{"id":"F2005L03914","name":"AD/B747/337 - Upper Chords of the Upper Deck Floor Beams","slug":"ad-b747-337-upper-chords-of-the-upper-deck-floor-beams","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":39720,"registerId":"commonwealth-F2005L03914-current","compilationNumber":null,"startDate":"2026-04-01","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/B747/337 | Upper Chords of the Upper Deck Floor Beams | 1/2006 |\n| ----------- | ------------------------------------------ | ------ |\n\n| Applicability: | Model 747-100, -100B, -100B SUD, 747-200B, 747-300, 747SP, and 747SR series aircraft; as identified in Boeing Alert Service Bulletin 747-53A2452, dated 3 April 2003, or later FAA approved revision.                                                                                                                                                          |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2005-20-29Amdt 39-14326.Note: Boeing Service Bulletin 747-53-2349 and Boeing Alert Service Bulletins747-53A2349 Revision 1 and Revision 2; or later FAA approved revisions, refer.                                                                                                              |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of19 January 2006.                                                                                                                                                                                                                                                                     |\n|                | This Airworthiness Directive becomes effective on 19 January 2006.                                                                                                                                                                                                                                                                                             |\n| Background:    | Fatigue testing by the manufacturer revealed severed upper chords of the upper deck floor beams due to fatigue cracking. Undetected cracking could result in large deflection or deformation of the upper deck floor beams, resulting in damage to wire bundles and control cables for the flight control system, and reduced controllability of the aircraft. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n28 November 2005","sortOrder":0},{"sectionNumber":"AD/B747/337","sectionType":"part","heading":"AD/B747/337","content":"## AD/B747/337","sortOrder":1},{"sectionNumber":"Upper Chords of the Upper Deck Floor Bea","sectionType":"part","heading":"Upper Chords of the Upper Deck Floor Beams","content":"## Upper Chords of the Upper Deck Floor Beams","sortOrder":2},{"sectionNumber":"1/2006","sectionType":"part","heading":"1/2006","content":"## 1/2006","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD remains narrowly focused on the single technical problem identified by Boeing fatigue testing: fatigue cracking of the upper chords of upper-deck floor beams. This version primarily enforces the FAA AD and associated Boeing service bulletins for the specified 747 models and sets an effective date (19 January 2006). It does not expand the subject matter beyond the original safety purpose, nor add unrelated obligations; it mainly adopts external technical requirements and specifies applicability and compliance timing."},"complexity_factors":["Short AD referencing multiple external technical documents (FAA AD 2005-20-29 and several Boeing service bulletins).","Applicability limited to specific 747 variants but requires cross-checking a Boeing Alert Service Bulletin to identify individual affected airframes.","Technical compliance is delegated to detailed external documents (nested dependency): operators must follow procedures in FAA and Boeing publications rather than steps listed in the AD itself.","Effective-date revision and regulatory cross‑references (CASA adoption of FAA actions) introduce procedural nuance.","Potential need for regulator approvals for alternative methods of compliance or later revisions increases conditionality."],"plain_english_summary":"This AD requires operators of certain Boeing 747 variants (as listed in Boeing Alert Service Bulletin 747-53A2452) to carry out inspections and any corrective actions specified in FAA AD 2005-20-29 and referenced Boeing service bulletins, effective 19 January 2006.  \n\nIt responds to fatigue cracking of the upper-deck floor-beam upper chord that can sever and damage nearby control wiring/cables, affecting flight safety. Affected operators and maintenance providers must bear inspection, repair and downtime costs to meet the regulator-enforced safety requirement."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow airworthiness directive addressing a specific structural fatigue issue in defined aircraft models. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (approximately 200 words of substantive content)","No defined terms section — relies entirely on external technical references","Single, straightforward requirement: comply with external FAA directive and Boeing service bulletin","No conditional logic, exceptions, or nested provisions","Minimal cross-referencing — only references to FAA AD 2005-20-29 and Boeing Service Bulletins 747-53-2349 and 747-53A2349","Clear, unambiguous applicability table identifying specific aircraft models"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to specific **Boeing 747 aircraft models** (the -100, -200B, -300, SP, and SR series).\n\n**What the problem is:**\nFatigue testing found that the **upper chords** (the top structural supports) of the **upper deck floor beams** can crack and break due to metal fatigue. If this cracking isn't caught, it could cause the floor beams to bend or deform significantly. This risks damaging **wire bundles** (groups of electrical wires) and **control cables** that run through this area for the aircraft's flight control systems — potentially making the plane harder or impossible to control.\n\n**What must be done:**\nAircraft operators must follow the technical instructions in **FAA AD 2005-20-29** (a matching US safety order) and the referenced **Boeing Alert Service Bulletin**. This typically involves inspections, repairs, or modifications to check for and fix any cracking in these structural components.\n\n**Who it affects:**\nOwners and operators of the specified Boeing 747 models, as identified in Boeing's service bulletin.\n\n**When:**\nCompliance is required according to the timeline in the FAA directive, with this Australian directive taking effect on **19 January 2006**."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-337-upper-chords-of-the-upper-deck-floor-beams","history":"/api/acts/ad-b747-337-upper-chords-of-the-upper-deck-floor-beams/history","analysis":"/api/acts/ad-b747-337-upper-chords-of-the-upper-deck-floor-beams/analysis","conflicts":"/api/acts/ad-b747-337-upper-chords-of-the-upper-deck-floor-beams/conflicts","importantCases":"/api/acts/ad-b747-337-upper-chords-of-the-upper-deck-floor-beams/important-cases","documents":"/api/acts/ad-b747-337-upper-chords-of-the-upper-deck-floor-beams/documents"}}