{"id":"F2005L03019","name":"AD/LYC/112 - Lycoming Crankshaft Replacement","slug":"ad-lyc-112-lycoming-crankshaft-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":37926,"registerId":"commonwealth-F2005L03019-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Lycoming Piston Engines","sectionType":"division","heading":"Lycoming Piston Engines","content":"### Lycoming Piston Engines\n\n| AD/LYC/112 | Lycoming Crankshaft Replacement | 12/2005 DM |\n| ---------- | ------------------------------- | ---------- |\n\n| Applicability: | Lycoming Engines AEIO-360, IO-360, O-360, LIO-360, LO-360, AEIO-540, IO-540, O-540, and TIO-540 series reciprocating engines, rated at 300 horsepower (HP) or lower, that are manufactured new, rebuilt, overhauled after 01 March 1999; OR that had a crankshaft installed after 01 March 1999.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. AEIO-540, IO-540, O-540, and TIO-540 series engines manufactured new or rebuilt, overhauled, or that had a crankshaft installed after 01 March 1999:For AEIO-540, IO-540, O-540, and TIO-540 series engines manufactured new or rebuilt, overhauled, or that had a crankshaft installed after 01 March 1999, do the following:a. If Table 1 or Table 2 of Lycoming Mandatory Service Bulletin (MSB) No. 566 dated 11 July 2005 lists your engine serial number (SN), use Table 4 to verify the crankshaft SN.b. If Table 4 of Lycoming MSB 566 lists your crankshaft SN, replace the crankshaft with a crankshaft that is not listed in Table 4 of Lycoming MSB No. 566.2. AEIO-360, IO-360, O-360, LIO-360, and LO-360 series engines manufactured new or rebuilt, overhauled, or that had a crankshaft installed after 01 March 1999:For AEIO-360, IO-360, O-360, LIO-360, and LO-360 series engines manufactured new or rebuilt, overhauled, or that had a crankshaft installed after 01 March 1999, do the following:a. If Table 3 of Lycoming MSB 566 lists your engine SN, use Table 4 to verify the crankshaft SN.b. If Table 4 of Lycoming MSB 566 lists your crankshaft SN, replace the crankshaft with a crankshaft that is not listed in Table 4 of Lycoming MSB 566.3. Do not install any crankshaft that has a SN listed in Table 4 of Lycoming MSB 566 into any engine.Note: FAA Airworthiness Directive (AD) 2005-19-11 Amendment 39-14276 refers. |\n\n| Compliance: | 1. Unless accomplished earlier, within 50 hours time-in-service or 6 months after the effective date of this AD, whichever occurs first.2. Unless accomplished earlier, within 50 hours time-in-service or 6 months after the effective date of this AD, whichever occurs first.3. After the effective date of this AD.              |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n|             | This Airworthiness Directive becomes effective on 28 October 2005.                                                                                                                                                                                                                                                                   |\n| Background: | There have been various crankshaft failures in Lycoming model 360 and 540 series engines rated at 300 HP or lower. Failure of crankshaft may result in total engine power loss, in-flight engine failure, and possible loss of the airplane.The actions specified by this Airworthiness Directive address the risk identified above. |\n\n![](image.001.png)  \nJayaprakashan Ambali  \nDelegate of the Civil Aviation Safety Authority\n\n5 October 2005","sortOrder":0},{"sectionNumber":"AD/LYC/112","sectionType":"part","heading":"AD/LYC/112","content":"## AD/LYC/112","sortOrder":1},{"sectionNumber":"Lycoming Crankshaft Replacement","sectionType":"part","heading":"Lycoming Crankshaft Replacement","content":"## Lycoming Crankshaft Replacement","sortOrder":2},{"sectionNumber":"12/2005 DM","sectionType":"part","heading":"12/2005 DM","content":"## 12/2005 DM","sortOrder":3}],"analysis":{"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":4,"scope_assessment":{"changed":false,"description":"This AD stays within the original safety purpose: remove and prohibit the use of identified crankshafts that have shown a risk of failure. It does not broaden the regulatory subject matter beyond addressing crankshaft serial numbers on the specified Lycoming 360/540 series engines manufactured/rebuilt/overhauled or fitted after 1 March 1999. The instrument aligns with the FAA AD and relies on Lycoming's MSB tables to target specific parts; it therefore focuses rather than expands scope compared with the stated intent to mitigate crankshaft failure risk."},"complexity_factors":["Multiple engine models listed (9 model families: AEIO‑360, IO‑360, O‑360, LIO‑360, LO‑360, AEIO‑540, IO‑540, O‑540, TIO‑540)","Applicability conditioned on manufacture/overhaul/install date (after 1 March 1999) — a temporal cut‑off","Three numbered requirements with branching by engine family (Requirement 1 for 540 series; Requirement 2 for 360 series; Requirement 3 general prohibition)","Dependence on an external document (Lycoming MSB No. 566) with multiple tables (Tables 1–4) for critical determinations","Two alternative compliance constraints (50 hours time‑in‑service OR 6 months) requiring operational tracking","Prohibition on future installations (a standing ban) as well as a one‑off replacement requirement","Cross‑reference to FAA AD 2005‑19‑11 (external regulatory cross‑link)","Potential operational complexity in tracing crankshaft serial numbers in maintenance records"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- This is an airworthiness directive that requires owners/operators and maintenance organisations to check and, if necessary, replace certain Lycoming crankshafts. It applies only to specified Lycoming piston-engine models (AEIO‑360, IO‑360, O‑360, LIO‑360, LO‑360, AEIO‑540, IO‑540, O‑540 and TIO‑540) rated at 300 HP or lower where the engine was manufactured new, rebuilt, overhauled after 1 March 1999, or had a crankshaft installed after 1 March 1999.\n\n- The directive tells affected operators to use Lycoming Mandatory Service Bulletin (MSB) No. 566 (dated 11 July 2005) to: (a) check whether their engine serial number appears in the MSB tables; (b) if so, verify the crankshaft serial number against Table 4 of the MSB; and (c) if the crankshaft serial number is listed in Table 4, replace that crankshaft with one that is not listed in Table 4.\n\n- It also forbids installing any crankshaft whose serial number appears in Table 4 into any engine after the effective date.\n\n- Compliance deadlines: replacement (where required) must be done within 50 hours time‑in‑service (TIS) or 6 months after the AD takes effect, whichever comes first. The prohibition on installing listed crankshafts is immediate from the effective date.\n\n- The directive cites FAA Airworthiness Directive 2005‑19‑11 as a related reference.\n\nWho this affects\n\n- Aircraft owners/operators who operate the listed Lycoming engine models and whose engines or crankshafts meet the manufacturing/installation date criteria (after 1 March 1999).\n- Maintenance organisations, mechanics and parts suppliers who must inspect serial numbers, perform replacements and ensure no prohibited crankshafts are fitted.\n\nWhy it matters (purpose claim and mechanical effect)\n\n- The stated safety reason: there have been crankshaft failures in the affected Lycoming 360 and 540 series engines; crankshaft failure can cause total engine power loss and in‑flight engine failure. The directive's mechanical effect is to remove identified crankshafts (those listed in Table 4 of Lycoming MSB 566) from service and to prevent their future installation, thereby reducing the risk that a listed crankshaft will remain fitted to an aircraft.\n\nCosts, incentives and practical trade‑offs\n\n- Who pays: aircraft owners/operators pay the direct costs — parts and labour to replace a listed crankshaft, plus aircraft downtime. Maintenance organisations incur inspection and administrative effort to verify serial numbers and record compliance.\n\n- Supply and substitution effects: the requirement to replace with a crankshaft not listed in Table 4 may create short‑term demand for replacement crankshafts and potential supply constraints or price pressure on acceptable (unlisted) parts.\n\n- Behaviour change and incentives: operators have an incentive to verify serial numbers promptly (within the 50‑hour / 6‑month window) to avoid non‑compliance. Parts suppliers and overhaulers will avoid installing Table‑4 crankshafts into engines because installation is expressly prohibited.\n\n- Compliance burden and implementation risk: the directive relies on cross‑referencing external tables in MSB No. 566. That creates a modest administrative burden (look‑ups, record checks). If operators cannot source an acceptable crankshaft promptly, aircraft may be grounded or face operational disruption.\n\n- Concentration of benefits and diffusion of costs: the safety benefit is diffuse (reduced risk of in‑flight engine failure for any affected aircraft). The costs are concentrated on the owners/operators who actually have a listed crankshaft fitted.\n\n- Enforcement and discretion: the AD prescribes mandatory action and a clear deadline; practical discretion is limited to determining whether a crankshaft is listed and sourcing a replacement. The AD references the FAA AD but does not delegate substantive discretion to the regulator in the text provided.\n\nKey operative references in the text\n\n- Applicability clause (engine models + manufacture/installation date: after 1 March 1999).\n- Requirement 1 and 2 (separate procedures for 540‑series and 360‑series engines: check MSB tables, verify crankshaft SN, replace if SN is listed in Table 4).\n- Requirement 3 (do not install any crankshaft whose SN is in Table 4).\n- Compliance timing: within 50 hours TIS or 6 months from the effective date.\n\nPractical next steps for an affected owner/operator\n\n- Locate the engine serial number and any crankshaft serial number records.\n- Obtain Lycoming MSB No. 566 (11 July 2005) and check the relevant tables (Tables 1–4) as directed.\n- If the engine or crankshaft serial number is listed in the MSB, schedule and fund a replacement within the 50‑hour / 6‑month window.\n- Ensure maintenance records document compliance and that no Table‑4 crankshaft is installed in future.\n\nSources cited in the instrument: Lycoming MSB No. 566 (11 July 2005) and FAA AD 2005‑19‑11 (Amendment 39‑14276)."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific engine models. The scope remains tightly focused on crankshaft replacement for the identified Lycoming engine series. No evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Multiple overlapping applicability conditions (manufacture date OR rebuild/overhaul date OR crankshaft installation date, combined with horsepower limit and specific engine model series)","Cross-reference to external technical document (Lycoming MSB 566) with four separate tables that must be consulted in sequence","Different procedural pathways for 360-series versus 540-series engines (split requirements in sections 1 and 2)","Nested conditional logic: 'If Table X lists your SN, then check Table Y; if Table Y lists your SN, then replace'","Dual compliance timelines (50 hours/6 months for most requirements, immediate for installation prohibition)","Incorporation by reference to FAA Airworthiness Directive 2005-19-11, creating parallel regulatory obligations"],"plain_english_summary":"This AD requires owners/operators of certain Lycoming 360- and 540-series piston engines (built, rebuilt, overhauled, or with a crankshaft installed after 1 Mar 1999, and rated ≤300 hp) to check Lycoming Service Bulletin 566 for affected engine and crankshaft serial numbers. If a crankshaft is listed, it must be replaced immediately and must never be installed in any engine. Compliance (inspection and replacement) is mandated within 50 flight hours or six months. It addresses in-flight crankshaft failures that can cause total power loss."}},"importantCases":[],"_links":{"self":"/api/acts/ad-lyc-112-lycoming-crankshaft-replacement","history":"/api/acts/ad-lyc-112-lycoming-crankshaft-replacement/history","analysis":"/api/acts/ad-lyc-112-lycoming-crankshaft-replacement/analysis","conflicts":"/api/acts/ad-lyc-112-lycoming-crankshaft-replacement/conflicts","importantCases":"/api/acts/ad-lyc-112-lycoming-crankshaft-replacement/important-cases","documents":"/api/acts/ad-lyc-112-lycoming-crankshaft-replacement/documents"}}