{"id":"F2006B07329","name":"AD/TB20/25 - Autopilot Master Switch","slug":"ad-tb20-25-autopilot-master-switch","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49373,"registerId":"commonwealth-F2006B07329-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB20/25 - Autopilot Master Switch","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/TB20/25 Autopilot Master Switch 2/92\n\nApplicability: All TB20 and TB21 with S/No’s 275 thru 1222 fitted with one of the following options: 668, G668, 669, G669, 670 or G670.\n\n \n\nRequirement: Action in accordance with Aerospatiale SOCATA Service Bulletin No 60.\n\n \n\nNote: DGAC AD 91-145A refers.\n\n \n\nCompliance: Prior to the next Maintenance Release after 28 February 1992. Background:  To reduce the risk of a short circuit at the “A/P Master” switch.\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 AD’s stated purpose (reduce risk of a short circuit at the A/P Master switch) is reflected directly in the mandatory requirement to carry out Aerospatiale SOCATA Service Bulletin No 60 for the specified aircraft. The directive imposes a maintenance action on a defined subset of the fleet and sets a compliance deadline tied to the next Maintenance Release; there is no textual indication in the source material that the AD’s scope departs from its stated intent."},"complexity_factors":["Narrow applicability limited to TB20/TB21 serial numbers 275–1222 with options 668/G668/669/G669/670/G670 (straightforward identification). (Applicability)","Mandates compliance with an external technical document (Aerospatiale SOCATA Service Bulletin No 60), creating dependency on that document for the exact corrective action. (Requirement)","Fixed compliance timing tied to the next Maintenance Release after a specific date, requiring scheduling within operators’ maintenance cycles. (Compliance)","No technical detail in the AD itself; enforcement and acceptability of the remedy depend on maintenance organisations following the referenced Service Bulletin. (Requirement)","Reference to an additional foreign authority document (DGAC AD 91-145A) adds a secondary cross-reference to consider. (Note)"],"plain_english_summary":"This AD (AD/TB20/25) applies to Aerospatiale (Socata) TB20 and TB21 aeroplanes, S/N 275–1222, fitted with options 668/G668, 669/G669 or 670/G670, and makes compliance with Aerospatiale SOCATA Service Bulletin No 60 mandatory. It requires the SB work be completed before the aircraft’s next Maintenance Release after 28 February 1992 to reduce the risk of a short circuit at the autopilot “A/P Master” switch.\n\nAffected owners/operators must obtain and schedule the SB work, bearing parts, labour and downtime; the AD delegates technical detail to the Service Bulletin."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific electrical fault in specific aircraft. It has not expanded beyond its original purpose of mandating a manufacturer-recommended modification to prevent autopilot switch short circuits."},"complexity_factors":["Very short document (approximately 150 words)","Only 4 substantive paragraphs (Applicability, Requirement, Note, Compliance/Background)","Single cross-reference to external technical document (Service Bulletin No. 60)","Simple conditional logic: applies only to specific serial number range AND specific option numbers","No defined terms section — uses standard aviation terminology only","No nested exceptions or conditional sub-clauses"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice for aircraft owners and operators. It applies to specific **Socata TB20 and TB21 Trinidad aeroplanes** (serial numbers 275 through 1222) that were fitted with certain autopilot options.\n\n**What it requires:**\n- Aircraft owners must follow the instructions in **Aerospatiale SOCATA Service Bulletin No. 60** — a technical document from the manufacturer detailing a specific repair or modification.\n\n**Why it matters:**\n- The directive addresses a **safety risk of short circuits at the \"Autopilot Master\" switch**. A short circuit here could potentially cause the autopilot to malfunction or fail, which creates serious flight safety hazards.\n\n**Who must comply:**\n- Anyone operating or maintaining affected TB20/TB21 aircraft with the specified serial numbers and autopilot options (668, G668, 669, G669, 670, or G670).\n\n**Deadline:**\n- The work had to be completed **before the next Maintenance Release after 28 February 1992**. (A Maintenance Release is a document certifying an aircraft is airworthy — similar to a roadworthy certificate for a car.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb20-25-autopilot-master-switch","history":"/api/acts/ad-tb20-25-autopilot-master-switch/history","analysis":"/api/acts/ad-tb20-25-autopilot-master-switch/analysis","conflicts":"/api/acts/ad-tb20-25-autopilot-master-switch/conflicts","importantCases":"/api/acts/ad-tb20-25-autopilot-master-switch/important-cases","documents":"/api/acts/ad-tb20-25-autopilot-master-switch/documents"}}