{"id":"F2008L01486","name":"AD/B737/319 - Body Buttock Line 0.07 Floor Beam","slug":"ad-b737-319-body-buttock-line-0-07-floor-beam","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":119827,"registerId":"commonwealth-F2008L01486-current","compilationNumber":null,"startDate":"2026-04-03","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/B737/319 | Body Buttock Line 0.07 Floor Beam | 6/2008 |\n| ----------- | --------------------------------- | ------ |\n\n| Applicability: | Model 737-300, -400, and -500 series aircraft, as identified in Boeing Service Bulletin 737-57-1210 Revision 2, or later FAA approved revision.                                                                                                |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2008-04-21 Amdt 39-15393.                                                                                                                                                       |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of5 June 2008.                                                                                                                                                         |\n|                | This Airworthiness Directive becomes effective on 5 June 2008.                                                                                                                                                                                 |\n| Background:    | The FAA received reports of cracking in the BBL 0.07 floor beam. Undetected cracking could result in failure of the main deck floor beams at certain body stations due to fatigue cracking, with possible rapid decompression of the aircraft. |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n7 April 2008","sortOrder":0},{"sectionNumber":"AD/B737/319","sectionType":"part","heading":"AD/B737/319","content":"## AD/B737/319","sortOrder":1},{"sectionNumber":"Body Buttock Line 0.07 Floor Beam","sectionType":"part","heading":"Body Buttock Line 0.07 Floor Beam","content":"## Body Buttock Line 0.07 Floor Beam","sortOrder":2},{"sectionNumber":"6/2008","sectionType":"part","heading":"6/2008","content":"## 6/2008","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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Scope is consistent with the instrument's stated intent: it applies to the specified 737-300/-400/-500 aircraft as identified in the Boeing Service Bulletin and requires the actions set out in FAA AD 2008-04-21. The instrument revises the effective date to 5 June 2008 but does not broaden applicability or add new categories of affected aircraft."},"complexity_factors":["Cross-reference to external instruments: mandates actions in FAA AD 2008-04-21 and identification via Boeing Service Bulletin 737-57-1210 Rev 2 (requires users to consult multiple documents).","Technical nature of required work: structural inspection and possible repair of floor beam (specialist maintenance and engineering resources needed).","Limited applicability: applies only to specific 737 models, requiring operators to determine fleet applicability precisely.","Mandatory compliance with a firm effective date (5 June 2008) creates scheduling and operational constraints for carriers.","Safety-critical consequences (risk of floor-beam failure and rapid decompression) increase priority and potential regulatory scrutiny.","Enforcement and oversight by CASA delegate (administrative discretion in monitoring/compliance processes)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 737-300, -400 and -500 series aeroplanes (as identified in Boeing Service Bulletin 737-57-1210 Rev 2) to inspect and, if needed, repair the body buttock line (BBL) 0.07 floor beam in accordance with FAA AD 2008-04-21. (Applicability; Requirement.)\n\nCompliance is mandatory from 5 June 2008; the financial and operational costs of inspections/repairs fall on aircraft operators, and the Civil Aviation Safety Authority enforces the directive. (Compliance; Background.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive addressing a specific structural defect in specific aircraft models. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (approximately 200 words)","Only 1 defined term implicitly referenced (BBL 0.07 — Body Buttock Line 0.07)","No nested conditional logic or exceptions","Single cross-reference to external FAA document for technical requirements","Clear, direct applicability statement limited to specific aircraft models","No internal definitions section or interpretation clauses"],"plain_english_summary":"This AD mandates inspections and repairs on Boeing 737-300/-400/-500 series to address fatigue cracks found in a floor beam at Body Buttock Line 0.07. Operators must comply with FAA AD 2008-04-21 (effective June 5, 2008) to prevent floor-beam failure and the risk of rapid decompression, protecting flight safety."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-319-body-buttock-line-0-07-floor-beam","history":"/api/acts/ad-b737-319-body-buttock-line-0-07-floor-beam/history","analysis":"/api/acts/ad-b737-319-body-buttock-line-0-07-floor-beam/analysis","conflicts":"/api/acts/ad-b737-319-body-buttock-line-0-07-floor-beam/conflicts","importantCases":"/api/acts/ad-b737-319-body-buttock-line-0-07-floor-beam/important-cases","documents":"/api/acts/ad-b737-319-body-buttock-line-0-07-floor-beam/documents"}}