{"id":"F2006B04578","name":"AD/BELL 212/46 - Main Rotor Drag Brace Assembly","slug":"ad-bell-212-46-main-rotor-drag-brace-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114308,"registerId":"commonwealth-F2006B04578-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 212/46 - Main Rotor Drag Brace Assembly","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)  Bell Helicopter Textron 212 Series Helicopters\n\n \n\nAD/BELL 212/46 Main Rotor Drag Brace Assembly 7/91\n\nApplicability: All models.\n\n \n\nRequirement: Action in accordance with the Technical Requirements of FAA AD 90-26-11, Amendment 39-6840.\n\n \n\nCompliance: In accordance with the Requirement document with revised effective date 11 July 1991.\n\n \n\nBackground: Eight reports of drag brace assembly cracking have been attributed to high cycle, low stress fatigue. The cracks had gone undetected at daily visual inspections and were not actually detected until after hub assembly overhaul.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument does not indicate any change to the scope of applicability or to the underlying safety concern. It applies to all Bell 212 models and requires compliance with FAA AD 90-26-11 as of the revised effective date (Applicability; Requirement; Compliance). The text provides background on why the directive was issued (Background) but contains no statement that the directive expands or narrows scope compared with an earlier measure."},"complexity_factors":["External dependency: the AD mandates actions by reference to FAA AD 90-26-11 rather than containing technical steps itself (Requirement).","Sparse detail in the instrument: the CASA text does not list inspection methods, intervals or corrective actions — those are in the FAA AD (Compliance).","Technical subject matter: detecting high-cycle, low-stress fatigue cracking typically requires maintenance-level inspection or disassembly rather than simple visual checks (Background).","Broad applicability: the AD applies to all Bell 212 models, widening the set of affected operators (Applicability).","Administrative detail: compliance tied to a specific revised effective date creates a timing compliance requirement (Compliance)."],"plain_english_summary":"This CASA Airworthiness Directive requires all Bell 212 operators to comply with FAA AD 90-26-11, mandating inspections and corrective action on the main rotor drag brace assembly after reports of high‑cycle, low‑stress fatigue cracks that were not found by daily visual checks and only discovered during hub overhaul.\n\nOperators and their maintenance providers must bear the compliance costs and follow the FAA’s inspection timing and procedures rather than relying on routine visual inspections."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating inspection/repair of the main rotor drag brace assembly."},"complexity_factors":["Very short document (under 200 words)","Only 4 operative sections: Applicability, Requirement, Compliance, and Background","No defined terms section — relies entirely on external reference to FAA AD 90-26-11","Single, unambiguous compliance action (follow the FAA directive)","No nested conditions, exceptions, or cross-references to other Australian legislation","Straightforward applicability (all models of one helicopter series)"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it like a compulsory recall notice, but for aircraft parts.\n\n**What it does:** It requires owners and operators of **Bell 212 series helicopters** to inspect and fix a specific problem with the **main rotor drag brace assembly** — a critical component that helps stabilise the helicopter's main rotor.\n\n**The problem:** The drag brace assembly can develop **cracks due to metal fatigue** (repeated stress over many flight cycles, even at low stress levels). These cracks are sneaky — they weren't being caught during routine daily visual checks and were only found later during major overhauls. Eight cases had already been reported.\n\n**What must happen:** Operators must follow the technical instructions in an American safety order (**FAA AD 90-26-11**) to inspect, repair, or replace the affected parts. The deadline for compliance was **11 July 1991**.\n\n**Who it affects:** Anyone operating Bell 212 helicopters in Australia — including emergency services, military, and commercial operators.\n\n**Why it matters:** A cracked drag brace assembly could lead to **main rotor failure** and catastrophic loss of the aircraft. This directive closes a safety gap where routine inspections were missing a critical defect."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-212-46-main-rotor-drag-brace-assembly","history":"/api/acts/ad-bell-212-46-main-rotor-drag-brace-assembly/history","analysis":"/api/acts/ad-bell-212-46-main-rotor-drag-brace-assembly/analysis","conflicts":"/api/acts/ad-bell-212-46-main-rotor-drag-brace-assembly/conflicts","importantCases":"/api/acts/ad-bell-212-46-main-rotor-drag-brace-assembly/important-cases","documents":"/api/acts/ad-bell-212-46-main-rotor-drag-brace-assembly/documents"}}