{"id":"F2006B09565","name":"AD/ENST 28/10 - Tail Cone Attachment Bolts - Inspection and Replacement","slug":"ad-enst-28-10-tail-cone-attachment-bolts-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54226,"registerId":"commonwealth-F2006B09565-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ENST 28/10 - Tail Cone Attachment Bolts - Inspection and 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)  Enstrom F-28 Series Helicopters\n\n \n\nAD/ENST 28/10 Tail Cone Attachment Bolts - Inspection\n\nand Replacement\n\n\n1/76\n\n \n\nApplicability: All model F-28A with S/Nos. 03 to 347, and Model 280 with S/Nos. 1001 to 1030. Document:               Enstrom Service Note No. 0029.\n\nCompliance: 1. Inspect within 50 hours time in service after 15 January 1976 and thereafter at intervals not exceeding 50 hours time in service until replaced.\n\n \n\n2. Replace within 300 hours time in service after 15 January 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","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific helicopter models. It has not expanded beyond its original purpose of ensuring tail cone bolt integrity in the identified aircraft population."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined applicability criteria (specific serial number ranges)","Simple two-step compliance requirement (inspect periodically, then replace)","No cross-references to other legislation or regulations beyond the enabling authority (Civil Aviation Regulations 1998, Part 39)","No nested conditions or exceptions","Single technical reference document (Enstrom Service Note No. 0029)","Clear, unambiguous deadlines based on flight hours"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific helicopters.\n\n**What it does:**\nOrders owners and operators of certain **Enstrom F-28A and Model 280 helicopters** to inspect and eventually replace the bolts that attach the tail cone (the rear section of the helicopter) to the main body.\n\n**Who it affects:**\n- All Enstrom F-28A helicopters with serial numbers 03 through 347\n- All Enstrom Model 280 helicopters with serial numbers 1001 through 1030\n\n**What must be done:**\n1. **Inspection:** Check the tail cone attachment bolts within 50 hours of flying time after 15 January 1976, then re-inspect every 50 flight hours until replacement\n2. **Replacement:** Install new bolts within 300 flight hours after 15 January 1976\n\n**Why it matters:**\nTail cone attachment bolts are critical structural components. If they fail in flight, the tail section could separate from the helicopter, causing catastrophic loss of control. This AD was issued to prevent accidents due to bolt fatigue or failure before a permanent fix (replacement) could be completed.\n\n**Key terms explained:**\n- **Time in service:** Actual flight hours (not just calendar time)\n- **Airworthiness Directive (AD):** A legally enforceable safety notice that must be complied with to keep an aircraft certified as airworthy"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The document defines its scope by listing the affected models and serial numbers and by setting fixed inspection and replacement intervals (Applicability; Compliance 1–2). The text contains no indication that the scope has been expanded or narrowed from a prior instrument within the text provided; therefore no change of scope is evident in this document."},"complexity_factors":["Narrow applicability: specific models and serial number ranges only (Applicability).","Simple, time‑based compliance requirements: fixed inspection interval (50 hours TIS) and fixed replacement deadline (300 hours TIS) (Compliance 1–2).","No procedural detail in the AD text itself; it refers to an external service note for technical procedure (Document: Enstrom Service Note No. 0029).","Deterministic obligations with no discretionary exceptions or alternatives stated in the text (Compliance 1–2).","Regulatory context is a single airworthiness directive under Part 39, not a complex multi-part regulatory regime (Part 39 header)."],"plain_english_summary":"This AD requires owners/operators of Enstrom F‑28A (S/N 03–347) and Model 280 (S/N 1001–1030) helicopters to inspect tail-cone attachment bolts within 50 hours TIS after 15 Jan 1976 and every 50 hours until the bolts are replaced, and to replace them within 300 hours TIS after that date. Operators bear the cost and must schedule maintenance and records; the AD cites Enstrom Service Note No. 0029 for related procedures."}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-10-tail-cone-attachment-bolts-inspection-and-replacement","history":"/api/acts/ad-enst-28-10-tail-cone-attachment-bolts-inspection-and-replacement/history","analysis":"/api/acts/ad-enst-28-10-tail-cone-attachment-bolts-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-enst-28-10-tail-cone-attachment-bolts-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-enst-28-10-tail-cone-attachment-bolts-inspection-and-replacement/important-cases","documents":"/api/acts/ad-enst-28-10-tail-cone-attachment-bolts-inspection-and-replacement/documents"}}