{"id":"F2005L01047","name":"AD/B747/224 Amdt 1 - Upper Deck Floor Beams","slug":"ad-b747-224-amdt-1-upper-deck-floor-beams","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":34609,"registerId":"commonwealth-F2005L01047-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/B747/224 Amdt 1 | Upper Deck Floor Beams | 6/2005 |\n| ------------------ | ---------------------- | ------ |\n\n| Applicability: | Model 747-100, -100B, -100B SUD, -200B, and -300 series aircraft; and Model 747SR and 747SP aircraft; as listed in Boeing Alert Service Bulletin 747-53A2431 Revision 2, dated 13 June 2002.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | Inspect in accordance with the technical requirements of FAA AD 2005-06-11 Amdt 39-14019.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |\n| Compliance:    | As specified in the Requirement document, with a revised effective date of 9 June 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n|                | This Amendment becomes effective on 9 June 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n| Background:    | The FAA received a report from the manufacturer that, during a fatigue test, the upper chord and web of the upper deck floor beams located at body stations 340 and 360 were found severed at approximately 34,000 flight cycles. Another report by an operator indicated that a severed upper chord and web were found in the upper deck floor beam at body station 38 at approximately 33,000 total flight cycles.Amendment 1 is issued in response to a new FAA AD, which lowers the threshold for the existing inspections and requires new repetitive inspections of previously repaired areas, and repair if necessary. This new FAA AD was prompted by the results of an additional detailed analysis that indicate fatigue cracks can initiate sooner than has previously been observed. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n27 April 2005","sortOrder":0},{"sectionNumber":"AD/B747/224 Amdt 1","sectionType":"part","heading":"AD/B747/224 Amdt 1","content":"## AD/B747/224 Amdt 1","sortOrder":1},{"sectionNumber":"Upper Deck Floor Beams","sectionType":"part","heading":"Upper Deck Floor Beams","content":"## Upper Deck Floor Beams","sortOrder":2},{"sectionNumber":"6/2005","sectionType":"part","heading":"6/2005","content":"## 6/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment widens the operational scope compared with the earlier AD by lowering the threshold for initial inspections and by requiring new repetitive inspections of previously repaired areas. In practical terms it moves inspection points earlier in an aircraft’s life (fewer flight cycles before mandatory inspection) and increases the frequency and coverage of inspections (adds repaired areas to the repetitive-inspection regime). The change therefore expands the set of aircraft/airframe life stages at which mandatory inspections and potential repairs are required, increasing compliance obligations for operators of the listed 747 models."},"complexity_factors":["Short, single-issue instrument (structural inspections for upper-deck floor beams).","Cross-reference to an external FAA AD (2005-06-11) which contains the detailed technical requirements.","Cross-reference to Boeing Alert Service Bulletin 747-53A2431 Revision 2 for applicability and technical detail.","List of multiple affected 747 variants (several model subtypes) in the applicability clause.","Amendment changes timing/thresholds and adds repetitive inspections for repaired areas (one additional conditional layer).","Technical complexity of inspections/repairs lies in external documents rather than in the AD text itself."],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Requires owners/operators of certain Boeing 747 models (listed below) to carry out inspections and any necessary repairs on the upper-deck floor beams, by following the technical instructions in FAA Airworthiness Directive (AD) 2005-06-11 and Boeing Alert Service Bulletin 747-53A2431 Revision 2 (13 June 2002).  \n- It adopts the FAA AD’s revised inspection thresholds and adds repetitive inspections for previously repaired areas.  \n- The amended directive is effective from 9 June 2005.\n\nWhich aeroplanes are affected\n\n- Model 747-100, -100B, -100B SUD, -200B, and -300 series aircraft; and Model 747SR and 747SP aircraft, as listed in Boeing Alert Service Bulletin 747-53A2431 Revision 2 (13 June 2002).\n\nWhy the regulator says this is necessary (official rationale)\n\n- Manufacturer fatigue testing and operator reports found the upper chord and web of upper-deck floor beams severed at about 33,000–34,000 flight cycles.  \n- A further analysis indicated fatigue cracks can initiate earlier than previously observed.  \n- In response, the FAA lowered the threshold for initial inspections, introduced new repetitive inspections for repaired areas, and requires repair where cracks or damage are found. CASA’s amendment adopts those FAA requirements.\n\nPractical effect on operators and third parties\n\n- Who pays: aircraft owners/operators pay for inspections, repairs, parts, and aircraft downtime.  \n- Who decides: CASA (by issuing this AD) mandates compliance; the inspection and repair work must follow the FAA AD and Boeing service bulletin’s technical instructions.  \n- What behaviour changes: operators must schedule earlier and more frequent inspections of the upper-deck floor beams, inspect previously repaired areas on a recurring basis, and carry out repairs to meet airworthiness requirements.  \n- Enforcement: compliance with this AD is mandatory; non-compliance can render the aircraft un-airworthy and expose operators to regulatory action and commercial/insurance consequences.\n\nTesting the regulator’s rationale against costs, incentives and implementation risks\n\n- Direct costs and incentives: the amendment increases near-term maintenance costs (labour, non-destructive inspections, possible structural repairs or part replacement). Operators face an economic incentive to perform inspections early to avoid unplanned failures, but also a cost incentive to delay or stretch inspection intervals unless enforced.  \n- Concentrated benefits vs diffuse costs: the safety benefit (reduced risk of structural failure) is concentrated on passengers, crew and registry safety interest; the costs (inspection and repair) are concentrated on the aircraft owners/operators.  \n- Operational trade-offs: inspections and repairs can cause aircraft downtime and schedule disruption; some operators may accelerate retirement or redeploy aircraft if inspection/repair costs exceed residual value.  \n- Implementation risk and capacity: requirement relies on availability of qualified maintenance organisations and access to the structural area; locating and repairing cracks in upper-deck floor beams can be technically demanding and may require specialised parts or procedures.  \n- Contract, market and insurance effects: increased inspection frequency can raise maintenance reserves, affect lease negotiations, and influence insurers’ risk assessments and premiums.  \n- Substitution effects: operators may respond by changing fleet composition (e.g., earlier disposal of affected airframes), adjusting utilisation rates, or incurring capital expenditure to modify structures if authorised repairs are available.\n\nSummary statement\n\nThis CASA amendment mandates earlier and repetitive inspections and repairs for upper-deck floor beams on specified Boeing 747 variants by adopting FAA AD 2005-06-11 and the referenced Boeing service bulletin. Mechanically it forces operators to inspect and repair structural elements sooner and more often than under the prior regime. The amendment increases maintenance and operational costs for the listed operators, while aiming to reduce the risk of fatigue-related structural failure identified in fatigue tests and operator reports. The central implementation issues are maintenance capacity, inspection accessibility, repair availability, aircraft downtime and the economic choices operators will make about continued operation, repair or retirement of affected airframes."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment stays within the original scope of the airworthiness directive. It tightens inspection thresholds and adds requirements for previously repaired areas, but this is a natural evolution of the same safety issue (fatigue cracking in upper deck floor beams) rather than an expansion into new regulatory territory. The amendment responds to new technical data about the same structural component."},"complexity_factors":["Short, single-purpose document (1 page)","Only 1 defined term implicitly referenced (FAA AD 2005-06-11)","Simple conditional structure: inspect if applicable, comply by specified date","Heavy reliance on external technical document (FAA AD) for actual inspection procedures — the 'Requirement' simply points to another document rather than detailing steps","No nested exceptions or complex logical operators","Clear applicability table identifying specific aircraft models by reference to Boeing service bulletin"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice for aircraft. It requires airlines and operators to inspect specific Boeing 747 aircraft for dangerous cracks in the upper deck floor beams.\n\n**What it does:**\n- Orders inspections of the upper deck floor beams on certain Boeing 747 models (the -100, -200B, -300 series, plus the SR and SP variants)\n- These inspections must follow technical rules set by the US Federal Aviation Administration (FAA AD 2005-06-11)\n- The directive tightens safety requirements — lowering the number of flight cycles before inspections must begin, and adding new checks for areas that were previously repaired\n\n**Why it matters:**\n- During fatigue testing, Boeing found that floor beams could crack and sever after around 33,000–34,000 flight cycles — earlier than previously thought\n- Cracks in floor beams could compromise the aircraft's structural integrity\n- This amendment makes the rules stricter based on new engineering analysis showing fatigue cracks appear sooner than expected\n\n**Who it affects:**\n- Airlines and operators flying the specified Boeing 747 models\n- Maintenance crews who must carry out the inspections\n- The Civil Aviation Safety Authority (CASA) — Australia's aviation safety regulator — which enforces compliance\n\n**Key change in this amendment:**\n- The original directive required inspections at higher flight cycle thresholds\n- Amendment 1 lowers those thresholds and adds new repetitive inspections for repaired areas, plus requires repairs if cracks are found"},"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-b747-224-amdt-1-upper-deck-floor-beams","history":"/api/acts/ad-b747-224-amdt-1-upper-deck-floor-beams/history","analysis":"/api/acts/ad-b747-224-amdt-1-upper-deck-floor-beams/analysis","conflicts":"/api/acts/ad-b747-224-amdt-1-upper-deck-floor-beams/conflicts","importantCases":"/api/acts/ad-b747-224-amdt-1-upper-deck-floor-beams/important-cases","documents":"/api/acts/ad-b747-224-amdt-1-upper-deck-floor-beams/documents"}}