{"id":"F2006B03581","name":"AD/BEA 121/17 - Nosewheel Steering Mechanism","slug":"ad-bea-121-17-nosewheel-steering-mechanism","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43149,"registerId":"commonwealth-F2006B03581-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BEA 121/17 - Nosewheel Steering Mechanism","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 121/17 Nosewheel Steering Mechanism 1/77\n\nApplicability: All model B121 not incorporating Mod. No. BE314. Requirement:  Action in accordance with Scottish Aviation SB No. B121/69.\n\nCompliance: Within 100 hours time in service after 31 January 1977 and thereafter at intervals not exceeding 100 hours time in service.\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\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 discrete, single-issue safety directive from 1977 concerning one specific mechanical system on one aircraft type. It has not expanded beyond its original purpose of ensuring nosewheel steering integrity through periodic inspection."},"complexity_factors":["Extremely short document (under 150 words of substantive content)","Only 4 operative elements: applicability, requirement, compliance deadline, and recurring interval","Single cross-reference to external technical document (Scottish Aviation SB No. B121/69) — the actual detailed instructions are contained there, not in this instrument","No defined terms section — all language is plain technical aviation terminology","Simple binary applicability test (incorporating Mod. No. BE314 or not)","No nested conditions, exceptions, or sub-delegations"],"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) for a specific aircraft type.\n\n**Which aircraft:** Beagle B121 \"Pup\" series aeroplanes (small, single-engine British aircraft from the 1960s–70s).\n\n**What it requires:** Owners and operators must inspect or fix the **nosewheel steering mechanism** on these planes. Specifically, they must follow the instructions in **Scottish Aviation Service Bulletin B121/69** — a technical notice from the original manufacturer about a known problem with the steering system.\n\n**Who must comply:** Anyone operating a B121 model that **hasn't** been modified with \"Mod. No. BE314\" (a factory fix that solves this particular problem).\n\n**When to do it:**\n- **First time:** Within 100 hours of flying time after 31 January 1977\n- **Ongoing:** Every 100 hours of flying time after that\n\n**Why it matters:** Faulty nosewheel steering can cause loss of directional control during taxi, takeoff, or landing — potentially leading to runway excursions or accidents. This AD ensures the steering mechanism is checked regularly to catch wear or failure before it becomes dangerous."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument’s scope, as stated, is limited to all Beagle B121 aircraft that do not incorporate Mod. No. BE314 and requires action per Scottish Aviation SB No. B121/69 at 100-hour intervals. The text presents a targeted, recurring maintenance mandate addressing the nosewheel steering mechanism and does not indicate any expansion or narrowing of that scope within the instrument itself."},"complexity_factors":["Narrow applicability limited to Beagle B121 aircraft without Mod. No. BE314 (low breadth). (Applicability)","Mandates action by reference to an external technical document (Scottish Aviation SB No. B121/69), requiring operators to obtain and follow that bulletin (adds procedural dependency). (Requirement)","Simple, fixed recurring compliance interval (every 100 hours time in service) with a definite initial deadline (within 100 hours after 31 January 1977) — straightforward scheduling but recurring burden. (Compliance)","No detailed technical steps in the directive text itself, so practical compliance complexity depends on the contents and clarity of the referenced service bulletin. (Requirement)","Regulatory discretion is limited in the directive text; enforcement relies on routine maintenance oversight rather than complex regulatory decision-making (low administrative complexity)."],"plain_english_summary":"This directive requires owners/operators of Beagle B121 (Pup) aeroplanes without Modification No. BE314 to perform the nosewheel steering maintenance/modification in Scottish Aviation Service Bulletin No. B121/69 within 100 hours TIS after 31 Jan 1977 and then at 100‑hour intervals. It enforces the SB’s technical measures to address nosewheel steering safety.\n\nAffected operators bear the recurring cost and downtime, creating an incentive to fit Mod. BE314 to avoid the recurring requirement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bea-121-17-nosewheel-steering-mechanism","history":"/api/acts/ad-bea-121-17-nosewheel-steering-mechanism/history","analysis":"/api/acts/ad-bea-121-17-nosewheel-steering-mechanism/analysis","conflicts":"/api/acts/ad-bea-121-17-nosewheel-steering-mechanism/conflicts","importantCases":"/api/acts/ad-bea-121-17-nosewheel-steering-mechanism/important-cases","documents":"/api/acts/ad-bea-121-17-nosewheel-steering-mechanism/documents"}}