’s ASB (dual-source dependency)."],"plain_english_summary":"**What this directive does (mechanically)\n\n- This is an Airworthiness Directive (an official safety order) that tells operators of certain Boeing 737 variants what inspections and hardware changes they must do to the wiring for the aft fuel boost pumps in the main fuel tanks.  \n- It applies to Boeing 737-600, -700, -700C, -800 and -900 series aeroplanes listed in Boeing Alert Service Bulletin (ASB) 737-28A1148, Revision 2 (the service bulletin is the set of technical instructions to use) (Applicability; Note 1).  \n- The AD gives a set of required actions, depending on which Group the aeroplane is listed in and whether an earlier Boeing ASB (dated 14 September 2000) was already accomplished on that aeroplane. The required actions are:  \n  - Install screws and spacers to secure the aft fuel boost pump wire bundles (Requirement 1).  \n  - For aircraft in certain groups that have not had the earlier ASB done, perform a general visual inspection for chafing or other damage (Requirement 2 and Requirement 4).  \n  - If damage is found, repair the wiring and install a new bracket, clamp and spacers to secure the bundles and ensure clearance from structure (Requirement 3 and Requirement 5).  \n- All work must be done in accordance with the Accomplishment Instructions of Boeing ASB 737-28A1148, Revision 2 (Note 1).\n\nWho this affects\n\n- Aircraft operators (airlines, lessors, maintenance organisations) who operate the affected 737 models listed in the Boeing ASB. They must schedule the inspections and hardware installations, pay for parts and labour, and record compliance.  \n- Maintenance organisations that perform the work — they must follow the Boeing service bulletin instructions and any regulatory paperwork.  \n- The regulator (the CASA delegate named in the AD) issues the requirement and enforces compliance.\n\nWhy it matters (stated purpose, then practical implications)\n\n- The AD is issued to correct an unsafe condition related to the aft fuel boost pump wiring in the main fuel tanks: unsecured or chafed wiring can contact structure and create a potential ignition source. The AD’s mechanical purpose is to secure the wire bundles (install brackets/clamps/spacers) and to identify and fix any chafing or damage (Requirements 1–5).  \n- Practically, this reduces the risk that fuel tank wiring could be damaged and subsequently create a fire or ignition hazard. The directive achieves that by mandating physical restraint of the wiring and repairs where wear is found.\n\nCosts, incentives, trade-offs and implementation details\n\n- Who pays: the aircraft operator pays for inspections, replacement parts (screws, spacers, brackets, clamps) and labour. If repairs require parts or grounding time, there are direct maintenance costs and opportunity costs from aircraft downtime. (See Requirements 1–5.)  \n- Who decides and how: the AD prescribes what must be done and references Boeing’s ASB for the technical method. Operators choose scheduling and which approved maintenance provider performs the work, but they must follow the AD and ASB instructions. The CASA delegate enforces compliance under the regulatory power cited at the front of the AD.  \n- Incentives and behaviour: operators are incentivised to comply promptly to maintain airworthiness and regulatory compliance. Where the earlier ASB (14 September 2000) was already done, this AD can still require additional hardware installation (Requirement 1), which reduces the incentive to treat older compliance as final.  \n- Trade-offs and opportunity cost: improved wiring security versus maintenance cost and aircraft time out of service. Operators must weigh the direct cost of parts and maintenance scheduling against the safety risk the AD addresses.  \n- Implementation risk and compliance burden: the AD requires following an external manufacturer service bulletin. That creates dependency on Boeing’s technical instructions and on availability of parts. The AD also contains conditional steps (different actions depending on aircraft Group and prior accomplishment of the earlier ASB), which can complicate compliance planning and record checks.\n\nConcrete behavioural changes required\n\n- Inspectors/maintenance staff must perform general visual inspections of the aft fuel boost pump wire bundles where required (Requirements 2 and 4).  \n- If chafing/damage is found, they must repair wiring and install new hardware (Requirements 3 and 5).  \n- In many cases they must install screws, brackets, clamps and spacers even if prior work was done under the older ASB (Requirement 1).\n\nSource attribution and how the AD is implemented\n\n- The AD explicitly relies on Boeing ASB 737-28A1148, Revision 2 — the AD treats the ASB’s Accomplishment Instructions as the mandated method (Note 1). The AD’s numbered paragraphs (Requirements 1–5) set the compliance logic: install hardware where required; inspect where the previous SB wasn’t accomplished; repair and install hardware if damage or missing clamps are found.\n\n(Referenced sections: Applicability; Note 1; Requirement 1, Requirement 2, Requirement 3, Requirement 4, Requirement 5.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-226-main-fuel-tank-aft-fuel-boost-pump-wiring","history":"/api/acts/ad-b737-226-main-fuel-tank-aft-fuel-boost-pump-wiring/history","analysis":"/api/acts/ad-b737-226-main-fuel-tank-aft-fuel-boost-pump-wiring/analysis","conflicts":"/api/acts/ad-b737-226-main-fuel-tank-aft-fuel-boost-pump-wiring/conflicts","importantCases":"/api/acts/ad-b737-226-main-fuel-tank-aft-fuel-boost-pump-wiring/important-cases","documents":"/api/acts/ad-b737-226-main-fuel-tank-aft-fuel-boost-pump-wiring/documents"}}