{"id":"F2006B03090","name":"AD/B747/189 - Body Station 2598 Bulkhead Inner Chord","slug":"ad-b747-189-body-station-2598-bulkhead-inner-chord","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42461,"registerId":"commonwealth-F2006B03090-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/189 - Body Station 2598 Bulkhead Inner Chord","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBoeing 747 Series Aeroplanes\n\nAD/B747/189 Body Station 2598 Bulkhead Inner Chord 11/98\n\nApplicability: Model 747 series aircraft having line positions 1 through 1157.\n\nRequirement: Inspect in accordance with the technical requirements of FAA AD 98-16-13 Amdt 39- 10689.\n\nNote: Boeing Alert Service Bulletin 747-53A2423 refers.\n\nCompliance: As specified in the Requirement document with a revised effective date of 8 October 1998.\n\nThis airworthiness directive becomes effective on 8 October 1998.\n\nBackground: The FAA received a report that fasteners were missing from the splice fitting of the forward inner chord of the Body Station 2598 bulkhead. The actions specified in this Directive are intended to prevent accelerated fatigue cracking of the inner chords, which could result in inability of the structure to carry horizontal stabiliser flight loads.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete airworthiness directive addressing a specific structural defect in a specific aircraft type. It has not expanded beyond its original safety purpose."},"complexity_factors":["Single, specific technical requirement (inspect one structural component)","No defined terms section — relies entirely on external technical documents (FAA AD and Boeing Service Bulletin)","No conditional logic or nested exceptions","Very short document (under 200 words)","Clear applicability criteria (line positions 1-1157)","Single compliance pathway with reference to external standard"],"plain_english_summary":"This is a **safety order for Boeing 747 aircraft**.\n\n**What it does:**\nIt requires airlines and aircraft operators to inspect a specific structural part of certain Boeing 747 planes — the \"Body Station 2598 bulkhead inner chord\" (a structural component near the tail section that helps carry flight loads from the horizontal stabiliser).\n\n**Why it matters:**\nThe US aviation safety authority (FAA) discovered that fasteners (bolts/screws) were missing from this area. Without proper inspection and repair, this could lead to **metal fatigue cracking**. If the structure fails, the plane might not be able to handle the aerodynamic forces on its tail, potentially causing loss of control.\n\n**Who it affects:**\n- **Aircraft covered:** Boeing 747 models with production line numbers 1 through 1157 (essentially early to mid-production aircraft)\n- **Operators:** Airlines and maintenance organisations flying or servicing these specific aircraft in Australia\n\n**What must be done:**\nOperators must follow the inspection procedures set out in **FAA Airworthiness Directive 98-16-13** (a US safety order that CASA is adopting). They must also follow **Boeing Alert Service Bulletin 747-53A2423** for technical guidance.\n\n**When:**\nCompliance deadlines follow the US directive, with an effective date of 8 October 1998."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive applies to the specified Model 747 series aircraft (line positions 1–1157) and requires inspection according to FAA AD 98-16-13; the instrument also sets a revised effective date of 8 October 1998. The text does not indicate any expansion or narrowing of the population or requirements beyond those references (Applicability; Requirement; Compliance)."},"complexity_factors":["Cross-reference to an external FAA AD (FAA AD 98-16-13) that contains the technical inspection criteria (Requirement), requiring operators to consult another document.","Reference to a manufacturer Alert Service Bulletin (Boeing 747-53A2423) as related material (Note), adding another source to interpret.","Limited and specific applicability (Model 747 series, line positions 1–1157) that requires operators to check fleet serial/line position records (Applicability).","Operational scheduling and potential aircraft downtime for inspections and any corrective action (Requirement; Compliance).","Possible need for regulatory clarification or approved alternative methods where technical interpretation is required (implicit in cross-references to external technical documents).","A fixed effective date (8 October 1998) that creates a firm compliance milestone to manage (Compliance)."],"plain_english_summary":"This AD requires operators of specified Boeing 747s (line positions 1–1157) to carry out inspections per FAA AD 98-16-13, with Boeing Alert Service Bulletin 747-53A2423 as related material, effective 8 October 1998. It affects aircraft operators and maintenance organisations by mandating inspections to find missing fasteners and prevent fatigue cracking of the Body Station 2598 forward inner chord splice fitting—risks that could compromise horizontal stabiliser load capacity. Operators fund and schedule the work."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-189-body-station-2598-bulkhead-inner-chord","history":"/api/acts/ad-b747-189-body-station-2598-bulkhead-inner-chord/history","analysis":"/api/acts/ad-b747-189-body-station-2598-bulkhead-inner-chord/analysis","conflicts":"/api/acts/ad-b747-189-body-station-2598-bulkhead-inner-chord/conflicts","importantCases":"/api/acts/ad-b747-189-body-station-2598-bulkhead-inner-chord/important-cases","documents":"/api/acts/ad-b747-189-body-station-2598-bulkhead-inner-chord/documents"}}