{"id":"F2006B08882","name":"AD/DH 104/4 - Aileron Differential Pulley Stud - Modification","slug":"ad-dh-104-4-aileron-differential-pulley-stud-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52357,"registerId":"commonwealth-F2006B08882-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DH 104/4 - Aileron Differential Pulley Stud - Modification","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)  DH 104 (Dove) Series Aeroplanes\n\n \n\nAD/DH 104/4 Aileron Differential Pulley Stud - Modification 8/71\n\nApplicability: All models.\n\n \n\nDocument: 1. De Havilland Mod. No. Dove. 765; or 2. ANO 105.1.14.13.5.7\n\nCompliance: Before 1 September 1971.\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\n \n\n \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 1971. It addresses one specific mechanical modification and has not expanded beyond its original safety purpose."},"complexity_factors":["Extremely short document (under 200 words)","Only 2 defined references (the modification documents)","No conditional logic or exceptions","Single, unambiguous compliance requirement with fixed deadline","No cross-referencing to other legislation sections","Straightforward applicability (all models)"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for **De Havilland DH 104 Dove aircraft**.\n\n**What it does:**\n- Requires owners/operators to modify the **aileron differential pulley stud** (a component in the wing control system that helps the ailerons move properly)\n- The modification must follow specific technical documents: either De Havilland Modification No. Dove 765, or Airworthiness Notice 105.1.14.13.5.7\n\n**Who it affects:**\n- All owners and operators of DH 104 (Dove) series aeroplanes\n\n**Why it matters:**\n- This is a **safety-critical fix** with a hard deadline. The modification had to be completed **before 1 September 1971** to ensure the aircraft remained airworthy. Failure to comply would ground the aircraft.\n- Aileron control issues can lead to loss of roll control, making this a serious airworthiness concern."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD text prescribes a modification applicable to all DH 104 models and sets a compliance deadline. The instrument itself contains no indication that it expands or narrows a prior requirement or original intent; there is no comparative or historical scope statement in the provided text to show a change. Therefore, based on the supplied text alone, the scope is not shown to have changed."},"complexity_factors":["Very short, narrowly framed directive limited to a single modification and deadline (see \"Aileron Differential Pulley Stud - Modification\" and \"Compliance: Before 1 September 1971\").","Applicability is universal across the type (\"Applicability: All models.\"), which simplifies applicability analysis but increases practical workload for all operators.","Procedure and technical detail are delegated to external documents (\"Document: De Havilland Mod. No. Dove. 765; or ANO 105.1.14.13.5.7\"), requiring users to obtain and interpret those documents.","No rationale, defect description, or acceptance criteria are included in the AD text, creating interpretive work for maintainers and regulators when judging compliance.","Fixed deadline creates scheduling complexity (operators must complete work before 1 September 1971) and potential supply/maintenance capacity constraints."],"plain_english_summary":"## What this instrument does\n\nThis airworthiness directive (AD/DH 104/4 — “Aileron Differential Pulley Stud - Modification”, dated 8/71) requires a physical modification to the aileron differential pulley stud on DH 104 (Dove) series aeroplanes. The directive applies to all DH 104 models (\"Applicability: All models.\") and requires the modification to be carried out in accordance with one of two listed documents: De Havilland Mod. No. Dove. 765 or ANO 105.1.14.13.5.7 (\"Document: 1. De Havilland Mod. No. Dove. 765; or 2. ANO 105.1.14.13.5.7\"). The work must be completed before 1 September 1971 (\"Compliance: Before 1 September 1971.\").\n\n## Who this affects and who decides\n\n- Aircraft owners/operators of DH 104 series aeroplanes must arrange and pay for the required modification (requirement and deadline are specified in the AD; see \"Applicability\" and \"Compliance\").\n- The AD references specific technical documents that decide the method and details of the modification (see \"Document\").\n- The directive is issued under the Civil Aviation Safety Authority schedule of airworthiness directives (header identifies Part 39 — Civil Aviation Safety Authority).\n\n## Why it matters (what it changes mechanically)\n\n- Mechanically, the AD imposes a mandatory maintenance/airworthiness action with a fixed deadline. Operators cannot defer the work past the stated compliance date without contravening the directive.\n- The AD delegates procedural detail to the referenced documents; the directive itself does not set out the modification steps in full (see \"Document\").\n\n## Practical implications, trade-offs and implementation points\n\n- Costs and who pays: Owners/operators bear the direct costs of parts, labour and any aircraft downtime required to perform the modification (implied by the AD’s requirement and deadline; see \"Applicability\" and \"Compliance\").\n- Compliance burden: Operators must obtain the referenced document(s), schedule the work, perform or contract the modification, and retain records of compliance to show the AD was met (the AD supplies the document references and deadline; see \"Document\" and \"Compliance\").\n- Timing risk and opportunity cost: The fixed deadline means operators will need to schedule maintenance before 1 September 1971; this can produce increased demand for maintenance facilities and parts in the run-up to the date.\n- Effects on service providers: Maintenance organisations and technicians who can perform the specified modification are the likely recipients of the work created by the AD (the AD requires a modification and cites the controlling documents; see \"Document\").\n- Administrative discretion and detail: The AD prescribes that modification be done according to the listed documents; any interpretation of those technical steps is exercised by the mechanic/organisation following the documents and by the regulator insofar as they accept the work as compliant (the AD itself does not itemise those steps; see \"Document\").\n\n## What the text does not state\n\n- The AD text provided does not set out its reason, technical findings, or a risk assessment explaining why the modification is required. It only prescribes the modification, references the controlling documents, and sets the compliance date (see full text: \"Document\" and \"Compliance\").\n\n"}},"importantCases":[],"_links":{"self":"/api/acts/ad-dh-104-4-aileron-differential-pulley-stud-modification","history":"/api/acts/ad-dh-104-4-aileron-differential-pulley-stud-modification/history","analysis":"/api/acts/ad-dh-104-4-aileron-differential-pulley-stud-modification/analysis","conflicts":"/api/acts/ad-dh-104-4-aileron-differential-pulley-stud-modification/conflicts","importantCases":"/api/acts/ad-dh-104-4-aileron-differential-pulley-stud-modification/important-cases","documents":"/api/acts/ad-dh-104-4-aileron-differential-pulley-stud-modification/documents"}}