{"id":"F2006B11146","name":"AD/LEARJET/29 - Aileron Trim Tab Balance Weight - Replacement","slug":"ad-learjet-29-aileron-trim-tab-balance-weight-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56833,"registerId":"commonwealth-F2006B11146-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET/29 - 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 24 & 25 Series Aeroplanes\n\n \n\n# AD/LEARJET/29 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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD text indicates a single, specific safety modification: replacement of the aileron trim tab balance weight for the Learjet serial numbers listed in the Requirement Document to meet failsafe design requirements (Background; Requirement). The document itself contains no language indicating any expansion or narrowing of scope from an earlier or original intent; it sets the applicability, the technical requirement (AMK 83-3) and the compliance timing without showing any change in scope."},"complexity_factors":["Single, targeted technical requirement (replacement of one component) reduces substantive legislative complexity.","Compliance timing rule includes an alternative event (600 hours after 31 Dec 1984 OR next removal/rebalance), which adds a conditional scheduling nuance.","Applicability depends on a listed set of serial numbers in a separate Requirement Document, requiring cross-reference to external material.","Technical execution depends on a manufacturer document (Gates Learjet AMK 83-3), which delegates the procedural detail outside the AD text.","Cross-reference to FAA AD 84-19-06 creates an additional external reference operators may need to consult."],"plain_english_summary":"This AD mandates replacement of the aileron trim‑tab balance weight on specified Gates Learjet serial numbers, carried out per Gates Learjet AMK 83‑3, within 600 flight hours after 31 Dec 1984 or at the next aileron/trim‑tab removal/rebalance.  \n\nIt affects owners/operators (who pay and must schedule certified maintenance) to fix an identified failsafe/possible‑flutter deficiency; expect parts, labour, and downtime impacts concentrated on the listed aircraft."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused specifically on a known mechanical defect in particular aircraft models. It has not expanded beyond its original purpose of mandating a specific hardware replacement to prevent flutter."},"complexity_factors":["Very short document (under 200 words)","Only 1 defined term implicitly referenced (Requirement Document)","Single, straightforward compliance requirement with clear deadline","No cross-references to other legislation beyond a single note about FAA AD","No conditional logic or nested exceptions — simple 'do this by this date' structure","Background explanation is plain language and technically accessible"],"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 Gates Learjet 24 and 25 series aeroplanes must replace the aileron trim tab balance weight (a small counterweight on the wing's control surface) according to the manufacturer's service bulletin AMK 83-3.\n\n**Why it matters:** The original balance weight is too light to meet safety standards. If the trim tab system breaks or disconnects, the aircraft could experience \"flutter\" — a dangerous, rapid vibration that can destroy control surfaces and cause a crash. This fix prevents that catastrophic failure.\n\n**Who must comply:** Anyone operating affected Learjet 24 and 25 series aircraft with serial numbers listed in the requirement document.\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 mirrors an American FAA directive (AD 84-19-06), showing this was a known international safety issue."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-29-aileron-trim-tab-balance-weight-replacement","history":"/api/acts/ad-learjet-29-aileron-trim-tab-balance-weight-replacement/history","analysis":"/api/acts/ad-learjet-29-aileron-trim-tab-balance-weight-replacement/analysis","conflicts":"/api/acts/ad-learjet-29-aileron-trim-tab-balance-weight-replacement/conflicts","importantCases":"/api/acts/ad-learjet-29-aileron-trim-tab-balance-weight-replacement/important-cases","documents":"/api/acts/ad-learjet-29-aileron-trim-tab-balance-weight-replacement/documents"}}