{"id":"F2006B11199","name":"AD/LYC/107 Amdt 2 - Crankshaft Replacement","slug":"ad-lyc-107-amdt-2-crankshaft-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56909,"registerId":"commonwealth-F2006B11199-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Lycoming Piston Engines","sectionType":"part","heading":"Lycoming Piston Engines","content":"# Lycoming Piston Engines\n\nAD/LYC/107 Amdt 2 (continued)\n\nRequirement: 1. MSB 552 listed TIO-540 and LTIO-540 engines: Replace the crankshaft in accordance with the requirements of Textron Lycoming MSB 552.\n\n    2. MSB 552 listed TIO-540 and LTIO-540 crankshafts: Replace the crankshaft in accordance with the requirements of Textron Lycoming MSB 552.\n\n    3. IO-540 series engines incorporating an turbocharger STC:\n\n    Determine the serial number of the crankshaft; and\n\n    b. If listed in Table 2 of Textron Lycoming MSB 552, replace the crankshaft in accordance with the requirements of Textron Lycoming MSB 552.\n\nNote 2: Prior replacement of a crankshaft in accordance with either MSB 550 or 552 constitutes compliance with the requirements of this directive.\n\nNote 3: FAA Airworthiness Directive 2002-19-03 Amdt 39-12883 refers.\n\nCompliance: Unless previously accomplished:\n\n    Installed engines: Within 5 hours time in service from the effective date of this Directive.\n\n    b. Spare engines: Before installation in an aircraft. This Amendment becomes effective on 2 October 2002.\n\nBackground: This Directive was originally issued to require certain crankshafts to be removed from service. The requirement follows advice from the engine manufacturer of a crankshaft material defect being identified in the investigation of a number of engine failures. This amendment increases the engines applicable to include IO-540 engines incorporating an STC approved turbocharger.","sortOrder":0}],"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":5,"scope_assessment":{"changed":true,"description":"Yes. Amendment 2 expands the directive's applicability to include IO‑540 engines that incorporate an STC‑approved turbocharger (Background). Previously the directive focused on certain TIO‑540 and LTIO‑540 crankshafts; the amendment requires serial‑number checks and possible replacement for the newly included IO‑540/STC installations, increasing the population of affected engines while retaining the original compliance timings and acceptance of prior MSB 550/552 replacements (Note 2; Compliance)."},"complexity_factors":["Relies on an external manufacturer document (Textron Lycoming MSB 552) to define exactly which crankshafts must be replaced and how (Requirements 1–3).","Requires serial‑number verification against Table 2 of MSB 552 for IO‑540 engines with STC turbochargers (Requirement 3), adding a record‑checking step.","Different deadlines for installed engines (within 5 hours TIS) versus spare engines (before installation) increase operational urgency and logistical complexity (Compliance).","Accepts prior compliance under MSB 550 or 552 as satisfying the directive (Note 2), requiring review of historical maintenance records.","Cross‑references FAA Airworthiness Directive 2002‑19‑03 (Note 3), creating cross‑jurisdictional conformity considerations.","Scope differentiates by engine model and by retrofit configuration (STC), requiring technical identification and possibly specialist inspection or parts sourcing.","Tight compliance window shifts costs and downtime onto aircraft owners/operators, who must arrange replacements quickly."],"plain_english_summary":"This Airworthiness Directive requires owners/operators to replace specified Lycoming TIO‑540 and LTIO‑540 crankshafts, and certain IO‑540 crankshafts fitted with STC‑approved turbochargers, in accordance with Textron Lycoming MSB 552. Installed engines must be grounded within five hours of the directive; spare engines must be removed before installation. The action follows a manufacturer‑reported crankshaft material defect and places replacement cost, downtime and compliance verification on aircraft owners/operators."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"This Amendment 2 expands the original directive's scope. The original AD (February 2002) and Amendment 1 (August 2002) applied only to TIO-540 and LTIO-540 engines. This amendment adds IO-540 series engines that have been modified with turbocharger STCs, significantly broadening the affected fleet to include more aircraft that might contain the defective crankshaft."},"complexity_factors":["Short, single-purpose directive with only 3 numbered requirements","Minimal defined terms (relies on external references to engine model numbers and manufacturer service bulletins)","Simple conditional logic: 'if listed in Table 2, then replace'","Two straightforward compliance pathways based on engine status (installed vs spare)","Contains helpful compliance relief (Note 2) for prior work done under related bulletins","No nested exceptions or complex cross-referencing within the instrument itself"],"plain_english_summary":"This AD mandates replacement of defective crankshafts in certain Lycoming TIO-540 and LTIO-540 engines, and IO-540 engines modified with an approved turbocharger (STC), after a material defect caused multiple in‑flight engine failures. Installed engines must have the crankshaft replaced within 5 flight hours; spare engines must be corrected before installation. Crankshafts already replaced under Lycoming MSB 550 or 552 are acceptable and need no further action."}},"importantCases":[],"_links":{"self":"/api/acts/ad-lyc-107-amdt-2-crankshaft-replacement","history":"/api/acts/ad-lyc-107-amdt-2-crankshaft-replacement/history","analysis":"/api/acts/ad-lyc-107-amdt-2-crankshaft-replacement/analysis","conflicts":"/api/acts/ad-lyc-107-amdt-2-crankshaft-replacement/conflicts","importantCases":"/api/acts/ad-lyc-107-amdt-2-crankshaft-replacement/important-cases","documents":"/api/acts/ad-lyc-107-amdt-2-crankshaft-replacement/documents"}}