{"id":"F2006B08800","name":"AD/DC3/24 - DME Aerial Installation - Modification","slug":"ad-dc3-24-dme-aerial-installation-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52162,"registerId":"commonwealth-F2006B08800-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DC3/24 - DME Aerial Installation - 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)  Douglas DC3 Series Aeroplanes\n\n \n\nAD/DC3/24 DME Aerial Installation - Modification NK\n\nApplicability: All models with DME aerials type VJN-3, VJN-3A or VJN-3B mounted forward of station 136 1/2.\n\n \n\nRequirement: Relocate the aerial to a position aft of station 136 1/2 or alternatively replace the aerial with a type AT-256A/ARC and associated matching stub.\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\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive targeting a specific technical issue on a specific vintage aircraft type. It has not expanded beyond its original purpose of mandating a safety modification for DME aerial installation."},"complexity_factors":["Extremely short document (under 200 words)","Only 3 defined technical terms (station 136 1/2, aerial types VJN-3/VJN-3A/VJN-3B, AT-256A/ARC)","Single binary compliance path (relocate OR replace)","No cross-references to other legislation or regulations","No conditional exceptions or nested logic","Clear applicability criteria (specific aircraft model + specific aerial types + specific mounting location)"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — essentially a mandatory safety fix ordered by Australia's aviation safety regulator (CASA) for a specific type of aircraft.\n\n**What it does:**\n- **Targets:** Douglas DC-3 aircraft (vintage propeller planes, some still flying in Australia)\n- **Problem:** Certain Distance Measuring Equipment (DME) aerials — radio antennas that help pilots know their exact position — are mounted too far forward on the fuselage (before \"station 136 1/2,\" a technical measurement point on the airframe).\n- **The fix:** Owners must either:\n  - Move the aerial to a position further back on the aircraft (aft of station 136 1/2), **or**\n  - Replace it entirely with a different approved aerial type (AT-256A/ARC) plus its matching component\n\n**Who it affects:** Anyone operating a DC-3 with the specific VJN-3, VJN-3A, or VJN-3B aerial models mounted in the forward position.\n\n**Why it matters:** This is a safety-critical modification. The current aerial placement likely creates interference, structural stress, or aerodynamic issues that could affect navigation reliability or airframe integrity. Non-compliance grounds the aircraft — you cannot legally fly until fixed."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument, as presented, sets a specific modification requirement for a defined subset of DC3 aircraft. The text contains no statement comparing this requirement to an earlier scope or intent, so there is no indication within this document that the scope has been expanded or narrowed relative to a prior instrument. (Applicability; Requirement)"},"complexity_factors":["Narrow, clearly defined applicability (applies only to DC3s with DME aerials type VJN-3, VJN-3A or VJN-3B mounted forward of station 136 1/2) (Applicability).","Single clear binary requirement: relocate aft of station 136 1/2 OR replace with specified type AT-256A/ARC and matching stub (Requirement).","Technical measurement requirement (location defined relative to fuselage station 136 1/2) adds a small administrative/technical step (Applicability; Requirement).","No implementation timetable, procedural approvals, or compliance-evidence details included in the text, which creates modest ambiguity about administrative steps beyond the physical work (entire document)."],"plain_english_summary":"This airworthiness directive requires owners/operators of Douglas DC‑3 series aeroplanes with VJN‑3/3A/3B DME aerials mounted forward of fuselage station 136½ to modify them: either relocate the aerial aft of station 136½ or replace it with an AT‑256A/ARC and matching stub. Compliance and costs (parts, labour, downtime) fall to the owner/operator. The excerpt sets the required outcome but gives no technical rationale, timetable, or procedural detail."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dc3-24-dme-aerial-installation-modification","history":"/api/acts/ad-dc3-24-dme-aerial-installation-modification/history","analysis":"/api/acts/ad-dc3-24-dme-aerial-installation-modification/analysis","conflicts":"/api/acts/ad-dc3-24-dme-aerial-installation-modification/conflicts","importantCases":"/api/acts/ad-dc3-24-dme-aerial-installation-modification/important-cases","documents":"/api/acts/ad-dc3-24-dme-aerial-installation-modification/documents"}}