{"id":"F2008L04461","name":"AD/B737/345 - Fuel Tank Safety","slug":"ad-b737-345-fuel-tank-safety","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":76463,"registerId":"commonwealth-F2008L04461-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/B737/345 | Fuel Tank Safety | 13/2008 |\n| ----------- | ---------------- | ------- |\n\n| Applicability: | Model 737-600, -700, -800 and -900 series aeroplanes, as identified in Boeing Alert Service Bulletin (ASB) 737-28A1221, Revision 1, dated 9 November 2007.                                                                                                                                                                                                                          |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Install the hot short protector (HSP) support brackets and equipment for the fuel quantity indicating system (FQIS) fuel densitometer and do all the other specified actions as applicable, by accomplishing all of the applicable actions specified in the Accomplishment Instructions of ASB 737-28A1221, Revision 1.                                                          |\n|                | Actions accomplished before the effective date of this Directive in accordance with ASB 737-28A1221, dated 14 January 2007, are acceptable for compliance with the Requirement 1.                                                                                                                                                                                                   |\n|                | 2. Revise the Airworthiness Limitations (AWL) section of the Instructions for Continued Airworthiness (ICA) by incorporating AWL No. 28-AWL-07 of Subsection F, \"AIRWORTHINESS LIMITATIONS-FUEL SYSTEM AWLs,'' of Section 9 of the Boeing 737-600/700/800/900 Maintenance Planning Data (MPD) Document, D626A001-CMR, Revision March 2007 R2 (hereafter referred to as \"the MPD''). |\n|                | Incorporating AWL No. 28-AWL-07 into the AWLs section of the ICA in accordance with Requirement 1.c. of AD/B737/329 (paragraph (g)(3) of United States Federal Aviation Administration (FAA) AD 2008-10-10), terminates the action required by Requirement 2.                                                                                                                       |\n|                | 3. No alternative Critical Design Configuration Control Limitations (CDCCL) may be used unless the CDCCLs are approved as an alternative method of compliance (AMOC) by the Manager, Seattle Aircraft Certification Office, FAA.                                                                                                                                                    |\n|                | Later revisions of ASB 737-28A1221, approved by the FAA as an AMOC to FAA AD 2008-17-15, are considered acceptable for compliance with the equivalent Requirements of this Directive.                                                                                                                                                                                               |\n|                | Note: FAA AD 2008-17-15 Amdt 39-15653 refers.                                                                                                                                                                                                                                                                                                                                       |\n| Compliance:    | For Requirement 1 - Within 60 months after the effective date of this Directive.                                                                                                                                                                                                                                                                                                    |\n|                | For Requirement 2 - Concurrently with accomplishing the Requirement 1 actions.                                                                                                                                                                                                                                                                                                      |\n\n|             | For Requirement 3 - After accomplishing the action specified in Requirement 2.                                                                                                                                                                                                                                                                                                  |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Airworthiness Directive becomes effective on 18 December 2008.                                                                                                                                                                                                                                                                                                             |\n| Background: | This Directive results from fuel system reviews conducted by the manufacturer. The Directive is issued to prevent the centre tank fuel densitometer from overheating and becoming a potential ignition source inside the centre fuel tank which, in combination with flammable fuel vapours, could result in a centre fuel tank explosion and consequent loss of the aeroplane. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n6 November 2008","sortOrder":0},{"sectionNumber":"AD/B737/345","sectionType":"part","heading":"AD/B737/345","content":"## AD/B737/345","sortOrder":1},{"sectionNumber":"Fuel Tank Safety","sectionType":"part","heading":"Fuel Tank Safety","content":"## Fuel Tank Safety","sortOrder":2},{"sectionNumber":"13/2008","sectionType":"part","heading":"13/2008","content":"## 13/2008","sortOrder":3}],"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":5,"scope_assessment":{"changed":false,"description":"The Directive applies to the specified Boeing 737-600/700/800/900 models identified in Boeing ASB 737-28A1221 Rev 1 and incorporates actions and timing consistent with the cited FAA AD and Boeing documents. The text accepts prior compliance under the earlier ASB and allows FAA‑approved AMOCs and later ASB revisions; there is no statement in this instrument that expands or narrows the stated applicability beyond the source documents."},"complexity_factors":["Multiple action types: hardware installation (HSP brackets and FQIS densitometer work) and documentation change (AWL insertion) increase technical and administrative workload (Requirement 1 and 2).","Cross-references to external documents: compliance depends on Boeing ASB 737-28A1221 Rev 1 and MPD D626A001-CMR, creating reliance on non-legislative materials and later revisions (Applicability; Requirement notes).","Interaction with prior directives: acceptance of earlier ASB accomplishment and termination linkage to AD/B737/329 adds sequencing complexity (Requirement 1 note; Requirement 2).","Approval/discretion point for alternatives: any alternative CDCCL requires FAA Manager, Seattle ACO approval (AMOC) — introduces case-by-case regulatory discretion and administrative delay risk (Requirement 3).","Compliance timing and sequencing: 60-month compliance window for physical modification and concurrent AWL update, with a sequence for use of alternatives after AWL insertion, requires coordinated program planning (Compliance).","Operational cost and scheduling: operators must fund, schedule, and record modifications and ICA changes; potential downtime and labour/materials costs are concentrated on airlines/operators (Requirement 1; Compliance).","Acceptability of later ASB revisions if FAA-approved as AMOC creates conditional compliance paths that require regulatory monitoring (Requirement note on later revisions)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 737-600/700/800/900 aeroplanes (as identified in Boeing ASB 737-28A1221 Rev 1) to install hot-short protector support brackets and related fuel‑quantity densitometer equipment, and to revise the aircraft Airworthiness Limitations to include a specified fuel‑system AWL. Operators must complete the work within 60 months. The rule mechanically forces a hardware modification and manual update (operators pay and schedule the work); FAA approval is required for any alternative compliance methods. The stated purpose is to prevent densitometer overheating that could ignite centre‑tank vapours."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific fuel tank ignition hazard on specific Boeing 737 models. The cross-references to other ADs and service bulletins are typical of aviation safety instruments and do not represent scope creep; they simply acknowledge related regulatory actions and provide alternative compliance pathways for operators who may have already completed similar work under US FAA orders."},"complexity_factors":["Multiple nested compliance pathways: Requirement 2 can be satisfied by prior compliance with a different AD (AD/B737/329), creating a conditional dependency","Cross-references to external documents: Boeing Alert Service Bulletin 737-28A1221, FAA AD 2008-17-15, FAA AD 2008-10-10, and the Boeing Maintenance Planning Data Document D626A001-CMR","Technical aviation terminology requiring specialist knowledge: 'hot short protector', 'fuel quantity indicating system (FQIS)', 'densitometer', 'Critical Design Configuration Control Limitations (CDCCL)', 'Airworthiness Limitations (AWL)', 'Instructions for Continued Airworthiness (ICA)'","Alternative compliance mechanism (AMOC) requiring approval from a foreign regulator (FAA Seattle Aircraft Certification Office)","Acceptance of prior work clause with specific date/version conditions (ASB dated 14 January 2007 vs Revision 1 dated 9 November 2007)","Temporal dependencies between requirements: Requirement 2 must be done concurrently with Requirement 1; Requirement 3 applies after Requirement 2"],"plain_english_summary":"This AD mandates that Australian owners/operators of certain Boeing 737-600/700/800/900 series install protective hardware and update maintenance limitations to prevent the centre fuel tank densitometer from overheating and igniting fuel vapour. Compliance is required within 60 months; alternatives need FAA approval. It’s a compulsory safety fix to eliminate a design-related explosion risk identified by the manufacturer and regulators."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-345-fuel-tank-safety","history":"/api/acts/ad-b737-345-fuel-tank-safety/history","analysis":"/api/acts/ad-b737-345-fuel-tank-safety/analysis","conflicts":"/api/acts/ad-b737-345-fuel-tank-safety/conflicts","importantCases":"/api/acts/ad-b737-345-fuel-tank-safety/important-cases","documents":"/api/acts/ad-b737-345-fuel-tank-safety/documents"}}