{"id":"F2006B11087","name":"AD/LEARJET 35/1 - Primary Control System Stop Bolts - Inspection and Replacement","slug":"ad-learjet-35-1-primary-control-system-stop-bolts-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56746,"registerId":"commonwealth-F2006B11087-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET 35/1 - Primary Control System Stop Bolts - Inspection and Replacement","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 35/1  Primary Control System Stop Bolts - Inspection and Replacement\n\nApplicability: All model 35 with S/Nos. 35-001 to 35-039.\n\n \n\nAll model 36 with S/Nos. 36-001 to 36-016.\n\n \n\nDocument: Gates Learjet SB 35/36-27-3.\n\n \n\nCompliance: Within 300 hours time in service after 30 April 1976.\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\n4/76\n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"Based on the text provided, the directive sets a narrow, time-limited requirement for a defined set of serial-numbered aircraft and points to a service bulletin for technical detail. There is no indication in the supplied text that the scope has been broadened or narrowed from any prior version; the operative scope is the serial-number list and the compliance timeframe as stated (Applicability; Compliance; Document)."},"complexity_factors":["Narrow and explicit applicability by specific serial numbers reduces scope ambiguity.","Single required actions (inspection and replacement) are straightforward, lowering procedural complexity.","Technical details and exact procedures are delegated to an external service bulletin (Gates Learjet SB 35/36-27-3), which creates a dependency on that document for implementation specifics.","A fixed, short compliance window (300 hours after 30 April 1976) imposes scheduling pressure on operators.","Practical compliance complexity depends on availability of parts, qualified technicians and access to the service bulletin."],"plain_english_summary":"# What this directive does\n\nThis airworthiness directive orders owners/operators of certain Learjet 35 and 36 aeroplanes to inspect the primary control system stop bolts and replace them if necessary. Mechanically, it (a) identifies which aeroplanes are covered, (b) points to the detailed procedure in a Gates Learjet service bulletin, and (c) sets a mandatory compliance window.\n\n- Legal basis and placement: Issued under the Civil Aviation Regulations regime as a Schedule of Airworthiness Directives (see heading). This makes the requirement mandatory for the listed aeroplanes.\n- Which aircraft are affected: All Model 35 with serial numbers 35-001 to 35-039, and all Model 36 with serial numbers 36-001 to 36-016 (Applicability).\n- What must be done: Inspect the primary control system stop bolts and perform replacement as indicated in Gates Learjet Service Bulletin 35/36-27-3 (Document: Gates Learjet SB 35/36-27-3).\n- When it must be done: Within 300 hours time in service after 30 April 1976 (Compliance).\n\n# Stated purpose and how it operates mechanically\n\nThe directive’s title and placement in the Airworthiness Directives schedule indicate its purpose is to address the condition of primary control system stop bolts. The directive accomplishes that purpose by: (1) mandating an inspection and replacement regime for a specified fleet subset (Applicability); (2) delegating the technical steps to a named service bulletin (Document); and (3) imposing a fixed compliance deadline (Compliance).\n\n# Who pays, who decides, and what changes in behaviour\n\n- Who pays: Owners/operators of the affected aircraft must bear the cost of inspections, any replacements, parts, and the labour and downtime required to comply (implicit from the directive requiring the work on specified aircraft).\n- Who decides how to comply: The directive requires following the Gates Learjet Service Bulletin referenced; that bulletin contains the technical method and therefore constrains the maintenance organisation’s choices (Document: Gates Learjet SB 35/36-27-3).\n- Behaviour change required: Operators must schedule and carry out the inspection and any replacement within the 300 flight-hour window set after 30 April 1976. This may require pulling aircraft from service temporarily to complete the work (Compliance).\n\n# Costs, incentives, trade-offs and implementation considerations\n\n- Direct costs and opportunity costs: Operators incur inspection and replacement costs, part costs, labour, and aircraft downtime during the compliance window. Those are concrete, immediate costs to the listed operators (Applicability; Compliance).\n- Incentives: The mandatory deadline creates a near-term scheduling and maintenance incentive: operators must prioritise the work within the specified hours. Non-compliance would leave aircraft out of regulatory conformity.\n- Trade-offs: The directive trades operator expense and downtime for the intended outcome of addressing the bolt condition. The method and scope of the technical work are set by the service bulletin, limiting alternative compliance methods (Document).\n- Implementation risks and practical constraints: Compliance depends on access to the referenced Gates Learjet SB and any required parts and qualified maintenance personnel. Delays in parts or technical support would affect operators’ ability to meet the deadline (Document; Compliance).\n- Compliance burden and discretion: The directive prescribes mandatory action and a fixed compliance window; there is limited discretion for operators except in timing within that window and any alternative methods explicitly permitted by the regulator (the directive itself references the SB for method).\n\n# Concentration of benefits and costs\n\n- Concentrated beneficiaries: The immediate safety benefit (as framed by the directive’s title) accrues to operators, crews and passengers of the affected aircraft when the bolt condition is addressed. Those beneficiaries are the same entities that must pay for compliance.\n- Diffuse costs: Because the rule applies only to a limited set of serial numbers, the cost burden is concentrated on a comparatively small group of owners/operators (Applicability).\n\n# Citation of the operative parts of the document\n\n- Applicability: lists serial numbers of covered aircraft (Model 35: 35-001 to 35-039; Model 36: 36-001 to 36-016).\n- Document: Gates Learjet SB 35/36-27-3 (technical instructions).\n- Compliance: Within 300 hours time in service after 30 April 1976.\n\n(Directive dated 4/76.)"},"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 limited fleet of aircraft. It has not expanded beyond its original purpose of mandating inspection/replacement of stop bolts in early-production Learjet 35/36 aircraft."},"complexity_factors":["Extremely short document (approximately 150 words)","Only 2 defined applicability criteria (serial number ranges for two models)","Single cross-reference to one external technical document (Service Bulletin 35/36-27-3)","No nested conditions, exceptions, or conditional logic","Simple compliance deadline structure (single time-in-service threshold)","No interpretation section or defined terms"],"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) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires owners and operators of specific Gates Learjet 35 and 36 series aircraft to **inspect and replace the stop bolts in their primary control systems**. Stop bolts are mechanical components that limit how far control surfaces (like ailerons, elevators, or rudders) can move. If these bolts fail, pilots could lose control of the aircraft.\n\n**Who it affects:** \n- **Model 35 aircraft** with serial numbers 35-001 through 35-039\n- **Model 36 aircraft** with serial numbers 36-001 through 36-016\n\n**What must be done:** Operators must follow the technical instructions in **Gates Learjet Service Bulletin 35/36-27-3** and complete the work **within 300 hours of flight time after 30 April 1976**.\n\n**Why it matters:** This directive addresses a specific safety defect that could lead to catastrophic loss of aircraft control. Compliance is **legally mandatory** — flying without completing this work would violate civil aviation law and put lives at risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-35-1-primary-control-system-stop-bolts-inspection-and-replacement","history":"/api/acts/ad-learjet-35-1-primary-control-system-stop-bolts-inspection-and-replacement/history","analysis":"/api/acts/ad-learjet-35-1-primary-control-system-stop-bolts-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-learjet-35-1-primary-control-system-stop-bolts-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-learjet-35-1-primary-control-system-stop-bolts-inspection-and-replacement/important-cases","documents":"/api/acts/ad-learjet-35-1-primary-control-system-stop-bolts-inspection-and-replacement/documents"}}