{"id":"F2006B09097","name":"AD/DHC-6/10 - Left Hand Elevator Trim Tab - Replacement","slug":"ad-dhc-6-10-left-hand-elevator-trim-tab-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115650,"registerId":"commonwealth-F2006B09097-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/10 - Left Hand Elevator Trim Tab - 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)  DHC-6 (Twin Otter) Series Aeroplanes\n\n \n\nAD/DHC-6/10 Left Hand Elevator Trim Tab - Replacement 1/68\n\nApplicability: All models with S/Nos. 1 to 87.\n\n \n\nDocument:  De Havilland of Canada Mod. Bulletin 6/1120. Compliance: Before 1 April 1968.\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 1968. It has not expanded beyond its original narrow scope of requiring a specific hardware replacement on early Twin Otter aircraft."},"complexity_factors":["Single, specific mechanical component addressed","Narrow applicability (only serial numbers 1-87)","No defined terms section","No cross-references to other legislation","Simple compliance structure: one action, one deadline, one reference document","Total length: approximately 100 words"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific De Havilland DHC-6 Twin Otter aircraft to replace the left-hand elevator trim tab.\n\n**Who it affects:**\n- Owners and operators of DHC-6 Twin Otter aircraft with **serial numbers 1 to 87**\n\n**What it requires:**\n- Replacement of the **left-hand elevator trim tab** (a small adjustable surface on the tail that helps control the aircraft's pitch)\n- Compliance with **De Havilland Modification Bulletin 6/1120**\n- **Deadline:** Before 1 April 1968\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety instructions. They are issued when a design flaw, manufacturing defect, or operational issue poses a risk to flight safety. Non-compliance can ground an aircraft. This particular AD addresses a specific component on early-production Twin Otters to prevent potential loss of control."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument itself sets a single, specific requirement applicable to DHC-6 aircraft with serial numbers 1–87 to replace the left-hand elevator trim tab per De Havilland Mod. Bulletin 6/1120 before 1 April 1968. The text contains no indication that the scope was altered from an earlier or broader original intent; it states the applicable serials, the referenced technical document and the compliance date, and no internal provision expands or narrows that scope further. (Applicability; Document; Compliance)"},"complexity_factors":["Narrow technical scope limited to one component and a defined set of serial numbers (Applicability)","Single mandatory action (replacement of left-hand elevator trim tab) stated in the AD title","Fixed, short-term compliance deadline (Compliance)","Dependence on an external technical document for procedure (De Havilland Mod. Bulletin 6/1120) (Document)","Absence of procedural, cost, enforcement or exemption detail in the text (Compliance; Document)","Historic nature and brevity of the instrument limit contextual information and create interpretive gaps"],"plain_english_summary":"Owners/operators of De Havilland DHC‑6 (Twin Otter) aeroplanes serial nos. 1–87 are legally required to replace the left‑hand elevator trim tab in accordance with De Havilland Mod. Bulletin 6/1120 by 1 April 1968.  \n\nThe directive fixes the action, technical reference and deadline but does not state who pays, detailed procedures beyond the bulletin, or enforcement/exemption arrangements."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-10-left-hand-elevator-trim-tab-replacement","history":"/api/acts/ad-dhc-6-10-left-hand-elevator-trim-tab-replacement/history","analysis":"/api/acts/ad-dhc-6-10-left-hand-elevator-trim-tab-replacement/analysis","conflicts":"/api/acts/ad-dhc-6-10-left-hand-elevator-trim-tab-replacement/conflicts","importantCases":"/api/acts/ad-dhc-6-10-left-hand-elevator-trim-tab-replacement/important-cases","documents":"/api/acts/ad-dhc-6-10-left-hand-elevator-trim-tab-replacement/documents"}}