{"id":"F2006B11122","name":"AD/LEARJET 35/7 - Spoileron Computer - Modification","slug":"ad-learjet-35-7-spoileron-computer-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56794,"registerId":"commonwealth-F2006B11122-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET 35/7 - Spoileron Computer - Modification","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)  Gates Learjet 35 and 36 Series Aeroplanes\n\n \n\nAD/LEARJET 35/7 Spoileron Computer - Modification 4/78\n\nApplicability: Model 35 S/Nos. 35-001 to 35-142.\n\n \n\nModel 36 with S/Nos. 36-001 to 36-035.\n\n \n\nDocument: Gates Learjet SB 35/36-27-7.\n\n \n\nCompliance: Within 300 hours time in service after 30 April 1978.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope, as published, is confined to the listed serial-number ranges for Learjet Models 35 and 36 and requires the spoileron computer modification per Gates Learjet SB 35/36-27-7 within the stated 300-hour window. The text contains no indication that the applicability or required action has been expanded or narrowed beyond those stated requirements."},"complexity_factors":["Narrow applicability limited to specific serial numbers (Models 35 and 36).","Single technical action required (modification of the spoileron computer) rather than multiple interdependent changes.","Technical detail is external to the directive and delegated to the manufacturer’s service bulletin (requires obtaining and following that document).","A fixed, short compliance window (300 hours time in service after a specified date) creates scheduling constraints for operators.","Issued under a clear regulatory authority (Civil Aviation Regulations 1998, Part 39), so legal effect is straightforward but enforcement details are not contained in the text."],"plain_english_summary":"# What this directive does\n\n- Mechanically, this instrument requires a specific hardware change: modify the spoileron computer on certain Gates Learjet Model 35 and Model 36 aeroplanes by following the procedures in Gates Learjet Service Bulletin 35/36-27-7 (Document: Gates Learjet SB 35/36-27-7). (See: \"Document\" and title lines.)\n\n- It applies only to aircraft with the listed serial numbers: Model 35 S/Ns 35-001 to 35-142; Model 36 S/Ns 36-001 to 36-035. (See: \"Applicability\".)\n\n- The work must be carried out within 300 hours time in service after 30 April 1978. (See: \"Compliance\".)\n\n- The directive is issued under the Civil Aviation Regulations 1998, Part 39, as an item in the Civil Aviation Safety Authority schedule of Airworthiness Directives. (See header.)\n\n# Who is affected and who decides\n\n- Aircraft owners and operators of the listed Learjet 35/36 serial numbers must arrange and pay for the modification. (Requirement and applicability lines.)\n\n- The technical steps to perform the modification are specified by the manufacturer in the referenced service bulletin; the regulator has mandated compliance with that manufacturer document. (See: \"Document: Gates Learjet SB 35/36-27-7\".)\n\n- The Civil Aviation Safety Authority (under Part 39) is the regulatory source that issues the directive and enforces compliance. (See header.)\n\n# Why it matters (official claim and practical implications)\n\n- The instrument is an airworthiness directive; its stated mechanism is to require a manufacturer-specified modification. The text itself does not set out the operational problem being corrected; it instead prescribes the corrective action and timetable. (See: title, document and compliance lines.)\n\n- Practical implications and trade-offs:\n  - Who pays: owners/operators must bear the financial cost and scheduling burden of having the modification performed (labour, parts, downtime). (Implicit from the requirement to comply.)\n  - Who decides the technical method: the manufacturer’s service bulletin supplies the technical instructions; the regulator makes following that work mandatory by aircraft and serial number. This places technical specification with the manufacturer while legal obligation rests with operators. (See: \"Document\" and applicability lines.)\n  - Compliance burden and timing: compliance must occur within a specified flight-hours window (300 hours after 30 April 1978), so operators must plan the work into maintenance schedules within that service-hour limit. (See: \"Compliance\".)\n  - Effects on maintenance market: mandating a defined modification creates demand for parts and qualified technicians able to perform the manufacturer-prescribed procedure; independent maintenance providers may be engaged to carry out the work under the service bulletin. (Inferred from the requirement to perform the modification per the referenced SB.)\n  - Concentrated benefits and costs: the manufacturer provides the service instructions (potentially increasing demand for its parts or authorized work) while costs (parts, labour, downtime) are borne by individual operators whose aircraft fall within the listed serial-number range. (See: \"Document\" and \"Applicability\".)\n  - Implementation risks and compliance enforcement: the regulator’s Part 39 authority supplies the legal force to require the modification; operators must demonstrate compliance within the specified hours. The directive itself does not describe enforcement mechanisms or penalties. (See header and compliance line.)\n\n# Net description\n\nThis is a narrowly targeted regulatory requirement: a mandated modification of a specific component (the spoileron computer) on a defined set of Learjet 35 and 36 airframes, to be completed according to a manufacturer service bulletin within a short, specified hours window. The directive assigns the legal obligation to operators, references the manufacturer for technical instructions, and imposes a timing constraint that affects maintenance planning and costs for those operators."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive issued in 1978 (as indicated by '4/78' in the title and the April 1978 compliance date). It has not expanded beyond its original narrow purpose: mandating a specific hardware modification to a specific flight control computer on specific early-production Learjet aircraft. The scope remains precisely limited to the identified serial number ranges and has not grown to encompass additional aircraft models, systems, or ongoing obligations."},"complexity_factors":["Extremely short document (under 200 words)","Only 4 operative provisions: applicability, reference document, compliance deadline, and affected aircraft serial numbers","No defined terms section","No cross-references to other legislation beyond the enabling Civil Aviation Regulations 1998","Simple conditional structure: if you own these specific aircraft, you must do this specific thing by this specific deadline","Single technical reference to an external service bulletin rather than detailed technical specifications within the instrument itself"],"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 as a \"recall notice\" for aircraft, but legally binding.\n\n**What it requires:** Owners and operators of specific **Gates Learjet 35 and 36 series aircraft** must modify the **spoileron computer** — the electronic system that controls spoilerons (flight control surfaces that act as both spoilers and ailerons to help steer and slow the plane).\n\n**Who it affects:**\n- **Learjet Model 35** aircraft with serial numbers 35-001 through 35-142\n- **Learjet Model 36** aircraft with serial numbers 36-001 through 36-035\n\n**The fix:** Operators must follow the technical instructions in **Gates Learjet Service Bulletin 35/36-27-7** to modify the spoileron computer.\n\n**Deadline:** The modification must be completed within **300 hours of flight time** after 30 April 1978.\n\n**Why it matters:** Airworthiness Directives exist to prevent accidents. This particular AD addresses a specific safety issue with the spoileron computer system in early-model Learjet 35s and 36s. Non-compliance means the aircraft cannot legally fly in Australian airspace."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-35-7-spoileron-computer-modification","history":"/api/acts/ad-learjet-35-7-spoileron-computer-modification/history","analysis":"/api/acts/ad-learjet-35-7-spoileron-computer-modification/analysis","conflicts":"/api/acts/ad-learjet-35-7-spoileron-computer-modification/conflicts","importantCases":"/api/acts/ad-learjet-35-7-spoileron-computer-modification/important-cases","documents":"/api/acts/ad-learjet-35-7-spoileron-computer-modification/documents"}}