{"id":"F2006B08913","name":"AD/DH 89/1 - Fuel System Control - Modification","slug":"ad-dh-89-1-fuel-system-control-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52452,"registerId":"commonwealth-F2006B08913-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DH 89/1 - 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 89 (Dragon Rapide) Series Aeroplanes\n\n \n\nAD/DH 89/1 Fuel System Control - Modification NK\n\nApplicability: All models.\n\n \n\nRequirement: Modify the fuel system controls 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 the event of an emergency; or\n\n \n\nPart 100, Appendix “A” Notice No. 10/2; or ANO 105.1.14.0.1.1.\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","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument, as provided, sets immediate hardware modification requirements that apply to all DH 89 series aeroplanes. There is no information in the text indicating a change from an earlier scope or intent; the directive is framed as a standalone, fleet‑wide modification requirement with an immediate compliance expectation. (Applicability; Requirement; Compliance)"},"complexity_factors":["Single aircraft type but applies to all models (broad applicability within that fleet). (Applicability)","Two discrete physical modifications required (cable clamping; pilot lever locking) rather than extensive regulatory overhaul. (Requirement 1 and 2)","Immediate compliance required (‘Forthwith’), increasing scheduling and funding pressure on operators. (Compliance)","Technical requirements are performance‑oriented and not prescriptive (terms like ‘positive method’ and ‘means of locking’), creating implementation discretion. (Requirement 1 and 2)","Alternative compliance paths for the lever locking requirement reference other documents (Part 100 Appendix A Notice No.10/2; ANO 105.1.14.0.1.1), adding cross‑document interpretation. (Requirement 2)","Potential need for engineering, parts procurement and downtime for installation increases practical complexity despite the textual simplicity. (Requirement; Compliance)"],"plain_english_summary":"What this instrument does (mechanically)\n\n- Applies to: all DH 89 (Dragon Rapide) series aeroplanes. (Applicability)\n- Requires immediate modification of the aeroplane fuel system controls. (Requirement; Compliance: Forthwith)\n- Two specific modification requirements are set out: 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; and 2) provide a means to lock the pilot’s fuel-control lever in the “ON” position while allowing the lever to be moved rapidly to “OFF” in an emergency. (Requirement 1 and 2)\n- The instrument lists three ways of addressing requirement 2: implement the locking mechanism described; or comply with Part 100, Appendix “A” Notice No. 10/2; or comply with ANO 105.1.14.0.1.1. (Requirement 2)\n\nWho this affects and who pays\n\n- Operators and owners of DH 89 series aeroplanes are the parties required to carry out the work. (Applicability; Requirement)\n- Those operators/owners will bear the direct costs of parts, engineering, labour and any associated downtime while the modifications are fitted. (Requirement; Compliance)\n\nHow it changes behaviour and decision-making\n\n- Aircraft owners must arrange and complete the specified physical modifications without delay. (Compliance: Forthwith)\n- Implementers must choose a method to satisfy each requirement. The directive sets performance goals (a ‘‘positive method of retaining and clamping’’; a ‘‘means of locking’’ allowing rapid movement to OFF) but does not specify a single technical design in this text. That choice affects which parts are purchased and which procedures are used. (Requirement 1 and 2)\n- For the pilot lever requirement there is an explicit option to comply via one of two referenced documents instead of the unspecified locking method in this notice. That gives operators a choice between (a) a bespoke locking solution or (b) meeting the standards in the cross‑referenced documents. (Requirement 2)\n\nStated purpose and testing against practical trade-offs\n\n- The instrument itself does not include a separate explanatory statement of reasons; its mechanics are to mandate two modifications to fuel control hardware. (Entire text)\n- Practical trade-offs and implementation points implied by the text:\n  - Timing: compliance is required forthwith, so owners/operators face immediate scheduling and funding needs. (Compliance)\n  - Specification vs discretion: the text prescribes the safety function but leaves technical design largely open (uses terms like “positive method” and “means”), which requires implementers to select or design an acceptable solution. That creates implementation discretion and potential variation between installations. (Requirement 1 and 2)\n  - Alternatives and paperwork: the inclusion of cross-references (Part 100, Appendix “A” Notice No. 10/2; ANO 105.1.14.0.1.1) provides explicitly allowed alternative compliance paths for requirement 2, which can reduce redesign work if an operator already meets those standards. Choosing an alternative may require the operator to demonstrate compliance with that document. (Requirement 2)\n  - Who decides technical acceptability: because the directive does not fix a single design, approval of the chosen method or parts (where required by airworthiness regulation) will determine what work is acceptable. The text itself does not state the approval process. (Entire text)\n\nCosts, incentives and compliance burden (mechanical view)\n\n- Direct costs: parts, engineering time, workshop labour and aircraft downtime. (Requirement; Compliance)\n- Incentive structure: owners have an immediate regulatory requirement to modify; the cross‑reference option for requirement 2 creates an incentive to adopt an existing, approved standard if available. (Requirement 2)\n- Concentration of costs: the expense is concentrated on DH 89 owners/operators; the benefit (safety function implied by a fuel-system AD) would be dispersed across their operations. The text itself does not quantify costs or benefits. (Applicability; Requirement)\n\nImplementation risks and uncertainties in the instrument\n\n- Vague technical language leaves room for differing interpretations of what is an acceptable ‘‘positive method’’ or ‘‘means of locking’’. That may create delays while operators seek technical guidance or approval. (Requirement 1 and 2)\n- The text provides no timeline beyond “Forthwith,” nor does it specify certification steps in this notice; the absence of procedural detail shifts the immediate implementation burden onto operators and their maintenance providers. (Compliance)\n\nWhat to expect next (procedural consequences implicit in the text)\n\n- Owners/operators must arrange for the physical modifications to be designed and fitted promptly or choose one of the cross‑referenced compliance routes for requirement 2. (Requirement 1 and 2; Compliance)\n- The modification will change maintenance, parts and inspection tasks for the affected aeroplanes once fitted; the notice does not itself list follow‑up inspection intervals or paperwork beyond the modification requirement. (Entire text)\n\nSource citations (where items are stated above): Applicability; Requirement 1; Requirement 2 (including cross-references); Compliance: Forthwith."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive for 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 300 words)","Only 2 substantive requirements with clear mechanical descriptions","Zero defined terms in an interpretation section","Minimal conditional logic (simple 'or' alternative for compliance method)","No cross-references to other legislation beyond optional alternative standards","Single applicability criterion ('All models')","Plain language mechanical instructions ('clamp', 'lock', 'ON position')"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for a specific vintage aircraft—the **DH 89 Dragon Rapide**, a 1930s-era British twin-engine biplane.\n\n**What it does:**\nThe directive requires owners/operators to make two specific safety modifications to the fuel system controls:\n\n- **Secure the fuel cable housing:** 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 shifting or chafing, which could cause fuel flow problems or fires.\n\n- **Add a safety lock for the fuel lever:** Modify the pilot's fuel control lever so it can be locked in the \"ON\" (fuel flowing) position, but with a quick-release mechanism allowing instant shut-off in an emergency—such as an engine fire or crash landing.\n\n**Who it affects:**\nAnyone operating a DH 89 Dragon Rapide aircraft in Australia (these are mostly heritage/vintage aircraft in museums, private collections, or used for scenic flights).\n\n**Why it matters:**\nLoose fuel cables can cause fuel starvation (engine failure) or fuel leaks (fire risk). A lever that accidentally moves to \"OFF\" cuts fuel unexpectedly; one that can't be reached quickly in an emergency wastes precious seconds. This directive prevents both scenarios. The \"Forthwith\" compliance deadline means **do it immediately**—no grace period.\n\n**Alternative compliance:** Operators may instead follow two referenced British aviation notices (Part 100 Appendix A Notice 10/2, or ANO 105.1.14.0.1.1) if those achieve the same safety outcome."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dh-89-1-fuel-system-control-modification","history":"/api/acts/ad-dh-89-1-fuel-system-control-modification/history","analysis":"/api/acts/ad-dh-89-1-fuel-system-control-modification/analysis","conflicts":"/api/acts/ad-dh-89-1-fuel-system-control-modification/conflicts","importantCases":"/api/acts/ad-dh-89-1-fuel-system-control-modification/important-cases","documents":"/api/acts/ad-dh-89-1-fuel-system-control-modification/documents"}}