{"id":"F2006B01801","name":"AD/A109/17 Amdt 1 - Main Gearbox Gleason Crown Bolts","slug":"ad-a109-17-amdt-1-main-gearbox-gleason-crown-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":40999,"registerId":"commonwealth-F2006B01801-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/A109/17 Amdt 1 - Main Gearbox Gleason Crown Bolts","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/A109/17\n\nAmdt 1\n\n  \nMain Gearbox Gleason Crown Bolts 4/93\n\nApplicability: All A109A and A109 AII helicopters up to and including aircraft S/N 7437 fitted with main gearbox (MGB) 109-0400-02-1, -3 & -5 up to and including MGB S/N 363.\n\nNote: MGB S/N 173, 176, 187, 207, 211, 267, 345 and 346 already comply.\n\nRequirement: Unless previously carried out replace gleason crown bolts in accordance with mandatory Agusta Bollettino Tecnico No 109-77 Rev A.\n\nNote: RAI AD 92-400 refers.\n\nCompliance: 1. For gearboxes with less than 1100 hours’ time in service, prior to reaching 1200 hours’ time in service or by 31 January 1994, whichever occur first.\n\n2. For gearboxes with more than 1200 hours’ time in service, within 300 hours’ time in service from 1 April 1993 or by 31 January 1994, whichever occurs first.\n\nBackground: During routine maintenance of the MGB oil filter magnesium flakes were noticed.\n\nDisassembly of the gearbox revealed 4 bolts, P/N 109-0406-69-1, had sheared in the Gleason Crown assembly. This amendment raised in sequence to add a calendar time and to include the Italian AD reference.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a narrow, technical safety directive focused on a specific mechanical defect in specific helicopter models. The amendment adds a calendar compliance deadline and an Italian regulatory reference, but does not expand beyond the original safety purpose of addressing the failed Gleason crown bolts."},"complexity_factors":["Short, single-purpose directive with one primary requirement","Limited applicability criteria (specific aircraft models, serial number ranges, and gearbox serial numbers)","Two-tier compliance schedule based on flight hours with calendar cut-offs","Cross-reference to external technical document (Agusta Bollettino Tecnico No 109-77 Rev A)","Cross-reference to Italian aviation authority directive (RAI AD 92-400)","No defined terms section or complex legislative machinery"],"plain_english_summary":"Owners/operators of Agusta A109A and A109 AII helicopters (serials up to 7437) fitted with certain main gearboxes (109‑0400‑02‑1, ‑3, ‑5, serials to 363; some listed gearboxes already compliant) must replace Gleason crown bolts found to fail after magnesium flakes and snapped bolts were discovered in the gearbox. Replacement must follow Agusta Bollettino Tecnico No 109‑77 Rev A within the specified flight‑hour/calendar deadlines. This AD is Amendment 1, adding a calendar cutoff and referencing the Italian authority’s order."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment added a calendar compliance date and incorporated the Italian AD reference while keeping the core requirement to replace the Gleason crown bolts; it did not expand the affected helicopter models but introduced an additional timing constraint (source: \"This amendment raised in sequence to add a calendar time and to include the Italian AD reference.\")."},"complexity_factors":["Applicability limited to specific airframe types and precise MGB serial‑number ranges (Applicability)","Exemptions for certain MGB serial numbers already compliant (Note under Applicability)","Mandatory incorporation of a manufacturer service bulletin (Agusta Bollettino Tecnico No 109-77 Rev A) as the means of compliance (Requirement)","Dual compliance triggers: flight‑hour thresholds and fixed calendar deadlines, with different windows depending on current hours (Compliance clauses 1 and 2)","Reference to a foreign authority AD (Italian AD / RAI AD 92-400) introduces cross‑reference complexity","Technical specificity: replacement of a defined part number (bolts P/N 109-0406-69-1) after discovery of a particular failure mode (sheared bolts, magnesium flakes) (Background/Requirement)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of specified Agusta A109A and A109AII helicopters fitted with certain main gearboxes to replace the Gleason crown bolts following Agusta Bollettino Tecnico No 109-77 Rev A. It imposes firm flight‑hour and calendar deadlines for replacement (see Compliance) after discovery of sheared bolts and magnesium flakes in the gearbox (Background). Owners/operators pay for and schedule the replacement; compliance is limited to listed serial‑number ranges and excludes gearboxes already noted as compliant (Applicability/Note)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-a109-17-amdt-1-main-gearbox-gleason-crown-bolts","history":"/api/acts/ad-a109-17-amdt-1-main-gearbox-gleason-crown-bolts/history","analysis":"/api/acts/ad-a109-17-amdt-1-main-gearbox-gleason-crown-bolts/analysis","conflicts":"/api/acts/ad-a109-17-amdt-1-main-gearbox-gleason-crown-bolts/conflicts","importantCases":"/api/acts/ad-a109-17-amdt-1-main-gearbox-gleason-crown-bolts/important-cases","documents":"/api/acts/ad-a109-17-amdt-1-main-gearbox-gleason-crown-bolts/documents"}}