{"id":"F2006B09595","name":"AD/ENST 28/38 - Main Rotor Hub Plates","slug":"ad-enst-28-38-main-rotor-hub-plates","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54314,"registerId":"commonwealth-F2006B09595-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nEnstrom F-28 Series Helicopters","sortOrder":0},{"sectionNumber":"AD/ENST 28/38 Main Rotor Hub Plates 3/20","sectionType":"part","heading":"AD/ENST 28/38 Main Rotor Hub Plates 3/2004","content":"# AD/ENST 28/38 Main Rotor Hub Plates 3/2004\n\nApplicability: Model TH-28 and 480 helicopters, with main rotor upper hub plate part number 28- 14280-1, and main rotor lower hub plate part number 28-14281-1, installed.\n\nRequirement: 1. Create a component history card or equivalent record for the upper hub plate part number 28-14280-1, and the lower hub plate part number 28-14281-1, and determine the total hours time in service. Thereafter, record the hours time in service for each hub plate and replace each hub plate upon accumulation of 5,000 hours time in service as follows:\n\n    Install hub plates, part number 28-14280-3 and 28-14281-3, on helicopters with main rotor damper part number 28-14375-8 installed.\n\n    b. Install hub plates, part number 28-14280-5 and 28-14281-5, on helicopters with main rotor damper part number 28-14375-10 installed.\n\n2. This Directive revises the Limitations section of the applicable maintenance manual by establishing a life limit of 5,000 hours time in service for the upper hub plate part number 28-14280-1, and for the lower hub plate part number 28- 14281-1.\n\nNote: FAA AD 2001-25-02 Amdt 39-12554 refers.\n\nCompliance: 1. Within 30 days after 18 March 2004, unless already accomplished.\n\n2. From the effective date of this Directive.\n\nThis Airworthiness Directive becomes effective on 18 March 2004.","sortOrder":1}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope. It addresses a specific unsafe condition in specific part numbers on specific helicopter models, exactly as intended when issued. There is no evidence of scope creep or expansion beyond the original safety purpose."},"complexity_factors":["Short, single-purpose directive with only 2 main requirements","Limited applicability: only 2 specific helicopter models with 2 specific part numbers","Simple conditional logic: replacement part selection depends on one variable (damper part number)","No nested exceptions or complex cross-referencing—only one external reference to FAA AD 2001-25-02","Clear, fixed compliance date with straightforward 30-day window","Minimal defined terms (only standard aviation terms like 'time in service')"],"plain_english_summary":"This safety order applies to Enstrom TH-28 and 480 helicopters with main rotor hub plates (part nos. 28-14280-1 and 28-14281-1) and addresses unsafe wear found in those plates.  \n\nOwners/operators must start tracking each plate’s flight hours within 30 days of March 18, 2004, and retire and replace plates at 5,000 hours (with replacement part numbers varying by damper type). It prevents catastrophic rotor failure by imposing a hard service life limit."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive sets a defined life limit (5,000 hours) and replacement requirements for specified hub plate part numbers on Enstrom TH-28 and 480 helicopters and mandates related recordkeeping and maintenance-manual changes. It does not expand applicability beyond the models and part numbers listed; it changes operational requirements (life-limit and replacement) rather than scope of affected aircraft."},"complexity_factors":["Technical specificity: precise part numbers for affected hub plates (28-14280-1, 28-14281-1) and replacement part numbers (28-14280-3/5, 28-14281-3/5).","Conditional replacement: required successor part depends on installed main rotor damper PN (28-14375-8 or 28-14375-10), adding a matching step to compliance.","Administrative burden: creation and ongoing maintenance of component history cards or equivalent records and recording hours for each hub plate.","Maintenance-manual change: directive revises Limitations section to establish life limit of 5,000 hours, requiring formal amendments to operator manuals.","Compliance timing: initial action required within 30 days of 18 March 2004 for existing items, requiring retrospective accumulation of hours.","Interpretation issues: operators must determine total hours for existing parts without further guidance in the text on acceptable evidence or calculation method.","Cross-reference: note references FAA AD 2001-25-02, which may affect interpretation or follow-up actions by operators and regulators."],"plain_english_summary":"**This Airworthiness Directive requires owners/operators of Enstrom TH-28 and 480 helicopters fitted with main rotor upper hub plate PN 28-14280-1 or lower hub plate PN 28-14281-1 to create service-history records and retire each plate at 5,000 flight hours, replacing them with specified successor part numbers matched to the helicopter’s damper PN.**\n\nIssued under CASR subreg 39.1(1), it also requires updating maintenance-manual life limits; operators bear the costs of inspections, recordkeeping and replacement, with initial compliance due within 30 days of 18 March 2004."}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-38-main-rotor-hub-plates","history":"/api/acts/ad-enst-28-38-main-rotor-hub-plates/history","analysis":"/api/acts/ad-enst-28-38-main-rotor-hub-plates/analysis","conflicts":"/api/acts/ad-enst-28-38-main-rotor-hub-plates/conflicts","importantCases":"/api/acts/ad-enst-28-38-main-rotor-hub-plates/important-cases","documents":"/api/acts/ad-enst-28-38-main-rotor-hub-plates/documents"}}