{"id":"F2006B03265","name":"AD/B747/88 - CWT Secondary Fuel Barrier","slug":"ad-b747-88-cwt-secondary-fuel-barrier","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42689,"registerId":"commonwealth-F2006B03265-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/88 - CWT Secondary Fuel Barrier","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Safety Regulations 1998), PART 39-105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Boeing 747 Series Aeroplanes\n\n \n\nAD/B747/88 CWT Secondary Fuel Barrier 4/91\n\nApplicability: Model 747 series aircraft as listed in Boeing SB 747-57-2253, Revision 1. Requirement:              Action in accordance with the technical requirements of FA AD 91-03-13 Amdt 39-\n\n6882.\n\n \n\nNote: Boeing SB 747-57-2253 Rev. 1 refers.\n\n \n\nCompliance: As specified in the Requirement Document but with a revised effectivity date of 18 April 1991 for Australian registered aircraft.\n\n \n\nBackground: The FAA has received reports of the secondary fuel barrier not being applied correctly. This condition, if not corrected, could result in fuel or fuel vapours entering the cargo and passenger compartments in the event of failure of a primary seal or crack in the centre wing box structure.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive implementing a foreign (FAA) safety mandate with minor local adaptation (Australian compliance date). It remains tightly scoped to its original purpose: addressing a specific fuel barrier defect in Boeing 747 aircraft."},"complexity_factors":["Very short document (under 200 words)","Only 1 substantive requirement (comply with external FAA directive)","No defined terms section","No conditional logic or nested exceptions","Single cross-reference to Boeing Service Bulletin and FAA AD","Straightforward applicability test (specific aircraft models listed in external document)"],"plain_english_summary":"This AD mandates inspection and correction of the centre wing tank’s secondary fuel barrier on certain Boeing 747s to ensure the backup seal prevents fuel or vapour leaking into passenger and cargo areas. It applies to Australian-registered 747s covered by Boeing Service Bulletin 747-57-2253 Rev 1 and follows FAA AD 91-03-13; compliance is required by 18 April 1991 to mitigate fire and explosion risk."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The AD adopts the FAA technical requirements and Boeing SB but revises the effectivity date for Australian-registered aircraft to 18 April 1991. Applicability remains limited to the Model 747 series listed in Boeing SB 747-57-2253 Rev. 1; no other scope extensions or substantive content changes are stated in the source."},"complexity_factors":["Cross-reference to external technical documents: Requirement directs action “in accordance with the technical requirements of FA[?] AD 91-03-13 Amdt 39-6882” and refers to Boeing SB 747-57-2253 Rev. 1, requiring operators to obtain and follow those documents.","Applicability framing: Applies only to “Model 747 series aircraft as listed in Boeing SB 747-57-2253, Revision 1,” so scope depends on another document’s effectivity list.","Compliance specification: “As specified in the Requirement Document but with a revised effectivity date of 18 April 1991 for Australian registered aircraft” — compliance timing is altered locally while technical content remains external.","Operational cost and effort: Technical maintenance/repair work to apply or verify a secondary fuel barrier imposes labour, parts, and scheduling costs on aircraft operators (source: Requirement/Service Bulletin cross-reference).","Safety-critical execution: The work affects fuel containment and thus requires correct technical execution and possibly repeated inspections; improper application is the identified safety risk (source: Background).","Regulatory enforcement and recordkeeping burden on operators and maintenance organisations to demonstrate compliance with the AD and the referenced service bulletin.","Minor textual ambiguity: document text reads “FA AD” (likely FAA AD), creating a small risk of misreading the precise referenced instrument without checking the Requirement Document."],"plain_english_summary":"Mandates operators of specified Boeing 747 models to perform the maintenance and corrective actions set out in FAA AD 91-03-13 and Boeing Service Bulletin 747-57-2253 Rev. 1, with a revised Australian effectivity date of 18 April 1991.\n\nIt is intended to ensure the centre wing tank (CWT) secondary fuel barrier is correctly applied so fuel or fuel vapour cannot enter cargo or passenger compartments if a primary seal fails or the centre wing box cracks."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-88-cwt-secondary-fuel-barrier","history":"/api/acts/ad-b747-88-cwt-secondary-fuel-barrier/history","analysis":"/api/acts/ad-b747-88-cwt-secondary-fuel-barrier/analysis","conflicts":"/api/acts/ad-b747-88-cwt-secondary-fuel-barrier/conflicts","importantCases":"/api/acts/ad-b747-88-cwt-secondary-fuel-barrier/important-cases","documents":"/api/acts/ad-b747-88-cwt-secondary-fuel-barrier/documents"}}