{"id":"F2006B03591","name":"AD/BEA 121/26 - Rudder Control Tube Bolt","slug":"ad-bea-121-26-rudder-control-tube-bolt","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43181,"registerId":"commonwealth-F2006B03591-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BEA 121/26 - Rudder Control Tube Bolt","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 121/26 Rudder Control Tube Bolt 10/88 DM\n\nApplicability: All models.\n\n \n\nRequirement: Action in accordance with British Aerospace Alert SB B121/94.\n\n \n\nCompliance: Prior to further flight after 27 July 1988 and thereafter at each removal/replacement of the subject bolt.\n\n \n\nBackground:  Certain combinations of rudder and elevator control settings have resulted in this bolt fouling the elevator control tube. This may restrict or jam control movement.\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, targeted safety directive addressing a specific mechanical defect in a specific aircraft type. The scope remains precisely limited to the rudder control tube bolt issue as originally identified."},"complexity_factors":["Very short document (approximately 150 words)","Only 1 defined applicability (\"All models\")","Single cross-reference to external technical document (British Aerospace Alert SB B121/94)","No nested conditions or exceptions","Simple binary compliance trigger (prior to further flight after specific date, plus recurring trigger at bolt replacement)","Straightforward causal chain in background section"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for **Beagle B121 (Pup) series aeroplanes**.\n\n**What it does:**\n- Requires owners/operators to inspect or modify a specific **rudder control tube bolt**\n- The bolt can interfere with the elevator control tube in certain flight control configurations, potentially **jamming or restricting the controls** — a serious safety risk\n\n**Who must comply:**\n- Anyone operating any model of Beagle B121 (Pup) aircraft\n\n**What action is required:**\n- Follow the instructions in **British Aerospace Alert Service Bulletin B121/94**\n- Must be done **before flying again after 27 July 1988**\n- Must be **re-checked every time the bolt is removed and replaced**\n\n**Why it matters:**\nControl jamming in flight can lead to loss of aircraft control. This directive prevents a known mechanical interference problem that could endanger pilots and passengers."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope, as stated, applies to all Beagle B121 (Pup) series aeroplanes and requires the actions in British Aerospace Alert SB B121/94 prior to flight after 27 July 1988 and on each removal/replacement of the subject bolt. There is no indication in the text that the compliance obligations or applicability have been broadened or narrowed from the instrument’s stated purpose (Applicability, Requirement, Compliance, Background)."},"complexity_factors":["Reliance on an external technical document (British Aerospace Alert SB B121/94) for the actual work instructions (Requirement).","A clear, time-bound compliance trigger (prior to further flight after 27 July 1988) plus a recurring trigger on each removal/replacement of the bolt (Compliance).","Narrow technical scope (a single bolt and its interaction with control tubes) but safety-critical consequences (Background).","Applicability to all models of the aircraft type, creating uniform obligation across the fleet (Applicability).","Potential ambiguity in how the service bulletin should be interpreted or implemented by different maintenance organisations (implicit in Requirement)."],"plain_english_summary":"This Airworthiness Directive makes British Aerospace Alert Service Bulletin B121/94 mandatory for Beagle B121 (Pup) aircraft, requiring the specified maintenance before the next flight after 27 July 1988 and thereafter whenever the named bolt is removed or replaced.  \n\nIt addresses a risk that the bolt can foul the elevator control tube and restrict or jam controls; compliance costs (parts, labour, downtime) fall to owners/operators and their maintenance organisations."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bea-121-26-rudder-control-tube-bolt","history":"/api/acts/ad-bea-121-26-rudder-control-tube-bolt/history","analysis":"/api/acts/ad-bea-121-26-rudder-control-tube-bolt/analysis","conflicts":"/api/acts/ad-bea-121-26-rudder-control-tube-bolt/conflicts","importantCases":"/api/acts/ad-bea-121-26-rudder-control-tube-bolt/important-cases","documents":"/api/acts/ad-bea-121-26-rudder-control-tube-bolt/documents"}}