{"id":"F2006B01808","name":"AD/A109/23 - Tail Boom and Vertical Fin Modification","slug":"ad-a109-23-tail-boom-and-vertical-fin-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41006,"registerId":"commonwealth-F2006B01808-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/A109/23 - Tail Boom and Vertical Fin Modification","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-description: CASA Airworthiness Directive\nmeta-generator: Aspose.Words for .NET 22.10.0\nmeta-keywords: Issue 8/1994,Rotorcraft,Agusta A109 Series Helicopters,Tail Boom and Vertical Fin Modification,23\ntitle: Airworthiness Directive - AD/A109/23 - Tail Boom and Vertical Fin Modification\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)  Agusta A109 Series Helicopters\n\n \n\nAD/A109/23 Tail Boom and Vertical Fin Modification 8/94\n\nApplicability: All models A109A, A109AII and A109C with serial numbers up to and including 7670, except for serial numbers 7630, 7633, 7645, 7651, 7654, 7663, and 7665 to\n\n7669.\n\n \n\nRequirement: Action in accordance with Agusta Bollettino Technico 109-96.\n\n \n\nNote: RAI AD 94-098 refers.\n\n \n\nCompliance: Part I - Within 100 hours time in service after 21 July 1994 or prior to 30 June 1995, whichever occurs first.\n\n \n\nPart II - At each 300 hour inspection after accomplishment of Part I.\n\n \n\nBackground:  Some cracking of structural parts has been found in the vertical fin attachment area of the tail boom. This Directive provides for ready access to the area, and the inspection requirements.\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":3,"scope_assessment":{"changed":false,"description":"The directive's scope matches its stated purpose: to provide access for inspection and to require initial and recurring inspections of the vertical fin attachment area on specified A109 serials in response to detected cracking. It does not expand obligations beyond the modification/inspection regime set out in the requirement and compliance sections."},"complexity_factors":["Model-and-serial-number applicability with a list of specific serial exclusions (Applicability)","Mandates compliance with an external manufacturer technical bulletin (Agusta Bollettino Technico 109-96) rather than prescribing detailed work in the AD (Requirement)","Two-tier compliance timetable: an initial deadline (Part I) tied to a date or flight-hours and recurring 300-hour inspections (Compliance)","Safety trigger is a discrete structural finding (cracking) focused on the vertical fin attachment area (Background)","Cross-reference to a related foreign AD (RAI AD 94-098) creates interlocking compliance context (Note)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of Agusta A109A, A109AII and A109C helicopters (serials up to 7670, with specific serial exclusions) to carry out a tail boom/vertical fin modification and inspections in accordance with Agusta Bollettino Technico 109-96. The directive responds to discovered cracking in the vertical fin attachment area: the initial action must be done within 100 flight hours after 21 July 1994 or by 30 June 1995, and inspections are then required every 300 flight hours."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural defect in a defined aircraft population. It has not expanded beyond its original purpose of mandating inspection and modification of tail boom structures."},"complexity_factors":["Single, clearly defined applicability clause with explicit serial number exclusions","Two-part compliance schedule with straightforward time-in-service triggers","No defined terms section or interpretation provisions","No cross-references to other legislation beyond a single note referencing related foreign airworthiness directive","Single technical reference to manufacturer bulletin rather than detailed procedural requirements in the text itself","No conditional logic, exceptions to exceptions, or nested provisions"],"plain_english_summary":"Owners/operators of Agusta A109A, A109AII and A109C helicopters (serials up to 7670, excluding 7630, 7633, 7645, 7651, 7654, 7663 and 7665–7669) must inspect and modify the tail boom/vertical fin attachment to address discovered cracking that could cause tail failure. The modification must be done within the stated compliance window, followed by recurring inspections every 300 flight hours, using Agusta Bollettino Technico 109-96."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a109-23-tail-boom-and-vertical-fin-modification","history":"/api/acts/ad-a109-23-tail-boom-and-vertical-fin-modification/history","analysis":"/api/acts/ad-a109-23-tail-boom-and-vertical-fin-modification/analysis","conflicts":"/api/acts/ad-a109-23-tail-boom-and-vertical-fin-modification/conflicts","importantCases":"/api/acts/ad-a109-23-tail-boom-and-vertical-fin-modification/important-cases","documents":"/api/acts/ad-a109-23-tail-boom-and-vertical-fin-modification/documents"}}