{"id":"F2006B11101","name":"AD/LEARJET 35/22 - Aileron Trim Tab Balance Weight - Replacement","slug":"ad-learjet-35-22-aileron-trim-tab-balance-weight-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56761,"registerId":"commonwealth-F2006B11101-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET 35/22 - Aileron Trim Tab Balance Weight - 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\n# AD/LEARJET 35/22 Aileron Trim Tab Balance Weight - Replacement\n\nApplicability: All model Learjet with serial numbers listed in Requirement Document. Requirement:              Gates Learjet AMK 83-3.\n\nNote: FAA AD 84-19-06 refers.\n\n# 12/84\n\n \n\nCompliance: Within 600 hours time in service after 31 December 1984 or the next aileron/trim tab removal or rebalance whichever occurs first.\n\n \n\nBackground:  The manufacturer has determined that the aileron trim tab balance weight is insufficient to meet the failsafe design requirements. This modification is needed to prevent possible flutter in the event of a disconnect in the trim tab system.\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. It has not expanded beyond its original purpose of mandating a single hardware modification to prevent flutter."},"complexity_factors":["Single, specific technical requirement (replace one component)","Only one defined applicability criterion (serial numbers in external document)","Simple compliance deadline structure (hours-based with alternative trigger)","No nested exceptions or conditional logic","Short document (under 200 words of substantive content)","Single cross-reference to FAA AD 84-19-06 for additional context"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it requires:** Owners and operators of certain Gates Learjet 35 and 36 series aeroplanes must replace the aileron trim tab balance weight. This is a physical modification to the aircraft's control surfaces (the ailerons are the hinged parts on the wings that help the plane turn; the trim tab is a smaller adjustable surface that reduces pilot effort).\n\n**Why it matters:** The original balance weight is too light to meet safety standards for \"failsafe\" design — meaning if the trim tab system breaks or disconnects, the aircraft could experience dangerous vibrations called \"flutter\" (rapid, uncontrolled oscillations that can damage the wing or cause loss of control). The heavier replacement weight prevents this potentially catastrophic failure.\n\n**Who must comply:** All Learjet 35 and 36 models with specific serial numbers listed in the referenced technical document (Gates Learjet AMK 83-3).\n\n**When to do it:** Within 600 flight hours after 31 December 1984, or at the next time the aileron or trim tab is removed or rebalanced — whichever comes first.\n\n**Key point:** This is not optional. Non-compliance grounds the aircraft — it cannot legally fly until the fix is done."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument defines a targeted mandatory modification for specific Gates Learjet 35/36 series aeroplanes identified by serial number and prescribes the technical method (Gates Learjet AMK 83-3) and a fixed compliance window. There is no indication in the text that the scope of affected aircraft or the required action was altered from the directive’s stated content; it sets a clear, narrow scope tied to the Requirement Document and AMK."},"complexity_factors":["Technical specificity: compliance requires following an external technical instruction (Gates Learjet AMK 83-3) rather than procedural text in the AD itself (Requirement).","Applicability tied to a separate Requirement Document listing serial numbers, meaning readers must consult another document to determine if an aircraft is affected (Applicability).","Conditional timing: two alternative triggers for compliance (600 hours after 31/12/1984 OR next removal/rebalance, whichever first) require operational tracking of flight hours and maintenance events (Compliance).","Cross-reference to an external foreign regulator AD (FAA AD 84-19-06) creates an additional document chain to review (Note).","Low administrative discretion in the AD text (prescriptive requirement), but technical and logistical discretion remains with operators and maintenance providers when scheduling and executing the work."],"plain_english_summary":"What this instrument does (mechanically)\n\n- Requires replacement of the aileron trim tab balance weight on certain Gates Learjet 35/36 series aeroplanes. The work must be carried out in accordance with Gates Learjet AMK 83-3 (\"Requirement\") and applies to the aircraft models and serial numbers listed in the Requirement Document (\"Applicability\"). (Applicability; Requirement)\n- Sets a compliance window: the replacement must be done within 600 hours time in service after 31 December 1984 or at the next aileron/trim tab removal or rebalance, whichever happens first. (Compliance)\n- Cross-references a related FAA airworthiness directive (FAA AD 84-19-06). (Note)\n\nStated purpose\n\n- The document states the manufacturer determined the existing aileron trim tab balance weight is insufficient to meet failsafe design requirements and that the modification is needed to prevent possible flutter if the trim tab system disconnects. (Background)\n\nWho it affects and who pays\n\n- Affects owners/operators of the specific Learjet aircraft identified by model and serial number in the Requirement Document (Applicability). They must arrange and pay for the replacement work required by the AD (Requirement; Compliance).\n- Maintenance organisations or technicians performing the work must follow Gates Learjet AMK 83-3; that technical instruction is the operative method for compliance (Requirement).\n\nPractical incentives, costs and trade-offs\n\n- Incentive provided: reduces the risk (as claimed by the manufacturer) of trim-tab-induced flutter following a trim-system disconnect (Background). That is the safety rationale the requirement is tied to.\n- Direct costs and burdens fall on aircraft owners/operators: scheduling the work within the stated window, procuring parts and labour to perform the replacement to the AMK specification, and any aircraft downtime while the work is completed (Requirement; Compliance).\n- The directive concentrates obligation on a defined set of serial-numbered aircraft (Applicability). This concentrates the compliance cost on a specific group rather than spreading it across all operators.\n\nImplementation and compliance features, and where discretion lies\n\n- The AD prescribes the corrective action and cites the exact technical instruction to be used (Requirement). That reduces discretionary choice about how to comply: operators must follow the AMK procedure.\n- The timing rule gives a limited scheduling choice (within 600 hours TIS or the next removal/rebalance, whichever is first) but no long-term deferral option (Compliance).\n- The AD text does not itself specify enforcement or penalty mechanisms, only the mandatory requirement and the compliance timing (Requirement; Compliance). The Requirement Document and AMK provide the technical detail for carrying out the work.\n\nPotential implementation risks and operational impacts (mechanisms, not opinions)\n\n- Risks for operators include parts availability, booking qualified maintenance slots, and the opportunity cost of aircraft downtime during the modification (Requirement; Compliance).\n- Independent maintenance providers can perform the work only by meeting the AMK procedures; the AD’s reference to a specific AMK may require access to or purchase of that technical material (Requirement).\n\nSource references within the instrument\n\n- Applicability: \"All model Learjet with serial numbers listed in Requirement Document.\" (Applicability)\n- Requirement: \"Gates Learjet AMK 83-3.\" (Requirement)\n- Compliance: \"Within 600 hours time in service after 31 December 1984 or the next aileron/trim tab removal or rebalance whichever occurs first.\" (Compliance)\n- Background (stated rationale): manufacturer determined the balance weight is insufficient to meet failsafe design requirements; modification needed to prevent possible flutter in the event of a disconnect in the trim tab system. (Background)\n- Cross-reference: \"FAA AD 84-19-06 refers.\" (Note)\n"}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-35-22-aileron-trim-tab-balance-weight-replacement","history":"/api/acts/ad-learjet-35-22-aileron-trim-tab-balance-weight-replacement/history","analysis":"/api/acts/ad-learjet-35-22-aileron-trim-tab-balance-weight-replacement/analysis","conflicts":"/api/acts/ad-learjet-35-22-aileron-trim-tab-balance-weight-replacement/conflicts","importantCases":"/api/acts/ad-learjet-35-22-aileron-trim-tab-balance-weight-replacement/important-cases","documents":"/api/acts/ad-learjet-35-22-aileron-trim-tab-balance-weight-replacement/documents"}}