{"id":"F2006B09571","name":"AD/ENST 28/16 - Tail Rotor Pitch Link Retainer and Guide Bolt - Replacement","slug":"ad-enst-28-16-tail-rotor-pitch-link-retainer-and-guide-bolt-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54246,"registerId":"commonwealth-F2006B09571-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ENST 28/16 - Tail Rotor Pitch Link Retainer and Guide Bolt - 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 28/16 Tail Rotor Pitch Link Retainer and\n\nGuide Bolt - Replacement\n\n\n10/77\n\n \n\nApplicability: Models F-28C and 280C fitted with the Wide Cord tail rotors and S/Nos. as listed in the requirement document.\n\n \n\nRequirement: 1. Inspect the P/N 28-16320 pitch link retainer in accordance with Enstrom Service Directive Bulletin No. 0040.\n\n \n\n2. Replace the P/N 28-16320 pitch link retainer and guide bolts in accordance with Enstrom Service Directive Bulletin No. 0040 and 0043.\n\n \n\nFAA AD 77-15-04 refers.\n\n \n\nCompliance: 1. For Part 1 of the requirement document - before each flight, until part 2 is complied with.\n\n \n\n2. For Part 2 of the requirement document - within 100 hours time in service after 30 November 1977.\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 mandating inspection and replacement of a faulty tail rotor component."},"complexity_factors":["Very short document (approximately 200 words)","Only 2 substantive requirements with clear sequential logic","Single defined term in applicability (Wide Cord tail rotors)","No nested exceptions or conditional logic","Simple cross-reference to FAA AD 77-15-04 and two Enstrom service bulletins","Clear compliance deadlines (before each flight / within 100 hours)","Limited applicability (two specific models with specific serial numbers)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to specific **Enstrom F-28C and 280C helicopters** that have a particular type of tail rotor (the \"Wide Cord\" version).\n\n**What it requires:**\n- **Immediate action:** Before every flight, pilots or mechanics must inspect a specific part called the **pitch link retainer** (part number 28-16320). This is a component in the tail rotor system that helps control the helicopter's direction.\n- **Permanent fix:** Within 100 hours of flying time after 30 November 1977, the old pitch link retainer and its guide bolts must be replaced with improved parts.\n\n**Why it matters:**\nThis directive was issued because the original pitch link retainer was failing, which could cause loss of tail rotor control — a potentially catastrophic situation in flight. The directive forces owners to check the part frequently until they can replace it entirely, ensuring no unsafe helicopters remain in service.\n\n**Who must follow this:**\nOwners and operators of the affected Enstrom helicopter models. Non-compliance is illegal and dangerous."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"Scope is confined to the specified helicopter models, Wide Cord tail rotors and listed serial numbers and requires inspection then replacement of the specified part and guide bolts per the named service bulletins. The directive does not expand applicability or actions beyond those items and deadlines stated in the document."},"complexity_factors":["Narrow applicability: only Models F-28C and 280C with Wide Cord tail rotors and specific serial numbers (Applicability).","Part-specific actions: inspection of P/N 28-16320 retainer and replacement of that retainer plus guide bolts (Requirement: 1 & 2).","Manufacturer procedure dependence: compliance requires following Enstrom Service Directive Bulletins No. 0040 and 0043 (Requirement: 1 & 2).","Tight operational timing: inspections required before each flight until replacement is completed (Compliance: 1).","Firm completion deadline: replacement must occur within 100 hours time in service after 30 November 1977 (Compliance: 2).","Cross-reference to foreign AD: FAA AD 77-15-04 is cited, requiring cross-checking for equivalence (FAA AD reference).","Administrative burden: operators must identify affected serial numbers from the requirement document and schedule inspections/replacement.","Cost bearer: owners/operators are responsible for parts, labour and operational disruption (implied by requirement to perform work)."],"plain_english_summary":"This airworthiness directive requires inspection and replacement of the tail rotor pitch link retainer (P/N 28-16320) and its guide bolts on Enstrom F-28C and 280C helicopters fitted with Wide Cord tail rotors (specified serial numbers). Operators must inspect before each flight until replacement is done and complete the replacement within 100 hours time in service after 30 November 1977, following Enstrom Service Directive Bulletins No. 0040 and 0043. Operators/owners carry the cost and must schedule the work to remain compliant."}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-16-tail-rotor-pitch-link-retainer-and-guide-bolt-replacement","history":"/api/acts/ad-enst-28-16-tail-rotor-pitch-link-retainer-and-guide-bolt-replacement/history","analysis":"/api/acts/ad-enst-28-16-tail-rotor-pitch-link-retainer-and-guide-bolt-replacement/analysis","conflicts":"/api/acts/ad-enst-28-16-tail-rotor-pitch-link-retainer-and-guide-bolt-replacement/conflicts","importantCases":"/api/acts/ad-enst-28-16-tail-rotor-pitch-link-retainer-and-guide-bolt-replacement/important-cases","documents":"/api/acts/ad-enst-28-16-tail-rotor-pitch-link-retainer-and-guide-bolt-replacement/documents"}}