{"id":"F2006B05500","name":"AD/PA-23/73 - Stabilator Tab Horn - Replacement","slug":"ad-pa-23-73-stabilator-tab-horn-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46346,"registerId":"commonwealth-F2006B05500-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-23/73 - Stabilator Tab Horn - 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 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Piper PA-23 (Apache and Aztec) Series Aeroplanes\n\n \n\nAD/PA-23/73 Stabilator Tab Horn - Replacement 10/77\n\nApplicability: All model PA23-250 (6 Place) Aztec “F” with S/Nos. 27-7654001 to 27-7754127, 27-7754130, 27-7754131, 27-7754133 to 27-7754136 and 27-7754138 to 27-\n\n7754144.\n\n \n\nDocument: Piper SB No. 569.\n\n \n\nCompliance: Within 100 hours time in service after 31 October 1977.\n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The text provided contains a single-directional requirement with specific applicability and a compliance deadline. It does not include any amendments, expansions, repeals, or language indicating a change from an earlier scope. There is no information in the excerpt to indicate that the scope was altered from an original intent."},"complexity_factors":["Narrow, specific applicability limited to particular model and serial numbers (low scope breadth) [Applicability]","Single, simple mandated action (component replacement) referenced to an external service bulletin (procedural dependency) [Document]","Short, explicit compliance deadline (100 hours TIS after a specified date) — clear timing requirement [Compliance]","No procedural options, exemptions, or multiple compliance pathways stated (straightforward mandate) [Document; Compliance]","Dependence on an external technical document (Piper SB No. 569) for execution details adds a modest implementation dependency"],"plain_english_summary":"What this document does, in plain language\n\n- This is an Airworthiness Directive (an instruction issued under the Commonwealth Civil Aviation Regulations, Part 39) published by the Civil Aviation Safety Authority. It orders a specific mechanical change to affected aeroplanes. [header]\n\n- Mechanically, the directive requires the replacement of the stabilator tab horn on specified Piper PA-23-250 (6 place) Aztec “F” aeroplanes. The replacement must be carried out using the procedure referenced in Piper Service Bulletin No. 569. [Document]\n\nWho is affected and what they must do\n\n- The directive applies only to PA23-250 Aztec “F” aircraft with the serial numbers listed in the Applicability section. Operators or owners of those specific aircraft are the parties who must have the replacement carried out. [Applicability]\n\n- The work must be completed within 100 hours time in service after 31 October 1977. That is the compliance window set by the directive. [Compliance]\n\nWhat the document states (and what it does not)\n\n- The AD prescribes the action (replace the stabilator tab horn) and references the Piper Service Bulletin for the technical method. It sets a firm deadline for compliance. [Document; Compliance]\n\n- The text provided does not state an explicit reason or justification for the replacement (no cause or safety analysis appears in the excerpt). The AD form and placement under Part 39 indicate it is a regulatory instruction, but the excerpt itself contains no statement of the underlying defect or incident that prompted the directive. [header; Document]\n\nPractical implications, incentives and trade-offs (grounded in the document)\n\n- Who pays: The operator/owner of any affected serial-numbered aircraft will be the party required to arrange the replacement and therefore will bear the direct cost and operational impact of the work, because the AD requires the work on those aircraft. [Applicability; Compliance]\n\n- Timing and operational impact: The 100-hour time-in-service limit creates a short-term scheduling requirement. Carriers/operators will need to schedule maintenance within that window, which may cause aircraft downtime. [Compliance]\n\n- Technical implementation and discretion: The AD points to Piper SB No. 569 for the replacement procedure. That means technical execution is governed by the service bulletin’s instructions; a licensed maintenance organisation will typically perform the work according to that SB. The AD text does not specify alternatives or allow for discretionary deviations. [Document]\n\n- Concentration of effect: The obligation applies to a defined, narrow set of serial numbers, so the direct compliance costs are concentrated on owners/operators of those specific aeroplanes. [Applicability]\n\n- Unstated benefits and trade-offs: The directive mandates component replacement but does not state benefits in the text provided. If the replacement is intended to address a mechanical deficiency, potential benefits (not specified here) would need to be weighed against the immediate costs and aircraft downtime required to comply. The document itself does not provide that cost–benefit detail. [Document]\n\nSummary in one sentence\n\n- The AD requires owners/operators of the listed Piper PA-23-250 Aztec “F” aircraft to replace the stabilator tab horn in accordance with Piper SB No. 569 within 100 hours TIS after 31 October 1977; the directive specifies the action and timing but does not include a reason or cost assessment in the text provided. [Applicability; Document; Compliance]"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, original Airworthiness Directive with a narrow, well-defined scope targeting a specific mechanical defect in a limited fleet of aircraft. There is no indication of scope creep or expansion beyond its original safety purpose."},"complexity_factors":["Single, specific mechanical requirement (one part replacement)","Narrow applicability limited to specific aircraft model and serial number range","Simple compliance deadline (100 hours time-in-service after fixed date)","No nested exceptions, conditional logic, or cross-references to other legislation","References only one external technical document (Piper Service Bulletin 569)","Total length is approximately 100 words"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific Piper Aztec \"F\" model aeroplanes to replace a part called the **stabilator tab horn**.\n\n**What is a stabilator tab horn?**\nThe stabilator is the movable part of an aircraft's tail that controls pitch (nose up/down). The \"tab horn\" is a small lever-like component that connects the control system to this surface. If it fails, the pilot could lose pitch control — a serious safety risk.\n\n**Who must comply?**\nOwners of Piper PA-23-250 Aztec \"F\" six-seat aircraft with specific serial numbers (ranging from 27-7654001 to 27-7754144, with some gaps).\n\n**What must they do?**\nReplace the stabilator tab horn following Piper Service Bulletin No. 569, and complete this work within **100 hours of flight time** after 31 October 1977.\n\n**Why it matters:**\nAirworthiness Directives are legally binding. Non-compliance means the aircraft cannot legally fly in Australian airspace. This particular AD addresses a known defect that could compromise flight safety."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-23-73-stabilator-tab-horn-replacement","history":"/api/acts/ad-pa-23-73-stabilator-tab-horn-replacement/history","analysis":"/api/acts/ad-pa-23-73-stabilator-tab-horn-replacement/analysis","conflicts":"/api/acts/ad-pa-23-73-stabilator-tab-horn-replacement/conflicts","importantCases":"/api/acts/ad-pa-23-73-stabilator-tab-horn-replacement/important-cases","documents":"/api/acts/ad-pa-23-73-stabilator-tab-horn-replacement/documents"}}