{"id":"F2006B08789","name":"AD/DC3/12 Reissue - Oil Dilution Unit - Modification","slug":"ad-dc3-12-reissue-oil-dilution-unit-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52131,"registerId":"commonwealth-F2006B08789-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DC3/12 Reissue - Oil Dilution Unit - 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\n# AD/DC3/12\n\nReissue\n\nApplicability: All models.\n\n# Oil Dilution Unit - Modification 1/84\n\n \n\nRequirement: 1. Remove the 1/4-in OD pipe between the restrictor at the base of the Pioneer pressure warning switch and the oil dilution solenoid. Also remove the 1/4-in OD pipe between the oil dilution solenoid and the “T” drain on the engine oil system.\n\n \n\n2.    Replace the four hexagon nipples found on the restrictor, oil dilution valve and “T” drain with 1/8-in (gas) Dural plugs.\n\n \n\n3.    Render the oil dilution switches on the inboard side of the port electrical panel inoperative.\n\n \n\nCompliance: Unless already accomplished within 100 hours time in service after 29 February 1984.\n\n \n\nBackground:  This Directive is reissued with no changes made to the requirement. In order to reduce the possibility of fire, and in view of the fact that the dilution unit is not used in this country, the oil dilution system is rendered inoperative.\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 straightforward maintenance directive with a single, narrow purpose: disabling a specific unused system on one aircraft type. The reissue explicitly states 'no changes made to the requirement,' confirming the scope remains identical to the original 1984 directive."},"complexity_factors":["Very short document (under 300 words)","Only 3 mechanical requirements with specific measurements (1/4-in OD pipe, 1/8-in Dural plugs)","Single compliance deadline with straightforward exception clause","No defined terms section — all terminology is standard aviation/mechanical vocabulary","No cross-references to other legislation or regulations","Simple conditional logic: 'Unless already accomplished' creates one exception","Background section provides clear rationale without legal caveats"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Douglas DC-3 aircraft in Australia to permanently disable the engine oil dilution unit because its pipes and fittings present an unnecessary engine‑compartment fire risk. Compliance involves removing dilution piping, plugging four threaded connectors with Dural plugs, and rendering cockpit dilution controls inoperative.\n\nIt applied within 100 flight hours after 29 Feb 1984; this text is a reissue for administrative purposes."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive was reissued with \"no changes made to the requirement\" (Background). The scope remains: all DC‑3 models must have the specified oil-dilution components removed or plugged and the switches rendered inoperative within the original compliance window (Applicability; Requirement; Compliance)."},"complexity_factors":["Technical/mechanical work limited to pipe removal, fitting replacement and disabling switches (Requirement).","Applies to all DC‑3 models—broad fleet applicability increases affected parties (Applicability).","Mandatory compliance timeframe (100 hours after 29 February 1984) creates scheduling and recordkeeping obligations (Compliance).","Changes render an on-board system permanently inoperative, affecting maintenance and operational configuration (Requirement; Background).","Requires competent maintenance personnel and replacement parts (Dural plugs), imposing direct cost on owners/operators (Requirement).","Reissue states no change to requirements, so no additional regulatory discretion or new technical criteria were introduced (Background)."],"plain_english_summary":"This Directive requires removal of specific oil-dilution pipes and valves, replacement of four fittings with Dural plugs, and rendering the oil-dilution switches inoperative on all Douglas DC‑3 series aeroplanes. Aircraft owners and maintenance organisations must carry out these mechanical changes within 100 hours' time in service after 29 February 1984 at their expense; the stated aim is to reduce fire risk because the dilution unit is not used locally (Requirement; Compliance; Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dc3-12-reissue-oil-dilution-unit-modification","history":"/api/acts/ad-dc3-12-reissue-oil-dilution-unit-modification/history","analysis":"/api/acts/ad-dc3-12-reissue-oil-dilution-unit-modification/analysis","conflicts":"/api/acts/ad-dc3-12-reissue-oil-dilution-unit-modification/conflicts","importantCases":"/api/acts/ad-dc3-12-reissue-oil-dilution-unit-modification/important-cases","documents":"/api/acts/ad-dc3-12-reissue-oil-dilution-unit-modification/documents"}}