{"id":"F2006B09581","name":"AD/ENST 28/25 - Clutch Engagement Over Centre Lock Warning Light","slug":"ad-enst-28-25-clutch-engagement-over-centre-lock-warning-light","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54278,"registerId":"commonwealth-F2006B09581-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ENST 28/25 - Clutch Engagement Over Centre Lock Warning Light","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\n# AD/ENST 28/25 Clutch Engagement Over Centre\n\nLock Warning Light Applicability: All models F-28A, 280, F-28C, 280C, F-28F and 280F helicopters. Document:               Document SDB No. 0061.\n\nFAA AD 82-24-01 refers.\n\n \n\nCompliance: Within 100 hours time in service after 31 March 1983.\n\n# 1/83\n\n \n\nBackground:  To ensure that the clutch engaging mechanism is locked and over centre, a warning light indicator is installed.\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":"Based on the supplied text, the AD's scope is stated narrowly and consistently: it applies to the listed Enstrom F‑28 models and requires installation of a warning light within a fixed hours‑in‑service window. The text shows no indication that the scope was altered from an earlier intent within this document. Technical details and methods are referred out to Document SDB No. 0061 and FAA AD 82‑24‑01, but that delegation does not itself change the scope described here (Applicability; Compliance; Document)."},"complexity_factors":["Narrow technical scope limited to a single retrofit (warning light) for specified helicopter models (Applicability; Background).","Clear, short compliance timeframe expressed in hours-in-service (Compliance: within 100 hours after 31 March 1983).","Technical installation details are delegated to an external document (Document SDB No. 0061) and an FAA AD cross‑reference (FAA AD 82‑24‑01), adding a dependency on external technical material.","No multiple compliance options or staged requirements in the text supplied (reduces procedural complexity).","Measurement and scheduling require accurate time‑in‑service tracking by operators (operational detail but low legal complexity)."],"plain_english_summary":"Requires fitting a cockpit warning light that shows the clutch engaging mechanism is locked and “over‑centre” on Enstrom F‑28 series helicopters (F‑28A/280, F‑28C/280C, F‑28F/280F). Owners/operators must install the indicator per SDB No. 0061 within 100 hours TIS after 31 March 1983.\n\nThe change ensures flightcrew can verify clutch status; owners/operators bear parts, labour and downtime. The AD points to SDB No. 0061 and FAA AD 82‑24‑01 for technical details."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive focused specifically on clutch engagement warning systems. It has not expanded beyond its original narrow technical purpose."},"complexity_factors":["Very short document (approximately 150 words)","Only 1 substantive requirement (install warning light)","Single compliance deadline (100 hours time in service after fixed date)","No defined terms section","No cross-references to other legislation (only references FAA AD and manufacturer document)","Simple applicability test (specific model numbers listed explicitly)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) for specific Enstrom helicopter models. It mandates that owners and operators of F-28A, 280, F-28C, 280C, F-28F and 280F helicopters must install a **warning light** that alerts the pilot if the clutch engaging mechanism is not properly locked \"over centre\" (a mechanical position where the clutch is fully engaged and locked in place).\n\n**Why it matters:** If the clutch isn't properly locked, it could disengage during flight, leading to loss of rotor drive and potentially catastrophic failure. The warning light gives pilots immediate visual feedback about this critical safety system.\n\n**Who must comply:** All operators of the listed Enstrom helicopter models had to complete this modification within 100 hours of flight time after 31 March 1983."}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-25-clutch-engagement-over-centre-lock-warning-light","history":"/api/acts/ad-enst-28-25-clutch-engagement-over-centre-lock-warning-light/history","analysis":"/api/acts/ad-enst-28-25-clutch-engagement-over-centre-lock-warning-light/analysis","conflicts":"/api/acts/ad-enst-28-25-clutch-engagement-over-centre-lock-warning-light/conflicts","importantCases":"/api/acts/ad-enst-28-25-clutch-engagement-over-centre-lock-warning-light/important-cases","documents":"/api/acts/ad-enst-28-25-clutch-engagement-over-centre-lock-warning-light/documents"}}