{"id":"F2005L02835","name":"AD/JETSTREAM/101 - Down Lock Assembly","slug":"ad-jetstream-101-down-lock-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":37812,"registerId":"commonwealth-F2005L02835-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"British Aerospace BAe 3100 (Jetstream) S","sectionType":"division","heading":"British Aerospace BAe 3100 (Jetstream) Series Aeroplanes","content":"### British Aerospace BAe 3100 (Jetstream) Series Aeroplanes\n\n| AD/JETSTREAM/101 | Down Lock Assembly | 11/2005 |\n| ---------------- | ------------------ | ------- |\n\n| Applicability: | Model Jetstream HP137 Mark 1 and Jetstream Series 200, 3100 and 3200 aeroplanes.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | 1. Remove from service and replace with a new or serviceable part any incorrectly heat treated radius rod down lock piston listed in Paragraph 1A of BAE SYSTEMS Service Bulletin 32-JA040547 Original Issue or later EASA approved revision. Replace defective components in accordance with Paragraph 1 N of BAE SYSTEMS Service Bulletin 32-JA040547 Original Issue or later EASA revision.2. Do not install a radius rod assembly on an aircraft that contains a down lock piston identified in Paragraph 1A of BAE SYSTEMS Service Bulletin32-JA040547 Original Issue or later EASA approved revision.Note: UK CAA AD G-2005-0024, EASA reference No 2005-6188 dated 22 August 2005 refers. |\n| Compliance:    | 1. At the next main landing gear radius rod overhaul but no later than 31 August 2010.2. From the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n|                | This Airworthiness Directive becomes effective on 27 October 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| Background:    | A batch of main landing gear (MLG) downlock pistons with incorrect heat treatment have been installed into MLG radius rods fitted to the above aircraft types during overhaul. The effect of the incorrect heat treatment is reduced strength and hardness, which can lead to failure of the piston and/or contamination of the hydraulic system. Failure of the downlock piston in combination with a loss of hydraulic pressure could result in the collapse of the affected MLG, which during the critical phases of take-off and landing will result in a loss of directional control.                                                                                                       |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n15 September 2005","sortOrder":0},{"sectionNumber":"AD/JETSTREAM/101","sectionType":"part","heading":"AD/JETSTREAM/101","content":"## AD/JETSTREAM/101","sortOrder":1},{"sectionNumber":"Down Lock Assembly","sectionType":"part","heading":"Down Lock Assembly","content":"## Down Lock Assembly","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":"The AD remains narrowly focused on removing and replacing a specific batch of incorrectly heat-treated down lock pistons fitted to specified Jetstream models. It does not expand the subject matter beyond that original corrective safety purpose: the directive prescribes identification, replacement, and a prohibition on reinstalling the affected pistons, with a compliance deadline. There is no evidence in the text that the AD's scope grew beyond addressing this single part-failure risk."},"complexity_factors":["Short, single-issue directive focused on one defective part type (down lock piston)","External dependency on BAE SYSTEMS Service Bulletin 32-JA040547 for identification and repair procedures (Paragraphs 1A and 1N)","Simple conditional compliance window: at next radius rod overhaul or by a fixed calendar date (two timing conditions)","Prohibition on future installation of affected parts from the effective date (binary install/do-not-install rule)","Cross-references to other regulator actions (UK CAA AD and EASA reference) but no complex legal exceptions or multiple amendment layers"],"plain_english_summary":"**What this directive does**\n\n- This Airworthiness Directive (AD) orders owners/operators of certain British Aerospace Jetstream aeroplanes to remove and replace specific main landing gear (MLG) down lock pistons that were heat treated incorrectly. The affected piston parts are listed in Paragraph 1A of BAE SYSTEMS Service Bulletin 32-JA040547 (original issue) or any later EASA‑approved revision. (Requirement)\n- It also prohibits installing any radius rod assembly that contains one of the identified defective down lock pistons. Replacement of defective components must follow Paragraph 1N of the same Service Bulletin. (Requirement)\n\n**Which aircraft are affected**\n\n- Model Jetstream HP137 Mark 1 and Jetstream Series 200, 3100 and 3200 aeroplanes. (Applicability)\n\n**When the work must be done**\n\n- The replacements must be carried out at the next main landing gear radius rod overhaul, but no later than 31 August 2010. The prohibition on installing a radius rod with an affected piston applies from the AD's effective date (27 October 2005). (Compliance)\n\n**Why this matters (safety risk)**\n\n- A batch of down lock pistons was found to have incorrect heat treatment, reducing their strength and hardness. That can cause piston failure and/or hydraulic contamination. If a down lock piston fails and hydraulic pressure is lost, the main landing gear could collapse, particularly during take-off or landing, creating a risk of loss of directional control. (Background)\n\n**Who pays and who decides**\n\n- Aircraft owners/operators pay for parts, labour and any aircraft downtime needed to replace pistons. Maintenance organisations (approved MROs) carry out the work in accordance with the Service Bulletin (Requirement; Compliance). The regulator (Civil Aviation Safety Authority/CASA, via this AD) sets the legal requirement and enforces compliance.\n\n**How behaviour and supply chains must change**\n\n- Operators must: locate radius rods during overhaul, identify any pistons listed in Paragraph 1A of the BAE Service Bulletin, remove and replace defective pistons following Paragraph 1N of the Service Bulletin, and ensure no affected pistons are reinstalled. Maintenance providers must check part traceability and conform to the Service Bulletin's procedures. Parts suppliers and overhaul shops must verify heat‑treatment records and traceability before releasing parts for installation. (Requirement)\n\n**Costs, trade-offs and implementation risks**\n\n- Costs: replacement parts, labour and aircraft downtime; potentially concentrated on operators with many affected aircraft. Maintenance providers will incur workload and inventory management costs. Parts suppliers may face costs to segregate or rework suspect stock.\n- Benefits: reduces risk of MLG collapse and associated accident risk. The safety benefit accrues broadly to passengers, crew and the public.\n- Trade-offs: the AD allows operation until the next radius rod overhaul (but no later than the specified date), which defers immediate cost but extends exposure to risk until replacement occurs. Effectiveness depends on accurate identification of affected pistons (reliant on the Service Bulletin's list and traceability records) and availability of serviceable replacement parts.\n- Implementation risks: difficulty tracing and identifying all affected pistons, scarcity or lead times for replacement parts, and the administrative burden on small operators to schedule work before the mandatory date.\n\n**Cross-references and enforcement**\n\n- The AD relies on BAE SYSTEMS Service Bulletin 32-JA040547 (Original Issue) or any later EASA‑approved revision to identify affected parts and procedures (Requirement). It refers to the UK CAA AD G-2005-0024 and EASA reference No 2005-6188 (Background/Note). CASA enforces the AD as an airworthiness requirement.\n\n(Primary source sections: Applicability; Requirement; Compliance; Background.)"},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific manufacturing defect in a specific aircraft component. The scope remains precisely limited to the identified heat-treatment issue with down lock pistons in the specified Jetstream models, with no evidence of scope creep beyond this original safety purpose."},"complexity_factors":["Single, specific mechanical defect addressed with clear replacement instructions","Only 2 compliance deadlines (one immediate, one with 5-year grace period)","References external technical document (BAE SYSTEMS Service Bulletin 32-JA040547) for part identification rather than listing all affected parts in the text itself","No nested exceptions or conditional logic — applies to all listed aircraft models uniformly","Short document (approximately 300 words of substantive content)","Minimal defined terms (only standard aviation terminology like 'MLG' for main landing gear)"],"plain_english_summary":"This CASA Airworthiness Directive orders operators of Jetstream HP137 Mark 1 and Jetstream Series 200/3100/3200 aircraft to inspect and replace certain main landing gear down‑lock pistons that were improperly heat‑treated and may fail, risking gear collapse during critical phases.\n\nOperators and maintenance organisations must stop installing affected pistons immediately from 27 Oct 2005 and remove/replace any defective pistons by 31 Aug 2010, per the referenced British Aerospace service bulletin."}},"importantCases":[],"_links":{"self":"/api/acts/ad-jetstream-101-down-lock-assembly","history":"/api/acts/ad-jetstream-101-down-lock-assembly/history","analysis":"/api/acts/ad-jetstream-101-down-lock-assembly/analysis","conflicts":"/api/acts/ad-jetstream-101-down-lock-assembly/conflicts","importantCases":"/api/acts/ad-jetstream-101-down-lock-assembly/important-cases","documents":"/api/acts/ad-jetstream-101-down-lock-assembly/documents"}}