{"id":"F2006B08958","name":"AD/DH114/46 - Fuel System - Modification","slug":"ad-dh114-46-fuel-system-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52528,"registerId":"commonwealth-F2006B08958-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DH114/46 - Fuel System - 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)  DH114 (Heron) Series Aeroplanes\n\n \n\nAD/DH114/46 Fuel System - Modification  6/85 TX\n\nApplicability: DH114 model 2D/A1 aircraft which have been in modified in accordance with AVDEV Airlines drawing No AA17.\n\n \n\nRequirement: 1. Isolate outboard tank system in accordance with East Coast Airlines E.O. Sydney Q2/84 issue 2, or\n\n \n\n2.    Modify fuel system in a manner acceptable to the Secretary.\n\n \n\n3.    Approval of AVDEV Airlines Drawing No AA17 is withdrawn. Compliance: Before further flight.\n\nBackground: The modified fuel system has been found not to comply with BCAR section D5-2.\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, targeted safety directive addressing a specific airworthiness issue with a specific aircraft modification. It has not expanded beyond its original purpose of grounding and rectifying unsafe fuel system modifications."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 3 operative requirements with clear alternatives (Option 1 OR Option 2)","Single defined applicability criterion (specific aircraft model + specific prior modification)","No cross-references to other legislation beyond a single cited standard (BCAR section D5-2)","No nested exceptions or conditional logic","Immediate compliance deadline with no phased implementation","Minimal defined terms (only 'Secretary' requires contextual knowledge of aviation regulations)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific repairs or changes to aircraft.\n\n**What it does:**\nThis directive targets a specific model of aircraft — the **DH114 (Heron) Series**, specifically the **model 2D/A1** variant — but only those that were previously modified using a particular engineering drawing called **\"AVDEV Airlines drawing No AA17\"**.\n\nThe directive orders owners or operators of these aircraft to do **one of two things** before the plane can fly again:\n- **Option 1:** Disconnect or isolate the outboard fuel tank system following a specific set of instructions (East Coast Airlines Engineering Order Sydney Q2/84, issue 2); **OR**\n- **Option 2:** Modify the fuel system in some other way that the **Secretary** (the government official responsible for aviation safety) approves.\n\nAdditionally, the directive **cancels the approval** of the original AVDEV Airlines drawing — meaning that modification can no longer be used on any aircraft.\n\n**Why it matters:**\nThe modified fuel system was found to **not meet safety standards** (specifically, British Civil Airworthiness Requirements section D5-2). This is a serious issue because fuel system failures can cause engine stoppage or fires. The \"before further flight\" compliance deadline means these aircraft are **grounded until fixed** — this is an urgent safety intervention.\n\n**Who it affects:**\n- Owners and operators of DH114 Heron model 2D/A1 aircraft with the AVDEV AA17 modification\n- Maintenance engineers working on these aircraft\n- The company AVDEV Airlines (whose engineering drawing is now banned)"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"This directive removes the prior approval for AVDEV Airlines drawing No AA17 and requires corrective action for aircraft already modified under that drawing. Mechanically, it narrows acceptable configurations by withdrawing the AA17 approval and mandates either isolation of the outboard tank per East Coast Airlines E.O. Sydney Q2/84 issue 2 or an alternative modification acceptable to the Secretary, to be completed before further flight. (Applicability; Requirement 1–3; Compliance; Background)"},"complexity_factors":["Narrow and specific applicability (only DH114 model 2D/A1 aircraft modified per AVDEV AA17). (Applicability)","Simple binary corrective options: follow a named engineering order or implement an alternative acceptable to the regulator. (Requirement 1–2)","Immediate compliance deadline — \"Before further flight\" — which raises urgency but not procedural complexity. (Compliance)","Regulatory discretion where alternative modifications require Secretary approval, introducing case-by-case assessment. (Requirement 2)","Administrative action withdrawing a prior approval (AVDEV drawing No AA17), which affects prior operating approvals. (Requirement 3)"],"plain_english_summary":"This directive targets DH114 model 2D/A1 aeroplanes modified by AVDEV drawing No AA17, requiring owners/operators to either isolate the outboard tank per East Coast Airlines E.O. Sydney Q2/84 issue 2 or carry out a Secretary‑approved fuel‑system modification before further flight. It withdraws prior approval of AVDEV AA17 after finding the modification did not comply with BCAR D5‑2. The burden falls solely on operators of aircraft with that specific modification, who must ground and remedy affected aircraft unless an alternative is accepted by the regulator."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dh114-46-fuel-system-modification","history":"/api/acts/ad-dh114-46-fuel-system-modification/history","analysis":"/api/acts/ad-dh114-46-fuel-system-modification/analysis","conflicts":"/api/acts/ad-dh114-46-fuel-system-modification/conflicts","importantCases":"/api/acts/ad-dh114-46-fuel-system-modification/important-cases","documents":"/api/acts/ad-dh114-46-fuel-system-modification/documents"}}