{"id":"F2006B09583","name":"AD/ENST 28/27 - Narrow Chord Tail Rotor Forged Grips - Inspection","slug":"ad-enst-28-27-narrow-chord-tail-rotor-forged-grips-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54286,"registerId":"commonwealth-F2006B09583-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ENST 28/27 - Narrow Chord Tail Rotor Forged Grips - Inspection","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 28/27 Narrow Chord Tail Rotor Forged Grips \\- Inspection\n\n  \n2/85\n\nTX\n\nApplicability: All F-28A and 280 models with narrow chord tail rotor blade grips P/N 28-15012 or 28-150024-11.\n\nRequirement: Enstrom Service Directive Bulletin No. 0067.\n\nCompliance: Para. A: Prior to the next flight and each flight thereafter until Para B to I is accomplished.\n\nPara B to I: Within 25 hours time in service after 16 January 1985\\. Para J: As per Requirement Document.\n\nNote: Para A of this Directive may be accomplished by the pilot in command, in which case he shall enter and certify for this AD in Col 2, Part 3 of the Maintenance Release on each occasion.\n\nBackground: Three reported instances of blade grip cracking have been received. One accident has been attributed to complete failure and subsequent loss of the tail rotor blade.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The Directive, as presented, imposes inspection and recording obligations on all Enstrom F-28A and 280 helicopters fitted with the specified narrow-chord tail rotor blade grips, and delegates technical details to Enstrom Service Directive Bulletin No. 0067. There is no text in the instrument indicating an expansion or contraction of that scope from an earlier stated intent; the Directive's stated purpose (responding to reported cracking and one accident) matches the mechanical requirements (Applicability; Requirement; Background)."},"complexity_factors":["Multiple staged compliance requirements (immediate repeated pre-flight checks under Para A, followed by more detailed inspections under Paras B–I within a 25-hour window)","Dependency on an external technical document (Enstrom Service Directive Bulletin No. 0067) for procedural and corrective detail (Requirement; Para J)","Option allowing a non-maintenance person (pilot in command) to perform Para A with a formal certification requirement (Note)","Specific applicability limited to particular part numbers and helicopter models, requiring operators to identify affected airframes (Applicability)","Time-bound compliance tied to a calendar/reference date (25 hours time in service after 16 January 1985), creating concentrated operational pressure (Para B–I)"],"plain_english_summary":"This directive mandates inspections of certain narrow‑chord tail‑rotor blade grips on Enstrom F‑28/280 helicopters to address reported cracking and a related accident. Operators must do an immediate pre‑flight check repeated before each flight until the fuller inspections and any corrective work called for in Enstrom Service Directive Bulletin No. 0067 are completed within the 25‑hour compliance window.\n\nPilots may perform the immediate check but must certify it in the Maintenance Release; owners/operators bear the cost and scheduling burden of the detailed inspections and repairs."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific mechanical defect. It has not expanded beyond its original purpose of mandating inspection of cracked tail rotor grips on specific helicopter models."},"complexity_factors":["Single, specific mechanical component targeted","Clear, sequential compliance timeline (immediate + 25 hours)","Only 2 part numbers affected","Simple conditional: pilot may perform initial inspection with specific logging requirement","No nested definitions or cross-references to other legislation beyond one service bulletin reference","Total length: approximately 150 words"],"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 immediate inspection of a particular helicopter part — the \"narrow chord tail rotor forged grips\" — on Enstrom F-28A and 280 model helicopters. These are components that hold the tail rotor blades in place.\n\n**Who it affects:**\nOwners and operators of Enstrom F-28A and 280 helicopters that have specific part numbers for their tail rotor blade grips (P/N 28-15012 or 28-150024-11).\n\n**What must happen:**\n- **Immediately (before next flight):** A visual inspection must be done, and repeated before every flight until the full inspection is completed.\n- **Within 25 flight hours after 16 January 1985:** A more thorough inspection (paragraphs B through I of the referenced service bulletin) must be completed.\n- **Ongoing:** Additional requirements from the service bulletin must be followed as specified.\n\n**Special rule:** The pilot can do the immediate pre-flight inspection themselves, but must write it in the aircraft's maintenance log each time.\n\n**Why it matters:**\nThree helicopters had cracks in this part, and one crashed when the tail rotor blade completely broke off. This directive prevents that catastrophic failure by catching cracks early."}},"importantCases":[],"_links":{"self":"/api/acts/ad-enst-28-27-narrow-chord-tail-rotor-forged-grips-inspection","history":"/api/acts/ad-enst-28-27-narrow-chord-tail-rotor-forged-grips-inspection/history","analysis":"/api/acts/ad-enst-28-27-narrow-chord-tail-rotor-forged-grips-inspection/analysis","conflicts":"/api/acts/ad-enst-28-27-narrow-chord-tail-rotor-forged-grips-inspection/conflicts","importantCases":"/api/acts/ad-enst-28-27-narrow-chord-tail-rotor-forged-grips-inspection/important-cases","documents":"/api/acts/ad-enst-28-27-narrow-chord-tail-rotor-forged-grips-inspection/documents"}}