{"id":"F2006B09162","name":"AD/DHC-6/8 Amdt 1 - Airspeed Placard Installation and Left Elevator Trim Tab - Inspection","slug":"ad-dhc-6-8-amdt-1-airspeed-placard-installation-and-left-elevator-trim-tab-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52879,"registerId":"commonwealth-F2006B09162-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/8 Amdt 1 - Airspeed Placard Installation and Left Elevator Trim Tab - Inspection","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)  \nDHC-6 (Twin Otter) Series Aeroplanes\n\nAD/DHC-6/8\n\nAmdt 1\n\n  \n\nAirspeed Placard Installation and Left Elevator Trim Tab - Inspection\n\n  \n1/68\n\nApplicability: All models not incorporating De Havilland of Canada Mod. Bulletins 6/1120, 6/1135 and 6/1142.\n\nRequirement: 1. Install the following placard in fuell view of the pilot: “SPEED SHALL NOT EXCEED 125 KTS, I.A.S.”\n\n    2. On the left elevator trim tab assembly remove the bolt between the push rod and the elevator tab operating lever; operate the tab cockpit control until the screw jack in the elevator is fully retracted and adjust the push rod in order that the bolt can be re-inserted in the lowered tab without exerting pressure on the tab.\n\n    3. Ascertain that the total free play measured adjacent to the operating lever with the trim tab in the neutral position does not exceed 0.1 inch at the trailing edge of the tab.\n\n    4. Visually inspect the elevator trim tab top and bottom skins for diagonal buckling or concavity other than manufactured flutes.\n\nCompliance: For paragraphs 1, 2 and 3 \\- Forthwith.\n\nFor paragraph 4 \\- Before each flight.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive sets corrective actions and inspection frequency for specified DHC‑6 aircraft and excludes models carrying the listed modification bulletins. The text shows no expansion or narrowing of applicability beyond that stated in the 'Applicability' line."},"complexity_factors":["Short, prescriptive tasks with immediate compliance deadlines (Requirements 1–3: 'Forthwith').","A recurring pre‑flight visual inspection duty (Requirement 4) increases operational burden on flight crews/operators.","A precise mechanical tolerance required (0.1 inch free play) necessitates qualified maintenance action and measurement tools.","Applicability is conditional (excludes aircraft with specified De Havilland modifications), requiring record checks to determine whether the AD applies.","Physical installation of placard and mechanical adjustment can cause aircraft downtime and maintenance scheduling impacts."],"plain_english_summary":"This airworthiness directive requires owners/operators of DHC‑6 (Twin Otter) aeroplanes (unless fitted with the listed De Havilland mods) to fit a cockpit airspeed placard limiting speed to 125 Kts IAS and to inspect, adjust and monitor the left elevator trim tab for correct free play and skin damage. Operators must have maintenance personnel adjust the push‑rod/bolt relationship and ensure free play does not exceed 0.1 inch (Requirements 1–3: forthwith; Requirement 4: before each flight)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive maintaining its original purpose: mandating specific safety actions for a defined aircraft type. The amendment (Amdt 1) appears to be a revision to an existing directive (AD/DHC-6/8) but does not expand beyond the original scope of ensuring safe operation of DHC-6 aircraft control surfaces and speed limitations."},"complexity_factors":["Single-page document with only 4 operative paragraphs","No defined terms section — all language is technical but self-explanatory in context","No cross-references to other legislation beyond the enabling regulation (Civil Aviation Regulations 1998, Part 39)","Simple conditional logic: applicability is determined by a straightforward exclusion (aircraft NOT incorporating three specific modification bulletins)","Clear, unambiguous compliance deadlines ('Forthwith' and 'Before each flight')","Technical specificity is high but legally simple — describes mechanical actions in plain procedural terms"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of De Havilland DHC-6 Twin Otter aircraft (unless already modified per De Havilland SBs 6/1120, 6/1135, 6/1142) to make immediate safety modifications and start a routine pre‑flight check. \n\nIt requires adding a 125‑kt speed warning placard, correcting the left elevator trim tab so it moves freely and does not exceed a small allowable play, and a before‑flight visual inspection for buckling or unusual dents — actions deemed urgent to protect flight control safety."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-8-amdt-1-airspeed-placard-installation-and-left-elevator-trim-tab-inspection","history":"/api/acts/ad-dhc-6-8-amdt-1-airspeed-placard-installation-and-left-elevator-trim-tab-inspection/history","analysis":"/api/acts/ad-dhc-6-8-amdt-1-airspeed-placard-installation-and-left-elevator-trim-tab-inspection/analysis","conflicts":"/api/acts/ad-dhc-6-8-amdt-1-airspeed-placard-installation-and-left-elevator-trim-tab-inspection/conflicts","importantCases":"/api/acts/ad-dhc-6-8-amdt-1-airspeed-placard-installation-and-left-elevator-trim-tab-inspection/important-cases","documents":"/api/acts/ad-dhc-6-8-amdt-1-airspeed-placard-installation-and-left-elevator-trim-tab-inspection/documents"}}