{"id":"F2006B06230","name":"AD/PHZL/73 - Discrepant Y Shank Propellers","slug":"ad-phzl-73-discrepant-y-shank-propellers","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47161,"registerId":"commonwealth-F2006B06230-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\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\n![](image.001.png)\n\nPropellers – Variable Pitch \\- Hartzell","sortOrder":0},{"sectionNumber":"AD/PHZL/73 Discrepant “Y” Shank Propelle","sectionType":"part","heading":"AD/PHZL/73 Discrepant “Y” Shank Propellers 8/2001","content":"# AD/PHZL/73 Discrepant “Y” Shank Propellers 8/2001\n\nApplicability: All Hartzell “Y” shank propellers, ( )HC-( )( )Y( )-( ) as listed by serial number in Table 1. The subject propellers were overhauled by Brothers Aero Service Company, Inc (BASCO) in the USA from November 1996 to October 1998 inclusive.","sortOrder":1},{"sectionNumber":"Table 1 - Affected Hub Serial Numbers","sectionType":"part","heading":"Table 1 - Affected Hub Serial Numbers","content":"## Table 1 \\- Affected Hub Serial Numbers\n\n![](image.002.png)  \n\n121, 251, 715, 1111, 1387, 1661, 2383, 2479, 2883, 3059, 3343, 3479, 3717, 3890,\n\n![](image.002.png)![](image.002.png)3990, 4690, and 5523 AM911\n\n![](image.002.png)  \nAN1309, AN2773, AN2826, AN2828, and AN3883\n\nAU42, AU696, AU814, AU992, AU1226, AU1290, AU1416, AU2641, AU2643, AU2658, AU2699, AU2847, AU7186E, AU8364A, AU8418A and AU12997\n\n![](image.002.png)\n\n![](image.002.png)  \nBP344, BP715, BP1276, BP1772, BP2121, BP3811, BP3763, BP3978, BP5674, BP6126, BP6194, BP7141, BP7297, BP7513, BP8199, BP8708, and BP9586\n\nCH6190 & CH19251\n\n![](image.002.png)\n\n![](image.002.png)![](image.002.png)CJ52, CJ54, CJ419, and CJ649 DA1404 and DA1418\n\n![](image.002.png)![](image.002.png)  \nDG101\n\nDJ4431, DJ4449, DJ9521A, DJ10407A, DJ11249A, DJ11880A, and DJ11881A DN3775\n\n![](image.002.png)![](image.002.png)![](image.002.png)DV11 and DV12 FH307\n\n![](image.002.png)  \nP560\n\nRequirement: If an affected propeller is installed and it has not been overhauled since 1 November 1998, replace it with a serviceable propeller of the same type, or overhaul it in accordance with manufacturer’s approved maintenance data, or inspect the propeller in accordance with FAA AD 2001-07-03, Required Actions.\n\nNote: FAA AD 2001-07-03(Corrected) refers.","sortOrder":2},{"sectionNumber":"Propellers — Variable Pitch - Hartzell","sectionType":"part","heading":"Propellers — Variable Pitch - Hartzell","content":"## Propellers – Variable Pitch \\- Hartzell\n\nAD/PHZL/73 (Continued)\n\nCompliance: Within 10 flying hours after the effective date of this Airworthiness Directive.\n\nThis Airworthiness Directive becomes effective on 9 August 2001.\n\nBackground: This AD is prompted by advice from the FAA that a US repair organisation released a number of discrepant Hartzell “Y” shank propellers into service. The discrepancies identified by the FAA could lead to propeller failure and subsequent loss of an aircraft. The action prescribed in this AD will ensure no discrepant propellers remain in service on Australian registered aircraft.\n\n![Signature of Eugene Paul Holzapfel, Delegate of the Civil Aviation Safety Authority.](image.003.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 2 July 2001\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 11 July 2001.","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD is focused and narrowly targeted: it applies only to Hartzell \"Y\"‑shank propellers overhauled by BASCO in the specified date range and listed by serial number, and it prescribes short‑term corrective actions (replace, overhaul, or FAA‑specified inspection). There is no indication in the text provided that the AD expanded beyond that original safety purpose or added unrelated obligations."},"complexity_factors":["Single substantive requirement with three alternative compliance options (replace, overhaul, or inspect)","Short compliance window (10 flying hours) adds operational urgency","Applicability limited to a defined set of serial numbers listed in a table (many serial entries but straightforward matching task)","External cross‑reference to FAA AD 2001‑07‑03 for inspection procedures (requires obtaining and following another document)","Limited conditional logic and few exceptions — minimal nested clauses or definitions"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an Airworthiness Directive (AD) that applies to a specific set of Hartzell \"Y\"‑shank propellers listed by hub and/or part serial numbers (see \"Applicability\").\n- If one of the listed propellers is fitted to an aircraft and it has not been overhauled since 1 November 1998, the aircraft operator must, within 10 flying hours, do one of the following (see \"Requirement\" and \"Compliance\"):  \n  - replace the propeller with a serviceable propeller of the same type; or  \n  - overhaul the propeller following the manufacturer’s approved maintenance data; or  \n  - inspect the propeller in accordance with FAA AD 2001-07-03 (the FAA inspection procedure is incorporated by reference).\n\n**Who is affected**\n\n- Owners and operators of Australian‑registered aircraft that have one of the listed Hartzell \"Y\"‑shank propeller hubs/parts installed and that were overhauled by Brothers Aero Service Company, Inc. (BASCO) between November 1996 and October 1998 (see \"Applicability\" and table of serial numbers).\n- Maintenance organisations and mechanics who will perform the overhaul, replacement or the FAA‑specified inspection.\n\n**Why it matters (official rationale and practical effect)**\n\n- Officially, the AD was issued because the FAA advised that BASCO released a number of Hartzell \"Y\"‑shank propellers with discrepancies that could lead to propeller failure and loss of the aircraft (see \"Background\").\n- Mechanically, the AD forces removal, rework or inspection of the specified propellers within a short time window (10 flying hours). That reduces the risk of an undetected defect remaining in service by requiring operators to take active corrective steps.\n\n**Who pays and who decides**\n\n- Aircraft owners/operators pay direct costs: parts and labour to replace or overhaul propellers, or labour for the FAA‑prescribed inspection. There can also be indirect costs from aircraft downtime and logistics (sourcing serviceable propellers or arranging overhaul slots).\n- The Civil Aviation Safety Authority (CASA), via its delegate, issued the AD and sets the compliance obligation. Operators choose which of the three compliant actions to take (replace, overhaul, or inspect) but must meet the AD’s deadline.\n\n**Implementation mechanics and compliance burden**\n\n- Operators must: locate and check serial numbers on propeller hubs and maintenance records to confirm whether the propeller is in the listed set (administrative effort); then schedule and carry out replacement/overhaul/inspection within 10 flying hours (operational effort).\n- The AD refers to FAA AD 2001‑07‑03 for the inspection steps. That means some technical details and acceptance criteria are set outside the AD itself (external cross‑reference). The FAA document must be obtained and followed if inspection is chosen.\n\n**Incentives, trade‑offs and risks**\n\n- Short compliance time (10 flying hours) creates an incentive for operators to choose the fastest practical route (often replacement with a known serviceable propeller) rather than arrange an immediate overhaul.\n- Potential trade‑offs: replacing a propeller with one taken from another aircraft can shift risk or create a shortage of spares; choosing inspection over overhaul saves immediate cost but may leave subtle defects undetected if the inspection is imperfect.\n- Implementation risks include misidentifying serial numbers or incomplete overhaul records, limited immediate availability of serviceable spares or overhaul capacity, and reliance on an FAA AD for inspection criteria (if the FAA AD is updated/corrected operators must ensure they use the correct version referenced).\n\n**Distribution of costs and benefits**\n\n- Benefits (reduced risk of propeller failure) are diffuse (public safety) and accrue broadly, but compliance costs are concentrated on the relatively small set of aircraft/operators that have the listed propellers.\n\n**Concrete references in the AD text**\n\n- Applicability: identifies the affected Hartzell \"Y\"‑shank propellers and lists serial numbers (see \"Applicability\" and Table 1).  \n- Requirement: replacement, overhaul, or inspection per FAA AD 2001‑07‑03 (see \"Requirement\").  \n- Compliance: actions must be completed within 10 flying hours of the AD’s effective date (see \"Compliance\").  \n- Background: explains the FAA‑reported discrepancies from BASCO overhauls and the safety justification (see \"Background\").\n\n(Prepared as an analyst’s note: this summarises how the AD operates, who bears the costs, what choices operators have, and what practical compliance risks and trade‑offs are created by the AD.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope. It targets a specific safety defect identified in a discrete batch of propellers from a specific repair facility during a defined 24-month period. The directive has not expanded beyond this original purpose."},"complexity_factors":["Short, single-purpose directive with one clear requirement section","Limited applicability: only 67 specific serial numbers affected, with model number pattern matching","Simple conditional logic: applies only if propeller is installed AND not overhauled since 1 November 1998","Three alternative compliance paths (replace, overhaul, or inspect per FAA AD)","Single cross-reference to external FAA directive (AD 2001-07-03) for inspection procedures","No nested definitions or interpretation section — terms used are industry standard (\"serviceable\", \"overhaul\")","Clear compliance timeframe (10 flying hours) with explicit effective date"],"plain_english_summary":"This AD requires owners/operators of Australian aircraft fitted with certain Hartzell \"Y\" shank propellers (67 hub serial numbers serviced by Brothers Aero Service Company between Nov 1996 and Oct 1998) to have those propellers inspected, overhauled, or replaced.\n\nIf a propeller hasn’t been overhauled since 1 Nov 1998, compliance is required within 10 flying hours to prevent possible propeller failure and loss of the aircraft; effective 9 Aug 2001."},"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-phzl-73-discrepant-y-shank-propellers","history":"/api/acts/ad-phzl-73-discrepant-y-shank-propellers/history","analysis":"/api/acts/ad-phzl-73-discrepant-y-shank-propellers/analysis","conflicts":"/api/acts/ad-phzl-73-discrepant-y-shank-propellers/conflicts","importantCases":"/api/acts/ad-phzl-73-discrepant-y-shank-propellers/important-cases","documents":"/api/acts/ad-phzl-73-discrepant-y-shank-propellers/documents"}}