{"id":"F2006B06662","name":"AD/ROTAX/15 - Inspection of Exhaust Bends","slug":"ad-rotax-15-inspection-of-exhaust-bends","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48612,"registerId":"commonwealth-F2006B06662-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.001.png)  \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 CASR 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\nRotax Piston Engines","sortOrder":0},{"sectionNumber":"AD/ROTAX/15 Inspection of Exhaust Bends ","sectionType":"part","heading":"AD/ROTAX/15 Inspection of Exhaust Bends 12/2003","content":"# AD/ROTAX/15 Inspection of Exhaust Bends 12/2003\n\nApplicability: Rotax 914 F series engines with Serial Number (S/N) 4,420.001 up to 4,420.363, if equipped with genuine Rotax exhaust bends Part Number (PN) 979420/421/422, 979430/431/432, 979440/441/442, and 979450/451/452.\n\nRequirement: 1. Carry out a detailed visual inspection of the exhaust bends (exhaust tubes between cylinder head and exhaust) in accordance with instructions contained in Rotax Service Bulletin (SB) 914-017R1.\n\n2. If cracks are detected when carrying out Requirement 1, replace the exhaust bend in accordance with the relevant Maintenance Manual.\n\nNote: Austrian CAA AD 106R1 refers.\n\nCompliance: For Requirement 1: Every 50 hours time-in-service (TIS) from the effective date of this Directive.\n\nFor Requirement 2: Before further flight.\n\nThis Airworthiness Directive becomes effective on 27 November 2003.\n\nBackground: Cracks have been detected on Rotax engine exhaust bends which could have been caused by a number of reasons outlined in the SB relevant to this Directive. The Austrian CAA requires inspection of the exhaust bends at regular intervals.\n\n![Signature of Jim Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJim Coyne\n\nDelegate of the Civil Aviation Safety Authority 14 October 2003\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 5 November 2003.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD is narrowly focused on detecting and addressing cracks in specific Rotax 914 F series engine exhaust bends. There is no indication in the text that it expands beyond that original safety purpose. The measure remains limited in scope by serial-number and part-number applicability, prescribes a simple inspection and replacement regime, and cross-references the manufacturer’s service bulletin and maintenance manual for technical detail."},"complexity_factors":["Narrow, specific applicability (single engine family with a limited serial number range and explicit part numbers).","Only two required actions: a recurring visual inspection and, if cracks are found, replacement. (Requirement 1–2)","Short compliance logic: fixed interval (every 50 hours TIS) and immediate replacement before further flight. (Compliance)","Cross-references to external documents (Rotax SB 914-017R1 and the relevant Maintenance Manual) which contain the technical inspection and replacement procedures. (Requirement 1–2)","Reference to an external regulator’s AD (Austrian CAA AD 106R1) but no layered exceptions or conditional branches. (Background)"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- Requires owners/operators of certain Rotax 914 F series piston engines to carry out a detailed visual inspection of the exhaust bends (the exhaust tube between the cylinder head and the exhaust) and to replace any exhaust bend that shows cracks. (Applicability; Requirement 1–2; Compliance)\n- The inspection must follow the instructions in Rotax Service Bulletin SB 914-017R1. If a crack is found, the exhaust bend must be replaced according to the relevant Maintenance Manual. (Requirement 1–2)\n- The inspection interval is every 50 hours time-in-service (TIS) from the AD’s effective date; any required replacement must be done before further flight. (Compliance)\n\n**Who is affected**\n\n- Aircraft owners/operators, maintenance organisations and maintenance personnel responsible for aircraft fitted with Rotax 914 F series engines having serial numbers 4,420.001 through 4,420.363 and fitted with genuine Rotax exhaust bends with part numbers 979420/421/422, 979430/431/432, 979440/441/442, or 979450/451/452. (Applicability)\n\n**Why it matters (stated purpose and practical effect)**\n\n- Stated purpose: cracks have been detected in the exhaust bends; the AD is issued to correct that unsafe condition. (Background)\n- Practical effect: operators must add a recurring inspection task (every 50 hours TIS) and must ground and replace any cracked exhaust bend before flying again. That creates recurring labour and potential parts costs, and may cause aircraft downtime. (Requirement 1–2; Compliance)\n\n**How it works in practice and who decides/ pays**\n\n- Who decides: the Civil Aviation Safety Authority (CASA) delegate issued the AD under CASR 1998 subregulation 39.1(1). The AD sets the required action and interval. (Preamble)\n- Who pays: owners/operators pay for inspections (labour) and for replacement parts and associated labour if cracks are found. Maintenance organisations perform the work following Rotax SB 914-017R1 and the Maintenance Manual. (Requirement 1–2)\n- Behaviour change: maintenance planning must include an inspection every 50 hours TIS for the affected engines; flights may be delayed or cancelled if a cracked exhaust bend is found until replacement is completed. (Compliance)\n\n**Dependencies, trade-offs and implementation notes**\n\n- The AD cross-references Rotax Service Bulletin SB 914-017R1 for inspection instructions and the relevant Maintenance Manual for replacement procedures; compliance therefore depends on access to and following those documents. (Requirement 1–2)\n- Trade-offs: the AD imposes a recurring compliance burden (inspection frequency and possible replacements) to reduce the safety risk of cracked exhaust bends. That creates direct costs (parts and labour) and opportunity costs (aircraft downtime). Benefits (reduced risk of failure) are the outcome the AD seeks to secure. (Background; Requirement; Compliance)\n- Supply/implementation risk: availability of genuine Rotax exhaust bends and qualified maintenance resources will affect how quickly cracked parts can be replaced and aircraft returned to service. (Requirement 2)\n\n**Cross-reference**\n\n- The AD notes the Austrian CAA AD 106R1 as related material. (Background)\n\n**Mechanics summary (short)**\n\n- Inspect every 50 hours TIS per Rotax SB 914-017R1; replace any cracked exhaust bend per the Maintenance Manual before next flight. Applies only to Rotax 914 F engines within the specified S/N range and fitted with the listed Rotax part numbers. (Applicability; Requirement; Compliance)"},"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"},"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 identified in a particular engine series and does not expand beyond the original intent of ensuring exhaust bend integrity on affected Rotax 914 F engines."},"complexity_factors":["Single, specific mechanical issue addressed (exhaust bend cracks)","Only 4 defined part number ranges in applicability section","Two straightforward requirements: inspect every 50 hours, replace if cracked","No nested exceptions or conditional logic","Clear compliance timeline (50 hours TIS, or before further flight if cracked)","References only one external document (Rotax Service Bulletin 914-017R1) and one related foreign directive (Austrian CAA AD 106R1)","Total length: approximately 250 words of substantive text"],"plain_english_summary":"The Civil Aviation Safety Authority has issued a mandatory safety order requiring owners/operators of Rotax 914 F series engines (serials 4,420.001–4,420.363) using specified genuine Rotax exhaust bends to perform detailed visual inspections of those exhaust bends every 50 flight hours per Rotax SB 914‑017R1. Any cracked bend must be replaced before further flight. The measure, effective 27 Nov 2003, prevents in‑flight exhaust failure that could cause engine damage, power loss, or fire."}},"importantCases":[],"_links":{"self":"/api/acts/ad-rotax-15-inspection-of-exhaust-bends","history":"/api/acts/ad-rotax-15-inspection-of-exhaust-bends/history","analysis":"/api/acts/ad-rotax-15-inspection-of-exhaust-bends/analysis","conflicts":"/api/acts/ad-rotax-15-inspection-of-exhaust-bends/conflicts","importantCases":"/api/acts/ad-rotax-15-inspection-of-exhaust-bends/important-cases","documents":"/api/acts/ad-rotax-15-inspection-of-exhaust-bends/documents"}}