{"id":"F2006B06675","name":"AD/ROTAX/9 - Propeller Gearbox Inspection","slug":"ad-rotax-9-propeller-gearbox-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48665,"registerId":"commonwealth-F2006B06675-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS 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.","sortOrder":0},{"sectionNumber":"AD/ROTAX/9 Propeller Gearbox Inspection ","sectionType":"part","heading":"AD/ROTAX/9 Propeller Gearbox Inspection 8/2000","content":"# AD/ROTAX/9 Propeller Gearbox Inspection 8/2000\n\nApplicability: All Rotax 912A engines S/N 4,410.330 through 4,410.366 inclusive, 912F engines S/N 4,412.781 through 4,412.791 inclusive, 914F engines S/N 4,420.128 through 4,420.156 inclusive and gearboxes supplied as replacement parts S/N 15081, 15139, 15341, 15559, 15560, 15561 or 15562.\n\nNote 1: The stated engines and gearboxes are only affected if the dog hub, overload clutch or gearbox, for affected engines, have never been replaced.\n\nRequirement: Inspect and if necessary, replace the gearbox, in accordance with Rotax Service Bulletin SB-912-027 Revision 1 or SB-914-010, Revision 1, as applicable, both dated February 2000.\n\nNote 2: Austro Control (Austria) AD No 101 refers.\n\nCompliance: Unless previously accomplished, within 30 hours time in service or prior to 30 November 2000, whichever comes first.\n\nThis Airworthiness Directive becomes effective on 10 August 2000.\n\nBackground: The manufacturer has advised that a combination of 7 degrees tapered dog hub and 30 degrees backlash dog gears may have been combined in the gearbox of affected engines or replacement gearboxes.\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 27 June 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 12 July 2000.","sortOrder":1}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted Airworthiness Directive addressing a specific manufacturing defect in specific engine serial numbers. The scope remains precisely limited to the identified unsafe condition and affected products."},"complexity_factors":["Very short document (approximately 300 words)","Only 3 defined serial number ranges for engines plus 7 specific gearbox serial numbers","Single clear requirement with reference to external technical documents (service bulletins)","Simple compliance deadline (whichever comes first of two conditions)","One conditional applicability note (unaffected if parts already replaced)","No nested exceptions or complex cross-referencing within the legislative instrument itself"],"plain_english_summary":"This AD mandates owners/operators of certain Rotax 912A/912F/914F engines with specific serial-numbered gearboxes to inspect their propeller gearbox for a manufacturing mismatch (a 7° tapered dog hub paired with 30° dog gears) that can cause in-flight gearbox failure. It applies only where the dog hub, overload clutch, or gearbox has never been replaced. Inspect per the manufacturer’s service bulletin and replace any faulty gearbox within 30 flight hours or by 30 Nov 2000."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD is narrowly tailored to correct a specific mismatch risk (combination of a 7° tapered dog hub with 30° backlash dog gears) in clearly listed engine and gearbox serial numbers. It requires inspection and replacement only where the components have not previously been replaced. The instrument therefore remains within the original safety-focused purpose described in its Background: identifying and correcting a potential gearbox assembly mismatch. It does not broaden the subject matter beyond that purpose or add additional unrelated regulatory obligations."},"complexity_factors":["Short, single-issue AD focused on gearbox condition and specific serial numbers","Three engine serial-number ranges plus seven specific replacement gearbox serial numbers in the applicability section","Conditional applicability in Note 1 (applies only if dog hub, overload clutch or gearbox have never been replaced)","Mandates compliance with external documents (Rotax Service Bulletins SB-912-027 Rev 1 and SB-914-010 Rev 1), creating dependency on those texts for technical detail","Cross-reference to a foreign AD (Austro Control) in Note 2","Two-way compliance deadline: within 30 hours TIS or before a fixed calendar date (creates an either/or timing condition)"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- It requires owners/operators of certain Rotax engines and replacement gearboxes to have the propeller gearbox inspected, and to replace it if the inspection shows replacement is necessary. (See Requirement.)\n\n**Which engines/parts are affected**\n\n- The AD applies to Rotax engines with the following serial number ranges and to specific replacement gearbox serial numbers: 912A S/N 4,410.330–4,410.366; 912F S/N 4,412.781–4,412.791; 914F S/N 4,420.128–4,420.156; and replacement gearboxes S/N 15081, 15139, 15341, 15559, 15560, 15561 or 15562. (Applicability.)\n\n- Important conditional limitation: the listed engines/gearboxes are affected only if the dog hub, overload clutch or gearbox have never been replaced. In other words, if a listed engine has had those components replaced earlier, the AD does not apply to that engine. (Note 1.)\n\n**Exactly what the operator must do**\n\n- Have the gearbox inspected and, if the inspection indicates, replace the gearbox. The inspection and any replacement must follow the procedures in the manufacturer's Rotax Service Bulletin SB-912-027 Revision 1 or SB-914-010 Revision 1 (as appropriate). (Requirement.)\n\n**When it must be done**\n\n- Unless already done, the inspection (and any needed replacement) must be completed within 30 hours time-in-service (TIS) or before 30 November 2000 — whichever comes first. (Compliance.)\n\n**Why the AD was issued (the stated reason)**\n\n- The manufacturer advised that a 7° tapered dog hub may have been combined with 30° backlash dog gears in some affected gearboxes, creating a mismatch that could produce an unsafe condition. The AD directs inspection and correction to address that risk. (Background.)\n\n**Who pays and who decides**\n\n- Aircraft owners/operators bear the cost for the inspection, parts and any maintenance downtime. Certified maintenance organisations or licensed engineers will perform the inspection and repairs, following the Rotax service bulletins. The CASA delegate (the regulator) is the authority that issued and enforces the requirement. (Authority: CASA delegate under CAR 1998 subregulation 39.1(1), and the AD's Requirement/Compliance sections.)\n\n**Practical implementation notes and trade-offs**\n\n- The AD delegates technical detail to the Rotax service bulletins: the AD mandates compliance with those procedures rather than reproducing technical steps. That means the inspector must have and follow the correct SB revision to determine whether replacement is \"necessary.\" (Requirement.)\n\n- Cost and downtime: the owner pays for labour, parts and aircraft out-of-service time. If replacement parts are scarce, compliance could cause longer grounding and higher costs.\n\n- Verification difficulty: the AD exempts engines where the dog hub, overload clutch or gearbox were previously replaced. Operators must be able to verify maintenance history and serial numbers to determine applicability. (Note 1.)\n\n- Timing pressure: the compliance window is short (30 hours TIS or a calendar date). That concentrates costs on operators who cannot schedule prompt maintenance; it also creates an incentive to prioritise the inspection and, if necessary, to source replacement gearboxes quickly. (Compliance.)\n\n- Cross-reference and foreign coordination: the AD refers the operator to specific Rotax service bulletins and notes an Austro Control (Austria) AD. These cross-references create a reliance on external documents and on the availability of the correct SB revisions. (Note 2; Requirement.)\n\n**Net effect on behaviour**\n\n- Operators of affected engines must check serial numbers and maintenance history, arrange a gearbox inspection per the appropriate Rotax SB, and replace the gearbox if the SB determines replacement is required. Failure to comply would leave the operator non‑compliant with the regulator's mandatory safety directive. (Applicability, Requirement, Compliance.)\n\n\n"},"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-rotax-9-propeller-gearbox-inspection","history":"/api/acts/ad-rotax-9-propeller-gearbox-inspection/history","analysis":"/api/acts/ad-rotax-9-propeller-gearbox-inspection/analysis","conflicts":"/api/acts/ad-rotax-9-propeller-gearbox-inspection/conflicts","importantCases":"/api/acts/ad-rotax-9-propeller-gearbox-inspection/important-cases","documents":"/api/acts/ad-rotax-9-propeller-gearbox-inspection/documents"}}