{"id":"F2006B06292","name":"AD/PMC/37 - Blade Counterweight Bolt Replacement","slug":"ad-pmc-37-blade-counterweight-bolt-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47371,"registerId":"commonwealth-F2006B06292-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PMC/37 - Blade Counterweight Bolt Replacement","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Propellers - Variable Pitch - McCauley\n\n \n\nAD/PMC/37 Blade Counterweight Bolt Replacement 5/83\n\nApplicability: All 3AF32C504, 3AF32C505, 3AF32C506, 3AF32C507, 3AF32C508 and\n\n3AF32C509 models with serial numbers 803546 through 816154.\n\n \n\nDocument: McCauley Service Bulletin 147.\n\n \n\nCompliance: By the next maintenance release inspection, after 31st May 1983.\n\n \n\nBackground: The manufacturer reports failures of blade counterweight bolts. This Directive introduces a new maintenance practise to nullify this problem.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive is limited to the specific McCauley propeller models and serial numbers listed and requires a maintenance action by a specified deadline to address reported bolt failures (Applicability, Compliance, Background). The instrument implements the manufacturer’s corrective action via a Service Bulletin (Document). There is no indication in the text that the Directive expands or narrows scope beyond that original corrective purpose; it stays aligned with the stated intent to eliminate the bolt-failure problem by mandating the new maintenance practice for the identified units."},"complexity_factors":["Narrow and clearly defined applicability by model and serial number (Applicability) — reduces ambiguity.","Mandatory compliance with a clear deadline tied to the next maintenance release inspection (Compliance) — straightforward scheduling requirement.","Technical details and procedures are delegated to an external document (McCauley Service Bulletin 147) (Document) — introduces dependency on that bulletin for complete implementation.","No step-by-step technical content in the Directive itself (Document) — operators must obtain and follow the Service Bulletin.","Potential logistical issues (parts availability, maintenance downtime) not resolved in the text — practical complexity in execution.","Regulatory enforcement is implied by AD format but enforcement mechanics (inspections, penalties) are not described in this text — minor procedural ambiguity."],"plain_english_summary":"What this requires (mechanical change)\n\n- This Airworthiness Directive (AD/PMC/37) requires replacement or a new maintenance practice for the blade counterweight bolts on specified McCauley variable-pitch propeller models and serial numbers. The technical instructions to do the work are contained in McCauley Service Bulletin 147 (Document).\n\nWho it affects\n\n- Owners and operators of propellers of models 3AF32C504, 3AF32C505, 3AF32C506, 3AF32C507, 3AF32C508 and 3AF32C509 with serial numbers 803546 through 816154 (Applicability).\n\nWhen it must be done\n\n- The work must be completed by the next maintenance release inspection after 31 May 1983 (Compliance).\n\nWhy it was issued (stated reason)\n\n- The manufacturer reported failures of blade counterweight bolts; the directive adopts a new maintenance practice intended to eliminate that failure mode (Background).\n\nHow it works in practice\n\n- The Directive makes compliance mandatory for the specified propellers and points to the Service Bulletin for the specific procedures (Applicability, Document, Compliance). Operators must schedule the replacement or maintenance action at their next maintenance release inspection after the specified date. The AD does not itself set out step-by-step technical detail; it delegates that to the referenced Service Bulletin (Document).\n\nWho pays, who decides, and what changes in behaviour\n\n- Who pays: The immediate costs (parts, labour, any additional downtime) fall on the owners/operators of affected propellers because they must carry out the maintenance by the specified time (Applicability, Compliance).\n- Who decides: The Civil Aviation Safety Authority issued the Directive; the manufacturer provides the technical instructions via the Service Bulletin (Document). The operator decides when to schedule the work within the compliance window (Compliance).\n- Behaviour change: Operators must inspect and perform the bolt replacement/maintenance practice at the next maintenance release inspection after 31 May 1983, which may alter maintenance scheduling and procurement of replacement parts (Compliance, Document).\n\nCosts, incentives and trade-offs\n\n- Direct costs: purchase of replacement bolts or parts and labour to perform the maintenance are borne by operators (Applicability, Compliance).\n- Time costs: aircraft/propmellor downtime may increase while the work is done, creating opportunity costs for operators who must reschedule flights or maintenance slots (Compliance).\n- Incentives: The AD creates a compliance incentive — operators must act to keep the propeller airworthy; the manufacturer’s Service Bulletin provides the technical route for compliance (Document).\n\nImplementation risks and practical considerations\n\n- The Directive depends on an external document (McCauley Service Bulletin 147) for the technical procedure; if parts or technical support are limited, operators may face delay or added cost (Document).\n- The text sets a clear compliance deadline relative to maintenance cycles but does not itself specify quantities, part numbers, or exact fitment steps — those details are in the Service Bulletin (Document). That delegation concentrates technical discretion in the manufacturer’s guidance.\n\nConcentrated benefits and diffuse costs\n\n- Benefits (reduced risk of bolt failure) are concentrated on operators and aircraft that have the affected propellers; costs (parts and labour) are borne directly by those same operators (Applicability, Background, Compliance).\n\nSummary statement\n\n- Mechanically, the AD requires a maintenance action (replacement/new practice for blade counterweight bolts) on a defined set of propellers by a defined date and points to a manufacturer Service Bulletin for the technical work. The stated purpose is to address reported bolt failures. The practical effects are a mandated maintenance task for affected operators, with associated parts, labour and scheduling costs, and reliance on the manufacturer’s bulletin for technical implementation (Applicability, Document, Compliance, Background)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive addressing a specific mechanical defect in specific equipment. It has not expanded beyond its original purpose of mandating bolt replacement for safety reasons."},"complexity_factors":["Very short document (under 200 words)","Only 6 specific propeller models affected, clearly listed by model and serial number range","Single compliance requirement with clear deadline","No defined terms section","No cross-references to other legislation beyond the enabling regulations","Simple conditional logic: if you have this equipment, you must do this action by this date"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority under the Civil Aviation Regulations 1998.\n\n**What it does:**\nIt requires owners and operators of specific McCauley variable-pitch aircraft propellers to replace certain bolts that hold the blade counterweights. These bolts have been failing, which could cause the propeller to malfunction.\n\n**Who it affects:**\nAnyone who owns or operates aircraft with McCauley propeller models **3AF32C504 through 3AF32C509** with serial numbers between **803546 and 816154**.\n\n**What must be done:**\n- Replace the faulty blade counterweight bolts following **McCauley Service Bulletin 147**\n- Complete this work **by the next scheduled maintenance inspection after 31 May 1983**\n\n**Why it matters:**\nFailed counterweight bolts can cause propeller blades to move unpredictably or detach, potentially leading to engine damage, loss of power, or catastrophic failure in flight. This directive forces a fix before the problem causes accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pmc-37-blade-counterweight-bolt-replacement","history":"/api/acts/ad-pmc-37-blade-counterweight-bolt-replacement/history","analysis":"/api/acts/ad-pmc-37-blade-counterweight-bolt-replacement/analysis","conflicts":"/api/acts/ad-pmc-37-blade-counterweight-bolt-replacement/conflicts","importantCases":"/api/acts/ad-pmc-37-blade-counterweight-bolt-replacement/important-cases","documents":"/api/acts/ad-pmc-37-blade-counterweight-bolt-replacement/documents"}}