{"id":"F2006B09095","name":"AD/DHC-3/9 - Tailplane Trim Indicator","slug":"ad-dhc-3-9-tailplane-trim-indicator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115648,"registerId":"commonwealth-F2006B09095-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-3/9 - Tailplane Trim Indicator","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-3 (Otter) Series Aeroplanes\n\n \n\nAD/DHC-3/9 Tailplane Trim Indicator NK\n\nApplicability: As detailed in Requirement Document.\n\n \n\nRequirement: Action in accordance with De H Canada EB “O” No 21.\n\n \n\nNote: Canadian AD 56-8 refers.\n\n \n\nCompliance: Forthwith.\n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD text contains no statement that it changes or supersedes a previous scope. The directive sets mandatory compliance with De Havilland Canada EB 'O' No 21 for the aircraft listed in the external Requirement Document; the AD itself does not indicate any change from an earlier stated intent or scope."},"complexity_factors":["Reliance on external documents for technical detail (De Havilland Canada EB 'O' No 21) increases procedural complexity.","Applicability is delegated to a separate \"Requirement Document,\" so scope is not self-contained in the AD.","Immediate timing requirement (\"Forthwith\") creates operational and scheduling pressure on operators.","No alternative compliance routes or detailed procedures stated in the AD itself—operators must interpret and implement external instructions.","Reference to foreign AD (Canadian AD 56-8) introduces cross‑jurisdictional documentation to consult."],"plain_english_summary":"What this directive does (mechanically)\n\n- This airworthiness directive (AD/DHC-3/9) orders operators of certain DHC-3 (Otter) series aeroplanes to carry out actions relating to the tailplane trim indicator. The AD itself does not list the tasks; it requires that the actions be performed \"in accordance with De H Canada EB 'O' No 21\" (Requirement). The AD also refers to Canadian AD 56-8 (Note).\n\nWho it affects\n\n- Aircraft owners, operators and maintenance organisations responsible for DHC-3 series aeroplanes covered by the referenced \"Requirement Document\" (Applicability). These parties must arrange and pay for any inspections, modifications, repairs or record-keeping required by the referenced De Havilland Canada engineering bulletin (Requirement).\n\nWho decides and what is mandatory\n\n- The Civil Aviation Safety Authority issues the directive. The AD makes compliance with the referenced engineering bulletin mandatory for affected aircraft (Requirement). The AD sets the timing as immediately (\"Forthwith\") so the work must be done without delay (Compliance).\n\nWhat the AD says about its purpose\n\n- The AD text does not include a detailed description of the defect or hazard in this document. By mandating compliance with De Havilland Canada EB \"O\" No 21 and referring to Canadian AD 56-8, the directive links required work to the content of those external documents; the AD itself does not restate the technical rationale (Requirement) (Note).\n\nPractical effects, incentives and trade-offs\n\n- Direct costs: Operators pay for the inspection, adjustment, repair or replacement steps specified in EB \"O\" No 21 and any associated downtime or parts (Requirement) (Compliance).\n- Timing pressure: The \"Forthwith\" compliance requirement forces near‑term scheduling of maintenance work; this can increase short‑term labour and opportunity costs if aircraft are grounded or removed from service (Compliance).\n- Uncertainty and compliance burden: The AD delegates technical detail to an external engineering bulletin and a referenced \"Requirement Document\" (Applicability) (Requirement). Parties must obtain and follow those documents to know precisely what to do, which raises administrative steps and potential for differing interpretations until the external documents are reviewed.\n- Limited local discretion: The AD instructs operators to follow the specified engineering bulletin; that reduces discretionary variation in corrective actions but leaves implementation choices (scheduling, contracted maintainer, spare parts supplier) to operators and maintainers (Requirement).\n- Implementation risk: If the referenced documents are ambiguous, unavailable, or require parts or skills not readily on hand, compliance may be delayed or require additional expenses. The AD does not set alternative compliance pathways in its text (Requirement) (Applicability).\n\nReferences in the AD text\n\n- Applicability: \"As detailed in Requirement Document.\" (Applicability)\n- Required action: \"Action in accordance with De H Canada EB 'O' No 21.\" (Requirement)\n- Related material: \"Note: Canadian AD 56-8 refers.\" (Note)\n- Timing: \"Compliance: Forthwith.\" (Compliance)\n\nSummary statement\n\n- The directive obliges affected DHC-3 operators to perform the work specified in De Havilland Canada EB \"O\" No 21 immediately. The AD itself is brief and relies on external documents to define the technical task and which aircraft are affected, shifting the substantive compliance detail outside the AD text."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive targeting a specific aircraft type (DHC-3 Otter) and a specific component (tailplane trim indicator). It reflects the original purpose of ADs: targeted, immediate safety actions for identified airworthiness issues. No scope creep evident."},"complexity_factors":["Extremely short document (under 150 words)","No defined terms section — relies entirely on external technical references","Single operative requirement referencing external document (De Havilland Canada EB \"O\" No. 21)","No conditional logic, exceptions, or nested provisions","Cross-reference to one Canadian AD only (56-8)","Simple structure: Applicability → Requirement → Note → Compliance"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA).\n\n**What it does:**\n- Requires owners and operators of **De Havilland Canada DHC-3 (Otter) series aeroplanes** to take specific action regarding the **tailplane trim indicator** (a cockpit instrument that shows the position of the horizontal stabiliser, which controls the aircraft's pitch).\n\n**Who it affects:**\n- Anyone who owns, operates, or maintains DHC-3 Otter aircraft in Australia.\n\n**What action is required:**\n- Operators must follow the instructions in **De Havilland Canada Engineering Bulletin \"O\" No. 21** (a technical document from the aircraft manufacturer).\n- The directive references **Canadian Airworthiness Directive 56-8**, indicating this aligns with a safety action already mandated in Canada.\n\n**Why it matters:**\n- **Immediate compliance required** (\"Forthwith\" means right now, without delay).\n- Tailplane trim indicators are critical for flight safety — incorrect trim settings can lead to loss of control during takeoff or landing.\n- This ensures Australian-registered Otters meet the same safety standard as Canadian-registered ones."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-3-9-tailplane-trim-indicator","history":"/api/acts/ad-dhc-3-9-tailplane-trim-indicator/history","analysis":"/api/acts/ad-dhc-3-9-tailplane-trim-indicator/analysis","conflicts":"/api/acts/ad-dhc-3-9-tailplane-trim-indicator/conflicts","importantCases":"/api/acts/ad-dhc-3-9-tailplane-trim-indicator/important-cases","documents":"/api/acts/ad-dhc-3-9-tailplane-trim-indicator/documents"}}