{"id":"F2005L03574","name":"AD/B737/268 - Floor Beams and Pressure Web Transverse Beams above the Main Wheel Well","slug":"ad-b737-268-floor-beams-and-pressure-web-transverse-beams-above-the-main-wheel-well","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":39148,"registerId":"commonwealth-F2005L03574-current","compilationNumber":null,"startDate":"2026-04-01","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/B737/268 | Floor Beams and Pressure Web Transverse Beams above the Main Wheel Well | 13/2005 |\n| ----------- | ----------------------------------------------------------------------- | ------- |\n\n| Applicability: | Model 737-100, -200, and -200C series aircraft, as listed in Boeing Service Bulletin (SB) 737-57-1139 Revision 4, or later FAA approved revision.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2001-17-18Amdt 39-12409.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Compliance:    | As specified in the Requirement document.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n|                | This Airworthiness Directive becomes effective on 22 December 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\n| Background:    | The Model 737 Ageing Fleet Structures Working Group has recommended accomplishment of SB 737-57-1139 Revision 4, which requires repetitive inspections of certain floor beams and transverse beams. For certain aircraft, this Directive also provides optional terminating action for the repetitive inspections. The actions specified by this Directive are intended to detect and correct cracking at the aileron control quadrant cut-outs and in the cabin floor beams and pressure web transverse beams above the main wheel well, which could result in rapid loss of cabin pressure and reduced structural integrity of the airframe. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n11 November 2005","sortOrder":0},{"sectionNumber":"AD/B737/268","sectionType":"part","heading":"AD/B737/268","content":"## AD/B737/268","sortOrder":1},{"sectionNumber":"Floor Beams and Pressure Web Transverse ","sectionType":"part","heading":"Floor Beams and Pressure Web Transverse Beams above the Main Wheel Well","content":"## Floor Beams and Pressure Web Transverse Beams above the Main Wheel Well","sortOrder":2},{"sectionNumber":"13/2005","sectionType":"part","heading":"13/2005","content":"## 13/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The AD implements the Ageing Fleet Structures Working Group recommendation by adopting the technical requirements of FAA AD 2001-17-18 and Boeing SB 737-57-1139 Rev 4. It does not broaden or narrow applicability beyond the aircraft list in the service bulletin and delegates technical/compliance detail to the referenced FAA AD, so the scope aligns with the stated intent to detect and correct cracking in the specified floor and transverse beams (Background; Applicability; Requirement)."},"complexity_factors":["Cross-reference to external instruments: requires compliance with FAA AD 2001-17-18 and Boeing SB 737-57-1139 Rev 4 (Requirement; Applicability).","Applicability is determined by a separate service bulletin's aircraft list rather than listed directly in the AD (Applicability).","Repetitive inspection regime with an optional terminating action for some aircraft creates choice and scheduling complexity (Background; Requirement).","Safety-critical structural inspections demand specialised technical expertise, possible repairs, and engineering judgements.","Compliance obligations (timing, methods, records) are delegated to the referenced FAA AD, so operators must interpret and apply an external document.","Operational and administrative burdens: recurring inspections, tracking intervals, and cost of corrective action fall on owners/operators (Compliance).","Effective date imposes implementation timing constraints (becomes effective on 22 December 2005)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 737‑100, ‑200 and ‑200C aircraft listed in Boeing Service Bulletin 737‑57‑1139 (Rev 4 or later FAA‑approved revision) to perform repetitive inspections — or, for eligible aircraft, an optional terminating modification — of floor beams and pressure‑web transverse beams above the main wheel well, following FAA AD 2001‑17‑18. It affects aircraft owners/operators who pay for inspections and repairs, must follow the compliance schedule in the referenced FAA AD, and seeks to detect and fix cracks that could cause rapid cabin pressure loss and weaken the airframe."},"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":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with a focused, narrow scope: addressing specific structural fatigue issues in defined aircraft models. The scope remains tightly constrained to the original safety concern (cracking in floor beams and transverse beams above the main wheel well) without expansion into unrelated operational or maintenance areas."},"complexity_factors":["Very short document (approximately 200 words of substantive content)","Only 1 defined term implicitly referenced (the Boeing Service Bulletin)","No nested conditional logic or exceptions to exceptions","Single cross-reference to an external FAA directive (AD 2001-17-18) which contains the actual technical requirements","No interpretation section or extensive definitions","Straightforward applicability criteria (specific aircraft models by reference to a service bulletin)"],"plain_english_summary":"This mandatory CASA Airworthiness Directive requires owners/operators of certain older Boeing 737-100/200/200C aircraft to carry out repetitive inspections of floor and transverse beams above the main wheel well per FAA AD 2001-17-18, with an optional terminating action available for some airplanes. It addresses cracking around aileron control quadrant cut-outs that can cause rapid decompression or reduced airframe integrity. Effective 22 December 2005."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-268-floor-beams-and-pressure-web-transverse-beams-above-the-main-wheel-well","history":"/api/acts/ad-b737-268-floor-beams-and-pressure-web-transverse-beams-above-the-main-wheel-well/history","analysis":"/api/acts/ad-b737-268-floor-beams-and-pressure-web-transverse-beams-above-the-main-wheel-well/analysis","conflicts":"/api/acts/ad-b737-268-floor-beams-and-pressure-web-transverse-beams-above-the-main-wheel-well/conflicts","importantCases":"/api/acts/ad-b737-268-floor-beams-and-pressure-web-transverse-beams-above-the-main-wheel-well/important-cases","documents":"/api/acts/ad-b737-268-floor-beams-and-pressure-web-transverse-beams-above-the-main-wheel-well/documents"}}