{"id":"F2006B03155","name":"AD/B747/256 - Body Station 1480 Bulkhead","slug":"ad-b747-256-body-station-1480-bulkhead","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42527,"registerId":"commonwealth-F2006B03155-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nBoeing 747 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B747/256 Body Station 1480 Bulkhead 1","sectionType":"part","heading":"AD/B747/256 Body Station 1480 Bulkhead 10/2001","content":"# AD/B747/256 Body Station 1480 Bulkhead 10/2001\n\nApplicability: Model 747 series aircraft, line numbers 1 through 1254.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 2001-11-06 Amdt 39-12248.\n\nNote: Boeing Service Bulletins 747-53A2390 and 747-53A2390 Revision 1 refer.\n\nCompliance: As specified in the Requirement document with a revised effective date of 4 October 2001.\n\nThis Airworthiness Directive becomes effective on 4 October 2001.\n\nBackground: The FAA received reports that fatigue cracking has been found in the outer chord of the BS 1480 bulkhead at the overwing longeron splice on aircraft not subject to previously issued AD 98-20-25, which was only applicable to Model 747-100 aircraft. Fatigue cracking of the skin, splice fittings, bulkhead web, and outer chord of the BS1480 upper and lower bulkhead and longeron splice fitting, unless detected and corrected, could result in reduced structural integrity of the fuselage and the inability to carry limit load.\n\n![Signature of David Villiers, Delegate of the Civil Aviation Safety Authority.](image.002.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 20 August 2001\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 12 September 2001.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This AD expands the population of affected aircraft compared with the earlier AD cited in the Background (FAA AD 98-20-25), which applied only to Model 747-100 aircraft. AD/B747/256 requires inspections and possible repairs for a wider set of Boeing 747 series aircraft (line numbers 1–1254). Functionally, the directive broadens mandatory obligations (inspections/repairs) to operators who were not covered by the earlier, more limited AD, thereby increasing the regulatory scope from a single model subset to a larger portion of the 747 fleet."},"complexity_factors":["Short, single-issue directive focused on BS1480 bulkhead inspections/repairs","Applicability specified by aircraft model and line numbers (Models 747, line numbers 1–1254)","Primary technical requirements are incorporated by reference to FAA AD 2001-11-06 rather than reproduced in full","References to external manufacturer documents: Boeing Service Bulletins 747-53A2390 and Revision 1","Clear effective date (4 October 2001) and simple compliance instruction (comply as specified in the Requirement document)","Limited internal conditional logic or nested exceptions within the AD text itself"],"plain_english_summary":"**What this Directive does (mechanically)**\n\n- This is an Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) that requires operators of certain Boeing 747 aircraft to inspect and, if necessary, repair a structural area of the fuselage called the Body Station (BS) 1480 bulkhead.  \n- The AD makes compliance with the technical steps and schedules in the U.S. Federal Aviation Administration (FAA) AD 2001-11-06 mandatory for the Australian-registered aircraft covered.  \n- The directive takes effect on 4 October 2001 and applies to Boeing 747 series aeroplanes with line numbers 1 through 1254 (see \"Applicability\").\n\n**Who is affected**\n\n- Aircraft operators (airlines, lessors, maintenance organisations) that operate or maintain Boeing 747s within the specified line-number range.  \n- Maintenance providers who must carry out the inspections and repairs described in the FAA AD and the Boeing Service Bulletin(s) cited.\n\n**Why it matters (stated purpose and mechanic of the risk)**\n\n- The FAA reported fatigue cracking in the outer chord of the BS1480 bulkhead at the overwing longeron splice on aircraft that were not covered by an earlier AD (98-20-25).  \n- If such cracking is not found and fixed, it could reduce fuselage structural integrity and potentially prevent the aircraft from carrying limit loads (i.e. it could compromise the airplane’s structural strength under normal/required load conditions).\n\n**What operators must do, who pays, and who decides**\n\n- Operators must follow the inspection, reporting and repair actions set out in FAA AD 2001-11-06. The FAA AD contains the technical instructions and schedule; CASA enforces those instructions for Australian-registered aircraft by issuing this AD.  \n- The costs of inspections, any corrective repairs, and associated aircraft downtime are borne by the operators or the organisations that maintain/own the aircraft.  \n- CASA (through the delegated decision-signer) decides that compliance with the FAA AD is required for Australian operations; the FAA AD and the referenced Boeing Service Bulletins specify the technical steps and timing.\n\n**Practical implementation points and trade-offs**\n\n- The AD delegates the detailed technical work to an external document (FAA AD 2001-11-06) and refers to Boeing Service Bulletins (747-53A2390 and its Revision 1). That means the precise inspection methods, thresholds for repair, and intervals are not reproduced in this Australian AD but are enforced by reference.  \n- Implementation costs are concentrated on operators of the affected aircraft: they fund inspections, repairs and possible operational disruption. The safety benefit (preventing structural failure) accrues broadly to passengers, crew and the public.  \n- The compliance burden includes availability of maintenance slots, access to the specific inspection and repair procedures, and potential lead time for parts or structural repairs. If inspections find cracks, operators must perform repairs before returning the aircraft to service.\n\n**Risk and operational effects to note**\n\n- Detection depends on following the inspection procedure in the FAA AD/Boeing Service Bulletin. If inspections or repairs are not performed per those technical instructions, the unsafe condition could remain.  \n- There is an economic trade-off: regular inspection and repair expense and aircraft downtime versus reducing the risk of structural failure.  \n- The AD extends the set of affected aircraft beyond the scope of a prior AD (98-20-25), so some operators who were not previously subject to an AD for this area now have mandatory obligations (see \"Background\").\n\n(References in text: the AD’s Applicability, Requirement, Compliance and Background sections; FAA AD 2001-11-06; Boeing Service Bulletins 747-53A2390 and 747-53A2390 Revision 1.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope: addressing a specific structural fatigue issue in a defined subset of Boeing 747 aircraft. It does not expand beyond the original safety purpose of correcting the BS 1480 bulkhead cracking problem."},"complexity_factors":["Very short document (under 300 words)","Only 1 defined applicability criterion (line numbers 1–1254)","Single requirement that cross-references an external FAA document rather than setting out detailed technical steps","No nested exceptions or conditional logic — straightforward mandatory compliance","Background section provides clear safety rationale without legal hedging"],"plain_english_summary":"This AD mandates inspections and repairs on Boeing 747s (line numbers 1–1254) to address fatigue cracking in the Body Station 1480 bulkhead—a structural area whose failure could compromise the fuselage. Operators must comply with the procedures and compliance dates in FAA AD 2001-11-06 (via Boeing service bulletins). Effective 4 October 2001, it applies to airlines and cargo operators of the affected aircraft."},"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-b747-256-body-station-1480-bulkhead","history":"/api/acts/ad-b747-256-body-station-1480-bulkhead/history","analysis":"/api/acts/ad-b747-256-body-station-1480-bulkhead/analysis","conflicts":"/api/acts/ad-b747-256-body-station-1480-bulkhead/conflicts","importantCases":"/api/acts/ad-b747-256-body-station-1480-bulkhead/important-cases","documents":"/api/acts/ad-b747-256-body-station-1480-bulkhead/documents"}}