{"id":"F2006B04594","name":"AD/BELL 212/61 - Main Hydraulic Servo Actuator Rod End Lock Washer","slug":"ad-bell-212-61-main-hydraulic-servo-actuator-rod-end-lock-washer","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44336,"registerId":"commonwealth-F2006B04594-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 212/61 - Main Hydraulic Servo Actuator Rod End Lock Washer","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)  \n![](image.002.png)  \nBell Helicopter Textron 212 Series Helicopters\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nAD/BELL 212/61 Main Hydraulic Servo Actuator\n\nRod End Lock Washer\n\n  \n9/2001\n\nDM\n\nApplicability: Model 212 helicopters incorporating hydraulic servo actuator, part number (P/No) 41000470, serial numbers with “HR’ prefix up to and including 10010.\n\nRequirement: 1. Inspect the tab on the rod end locking washer of each hydraulic servo actuator for bending and twisting in accordance with “Accomplishment Instructions”, Paragraph 2.A of Bell Helicopter Textron, Inc Service Bulletin 212-00-109.\n\n2. Replace P/No NAS513-6 lock washer with P/No NAS513K6C locking device in accordance with “Accomplishment Instructions”, Paragraph 2.B of Bell Helicopter Textron, Inc Service Bulletin 212-00-109.\n\nNote: FAA AD 2001-08-04 refers.\n\nCompliance: 1. Within 25 flight hours after the effective date of this Airworthiness Directive.\n\n2. Within 100 flight hours after the effective date of this Airworthiness Directive or at next actuator overhaul, whichever occurs first.\n\nThis Airworthiness Directive becomes effective on 25 July 2001.\n\nBackground: This Directive is prompted by reports of damaged main hydraulic actuator rod end lock washers which can result in rod end disengagement from the actuator and potential for loss of control of the main rotor.\n\n![](image.003.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 18 July 2001\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 25 July 2001.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original, narrow scope. It addresses a specific safety defect in a defined population of Bell 212 helicopters and mandates precise corrective actions. There is no evidence of scope creep; the directive remains tightly focused on the identified unsafe condition regarding the hydraulic servo actuator rod end lock washer."},"complexity_factors":["Single, specific mechanical component targeted (hydraulic servo actuator rod end lock washer)","Only two distinct compliance actions required (inspection and replacement)","Clear, unambiguous timeframes (25 flight hours and 100 flight hours/overhaul)","Minimal cross-referencing (only references one Service Bulletin and one FAA AD for context)","Narrow applicability criteria (specific part number and serial number range)","No nested exceptions, conditional logic, or alternative compliance methods","Short document length (approximately 300 words of substantive text)"],"plain_english_summary":"The Civil Aviation Safety Authority has issued a mandatory airworthiness directive for Bell 212 helicopters with hydraulic servo actuator P/N 41000470 (SNs beginning \"HR\" through 10010) because a distorted lock washer can let the rod end separate, risking loss of main-rotor control.  \n\nOperators must inspect the washer within 25 flight hours and replace NAS513-6 with improved NAS513K6C within 100 flight hours or at next overhaul. Compliance is urgent and legally required."},"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"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD is narrowly focused on correcting a specific unsafe condition (damaged rod-end lock washer on specified actuators). Its requirements (inspect then replace with a specified part within defined flight-hour limits) are consistent with that original safety purpose. There is no indication in the document that the AD’s scope was expanded beyond addressing that mechanical failure mode."},"complexity_factors":["Single-aircraft type focus (Bell 212) with narrow applicability defined by part number and serial-number prefix","Two discrete required actions (inspection, replacement) with separate compliance deadlines","External technical instructions referenced (Bell Service Bulletin 212-00-109) rather than full procedures set out in the AD","Cross-reference to an FAA AD (FAA AD 2001-08-04)","Mandatory replacement specifies a particular part number (NAS513K6C), limiting substitution options","Compliance timing includes a conditional option (replacement at next overhaul if it occurs within 100 flight hours)"],"plain_english_summary":"**What this instrument does (mechanics)**\n\n- This is an Airworthiness Directive (AD) that requires operators of certain Bell Helicopter Textron 212 series helicopters to inspect and, where required, replace a particular locking washer on the main hydraulic servo actuator rod end. (Applicability; Requirement)\n- Two mandatory actions are specified:\n  - Inspect the tab on the rod-end locking washer for bending or twisting, following the steps in Bell Service Bulletin 212-00-109. (Requirement 1)\n  - Replace the existing lock washer (part number NAS513-6) with a different locking device (part number NAS513K6C), again following the Service Bulletin. (Requirement 2)\n- Deadlines are set in flight hours: the inspection must be done within 25 flight hours of the AD becoming effective; the replacement must be done within 100 flight hours or at the next actuator overhaul, whichever comes first. (Compliance)\n\n**Who is affected**\n\n- Owners and operators of Bell 212 helicopters that have a hydraulic servo actuator, part number 41000470, with serial numbers that have the “HR” prefix up to and including 10010. (Applicability)\n- Maintenance organisations and mechanics who perform inspections and parts replacement are required to carry out the work in accordance with the referenced Bell Service Bulletin. (Requirement)\n\n**Why it matters (stated reason and practical effect)**\n\n- The AD was issued because there have been reports of damaged rod-end lock washers. If the washer tab is bent or twisted, the actuator rod end could disengage, creating a risk of loss of main rotor control. The AD’s purpose is to detect and correct that unsafe condition by inspection and, where necessary, replacement with an alternative locking device. (Background; Requirement)\n\n**Who pays and who decides**\n\n- Aircraft owners/operators pay for the inspection, any necessary parts (the replacement locking device) and labour, and for the helicopter downtime while the work is completed. (Requirement; Compliance)\n- The Civil Aviation Safety Authority (CASA) delegate issued the AD and requires compliance with the actions and the time limits; the Service Bulletin provides the technical instructions to be followed. (AD text; Requirement)\n\n**Costs, incentives and trade-offs**\n\n- Direct costs: inspections, replacement parts (P/No NAS513K6C) and maintenance labour, plus aircraft out-of-service time. (Requirement; Compliance)\n- Operators can defer replacement until overhaul if that occurs within the 100 flight-hour limit, which reduces immediate parts/labour costs but keeps the short-term inspection requirement. This creates a scheduling trade-off between immediate expenditure and planned maintenance timing. (Compliance; Requirement 2)\n- Implementation risks include availability of the specified replacement part, correct interpretation and faithful execution of the Bell Service Bulletin, and possible delays if many affected helicopters require work at the same time. (Requirement; Compliance)\n\n**Effects on market participants and private choice**\n\n- Independent maintenance providers must follow the Bell Service Bulletin instructions; this channels technical compliance through the manufacturer’s procedure. (Requirement)\n- Demand for the specified replacement locking device will concentrate on operators of the affected serial-numbered actuators and on suppliers of that part; if the replacement part is single-source, that could affect price and availability in the short term. (Requirement)\n- The directive constrains operator choice by mandating a specific part (P/No NAS513K6C) as the approved corrective action rather than leaving operators to substitute equivalent parts without approval. (Requirement)\n\n**Concentrated benefits, diffuse costs, and unintended consequences**\n\n- The safety benefit is concentrated on the operators, crews and passengers of the affected Bell 212 helicopters (and on ground personnel in the event of a failure). (Background)\n- Costs (parts, labour, downtime) are borne directly by those operators. The AD does not create a new ongoing regulatory program; it prescribes discrete corrective actions with specified time limits. (Requirement; Compliance)\n- Potential unintended consequences are limited but include short-term supply pressure for the specified replacement part and scheduling congestion for maintenance capacity if many aircraft require the same work within the compliance windows. (Requirement; Compliance)\n\n**Cross-references and sources**\n\n- The AD requires compliance with Bell Helicopter Textron Service Bulletin 212-00-109 for the technical steps. (Requirement)\n- The AD notes an equivalent FAA Airworthiness Directive (FAA AD 2001-08-04). (Note)\n\nOverall, the AD orders a short-term inspection and a near-term replacement option to address a specific mechanical wear/failure mode that can affect main rotor control. The mechanical mandate, the narrow applicability by actuator serial number and the short compliance windows are the key operational features."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-212-61-main-hydraulic-servo-actuator-rod-end-lock-washer","history":"/api/acts/ad-bell-212-61-main-hydraulic-servo-actuator-rod-end-lock-washer/history","analysis":"/api/acts/ad-bell-212-61-main-hydraulic-servo-actuator-rod-end-lock-washer/analysis","conflicts":"/api/acts/ad-bell-212-61-main-hydraulic-servo-actuator-rod-end-lock-washer/conflicts","importantCases":"/api/acts/ad-bell-212-61-main-hydraulic-servo-actuator-rod-end-lock-washer/important-cases","documents":"/api/acts/ad-bell-212-61-main-hydraulic-servo-actuator-rod-end-lock-washer/documents"}}