{"id":"F2006B09277","name":"AD/DHE/27 - Fuel Control Unit - Boost Capsule - Replacement","slug":"ad-dhe-27-fuel-control-unit-boost-capsule-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53316,"registerId":"commonwealth-F2006B09277-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHE/27 - Fuel Control Unit - Boost Capsule - Replacement","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 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  De Havilland Piston Engines\n\n \n\nAD/DHE/27 Fuel Control Unit - Boost Capsule - Replacement 2/84\n\nApplicability: All Gipsy Queen Series 70.\n\n \n\nDocument: Hants and Sussex: Gipsy Modification 3014 Issue 2. Compliance: In accordance with requirement document.\n\nBackground:  This directive is issued to require compliance with the quoted modification to preclude boost capsule failure causing loss of engine power.\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":2,"scope_assessment":{"changed":false,"description":"The directive text does not indicate any expansion or narrowing of scope from a prior instrument. It states applicability to \"All Gipsy Queen Series 70\" and requires compliance with the specified modification document (Hants and Sussex: Gipsy Modification 3014 Issue 2). There is no language in the provided text suggesting the scope has been changed from an earlier version."},"complexity_factors":["Very narrow technical and population scope: applies only to Gipsy Queen Series 70 engines (Applicability).","Mandatory action referenced but procedural detail is external: AD directs compliance with a separate technical document (Hants and Sussex: Gipsy Modification 3014 Issue 2) rather than including steps in the AD (Document; Compliance).","Regulatory mandatory nature with limited on-text discretion: the AD is issued \"to require compliance,\" leaving little interpretive flexibility within the AD itself (Background).","Safety-critical subject matter raises implementation importance despite low textual complexity (Background).","Lack of quantification or timing in the AD: the text does not state deadlines, costs, or certification steps in the directive itself (Document; Compliance)."],"plain_english_summary":"What this directive does (mechanically)\n\n- It requires owners/operators of all Gipsy Queen Series 70 piston engines to have the boost capsule in the fuel control unit replaced in accordance with a specified modification document (Hants and Sussex: Gipsy Modification 3014 Issue 2). (Applicability; Document; Compliance)\n- The Civil Aviation Safety Authority issued the directive as part of the Schedule of Airworthiness Directives under the Civil Aviation Regulations. (COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY)\n\nWhy the change is required (official rationale)\n\n- The directive states its purpose is to prevent boost capsule failure that could cause loss of engine power. That purpose is set out in the Background. (Background)\n\nWho decides and who must act\n\n- The Civil Aviation Safety Authority issued the requirement. The persons required to act are the owners/operators of the affected engines — specifically, aircraft with Gipsy Queen Series 70 engines. The AD requires compliance with the quoted modification document. (COMMONWEALTH OF AUSTRALIA...; Applicability; Document; Compliance)\n\nWho pays and what they must do\n\n- The text requires affected parties to implement the modification in accordance with the requirement document. That implies owners/operators (or their agents) must procure the replacement parts and arrange for the modification work; the directive itself does not specify who pays but places the obligation to comply on those responsible for the affected engines. (Applicability; Document; Compliance)\n\nPractical effects and implementation mechanics\n\n- The AD does not give step-by-step instructions in the directive itself; instead it references a technical modification document which contains the required procedure. Compliance is achieved by following that document. (Document; Compliance)\n- Implementing the modification will require allocating time, parts and maintenance labour to perform the replacement specified in Gipsy Modification 3014 Issue 2. The AD creates a mandatory demand for that technical work for every affected engine. (Document; Compliance)\n\nTrade-offs, incentives and risks (source statements and direct implications)\n\n- Benefit claimed: the modification is intended to reduce the risk of boost capsule failure and associated loss of engine power. This is the explicit safety rationale. (Background)\n- Cost and incentive allocation: the directive shifts the operational cost and logistic burden of the modification onto the owners/operators of the affected engines because they are required to comply with the specified modification document. (Applicability; Document; Compliance)\n- Compliance burden and discretion: the AD is issued \"to require compliance\" and therefore imposes a mandatory regulatory obligation; the AD itself delegates technical detail to the referenced modification document, limiting discretionary interpretation within the AD text. (Background; Document; Compliance)\n- Effects on service market: by mandating a specific modification document, the AD creates a need for suppliers or maintenance organisations that can carry out that modification. The directive does not address procurement methods, pricing, or market access for service providers — those remain matters for owners/operators and the market. (Document; Compliance)\n\nImplementation risk and opportunity costs\n\n- If the required modification is not performed, the directive identifies the safety risk it is intended to address (boost capsule failure leading to loss of engine power). The AD does not quantify that risk or offer alternatives. (Background)\n- Opportunity costs for owners/operators include the time, parts and labour devoted to implementing the modification instead of other uses; these are not specified in the directive. (Document; Compliance)\n\nConcise summary\n\n- Mandatory replacement of the fuel control unit boost capsule for all Gipsy Queen Series 70 engines by following Hants and Sussex: Gipsy Modification 3014 Issue 2, issued by the Civil Aviation Safety Authority to prevent boost capsule failure and potential loss of engine power. (Applicability; Document; Compliance; Background)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive focused on a specific mechanical component in a specific engine series. It has not expanded beyond its original purpose of preventing boost capsule failures."},"complexity_factors":["Extremely short document (under 200 words)","Only one defined applicability criterion (Gipsy Queen Series 70 engines)","Single compliance requirement referencing an external technical document","No nested conditions, exceptions, or cross-references to other legislation","Straightforward cause-and-effect logic (faulty part → mandatory replacement)"],"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).\n\n**What it does:** It requires owners and operators of specific aircraft engines (the De Havilland Gipsy Queen Series 70) to replace a part called the \"boost capsule\" in the fuel control unit. The replacement must follow a specific technical document: Hants and Sussex Modification 3014 Issue 2.\n\n**Why it matters:** The boost capsule can fail, which would cause a sudden loss of engine power — obviously dangerous when you're flying. This directive prevents that failure from happening.\n\n**Who it affects:** Anyone operating aircraft with Gipsy Queen Series 70 engines (these are vintage piston engines, commonly found in older British aircraft like the Dove and Devon).\n\n**Key point:** This isn't optional. \"Compliance\" means you must do it, following the exact instructions in the referenced document."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhe-27-fuel-control-unit-boost-capsule-replacement","history":"/api/acts/ad-dhe-27-fuel-control-unit-boost-capsule-replacement/history","analysis":"/api/acts/ad-dhe-27-fuel-control-unit-boost-capsule-replacement/analysis","conflicts":"/api/acts/ad-dhe-27-fuel-control-unit-boost-capsule-replacement/conflicts","importantCases":"/api/acts/ad-dhe-27-fuel-control-unit-boost-capsule-replacement/important-cases","documents":"/api/acts/ad-dhe-27-fuel-control-unit-boost-capsule-replacement/documents"}}