{"id":"F2006L00452","name":"AD/B747/339 - Fuselage Lower Lobe Skin STA 741 to STA 1741","slug":"ad-b747-339-fuselage-lower-lobe-skin-sta-741-to-sta-1741","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":117148,"registerId":"commonwealth-F2006L00452-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 747 Series Aeroplanes","sectionType":"division","heading":"Boeing 747 Series Aeroplanes","content":"### Boeing 747 Series Aeroplanes\n\n| AD/B747/339 | Fuselage Lower Lobe SkinSTA 741 to STA 1741 | 3/2006 |\n| ----------- | ------------------------------------------- | ------ |\n\n| Applicability: | Model 747-400, -400D, and -400F series aircraft; as identified in Boeing Alert Service Bulletin 747-53A2505 original issue, or later FAA approved revision.                                                                                                                                                               |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2005-25-26Amdt 39-14419.                                                                                                                                                                                                                                   |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of16 March 2006.                                                                                                                                                                                                                                  |\n|                | This Airworthiness Directive becomes effective on 16 March 2006.                                                                                                                                                                                                                                                          |\n| Background:    | The FAA received reports of skin corrosion in the cargo compartments of four Model 747 series aircraft that were delivered between 1995 and 1999. Such corrosion, unless detected and corrected, could penetrate the thickness of the skin and cause cracking, which could result in rapid decompression of the aircraft. |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n17 January 2006","sortOrder":0},{"sectionNumber":"AD/B747/339","sectionType":"part","heading":"AD/B747/339","content":"## AD/B747/339","sortOrder":1},{"sectionNumber":"Fuselage Lower Lobe Skin STA 741 to STA ","sectionType":"part","heading":"Fuselage Lower Lobe Skin STA 741 to STA 1741","content":"## Fuselage Lower Lobe Skin  \nSTA 741 to STA 1741","sortOrder":2},{"sectionNumber":"3/2006","sectionType":"part","heading":"3/2006","content":"## 3/2006","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD adopts the technical requirements of FAA AD 2005-25-26 and applies to the same models identified in Boeing Alert Service Bulletin 747-53A2505. The instrument does not broaden or narrow the substantive scope of mandated inspections/repairs; it principally sets the effective date (16 March 2006) and enforces the existing FAA/Boeing requirements under Australian regulation (Applicability; Requirement; Compliance)."},"complexity_factors":["Relies on external technical documents: FAA AD 2005-25-26 and Boeing Alert Service Bulletin 747-53A2505 determine the required inspections and corrective actions (Requirement).","Technical maintenance scope: inspections/repairs on lower-lobe skin across STA 741–1741 require specialist structural inspection and possible repairs.","Applicability identification: applies only to Model 747-400, -400D and -400F series as identified in the Boeing service bulletin, requiring operators to determine whether individual aircraft fall within scope (Applicability).","Administrative timing: this instrument sets a revised effective date (16 March 2006), affecting when compliance obligations begin (Compliance).","Regulatory enforcement: CASA (via its delegate) issues and enforces the AD, so operators must integrate the directive into continuing airworthiness processes."],"plain_english_summary":"Requires operators of Boeing 747-400, -400D and -400F series aircraft to inspect and, if needed, repair the lower-lobe fuselage skin between STA 741 and STA 1741 following the technical steps set out in FAA AD 2005-25-26 and Boeing Alert Service Bulletin 747-53A2505 (Applicability; Requirement). The directive is effective 16 March 2006. Operators pay for inspections and repairs; the Civil Aviation Safety Authority enforces compliance and relies on the FAA/Boeing documents for the technical details (Compliance; Requirement)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with narrow, targeted scope addressing a specific safety defect in specific aircraft models. No scope creep evident."},"complexity_factors":["Very short document (approximately 200 words of substantive content)","Only 1 defined applicability criterion (specific Boeing models)","Single requirement: comply with external FAA directive","No nested conditions, exceptions, or cross-references within the instrument itself","Technical complexity is outsourced to referenced FAA document (AD 2005-25-26)"],"plain_english_summary":"This Airworthiness Directive mandates inspection and repair of corrosion in the lower fuselage skin of certain Boeing 747-400 series aircraft (built 1995–1999) to prevent skin failure and possible rapid decompression. It applies to owners/operators of affected 747-400/-400D/-400F aircraft and requires compliance with the FAA’s referenced technical instructions; it took effect 16 March 2006."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-339-fuselage-lower-lobe-skin-sta-741-to-sta-1741","history":"/api/acts/ad-b747-339-fuselage-lower-lobe-skin-sta-741-to-sta-1741/history","analysis":"/api/acts/ad-b747-339-fuselage-lower-lobe-skin-sta-741-to-sta-1741/analysis","conflicts":"/api/acts/ad-b747-339-fuselage-lower-lobe-skin-sta-741-to-sta-1741/conflicts","importantCases":"/api/acts/ad-b747-339-fuselage-lower-lobe-skin-sta-741-to-sta-1741/important-cases","documents":"/api/acts/ad-b747-339-fuselage-lower-lobe-skin-sta-741-to-sta-1741/documents"}}