{"id":"F2006B08962","name":"AD/DH114/5 - Fuel Tank Filler - Modification","slug":"ad-dh114-5-fuel-tank-filler-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52539,"registerId":"commonwealth-F2006B08962-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DH114/5 - Fuel Tank Filler - 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/DH114/5 Fuel Tank Filler - Modification NK\n\nApplicability: All Series 1B not modified in accordance with DH Heron Mod. 219. Document:  1. DH Heron Mod. No. 311 and DH Heron Mod. 350 or 352; or\n\n2. ANO 105.1.14.17.5.6.\n\n \n\nCompliance: Before 1 September 1955.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument, as provided, sets a clear and limited scope: it applies to all DH114 Heron Series 1B aircraft not modified per Mod. 219 and requires specific modification documents to be applied by a stated date. The text does not indicate any expansion or narrowing of that scope compared with its own stated applicability."},"complexity_factors":["Narrow technical scope limited to DH114 (Heron) Series 1B aircraft (Applicability).","Directive names specific modification documents (DH Heron Mod. No. 311 and Mod. 350 or 352) or ANO reference, requiring consultation of external technical documents (Document).","Fixed compliance deadline requires scheduling and can create operational disruption (Compliance).","Instrument does not include the technical content of the modification or clarify alternative means of compliance, increasing reliance on other documents and regulator guidance (Document).","Regulatory provenance is clear (Civil Aviation Regulations; Civil Aviation Safety Authority), but enforcement mechanisms and penalties are not set out in the text provided (Header)."],"plain_english_summary":"### What this directive does\n\nThis is an airworthiness directive issued under the Civil Aviation Regulations requiring a physical modification to the fuel tank filler on certain De Havilland DH114 (Heron) aeroplanes.\n\n- Who it applies to: all DH114 Heron Series 1B aircraft that have not already been modified in accordance with DH Heron Modification 219. (See: \"Applicability\".)\n- What must be done: affected aircraft must be modified using one of the documents listed: DH Heron Mod. No. 311 and DH Heron Mod. 350 or 352; or alternatively the work identified in ANO 105.1.14.17.5.6. (See: \"Document\".)\n- When it must be done: the modification must be completed before 1 September 1955. (See: \"Compliance\".)\n\nThe directive is issued by the Civil Aviation Safety Authority under the Civil Aviation Regulations and appears in the Schedule of Airworthiness Directives.\n\n### Rationale stated by the instrument\n\nThe title of the instrument, \"Fuel Tank Filler - Modification,\" identifies the change required. The instrument itself does not set out a narrative explanation of the safety concern; it prescribes the required modification documents and a compliance date. Any claim that this action is to address a particular safety risk is an inference from the title and the use of an airworthiness directive rather than text contained in the instrument.\n\n### Who pays and who decides\n\n- Operators (owners or operators of the affected Series 1B Herons) are the parties required to carry out the modification and therefore bear the direct costs of parts, labour and aircraft downtime. (Applicability; Document; Compliance.)\n- The Civil Aviation Safety Authority is the issuing regulator under the cited Civil Aviation Regulations and is the authority that requires compliance. (Header: Civil Aviation Regulations 1998, Part 39; Civil Aviation Safety Authority; Schedule of Airworthiness Directives.)\n\n### Incentives, compliance burden and discretion\n\n- Incentives/costs: Operators face a one-off compliance cost for the specified modification(s) and the opportunity cost of aircraft out of service while the work is done. The directive specifies which modification documents to follow rather than prescribing technical detail, so parties must obtain and follow those documents. (Document; Compliance.)\n- Administrative burden: The directive sets a fixed compliance deadline which creates a scheduling requirement for maintenance organisations and operators; the directive does not state funding arrangements or exemptions in the text provided. (Compliance.)\n- Discretion: The directive limits technical discretion by naming specific modification documents (DH Heron Mod. No. 311 and Mod. 350 or 352, or ANO 105.1.14.17.5.6). Enforcement and any further direction about acceptable work standards or approvals would rest with the regulator under the Civil Aviation Regulations. (Document; Header.)\n\n### Trade-offs and implementation risk\n\n- To implement the directive an operator must consult the referenced modification documents (and possibly ANO material). That creates dependency on external documents for technical detail and can slow implementation if parts or approved maintenance providers are scarce.\n- The directive does not state whether alternative means of compliance are acceptable; therefore operators must follow the listed documents unless the regulator provides an alternative approval.\n\n### Effects on private choice and market actors\n\n- Independent maintenance organisations and parts suppliers may capture work from operators performing the modification, increasing demand for specialist services for these aircraft models.\n- The directive constrains operator choice by mandating specific modification documents; it does not itself set prices or ownership rules but imposes a regulatory compliance cost on owners/operators. (Document.)\n\n(References in parentheses refer to text sections of the instrument: \"Applicability\", \"Document\", \"Compliance\" and the header identifying the Civil Aviation Regulations and the Civil Aviation Safety Authority.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive for a specific aircraft modification. It has not expanded beyond its original purpose of mandating fuel tank filler upgrades for DH114 Heron Series 1B aircraft. The scope remains precisely limited to the technical modification described."},"complexity_factors":["Extremely short document (approximately 150 words)","Only 2 defined modification references (Mod. 219, Mod. 311/350/352)","Single compliance condition with hard deadline","No nested exceptions or conditional logic","Single applicability criterion (Series 1B not modified per Mod. 219)","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Straightforward binary compliance: either modified correctly or not"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for a specific type of aircraft.\n\n**What it does:** It requires owners and operators of **de Havilland DH114 Heron Series 1B aeroplanes** to modify the fuel tank filler system. Specifically, aircraft that haven't already been modified under \"DH Heron Mod. 219\" must be updated to comply with newer modification standards (Mod. 311 combined with Mod. 350 or 352, or alternatively meet the British Airworthiness Notice ANO 105.1.14.17.5.6).\n\n**Who it affects:** Anyone operating or maintaining DH114 Heron Series 1B aircraft that haven't had the earlier Mod. 219 upgrade.\n\n**Why it matters:** Fuel tank filler modifications prevent fuel leaks, spills, or contamination during refueling — critical safety issues that could lead to engine failure or fire. The directive sets a hard deadline (**before 1 September 1955**) for compliance, meaning this is a retrospective safety requirement for an aircraft type that first flew in the early 1950s.\n\n**Key takeaway:** If you owned one of these specific Heron aircraft in the mid-1950s, you had to upgrade your fuel tank filler system by September 1955 or ground the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dh114-5-fuel-tank-filler-modification","history":"/api/acts/ad-dh114-5-fuel-tank-filler-modification/history","analysis":"/api/acts/ad-dh114-5-fuel-tank-filler-modification/analysis","conflicts":"/api/acts/ad-dh114-5-fuel-tank-filler-modification/conflicts","importantCases":"/api/acts/ad-dh114-5-fuel-tank-filler-modification/important-cases","documents":"/api/acts/ad-dh114-5-fuel-tank-filler-modification/documents"}}