{"id":"F2005L01357","name":"AD/BELL 407/28 Amdt 1 - Freewheel Aft Bearing Cap","slug":"ad-bell-407-28-amdt-1-freewheel-aft-bearing-cap","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":35169,"registerId":"commonwealth-F2005L01357-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bell Helicopter Textron Canada (BHTC) 40","sectionType":"division","heading":"Bell Helicopter Textron Canada (BHTC) 407 Series Helicopters","content":"### Bell Helicopter Textron Canada (BHTC) 407 Series Helicopters\n\n| AD/BELL 407/28 Amdt 1 | Freewheel Aft Bearing Cap | 7/2005 |\n| --------------------- | ------------------------- | ------ |\n\n| Applicability: | Bell Helicopter Textron Canada (BHTC) model 407 helicopters fitted with freewheel aft bearing cap P/N 406-040-509-101, serial numbers A-1833 through A-1912.                                                                                                                                                                                                                                                                                                                                                                    |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Identify the aft bearing cap serial numbers for applicability in accordance with Part I of BHTC Alert Service Bulletin (ASB) 407-04-66 Revision A dated 01 December 2004 or later revision approved by Transport Canada.2. Depending on the average engine start cycle count, rework the affected freewheel aft bearing caps in accordance with Part II or Part III of the ASB.3. Rework the freewheel assembly in accordance with Part IV of the ASB.Note: Transport Canada AD CF-2004-17 R1 dated 11 February 2005 refers. |\n| Compliance:    | 1. Within 7 days after the effective date of this Directive.2. Unless previously accomplished, within 50 flight hours after the effective date of this directive.3. Unless previously accomplished, within 300 flight hours after the effective date of this directive, but no later than 30 September 2005.                                                                                                                                                                                                                    |\n|                | This Amendment becomes effective on 7 July 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n| Background:    | Due to an oversight during manufacturing, a lubrication channel to allow oil flow has not been machined into an identifiable batch of aft bearing caps. Omission of lubrication channel may cause lack of lubrication and reduced durability. As a result, freewheel unit may cease to function.Amendment 1 is issued in response to a revision of the related Transport Canada AD which places an ultimate life on affected freewheel assembly components that have operated with a defective aft bearing cap.                 |\n\n|     | The original issue of this Airworthiness Directive became effective on 23 December 2004. |\n| --- | ---------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n27 May 2005","sortOrder":0},{"sectionNumber":"AD/BELL 407/28 Amdt 1","sectionType":"part","heading":"AD/BELL 407/28 Amdt 1","content":"## AD/BELL 407/28 Amdt 1","sortOrder":1},{"sectionNumber":"Freewheel Aft Bearing Cap","sectionType":"part","heading":"Freewheel Aft Bearing Cap","content":"## Freewheel Aft Bearing Cap","sortOrder":2},{"sectionNumber":"7/2005","sectionType":"part","heading":"7/2005","content":"## 7/2005","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment expands the original directive by adding an \"ultimate life\" (a remaining service-life limit) for freewheel assembly components that have operated with the defective aft bearing cap. The original AD required inspection and corrective action; Amendment 1 additionally imposes a service-life limitation on components that have already been exposed to the defect, increasing the directive's scope from corrective rework to include retrospective operational life restrictions (Background/Amendment note)."},"complexity_factors":["Narrow applicability defined by part number (P/N 406-040-509-101) and a concrete serial-number range (A-1833 through A-1912).","Three-tiered required action structure tied to ASB Parts I–IV, with a conditional choice between Part II or Part III depending on average engine start-cycle count.","Multiple compliance deadlines of different kinds: immediate identification (7 days), flight-hour limits (50 and 300 flight hours), and an absolute calendar cutoff (30 September 2005).","Cross-reference required to an external document (BHTC ASB 407-04-66 Rev A or Transport Canada–approved later revision) for detailed procedures.","Cross-reference to a related Transport Canada AD (CF-2004-17 R1) and an amendment that introduces an ultimate life limit, increasing interpretive steps for affected components."],"plain_english_summary":"**What this directive does (mechanically):**\n\n- Requires operators of certain Bell 407 helicopters to check whether the freewheel aft bearing cap on their helicopter is from an affected batch and, if it is, to have the part reworked and the freewheel assembly serviced in line with Bell Helicopter Textron Canada's Alert Service Bulletin (ASB) 407-04-66 (Parts I–IV) or later Transport Canada–approved revisions. (See \"Requirement\".)\n\n**Who is affected:**\n\n- Owners/operators and maintenance organisations responsible for Bell Helicopter Textron Canada (BHTC) Model 407 helicopters fitted with freewheel aft bearing cap part number 406-040-509-101, serial numbers A-1833 through A-1912. (See \"Applicability\".)\n\n**Why it matters (safety and mechanical risk):**\n\n- A machining omission during manufacture left a lubrication channel out of a batch of aft bearing caps. Without that channel, oil cannot flow properly, which can reduce bearing durability and may cause the freewheel unit to fail to operate. A failed freewheel unit affects the drivetrain behaviour that the freewheel is designed to provide during engine-out or other abnormal conditions. The directive’s stated purpose is to restore correct lubrication and to impose a remaining-life limit on any freewheel components that have already operated with a defective cap. (See \"Background\" and amendment note.)\n\n**Required actions and timing (summary):**\n\n- Identify serial numbers of aft bearing caps to confirm applicability using Part I of ASB 407-04-66 Rev A (or later Transport Canada–approved revision). (Requirement 1; Compliance 1)\n- Depending on the average engine start cycle count, have the affected aft bearing caps reworked in accordance with Part II or Part III of the ASB. (Requirement 2; Compliance 2)\n- Rework the freewheel assembly per Part IV of the ASB. (Requirement 3; Compliance 3)\n- Timing: identification must be done within 7 days of the directive becoming effective; rework of caps must be done within 50 flight hours unless already completed; freewheel assembly rework must be done within 300 flight hours but not later than the absolute date specified in the directive. (See \"Compliance\".)\n\n**How it works in practice and who pays:**\n\n- The operator (owner or lessee) is the party who must arrange and pay for identification and for any rework or replacement. Maintenance organisations or approved repair stations will carry out the rework to the ASB procedures. The directive cross-references Transport Canada AD CF-2004-17 R1 and requires work to an ASB revision approved by Transport Canada, so the work must meet those documented technical steps. (See \"Requirement\" and \"Background\".)\n\n**Implementation issues, trade-offs and costs:**\n\n- Direct costs: labour and parts for inspection and rework; potential short-term grounded time for affected helicopters; scheduling costs if shop capacity is limited.\n- Incentives and allocation of cost: the directive places compliance cost on owners/operators rather than the manufacturer; operators may seek to recover costs under warranty if the defect falls within warranty terms, but the directive itself does not specify compensation. (Requirement/Background.)\n- Timing and deadlines: a mix of short-term (7 days) and flight-hour-based deadlines creates planning needs for operators; an absolute date on the longer deadline constrains operators with low utilisation. (Compliance.)\n- Implementation risk: correctly identifying serial numbers and tracking engine start-cycle counts is necessary to select the correct ASB part (II or III). Errors could lead to incorrect rework choices or missed deadlines. Availability of qualified maintenance capacity could cause delays and create temporary availability shortfalls for operators. (Requirement/Compliance.)\n- Effects on independent businesses: authorised maintenance providers who can perform the ASB work may see demand for the service; operators limited to in-house maintenance must have the appropriate approvals and tooling to perform the ASB procedures. The directive does not restrict which approved organisations may perform the work, but conformity to the ASB and Transport Canada approval is required. (Requirement/Background.)\n\n**Concentrated benefits, diffuse costs, and enforcement:**\n\n- The safety benefit (reduced risk of freewheel failure) accrues to users and their passengers in the affected serial-numbered fleet — a concentrated safety gain for those helicopters. The costs (inspection and repair) are concentrated on the owners/operators of the specific serial-numbered aircraft. The directive is mandatory: compliance is required by the regulator and non-compliance risks enforcement action and continued airworthiness risk. (Applicability/Requirement/Compliance.)\n\n**Source claims vs. consequences:**\n\n- The directive states that the machining omission may cause lack of lubrication and reduced durability, potentially causing the freewheel unit to cease functioning (Background). That is the technical cause the directive addresses. The amendment introduces a service-life limit for assemblies that have already operated with a defective cap; that operational limit changes how long those components may remain in service. The directive itself prescribes inspection and corrective action; it does not set warranty or compensation arrangements. (Background/Amendment note.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"This is Amendment 1 to an existing directive. The original AD (effective 23 December 2004) required identification and rework of the defective bearing caps. This amendment expands the scope by adding an 'ultimate life' limitation on other freewheel assembly components that have operated with the defective bearing cap — effectively recognising that the original fix was insufficient because collateral damage may have occurred to other parts during operation with the faulty component."},"complexity_factors":["Short, single-purpose instrument (approximately 300 words)","Only 4 defined elements: specific part number (P/N 406-040-509-101), serial number range (A-1833 through A-1912), reference to external technical document (BHTC Alert Service Bulletin 407-04-66 Revision A), and cross-reference to Canadian regulation (Transport Canada AD CF-2004-17 R1)","Clear, sequential compliance deadlines with simple conditional logic ('unless previously accomplished')","No nested exceptions or complex definitional sections","Technical aviation terminology requires some domain knowledge but is standard for the industry"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to **40 specific Bell 407 helicopters** in Australia that have a faulty part called a \"freewheel aft bearing cap\" (a component in the helicopter's transmission system that allows the rotor to spin freely when the engine is off).\n\n**The problem:** During manufacturing, a batch of these bearing caps was made without a crucial oil channel. Without proper lubrication, the freewheel unit could fail completely — a serious safety risk.\n\n**What must be done:**\n- **Within 7 days:** Check if your helicopter is affected by finding the serial number of the bearing cap\n- **Within 50 flight hours:** Rework (repair or replace) the faulty bearing caps, depending on how many times the engine has been started\n- **Within 300 flight hours (or by 30 September 2005, whichever comes first):** Rework the entire freewheel assembly\n\n**Why this matters:** This is an amended order that adds a \"use-by date\" for parts that have been running with the defective bearing cap. Even if the bearing cap is fixed, the other components in the freewheel assembly may have been damaged by running without proper lubrication, so they now have a limited lifespan."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-407-28-amdt-1-freewheel-aft-bearing-cap","history":"/api/acts/ad-bell-407-28-amdt-1-freewheel-aft-bearing-cap/history","analysis":"/api/acts/ad-bell-407-28-amdt-1-freewheel-aft-bearing-cap/analysis","conflicts":"/api/acts/ad-bell-407-28-amdt-1-freewheel-aft-bearing-cap/conflicts","importantCases":"/api/acts/ad-bell-407-28-amdt-1-freewheel-aft-bearing-cap/important-cases","documents":"/api/acts/ad-bell-407-28-amdt-1-freewheel-aft-bearing-cap/documents"}}