{"id":"F2010L01950","name":"AD/B747/53 Amdt 4 - Longitudinal Skin Lap Joint and Body Frame Corrosion and Cracking","slug":"ad-b747-53-amdt-4-longitudinal-skin-lap-joint-and-body-frame-corrosion-and-cracking","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":124390,"registerId":"commonwealth-F2010L01950-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/B747/53 Amdt 4 | Longitudinal Skin Lap Joint andBody Frame Corrosion and Cracking | 14/2010 |\n| ----------------- | ---------------------------------------------------------------- | ------- |\n\n| Applicability: | B747 aircraft line numbers 1 to 200.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Conduct an external visual inspection of the lower fuselage lap joints for corrosion in accordance with Boeing Service Bulletin (SB) 747-53A2267, dated 28 March 1986 or later FAA approved revision.Note: FAA AD 86-09-07 R1 refers.                                                                                                                                                                                                                                                                                                                                               |\n| Compliance:    | Inspect in accordance with the requirement before 12,000 hours time in service or before 100 hours time in service after 30 October 1986, whichever is the later.Re-inspect at intervals not to exceed 4000 hours time in service or 15 months, whichever is the sooner if no corrosion was found at the last inspection. If corrosion was found re-inspect at intervals not to exceed 1000 hours time in service. Inspect until modified in accordance with Boeing SB747-53A2267, dated 28 March 1986.                                                                             |\n|                | This Amendment becomes effective on 19 July 2010.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n| Background:    | Corrosion and fatigue cracking of fuselage skin lap joints has been reported on many B747 aircraft.The initial issue of this AD required visual inspections for corrosion and cracking.Amendment 1 allowed an optional terminating modification.Amendment 2 referenced FAA AD 86-09-07.Amendment 3 required inspection after modification in accordance with FAA AD94-17-01, which is no longer considered to be terminating. The inspection requirement is dependent on the SB revision at the time of installation. The modification is now mandatory before 20 years of service. |\n\n|     | This Amendment retains the requirement to visually inspect for corrosion mandated by FAA AD86-09-07 R1 whilst the requirements for ECI to the upper row of fasteners in the lap joints mandated by FAA AD 94-17-01 have been superseded by State of Design FAA AD 2010-14-10. |\n| --- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)\n\nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n6 July 2010","sortOrder":0},{"sectionNumber":"AD/B747/53 Amdt 4","sectionType":"part","heading":"AD/B747/53 Amdt 4","content":"## AD/B747/53 Amdt 4","sortOrder":1},{"sectionNumber":"Longitudinal Skin Lap Joint andBody Fram","sectionType":"part","heading":"Longitudinal Skin Lap Joint andBody Frame Corrosion and Cracking","content":"## Longitudinal Skin Lap Joint and  \nBody Frame Corrosion and Cracking","sortOrder":2},{"sectionNumber":"14/2010","sectionType":"part","heading":"14/2010","content":"## 14/2010","sortOrder":3}],"analysis":{"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":3,"scope_assessment":{"changed":true,"description":"The original directive required only visual inspections for corrosion and cracking. Through four amendments, the scope has expanded significantly: Amendment 1 added optional terminating modifications; Amendment 2 incorporated FAA regulatory references; Amendment 3 added mandatory modification requirements and post-modification inspections; and Amendment 4 (this version) retains corrosion inspections while removing superseded eddy current inspection requirements but adds a mandatory modification deadline (20 years service). The directive has evolved from a simple inspection mandate to a comprehensive structural integrity program with multiple compliance pathways and external regulatory dependencies."},"complexity_factors":["Multiple amendment history referenced (Amendments 1-4) creating layered context","Dual compliance triggers (flight hours vs. calendar dates) with 'whichever is later/sooner' logic","Conditional inspection intervals based on findings (corrosion found vs. not found)","Cross-references to external technical documents: Boeing Service Bulletin 747-53A2267 and FAA ADs 86-09-07 R1, 94-17-01, and 2010-14-10","Specific applicability limited by aircraft line numbers (1-200) requiring operators to check manufacturing records","Terminating action vs. continuing inspection requirements with modification deadline (20 years service)"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of early-model Boeing 747s (line numbers 1–200) to inspect lower fuselage lap joints for corrosion and cracking, impose recurring inspections, and mandate eventual modification per Boeing/FAA repair instructions. It affects airlines and maintenance organisations for those oldest 747s and aims to prevent structural failure, decompression, or loss of the aircraft."},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Scope has shifted from allowing an optional terminating modification (earlier amendments) to mandating the modification before 20 years of service, while retaining recurring visual inspection requirements and updating cross-references to newer FAA ADs (Background/Requirement)."},"complexity_factors":["Multiple, conditional inspection intervals: initial timing tied to hours-in-service or calendar proximity, re-inspect at 4,000 hours or 15 months if no corrosion, or 1,000 hours if corrosion was found (Compliance).","Inspections remain required until a modification is installed per Boeing SB 747-53A2267; the relevant SB revision at time of installation affects requirements (Requirement/Compliance/Background).","Cross-references to several FAA airworthiness directives (FAA AD 86-09-07 R1, FAA AD 94-17-01, and FAA AD 2010-14-10), creating dependency on State-of-Design rule changes (Background).","Applicability limited to specific aircraft line numbers (1–200), creating a bounded but technically specific affected cohort (Applicability).","History of amendments: earlier optional terminating modification became mandatory before 20 years of service, so compliance obligations changed over time (Background).","Technical subject matter (corrosion/fatigue of lap joints and fasteners) requires skilled inspection and possible structural work, increasing operational and maintenance burden (Requirement/Compliance).","Interplay between visual inspections and previously required eddy current inspections for fasteners, with some ECI requirements superseded, complicates choice of inspection technique (Background)."],"plain_english_summary":"This AD requires owners/operators of Boeing 747 line numbers 1–200 to perform external visual inspections of lower fuselage lap joints for corrosion per Boeing Service Bulletin 747-53A2267 (or later FAA‑approved revision). It sets initial and recurring inspection intervals and keeps inspections in place until a specified structural modification is installed. Operators pay for inspections and any required rework, must follow FAA/SB revisions, and meet a mandatory modification deadline before 20 years of service (see Compliance/Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-53-amdt-4-longitudinal-skin-lap-joint-and-body-frame-corrosion-and-cracking","history":"/api/acts/ad-b747-53-amdt-4-longitudinal-skin-lap-joint-and-body-frame-corrosion-and-cracking/history","analysis":"/api/acts/ad-b747-53-amdt-4-longitudinal-skin-lap-joint-and-body-frame-corrosion-and-cracking/analysis","conflicts":"/api/acts/ad-b747-53-amdt-4-longitudinal-skin-lap-joint-and-body-frame-corrosion-and-cracking/conflicts","importantCases":"/api/acts/ad-b747-53-amdt-4-longitudinal-skin-lap-joint-and-body-frame-corrosion-and-cracking/important-cases","documents":"/api/acts/ad-b747-53-amdt-4-longitudinal-skin-lap-joint-and-body-frame-corrosion-and-cracking/documents"}}