{"id":"F2006B07323","name":"AD/TB20/2 - Landing Gear Micro Switches - Adjustment","slug":"ad-tb20-2-landing-gear-micro-switches-adjustment","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49354,"registerId":"commonwealth-F2006B07323-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB20/2 - Landing Gear Micro Switches - Adjustment","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)  Aerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes\n\n \n\nAD/TB20/2 Landing Gear Micro Switches - Adjustment 3/85\n\nApplicability: All model TB20 with S/Nos up to and including 459.\n\n \n\nRequirement: Adjust the undercarriage micro switches according to the requirements contained in Socata TB SB No 23.\n\n \n\nNote: French AD 85-4(A) refers.\n\n \n\nCompliance: Within 50 hours time in service after 31 March 1985.\n\n \n\nBackground: Compliance with this Directive will minimise the possibility of inadvertent undercarriage collapse.\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":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1985 addressing a specific safety defect in a specific aircraft model. It has not expanded beyond its original purpose of preventing landing gear collapse through micro switch adjustment."},"complexity_factors":["Very short document (approximately 150 words)","Only one substantive requirement (adjust micro switches per manufacturer bulletin)","Simple applicability test (serial number range)","Single compliance deadline (50 hours time in service after fixed date)","No defined terms section, no cross-references to other legislation, no conditional logic or exceptions","References only one external technical document (Socata TB SB No 23)"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for a specific type of aircraft.\n\n**What it does:** It requires owners and operators of certain Socata TB20 \"Trinidad\" aeroplanes to adjust the landing gear micro switches. These are small electrical switches that detect whether the landing gear (undercarriage) is properly extended or retracted.\n\n**Who it affects:** Anyone who owns or operates a Socata TB20 aircraft with serial numbers up to and including 459.\n\n**What must be done:** The adjustment must follow the specific instructions in \"Socata TB Service Bulletin No. 23\" — a technical notice from the aircraft manufacturer.\n\n**When it must be done:** Within 50 hours of flying time after 31 March 1985.\n\n**Why it matters:** Faulty micro switches could fail to detect if the landing gear is properly locked in place. This creates a risk of the landing gear collapsing during landing, which could cause a serious accident. This directive was issued to prevent that."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive’s scope is consistent with its stated intent in the text: it targets TB20 aircraft up to and including serial number 459 and mandates adjustment of the undercarriage micro switches to reduce the risk of inadvertent gear collapse (Applicability; Requirement; Background). The directive does not expand or narrow that applicability beyond those elements."},"complexity_factors":["Narrow technical scope: single maintenance action (adjust undercarriage micro switches) (Requirement)","Clear limited applicability: specific models/serial numbers (Applicability)","Fixed, short compliance window expressed in flight hours creates scheduling pressure (Compliance)","Dependence on an external document (Socata TB SB No. 23) for procedural detail introduces a secondary source that must be obtained and followed (Requirement)","Implementation relies on maintenance personnel competence and interpretation of the service bulletin, creating operational risk (Requirement)","Minimal procedural ambiguity in the directive itself but absence of quantified benefit or inspection/verification protocol increases practical uncertainty about outcomes (Background; Requirement)"],"plain_english_summary":"This AD mandates adjustment of landing‑gear micro‑switches on TB20 (Trinidad) aeroplanes with serial numbers up to 459, to be done per Socata Technical/Service Bulletin No. 23 within 50 flight hours after 31 March 1985. It compels owners/operators and maintenance organisations to follow the SB (at their cost) to reduce the risk of inadvertent undercarriage collapse."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb20-2-landing-gear-micro-switches-adjustment","history":"/api/acts/ad-tb20-2-landing-gear-micro-switches-adjustment/history","analysis":"/api/acts/ad-tb20-2-landing-gear-micro-switches-adjustment/analysis","conflicts":"/api/acts/ad-tb20-2-landing-gear-micro-switches-adjustment/conflicts","importantCases":"/api/acts/ad-tb20-2-landing-gear-micro-switches-adjustment/important-cases","documents":"/api/acts/ad-tb20-2-landing-gear-micro-switches-adjustment/documents"}}