{"id":"F2006B09593","name":"AD/ENST 28/36 - Lamiflex Bearings","slug":"ad-enst-28-36-lamiflex-bearings","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54307,"registerId":"commonwealth-F2006B09593-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ENST 28/36 - Lamiflex Bearings","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nEnstrom F-28 Series Helicopters\n\nAD/ENST 28/36 Lamiflex Bearings 12/94 TX\n\nApplicability: Models F28A, C, C2, F; 280, 280C, F and FX with main rotor feathering elastomeric Lamiflex bearings P/N 28-14320-12 or 28-14320-15.\n\nRequirement: 1. Action in accordance with Enstrom Service Directive Bulletin No. 0081 Rev. A.\n\n    2. Remove from service any Lamiflex bearing where the Date of Manufacture is:\n\n    not visible or illegible, or\n\n    b. marked as being manufactured five years prior to any inspection carried out in accordance with this Directive.\n\nNote: FAA AD 94-17-15 refers.\n\nCompliance: Within five hours time in service after 26 September 1994. Thereafter at intervals not exceeding 100 hours time in service; and anytime the symptoms specified in paragraphs 4.1.1 to 4.1.4 of the Requirement Document are experienced.\n\nBackground: There have been reports of several failures of the subject bearings where the bearings have delaminated and extruded rubber and brass. Continued operation in this condition may result in complete delamination, resulting in failure of the bearing, and loss of control of the helicopter. This Directive also imposes a five year since manufacture calendar life on the bearings.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The Directive adds a compulsory five‑year calendar life and immediate short‑term inspection requirement for the specified Lamiflex bearings, shifting from ad hoc or condition‑based maintenance to a mandatory retirement and fixed inspection cycle (Requirement 2; Compliance; Background). This extends regulatory reach by imposing time‑since‑manufacture limits and an initial five‑hour compliance deadline, increasing operators' maintenance and replacement obligations."},"complexity_factors":["Narrow applicability to specific helicopter models and two part‑numbers (limits scope but requires careful part identification) (Applicability).","Mandatory calendar‑life retirement rule (five years since manufacture) for the bearings, regardless of hours (Requirement 2.b; Background).","Short initial compliance window — inspection within five hours TIS after 26 Sept 1994 — followed by recurring 100‑hour intervals (Compliance).","Removal criterion includes illegible or non‑visible manufacture date, creating recordkeeping and traceability demands (Requirement 2.a).","Direct reference to an external service document (Enstrom Service Directive Bulletin No. 0081 Rev. A) for corrective action details (Requirement 1).","Safety consequence is high (possible loss of control if bearing delaminates), increasing regulatory strictness and enforcement priority (Background).","Cross‑reference to FAA AD adds an international regulatory linkage that may affect imported parts and supplier obligations (Note).","Operational impact: inspection, replacement and downtime costs fall on operators; shops must access the service bulletin and manage parts inventory (Compliance/Requirement)."],"plain_english_summary":"This Airworthiness Directive forces Enstrom F‑28 operators to inspect and, where necessary, remove and replace specific Lamiflex elastomeric bearings (P/N 28‑14320‑12, 28‑14320‑15). Bearings with illegible manufacture dates or older than five years must be removed; inspections are required within five hours of 26 Sep 1994 and then every 100 hours. The Directive cites reported delaminations that can cause bearing failure and loss of control. Operators bear inspection, replacement, downtime and recordkeeping costs and must follow Enstrom Service Directive Bulletin No. 0081 Rev. A."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope — addressing a specific safety defect in specific helicopter models. It has not expanded beyond its original purpose of mandating inspection and retirement of defective Lamiflex bearings."},"complexity_factors":["Single, specific technical subject matter (helicopter rotor bearings)","Only 2 defined part numbers in applicability section","Clear, sequential requirements with specific timeframes (5 hours, 100 hours, 5 years)","Single cross-reference to FAA AD 94-17-15 and Enstrom Service Directive Bulletin No. 0081 Rev. A","No nested conditional logic or exceptions to exceptions","Short document (approximately 200 words)","Plain language background section explaining safety rationale"],"plain_english_summary":"CASA issues a mandatory Airworthiness Directive for certain Enstrom helicopters with Lamiflex main‑rotor bearings (P/N 28‑14320‑12 or ‑15). Operators must comply with Enstrom Service Directive Bulletin No. 0081 Rev. A within 5 flight hours, perform inspections every 100 flight hours, and remove bearings with unreadable or >5‑year manufacture dates.\n\nThis enforces a hard safety limit because these bearings can delaminate and fail, risking loss of control; noncompliance is legally punishable."}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-36-lamiflex-bearings","history":"/api/acts/ad-enst-28-36-lamiflex-bearings/history","analysis":"/api/acts/ad-enst-28-36-lamiflex-bearings/analysis","conflicts":"/api/acts/ad-enst-28-36-lamiflex-bearings/conflicts","importantCases":"/api/acts/ad-enst-28-36-lamiflex-bearings/important-cases","documents":"/api/acts/ad-enst-28-36-lamiflex-bearings/documents"}}