{"id":"F2006B09766","name":"AD/F28/29 - Horizontal Stabilizer Assemblies - Modification","slug":"ad-f28-29-horizontal-stabilizer-assemblies-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54650,"registerId":"commonwealth-F2006B09766-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F28/29 - Horizontal Stabilizer Assemblies - 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\nAD/F28/29 Horizontal Stabilizer Assemblies - Modification 2/75\n\nApplicability: All models with S/Nos. 11003 to 11020, 11022 to 11025 and 11991 to 11993. Document:               1. Fokker SB F28/55-17; or\n\n2. RLD AD A108/75.\n\n \n\nCompliance: Before 1 May 1976.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\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":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive focused solely on a specific mechanical modification to a specific aircraft type. It has not expanded beyond its original narrow safety purpose."},"complexity_factors":["Very short document (approximately 150 words)","Only 2 defined references (the technical documents Fokker SB F28/55-17 and RLD AD A108/75)","Simple applicability test based on aircraft serial numbers only","Single, absolute compliance deadline with no conditional logic or exceptions","No cross-references to other legislation or regulatory provisions beyond the enabling Civil Aviation Regulations 1998","No nested definitions or interpretive provisions"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it requires:** Owners and operators of specific **Fokker F28 series aircraft** must modify their **horizontal stabilizer assemblies** (the tail section that helps control the plane's pitch) according to technical instructions in Fokker Service Bulletin F28/55-17 or Dutch aviation authority directive RLD AD A108/75.\n\n**Who it affects:** This applies only to specific aircraft serial numbers: 11003–11020, 11022–11025, and 11991–11993.\n\n**Why it matters:** The modification addresses a safety defect in the horizontal stabilizer. Aircraft must comply **before 1 May 1976** — meaning this directive is long past its compliance deadline and is now of historical interest only, though it remains part of the regulatory record.\n\n**Key point:** This is a **time-expired safety mandate**. No currently flying Fokker F28 in Australia would need to comply with this now, as the deadline passed nearly 50 years ago."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The provided text sets a limited and specific scope: it applies only to Fokker F28 aeroplanes with the listed serial numbers and requires a modification to horizontal stabilizer assemblies according to the two referenced technical documents, to be completed before 1 May 1976. The text contains no information indicating a change from that original scope."},"complexity_factors":["Narrow, serial-number-specific applicability which limits affected fleet but requires precise identification of airframes (Applicability).","Reference to external technical documents (Fokker SB F28/55-17; RLD AD A108/75) rather than embedding procedures in the AD (Document).","Single, hard compliance deadline creating a firm scheduling requirement (Compliance: \"Before 1 May 1976\").","Lack of information in the AD about cost allocation or who performs the work (no cost/performer details in text).","No express provisions in the AD text for waivers, extensions, or alternative compliance methods (no discretion described in text).","Clear issuing authority (Civil Aviation Safety Authority) but limited procedural detail about implementation or enforcement (Header)."],"plain_english_summary":"This airworthiness directive requires operators/owners of specified Fokker F28 airframes (S/N 11003–11020, 11022–11025, 11991–11993) to modify the horizontal stabilizer assemblies per one of two referenced technical documents and complete the work before 1 May 1976. Issued by the Civil Aviation Safety Authority, it imposes a focused, mandatory safety modification and a fixed compliance deadline on that defined group of aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f28-29-horizontal-stabilizer-assemblies-modification","history":"/api/acts/ad-f28-29-horizontal-stabilizer-assemblies-modification/history","analysis":"/api/acts/ad-f28-29-horizontal-stabilizer-assemblies-modification/analysis","conflicts":"/api/acts/ad-f28-29-horizontal-stabilizer-assemblies-modification/conflicts","importantCases":"/api/acts/ad-f28-29-horizontal-stabilizer-assemblies-modification/important-cases","documents":"/api/acts/ad-f28-29-horizontal-stabilizer-assemblies-modification/documents"}}