{"id":"F2006B10933","name":"AD/JETSTREAM/63 - Aileron Control System Mounting Spigot Nut","slug":"ad-jetstream-63-aileron-control-system-mounting-spigot-nut","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56479,"registerId":"commonwealth-F2006B10933-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/JETSTREAM/63 - Aileron Control System Mounting Spigot Nut","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)  British Aerospace BAe 3100 (Jetstream) Series Aeroplanes\n\n \n\nAD/JETSTREAM/63 Aileron Control System Mounting Spigot Nut\n\n\n5/94\n\n \n\nApplicability: All Jetstream Series 3100 aircraft, and all Jetstream 3200 aircraft up to and including constructors number 979.\n\n \n\nRequirement: Action in accordance with Jetstream Mandatory Service Bulletin 57-JA 921140 or Service Bulletin 57-JA 921140 Revision 1.\n\n \n\nCompliance: Unless already accomplished, prior to 1 January 1995\n\n \n\nBackground: There have been reports of cracks and failures of the threaded portion of the aileron control mounting spigots. The cracking was attributed to stress corrosion.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope, as stated, is consistent with its expressed intent: to remedy reported cracking and failures of the aileron control mounting spigot threaded portion on the listed Jetstream aircraft by mandating the actions in the named service bulletin before 1 January 1995. The text contains no indication that the applicability, required action or deadline were broadened or narrowed from the originally stated purpose in this document."},"complexity_factors":["Clear, narrow applicability (specific aircraft series and constructor numbers) reduces scope complexity (Applicability).","Core requirement delegates technical detail to an external mandatory service bulletin, creating dependence on another document for implementation specifics (Requirement).","Single, fixed compliance deadline simplifies legal timing but may create operational scheduling pressure (Compliance).","Limited procedural content in the directive: no alternatives, enforcement details, or quantified risk metrics are provided (Requirement; Compliance; Background).","Technical subject matter (airframe component stress corrosion) is specialized, requiring maintenance/engineering capability even though the AD text is short (Background)."],"plain_english_summary":"What this directive does (mechanically)\n\n- Requires operators of certain British Aerospace Jetstream aeroplanes to carry out the work described in Jetstream Mandatory Service Bulletin 57-JA 921140 (or Revision 1) to address the aileron control system mounting spigot nut. (Requirement)\n- Sets a compliance deadline: unless the work has already been done, it must be completed prior to 1 January 1995. (Compliance)\n\nWho is affected\n\n- All Jetstream Series 3100 aircraft. (Applicability)\n- All Jetstream 3200 aircraft up to and including constructor's number 979. (Applicability)\n\nWhy it matters (official rationale and practical effect)\n\n- The background states there have been reports of cracks and failures of the threaded portion of the aileron control mounting spigots, attributed to stress corrosion. The mandated work is intended to address that condition. (Background)\n\nHow it changes behaviour and who pays\n\n- Aircraft operators or owners of the applicable Jetstream aircraft must arrange and fund whatever inspections, repairs, replacements or modifications are specified in the referenced mandatory service bulletin. (Requirement; Applicability)\n- The directive creates a legal obligation to comply by the stated date; failure to comply would leave the aircraft non‑conforming to this airworthiness directive. (Requirement; Compliance)\n\nTrade-offs, costs and implementation considerations\n\n- Direct costs and operational impacts are not specified in the text. The likely costs are the labour, parts and aircraft downtime necessary to perform the service bulletin instruction. (Requirement; Compliance)\n- The directive delegates the technical detail and method to the manufacturer’s service bulletin, so the nature and scope of the work (and therefore precise cost and downtime) depend on that external document. This concentrates technical decision‑making in the service‑bulletin instructions. (Requirement)\n- The deadline imposes a timing constraint; operators must schedule the work before 1 January 1995 unless it has already been done. This creates a short window for planning and may cause short‑term maintenance congestion. (Compliance)\n\nRisks, discretion and omissions in the text\n\n- The directive states the safety concern (cracking from stress corrosion) but does not quantify failure rates, operational risk, or specify enforcement or penalty measures. Those elements are outside the text provided. (Background)\n- The AD gives no alternative compliance options or provisional exemptions in the text; compliance is framed as the single required action (the referenced service bulletin). Any discretion about methods or extension would therefore depend on regulatory practice or further instructions not contained here. (Requirement; Compliance)\n\nNet, factual summary\n\n- The AD mandates that specified Jetstream 3100 and certain 3200 aeroplanes undergo the actions set out in the named mandatory service bulletin by the stated deadline to address reported cracking of the aileron control mounting spigot nut. Operators bear the costs and must schedule the work; the technical details and practical burdens follow from the referenced service bulletin rather than from this short directive itself. (Applicability; Requirement; Compliance; Background)\n"},"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 failure mode. It has not expanded beyond its original purpose of mandating inspection/replacement of a single component."},"complexity_factors":["Single, specific mechanical defect addressed","Only two applicability criteria (aircraft model and serial number range)","Single compliance action referencing an external technical document","No defined terms section, no cross-references to other legislation","No conditional logic or nested exceptions","Extremely short (under 200 words of substantive content)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations.\n\n**What it does:**\nOrders owners and operators of specific British Aerospace Jetstream aircraft to inspect and fix a dangerous defect in the aileron control system.\n\n**The problem:**\nThe \"mounting spigot nut\" — a threaded fitting that helps attach the aileron (the hinged flap on the wing that controls rolling) — has been cracking and failing due to **stress corrosion** (metal weakening caused by a combination of tension and environmental factors). If this part fails, the pilot could lose control of the aircraft's roll.\n\n**Who must act:**\n- All Jetstream 3100 series aircraft\n- All Jetstream 3200 aircraft with serial numbers up to 979\n\n**What they must do:**\nFollow the repair instructions in **Jetstream Mandatory Service Bulletin 57-JA 921140** (or its Revision 1). This is a technical document from the manufacturer detailing the inspection and replacement procedures.\n\n**Deadline:**\nBefore 1 January 1995 (unless already done).\n\n**Why it matters:**\nThis directive prevents potential catastrophic loss of flight control. It is legally binding — operators cannot fly these aircraft without completing this fix."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jetstream-63-aileron-control-system-mounting-spigot-nut","history":"/api/acts/ad-jetstream-63-aileron-control-system-mounting-spigot-nut/history","analysis":"/api/acts/ad-jetstream-63-aileron-control-system-mounting-spigot-nut/analysis","conflicts":"/api/acts/ad-jetstream-63-aileron-control-system-mounting-spigot-nut/conflicts","importantCases":"/api/acts/ad-jetstream-63-aileron-control-system-mounting-spigot-nut/important-cases","documents":"/api/acts/ad-jetstream-63-aileron-control-system-mounting-spigot-nut/documents"}}