{"id":"F2005L02817","name":"AD/BAe 146/73 Amdt 1 - MLG Door Lock and MLG Uplock","slug":"ad-bae-146-73-amdt-1-mlg-door-lock-and-mlg-uplock","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":37741,"registerId":"commonwealth-F2005L02817-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"British Aerospace BAe 146 Series Aeropla","sectionType":"division","heading":"British Aerospace BAe 146 Series Aeroplanes","content":"### British Aerospace BAe 146 Series Aeroplanes\n\n| AD/BAe 146/73 Amdt 1 | MLG Door Lock and MLG Uplock | 11/2005 |\n| -------------------- | ---------------------------- | ------- |\n\n| Applicability: | All BAe 146 Series and Avro 146-RJ Series aircraft.                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with British Aerospace Regional Aircraft Service Bulletin32-150-70656A Revision 1.Note: UK CAA AD 005-12-98 refers.                                                                                                                                                                                                                                                                                                                                                                                |\n| Compliance:    | As specified in the Requirement document.                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n|                | This Amendment becomes effective on 27 October 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |\n| Background:    | The manufacturer received a report of the roller assembly fitted to the main landing gear door lock breaking into segments. A roller assembly of the same type is fitted in the main landing gear uplock and cracks have been reported. Dowty Hydraulics have established that the cracks were initiated during manufacture. The modified rollers use a different manufacturing assembly process.Amendment 1 is issued to introduce the current issue of the Requirement document, and reference the related UK CAA AD. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n15 September 2005","sortOrder":0},{"sectionNumber":"AD/BAe 146/73 Amdt 1","sectionType":"part","heading":"AD/BAe 146/73 Amdt 1","content":"## AD/BAe 146/73 Amdt 1","sortOrder":1},{"sectionNumber":"MLG Door Lock and MLG Uplock","sectionType":"part","heading":"MLG Door Lock and MLG Uplock","content":"## MLG Door Lock and MLG Uplock","sortOrder":2},{"sectionNumber":"11/2005","sectionType":"part","heading":"11/2005","content":"## 11/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment updates the Requirement document to the current issue and references the related UK CAA AD. It does not materially expand the population of affected aircraft, add new technical areas, or broaden regulatory reach beyond the original intent to correct cracking in MLG door lock/uplock rollers. The change is administrative/technical (introducing the current service bulletin issue) rather than a substantive scope expansion."},"complexity_factors":["Short, single-subject airworthiness directive (limited length and scope)","Technical steps delegated to an external document (Service Bulletin 32-150-70656A Rev 1) rather than fully set out in the AD","Reference to a related foreign regulator AD (UK CAA AD 005-12-98) creates a cross-jurisdictional link","Applies to all variants of two closely related aircraft families (BAe 146 and Avro 146-RJ)","Amendment updates requirement document issue but does not add multiple nested exceptions or conditional pathways"],"plain_english_summary":"**What this directive does**\n\n- Requires operators to carry out the actions set out in British Aerospace Regional Aircraft Service Bulletin 32-150-70656A Revision 1 (the \"Requirement document\").\n- The required actions address cracked or failing roller assemblies fitted to the main landing gear (MLG) door lock and the MLG uplock. The manufacturer determined the cracks were initiated during manufacture and introduced a modified roller using a different assembly process.\n- The amendment updates the Requirement document to the current issue and explicitly references the related UK Civil Aviation Authority airworthiness directive (UK CAA AD 005-12-98).\n- The amendment becomes effective on 27 October 2005.\n\n**Who is affected**\n\n- Aircraft operators and owners of British Aerospace BAe 146 Series and Avro 146-RJ Series aeroplanes (all variants of these types). \n- Maintenance organisations and licensed engineers who must carry out the inspections/repairs and certify continued airworthiness.\n- Parts suppliers and manufacturers (notably Dowty Hydraulics as the roller supplier) because replacement or modified rollers will be required.\n- The regulator (Civil Aviation Safety Authority) which enforces compliance.\n\n**How it works (mechanically)**\n\n- The directive does not itself set detailed inspection steps in full; it requires compliance with the specified service bulletin. In practice that means operators must inspect, remove and replace or modify the roller assemblies in the MLG door lock and uplock as described in Service Bulletin 32-150-70656A Rev 1.\n- The service bulletin implements a manufacturing/process change to the roller assemblies intended to remove the defect that initiated the cracking.\n\n**Why it matters (stated purpose and practical test)**\n\n- Stated purpose: to prevent failure of MLG door lock/uplock rollers caused by manufacturing-initiated cracks, reducing the risk of landing gear door or uplock malfunction.\n\n- Costs and incentives: operators will incur direct costs for inspections, labour and replacement parts and may suffer aircraft downtime. The parts supplier and the OEM stand to gain from replacement parts and retrofit work. Small operators with tight schedules may face proportionally higher disruption costs.\n\n- Trade-offs and opportunity cost: the directive forces allocation of maintenance capacity and spare parts to this retrofit; that can delay other maintenance tasks or require short-term lease/flight rescheduling.\n\n- Implementation risk and compliance burden: the AD delegates technical detail to the service bulletin, so correct compliance depends on the clarity of that bulletin and on timely availability of approved replacement rollers. If supply or technical instruction is delayed, operators face operational and regulatory risk.\n\n- Bureaucratic discretion and enforcement: the AD makes compliance mandatory; the regulator enforces it but the technical steps are set by the manufacturer’s service bulletin referenced in the AD (i.e. the regulator requires the SB actions rather than specifying alternative methods). Operators may need to seek approval for alternative actions from the regulator.\n\n- Market effects: aftermarket and OEM parts suppliers benefit from mandated replacements while operators bear the cost; competition for supplying approved replacement rollers depends on certification and OEM/parts approvals which can concentrate benefit.\n\n**Concrete reference**\n\n- The AD requires actions \"in accordance with British Aerospace Regional Aircraft Service Bulletin 32-150-70656A Revision 1\" and notes the related UK CAA AD 005-12-98 (see \"Requirement\" and \"Background\")."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is an amendment to an existing Airworthiness Directive (AD/BAe 146/73). The amendment simply updates the reference to the current issue of the manufacturer service bulletin and adds the related UK CAA AD reference. The scope remains tightly focused on the original safety issue — defective roller assemblies in main landing gear door locks and uplocks. No expansion of scope beyond the original mechanical defect."},"complexity_factors":["Single mechanical defect addressed with specific reference to manufacturer service bulletin","No defined terms section — uses standard aviation terminology (MLG = Main Landing Gear)","Minimal conditional logic — applies to all specified aircraft types without exceptions","Short document (approximately 200 words of substantive content)","Single cross-reference to UK CAA AD 005-12-98 for additional context","Clear compliance pathway: follow the referenced service bulletin","No nested exceptions or layered applicability tests"],"plain_english_summary":"CASA orders immediate inspection and corrective action on the main landing gear roller assemblies of BAe 146 and Avro 146‑RJ series aircraft, mandating compliance with British Aerospace Regional Aircraft Service Bulletin 32‑150‑70656A Rev 1 after cracked rollers were traced to a manufacturing defect. \n\nThis life‑critical AD affects all Australian operators and maintenance organisations for these types; broken rollers can prevent the landing gear from deploying or locking, and non‑compliance grounds the aircraft."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-bae-146-73-amdt-1-mlg-door-lock-and-mlg-uplock","history":"/api/acts/ad-bae-146-73-amdt-1-mlg-door-lock-and-mlg-uplock/history","analysis":"/api/acts/ad-bae-146-73-amdt-1-mlg-door-lock-and-mlg-uplock/analysis","conflicts":"/api/acts/ad-bae-146-73-amdt-1-mlg-door-lock-and-mlg-uplock/conflicts","importantCases":"/api/acts/ad-bae-146-73-amdt-1-mlg-door-lock-and-mlg-uplock/important-cases","documents":"/api/acts/ad-bae-146-73-amdt-1-mlg-door-lock-and-mlg-uplock/documents"}}