{"id":"F2006B07341","name":"AD/TB20/36 - Propeller Governor Control","slug":"ad-tb20-36-propeller-governor-control","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49413,"registerId":"commonwealth-F2006B07341-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB20/36 - Propeller Governor Control","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes\n\nAD/TB20/36 Propeller Governor Control 13/99\n\nApplicability: TB20 aircraft, S/Nos. 1899, 1904 through 1909, TB21 aircraft, S/No 1911, and all TB20 and TB21 aircraft fitted with a propeller governor control delivered by SOCATA between 22 March 1999 and 31 August 1999.\n\nRequirement: Replace affected propeller governor controls in accordance with SOCATA mandatory Service Bulletin No. SB 10-112-61 dated August 1999.\n\nNote: DGAC AD 1999-386(A) also refers.\n\nCompliance: No later than 31 January 2000.\n\nThis Airworthiness Directive becomes effective on 30 December 1999.\n\nBackground: This directive is prompted by advice that faulty propeller governor controls have been released to the field. Failure of a non conforming control will lead to jamming of the propeller governor.","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 manufacturing defect in a limited production batch. The scope remains precisely limited to the identified faulty components and affected aircraft serial numbers, consistent with the standard purpose of Airworthiness Directives."},"complexity_factors":["Very short document (under 200 words)","Only 4 defined applicability criteria (specific serial numbers and date range)","Single, unambiguous compliance requirement with reference to external manufacturer bulletin","No nested exceptions, conditional logic, or cross-references to other legislation beyond a single note about a French aviation authority directive","Clear, fixed compliance deadline with no alternative methods of compliance stated"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific Socata TB20 and TB21 aircraft to replace faulty propeller governor controls.\n\n**What it does:**\n- **Targets specific aircraft:** TB20 planes with serial numbers 1899 and 1904–1909, TB21 plane serial number 1911, plus any TB20 or TB21 fitted with a propeller governor control supplied by the manufacturer between 22 March and 31 August 1999.\n- **Requires immediate action:** Owners must replace the affected propeller governor controls following the manufacturer's official repair instructions (Service Bulletin SB 10-112-61).\n- **Sets a hard deadline:** The replacement must be completed by **31 January 2000**.\n\n**Why it matters:**\nThe faulty controls can **jam the propeller governor** — a critical component that adjusts the angle of the propeller blades. If this jams in flight, the pilot could lose control of engine power and propeller performance, creating a serious safety risk.\n\n**Who it affects:**\n- Aircraft owners and operators of the specified Socata TB20 and TB21 models\n- Maintenance organisations servicing these aircraft\n- The manufacturer (SOCATA) and its supply chain"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive is narrowly targeted: it applies only to specific serial-numbered TB20/TB21 aircraft and to aircraft that received a propeller governor control from SOCATA within a defined delivery window. The text does not indicate any expansion or contraction of scope from an earlier instrument; it sets a single, specific corrective requirement and deadline (Applicability; Requirement; Compliance)."},"complexity_factors":["Narrow technical scope limited to specified aircraft serial numbers and delivery date range (Applicability)","Single mandatory corrective action defined by a specific manufacturer service bulletin (Requirement)","Short, fixed compliance timeline increasing logistical pressure (Compliance; Effective date)","Reliance on manufacturer procedure for technical details (Requirement)","No allocation of cost responsibility or enforcement procedure in the text (Requirement; Compliance)"],"plain_english_summary":"The AD mandates replacement of specified propeller governor control units on listed TB20/TB21 aircraft (and any that received SOCATA‑supplied units delivered 22 Mar–31 Aug 1999), to be done per SOCATA Service Bulletin SB 10‑112‑61 and completed by 31 Jan 2000. Issued because some controls may jam the governor, it forces operators to source parts, schedule certified maintenance and bear the resulting downtime and costs within a short compliance window."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb20-36-propeller-governor-control","history":"/api/acts/ad-tb20-36-propeller-governor-control/history","analysis":"/api/acts/ad-tb20-36-propeller-governor-control/analysis","conflicts":"/api/acts/ad-tb20-36-propeller-governor-control/conflicts","importantCases":"/api/acts/ad-tb20-36-propeller-governor-control/important-cases","documents":"/api/acts/ad-tb20-36-propeller-governor-control/documents"}}