{"id":"F2006B01796","name":"AD/A109/12 - Main Landing Gear Stiffening Struts","slug":"ad-a109-12-main-landing-gear-stiffening-struts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":40994,"registerId":"commonwealth-F2006B01796-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/A109/12 - Main Landing Gear Stiffening Struts","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)  \nAgusta A109 Series Helicopters\n\nAD/A109/12 Main Landing Gear Stiffening Struts 7/88\n\nApplicability: All A109A and A109AII helicopters as listed in the Requirement document. Requirement: Action in accordance with Agusta Bollettino Tecnico No 109-67.\n\nNote: RAI AD 88-37/A109-47 refers.\n\nCompliance: Part I of Requirement document: Unless already accomplished; prior to 31 May 1988.\n\nPart II of Requirement document: Every 600 flight hours.\n\nPart III of Requirement document: Before further flight if cracks are found during compliance with Parts I and II.\n\nBackground: The manufacturer reports cases of structural damage occurring in the area surrounding the MLG upper brackets. The prime factor for this damage is believed to be looseness of MLG stiffening strut attachment screws. This Directive requires the replacement of the MS 27039-1-08 screws with AN 3-4A bolts and introduces a repetitive inspection to increase the reliability of the MLG system.","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 aircraft. It has not expanded beyond its original purpose of mandating hardware replacement and inspection intervals for main landing gear stiffening struts."},"complexity_factors":["Very short document (under 200 words)","Only 2 defined terms (Part I, Part II, Part III refer to sections of an external technical document)","No cross-references to other legislation beyond a single note about a related airworthiness directive","Simple conditional logic: 'if cracks found, stop flying'","Single applicability criterion (specific helicopter models)","Relies entirely on external technical document (Agusta Bollettino Tecnico No 109-67) for actual implementation details"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific helicopters.\n\n**What it does:**\nOrders owners and operators of **Agusta A109A and A109AII helicopters** to fix a known safety problem with the main landing gear (the struts that support the helicopter when it's on the ground).\n\n**The problem:**\nThe manufacturer found that screws holding the main landing gear stiffening struts were coming loose, causing structural damage around the upper brackets. This could compromise the landing gear's integrity.\n\n**What must be done:**\n- **Part I:** Replace specific screws (MS 27039-1-08) with stronger bolts (AN 3-4A) — deadline was 31 May 1988\n- **Part II:** Inspect the landing gear every 600 flight hours to check for problems\n- **Part III:** If cracks are found during inspection, the helicopter cannot fly until fixed\n\n**Who it affects:**\nAnyone who owns or operates the specified Agusta helicopter models in Australia.\n\n**Why it matters:**\nLanding gear failure could cause accidents during takeoff or landing. This directive prevents that by mandating hardware upgrades and regular inspections."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The instrument changes maintenance obligations for the affected helicopters by mandating a hardware modification (replacement of MS 27039-1-08 screws with AN 3-4A bolts) and by introducing a recurring inspection cycle (every 600 flight hours). It also imposes an immediate no-further-flight requirement if cracks are found during inspections (Compliance: Parts I–III; Background). The AD therefore expands the operational and maintenance scope relative to a baseline without these mandated actions."},"complexity_factors":["Clear, discrete required actions: replace specific screws with AN 3-4A bolts (Background).","Fixed deadlines and intervals: one-off deadline (31 May 1988) and recurring inspection every 600 flight hours (Compliance: Parts I & II).","Immediate operational consequence on detection: 'before further flight' if cracks are found (Compliance: Part III).","Dependence on an external technical bulletin (Agusta Bollettino Tecnico No 109-67) for procedural detail (Requirement).","Applicability limited to specified helicopter models but requires checking the Requirement document for the exact list (Applicability).","Cross-reference to another AD (RAI AD 88-37/A109-47) that may require review (Note)."],"plain_english_summary":"This directive requires owners/operators of affected Agusta A109A and A109AII helicopters to replace existing MLG stiffening‑strut attachment screws with AN 3‑4A bolts and to perform recurring inspections to detect cracking. It responds to reported structural damage tied to loose fasteners; inspections occur on a 600‑flight‑hour cycle and any cracks must be repaired before further flight. Work and procedures follow Agusta Bollettino Tecnico No 109‑67 and are the operator’s responsibility and cost."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a109-12-main-landing-gear-stiffening-struts","history":"/api/acts/ad-a109-12-main-landing-gear-stiffening-struts/history","analysis":"/api/acts/ad-a109-12-main-landing-gear-stiffening-struts/analysis","conflicts":"/api/acts/ad-a109-12-main-landing-gear-stiffening-struts/conflicts","importantCases":"/api/acts/ad-a109-12-main-landing-gear-stiffening-struts/important-cases","documents":"/api/acts/ad-a109-12-main-landing-gear-stiffening-struts/documents"}}