{"id":"F2006B09752","name":"AD/F28/15 - Horizontal Stabilizer Control Unit - Modification","slug":"ad-f28-15-horizontal-stabilizer-control-unit-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54606,"registerId":"commonwealth-F2006B09752-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F28/15 - Horizontal Stabilizer Control Unit - 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)  Fokker F28 Series Aeroplanes\n\n \n\n \n\n| AD/F28/15 | Horizontal Stabilizer Control Unit - Modification | NK |\n| --- | --- | --- |\n| Applicability: | F28 aeroplanes with S/Nos. 11003 to 11024 and 11991 and 11992. |  |\n| Document: | Fokker SB F28/27-31. |  |\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 \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 supplied text does not indicate any change from an earlier or original scope. The AD explicitly applies to a defined set of Fokker F28 serial numbers (Applicability) and references a single service bulletin for the modification (Document). There is no information in the provided material showing an expansion or narrowing of scope relative to a prior instrument or original design intent."},"complexity_factors":["Narrow applicability identified by specific serial numbers increases administrative precision but requires operators to check serial records (Applicability).","Substantive technical requirements are not in the AD text itself but are deferred to an external document (Fokker SB F28/27-31), creating reliance on that bulletin for implementation (Document).","The AD is issued under the Civil Aviation Regulations, Part 39, so legal compliance and enforcement follow that regulatory framework (header), which operators must interpret or seek guidance on.","Absence of compliance timing, cost, and procedural detail in the supplied text increases operational uncertainty for affected operators (no deadline or procedures specified).","Concentrated set of affected aircraft means impacts (costs, downtime) are concentrated on a small group of owners/operators, which may complicate logistics for parts and maintenance resources."],"plain_english_summary":"This Airworthiness Directive from the Civil Aviation Safety Authority mandates modification of the horizontal stabilizer control unit on specified Fokker F28 aeroplanes (serials 11003–11024, 11991–11992) by following Fokker Service Bulletin F28/27-31.  \n\nIt affects the listed aircraft owners/operators, who will need to implement the referenced modification under Part 39 authority; the AD text does not state compliance times, costs, or alternative measures."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This appears to be a standard, narrow Airworthiness Directive targeting a specific technical modification on specific aircraft. There is no indication of scope creep — it addresses a discrete safety issue on defined aircraft models through established regulatory mechanisms."},"complexity_factors":["Extremely short document — essentially a reference to an external technical standard (Fokker Service Bulletin)","No defined terms section — relies entirely on external aviation terminology","No conditional logic or nested exceptions within the directive itself","Simple applicability clause limited to specific serial numbers","Substantive technical requirements contained in referenced document (Fokker SB F28/27-31) rather than in the legislation itself"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998. It applies to specific Fokker F28 series aircraft (serial numbers 11003 to 11024, plus 11991 and 11992).\n\n**What it does:**\nThe directive requires a **modification to the Horizontal Stabilizer Control Unit** — a critical flight control component that helps keep the aircraft stable during flight.\n\n**Who it affects:**\n- Owners and operators of the specified Fokker F28 aircraft\n- Maintenance organisations servicing these aircraft\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety orders. They typically address design defects, unsafe conditions, or maintenance issues discovered after an aircraft enters service. Compliance is mandatory — aircraft cannot legally fly until the required modification is completed.\n\n**What must be done:**\nOperators must follow the technical instructions in **Fokker Service Bulletin F28/27-31** to modify the horizontal stabilizer control unit. The \"NK\" notation likely indicates this is a new directive or specifies compliance timing (common in aviation regulatory shorthand)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f28-15-horizontal-stabilizer-control-unit-modification","history":"/api/acts/ad-f28-15-horizontal-stabilizer-control-unit-modification/history","analysis":"/api/acts/ad-f28-15-horizontal-stabilizer-control-unit-modification/analysis","conflicts":"/api/acts/ad-f28-15-horizontal-stabilizer-control-unit-modification/conflicts","importantCases":"/api/acts/ad-f28-15-horizontal-stabilizer-control-unit-modification/important-cases","documents":"/api/acts/ad-f28-15-horizontal-stabilizer-control-unit-modification/documents"}}