{"id":"F2006B08908","name":"AD/DH 84/1 - Fuel System Control - Modification","slug":"ad-dh-84-1-fuel-system-control-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52437,"registerId":"commonwealth-F2006B08908-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DH 84/1 - Fuel System Control - 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 84 (Dragon) Series Aeroplanes\n\n \n\nAD/DH 84/1 Fuel System Control - Modification NK\n\nApplicability: All models.\n\n \n\nRequirement: Modify the fuel system control as follows:\n\n \n\n1. Incorporate a positive method of retaining and clamping the fuel control cable housing at both ends, and at the bend where it enters the wing.\n\n\n \n\n2.    Incorporate a means of locking the pilot’s control lever in the “ON” position such that the lever can be moved rapidly to the “OFF” position in an emergency. OR Part 100, Appendix “A” Notice No. 10/2; or\n\n \n\nANO 105.1.14.0.1.1.\n\n \n\nCompliance: Forthwith.\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":4,"scope_assessment":{"changed":false,"description":"The instrument sets a clear, limited scope: it applies to all DH 84 (Dragon) series aeroplanes and requires two specific mechanical changes to the fuel system control (positive retention/clamping of the cable housing and a lever-locking means that still allows rapid OFF). (See: 'Applicability: All models' and 'Requirement' paragraphs 1 and 2.) Nothing in the text indicates the scope has been expanded or narrowed relative to the directive’s operative text; the compliance requirement remains immediate ('Compliance: Forthwith')."},"complexity_factors":["Technical specificity of required mechanical changes (cable housing retention/clamping and lever-locking) requires engineering skill.","Immediate compliance timing (‘Forthwith’) creates operational and logistical complexity.","Directive allows alternative compliance references (Part 100 Appendix A Notice No. 10/2; ANO 105.1.14.0.1.1), introducing regulatory cross-references that require consultation of other documents.","Lack of detailed design, testing or certification steps in the text means maintenance/approval pathways must be determined case-by-case.","Applicability to all models concentrates the population affected but does not distinguish variants, so implementers must assess model-specific installation details."],"plain_english_summary":"What this instrument requires (mechanics)\n\n- Who it applies to: all DH 84 (Dragon) series aeroplanes listed in the directive. (See: \"Applicability: All models\".)\n\n- Required changes: operators must modify the aeroplane fuel system control as follows (See: \"Requirement\"):\n  1. Fit a positive method to retain and clamp the fuel control cable housing at both ends and at the bend where it enters the wing.\n  2. Provide a way to lock the pilot’s fuel-control lever in the \"ON\" position while still allowing the lever to be moved rapidly to \"OFF\" in an emergency. The directive also allows compliance by following an alternate document: Part 100, Appendix \"A\" Notice No. 10/2 or ANO 105.1.14.0.1.1.\n\n- Timing: compliance is required immediately (\"Forthwith\"). (See: \"Compliance: Forthwith.\")\n\nWhy the directive exists (stated purpose and practical effect)\n\n- The directive’s stated actions are designed to change how the fuel control cable and pilot control lever are installed and secured. Those mechanical changes are intended to reduce the chance that the cable will work loose or the lever will behave in a way that prevents a quick shut-off. The requirement text presents those mechanical fixes as the means to address that operational risk. (See: \"Requirement.\")\n\nWho pays, who decides, and what changes in behaviour\n\n- Who pays: aircraft owners/operators are responsible for performing the modifications and paying for parts and labour. The directive does not supply funding or parts. (Source: the directive’s Requirement and Applicability.)\n- Who decides/forces compliance: the Civil Aviation Safety Authority issued the airworthiness directive and sets the requirement and compliance timing. (Source: heading identifying this as a Civil Aviation Safety Authority Schedule of Airworthiness Directives.)\n- Behavioural change: maintenance/engineering personnel must inspect and modify the cable housing clamps and the pilot’s control lever installation; pilots may face a slightly different lever locking arrangement and must be able to move the lever quickly to OFF in an emergency. Operators must schedule and complete the work immediately.\n\nCosts, trade-offs and implementation issues (tested against the directive text)\n\n- Direct costs and resource use: the operator pays for parts, tools and trained maintenance labour to implement the specified physical modifications. The directive gives no estimate of cost or allowable time window; it simply requires action forthwith. (See: \"Compliance: Forthwith.\")\n\n- Compliance burden and timing pressure: the immediate compliance requirement imposes urgency on operators; this can increase short-term costs (out-of-hours work, expedited parts) and may temporarily remove aircraft from service.\n\n- Technical specification and discretion: the directive sets the required outcomes (positive retention/clamping of the cable housing and a lever-locking method enabling rapid OFF). It does not set a single engineering design; operators and maintainers will select or design the specific hardware, subject to any applicable maintenance approvals or alternative documents cited (Part 100 Appendix \"A\" Notice No. 10/2; ANO 105.1.14.0.1.1). That creates discretion for engineers and regulators about acceptable solutions and approvals. (See: \"Requirement\" and alternatives cited.)\n\n- Implementation risk and potential interactions: physical modifications to cable routing, clamping and lever lock mechanisms can interact with other control components or require re-certification/inspection. The directive does not detail testing, documentation or approval steps beyond the modification requirement, so operators must follow normal maintenance and certification processes to ensure the changes do not introduce other hazards.\n\n- Effects on private choice and operations: operators decide how and when to schedule the modification (subject to the immediate compliance requirement). The requirement may temporarily reduce aircraft availability and increase maintenance workload for providers who service these aircraft.\n\n- Concentration of burden and benefits: the costs (parts, labour, downtime) fall on individual owners/operators of DH 84 aircraft. The potential operational safety benefit is dispersed across pilots, passengers and the public who may be affected by improved control reliability. The directive itself does not quantify benefits or costs. (See: \"Applicability\" and \"Requirement\".)\n\nConcrete references to the instrument text\n\n- Applicability: \"Applicability: All models.\" (top of text)\n- Requirements: numbered points 1 and 2 under \"Requirement.\"\n- Alternatives: \"OR Part 100, Appendix 'A' Notice No. 10/2; or ANO 105.1.14.0.1.1.\" (end of requirement 2)\n- Timing: \"Compliance: Forthwith.\""},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete safety directive targeting a specific mechanical issue in a specific aircraft type. It has not expanded beyond its original purpose of mandating fuel system modifications for airworthiness."},"complexity_factors":["Very short document (under 200 words)","Only 2 specific technical requirements with clear mechanical descriptions","Single defined applicability (all DH 84 models)","No nested exceptions or conditional logic","Simple compliance deadline ('forthwith' = immediate)","References to alternative technical standards (Part 100 Appendix A; ANO 105.1.14.0.1.1) but these are presented as options rather than complex cross-references"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by the Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nIt requires owners and operators of **DH 84 Dragon series aeroplanes** (a vintage twin-engine aircraft) to make two specific safety modifications to the fuel system:\n\n- **Secure the fuel control cable:** Install proper clamps and retention methods at both ends of the fuel control cable housing, plus at the point where it bends into the wing. This prevents the cable from moving or chafing, which could cause fuel flow problems or fires.\n- **Add a safety lock for the fuel lever:** Fit a mechanism that keeps the pilot's fuel control lever locked in the \"ON\" (fuel flowing) position, but allows the pilot to instantly snap it to \"OFF\" in an emergency (such as an engine fire or crash landing).\n\n**Who it affects:**\nAnyone who owns, operates, or maintains a DH 84 Dragon aircraft in Australia.\n\n**Why it matters:**\nLoose fuel cables can lead to fuel starvation (engine stops) or fuel leaks (fire risk). A fuel lever that accidentally moves to \"OFF\" could shut down an engine unexpectedly. These modifications prevent accidents and are required **immediately** (\"forthwith\" means right away, not later)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dh-84-1-fuel-system-control-modification","history":"/api/acts/ad-dh-84-1-fuel-system-control-modification/history","analysis":"/api/acts/ad-dh-84-1-fuel-system-control-modification/analysis","conflicts":"/api/acts/ad-dh-84-1-fuel-system-control-modification/conflicts","importantCases":"/api/acts/ad-dh-84-1-fuel-system-control-modification/important-cases","documents":"/api/acts/ad-dh-84-1-fuel-system-control-modification/documents"}}