{"id":"F2006B03593","name":"AD/BEA 121/28 - Wing to Fuselage Main Spar Attachment Fitting","slug":"ad-bea-121-28-wing-to-fuselage-main-spar-attachment-fitting","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43183,"registerId":"commonwealth-F2006B03593-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BEA 121/28 - Wing to Fuselage Main Spar Attachment Fitting","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Beagle B121 (Pup) Series Aeroplanes\n\n \n\nAD/BEA 121/28 Wing to Fuselage Main Spar Attachment Fitting 9/95\n\nApplicability: All Beagle B121 Pup Series 2 and Series 3 aircraft.\n\n \n\nRequirement: Perform a high frequency eddy current inspection of the wing to fuselage main spar attachment fitting in accordance with Jetstream Alert Service Bulletin (ASB) B121/100.\n\n \n\nNote: CAA(UK) AD 007-01-95 refers.\n\n \n\nCompliance: Inspect at the thresholds and intervals specified in Jetstream ASB B121/100 as adjusted by the role factors assigned by Jetstream SB B121/76.\n\n \n\nBackground:  Fatigue calculations by the manufacturer have indicated that additional inspections are required on the wing to fuselage main spar attachment fitting.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a narrow, specific scope — addressing a single identified safety issue on a specific aircraft type. It has not expanded beyond its original purpose of mandating inspection of the wing spar attachment fitting."},"complexity_factors":["Single, specific applicability (only Beagle B121 Pup Series 2 and 3)","Single requirement: one type of inspection on one component","No defined terms section — all technical terms reference external documents (service bulletins)","No conditional logic or nested exceptions","Short document (approximately 150 words of substantive content)","Cross-references to external technical documents (Jetstream ASB B121/100, SB B121/76, and UK CAA AD 007-01-95) rather than internal legislative provisions"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it does:**\nIt requires owners and operators of specific light aircraft (Beagle B121 Pup Series 2 and 3) to perform a specialised inspection on a critical structural component — the **wing-to-fuselage main spar attachment fitting**. This is the metal bracket that essentially bolts the wing to the body of the plane.\n\n**The inspection:**\nA **high frequency eddy current inspection** — a non-destructive testing method using electromagnetic fields to detect cracks or fatigue damage beneath the surface of the metal, without taking the part apart.\n\n**Who must follow this:**\nAnyone who owns or operates a Beagle B121 Pup Series 2 or Series 3 aircraft. This is not optional — compliance is legally mandatory.\n\n**When to do it:**\nAt the time intervals specified in the manufacturer's service bulletin (Jetstream ASB B121/100), adjusted by role factors (how hard the aircraft is used) set out in another bulletin (Jetstream SB B121/76).\n\n**Why it matters:**\nThe manufacturer discovered through fatigue calculations that this attachment point is wearing out faster than originally expected. If the fitting fails, the wing could separate from the fuselage in flight. This directive prevents catastrophic structural failure by catching cracks before they become dangerous."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive does not broaden the population or actions beyond its stated purpose: it requires additional inspections for all Beagle B121 Pup Series 2 and 3 aircraft as prompted by manufacturer fatigue calculations, without extending to other aircraft types or mandating corrective modifications."},"complexity_factors":["Technical inspection method: high‑frequency eddy current inspections require specialised equipment and trained personnel (Requirement).","Cross‑document references: procedural and interval details are in Jetstream ASB B121/100 and adjustments in SB B121/76 (Requirement; Compliance).","Applicability narrowness: applies only to Beagle B121 Pup Series 2 and 3, requiring accurate fleet identification (Applicability).","Compliance scheduling: operators must apply thresholds and intervals and integrate inspections into maintenance planning, creating operational downtime and cost (Compliance).","Safety rationale based on manufacturer analysis: directive issued because fatigue calculations indicated additional inspections were required (Background).","Enforcement and documentation: complying with an AD creates recordkeeping and audit exposure for operators (implied by AD structure and Compliance)."],"plain_english_summary":"This airworthiness directive requires owners/operators of Beagle B121 Pup Series 2 and 3 aircraft to carry out high‑frequency eddy‑current inspections of the wing‑to‑fuselage main spar attachment fitting, following Jetstream Alert Service Bulletin B121/100 and using role‑factor adjustments in Jetstream SB B121/76. The manufacturer’s fatigue calculations prompted the directive; operators pay for the inspections, must follow the specified thresholds and intervals, and schedule inspections to remain compliant with the directive."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bea-121-28-wing-to-fuselage-main-spar-attachment-fitting","history":"/api/acts/ad-bea-121-28-wing-to-fuselage-main-spar-attachment-fitting/history","analysis":"/api/acts/ad-bea-121-28-wing-to-fuselage-main-spar-attachment-fitting/analysis","conflicts":"/api/acts/ad-bea-121-28-wing-to-fuselage-main-spar-attachment-fitting/conflicts","importantCases":"/api/acts/ad-bea-121-28-wing-to-fuselage-main-spar-attachment-fitting/important-cases","documents":"/api/acts/ad-bea-121-28-wing-to-fuselage-main-spar-attachment-fitting/documents"}}