{"id":"F2006B11203","name":"AD/LYC/76 Amdt 6 - Propeller Attachment Flange","slug":"ad-lyc-76-amdt-6-propeller-attachment-flange","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56914,"registerId":"commonwealth-F2006B11203-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LYC/76 Amdt 6 - Propeller Attachment Flange","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nLycoming Piston Engines\n\nAD/LYC/76\n\nAmdt 6\n\n  \nPropeller Attachment Flange 10/94\n\nApplicability: All Lycoming O-360, IO-360, AIO-360 and AEIO-360 engines fitted with a light flange crankshaft and installed in an aircraft with a Certificate of Airworthiness in the acrobatic category or a Airplane Flight Manual approving aerobatic manoeuvres.\n\nNote 1: For the purpose of this Directive, a light flange crankshaft is a crankshaft incorporating lightening holes in a 0.38\" thick propeller attachment flange.\n\nRequirement: 1. Carry out a visual inspection of the propeller attachment flange in accordance with Lycoming Service Bulletin No. 465C, \"INSPECTION PROCEDURE I\", or\n\n    2. Carry out a Magnetic Particle Inspection (MPI) of the propeller attachment flange in accordance with Lycoming Service Bulletin No. 465C, \"INSPECTION PROCEDURE II\", or\n\n    3. Carry out an Eddy Current Inspection (ECI) of the propeller attachment flange in accordance with a procedure approved by the Authority.\n\nNote 1: FAA Airworthiness Directive 84-13-05 refers.\n\nNote 2: Replacement of a light flange crankshaft with a solid flange crankshaft is the terminating action for this Directive. A solid flange crankshaft does not have lightening holes in the propeller flange and the flange can be 0.38\" or 0.44\" thick.\n\nCompliance: Effective 15 September 1994:\n\n    Within 25 hours time in service, and thereafter at intervals not to exceed 25 hours time in service.\n\n    2. Unless previously accomplished, within 25 hours time in service, and thereafter at intervals not to exceed 110 hours time in service.\n\n    3. Unless previously accomplished, within 25 hours time in service, and thereafter at intervals not to exceed 110 hours time in service.\n\nBackground: This Directive has been amended, in part, to reflect the manufacturer's latest revision to the requirement document. Service Bulletin No. 465C provides a terminating action for engines fitted with light flange crankshafts.\n\nThe amendment also deletes direct reference to an Eddy Current Inspection (ECI) procedure detailed in a previous issue of this Directive. Inspection of the propeller flange by ECI shall be carried out in accordance with a procedure approved by the Authority.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains focused on its original purpose: ensuring safety of propeller attachment flanges on specific Lycoming engines. Amendment 6 updates the referenced service bulletin to the current version (465C), removes a specific ECI procedure in favour of Authority-approved procedures, and clarifies terminating actions. These are technical updates within the original scope, not expansion into new areas."},"complexity_factors":["Short, single-purpose document (approximately 300 words)","Only 1 defined term ('light flange crankshaft') with clear explanation in Note 1","Simple conditional structure: three alternative compliance paths with straightforward intervals","Minimal cross-referencing (references to Lycoming Service Bulletin 465C and FAA AD 84-13-05, but does not reproduce their content)","Clear applicability section using specific engine model numbers","No nested exceptions or complex temporal conditions beyond the initial 25-hour deadline and recurring intervals"],"plain_english_summary":"This AD requires regular inspections of the propeller attachment (light) flange on certain Lycoming O‑360-series engines used in aerobatic aircraft, to detect fatigue cracks before failure. Owners must either follow approved inspection methods (visual, MPI or eddy‑current) at the prescribed intervals or replace the light flange with a solid flange to eliminate recurring inspections.  \n\nIt targets operators of affected Lycoming engines and aims to prevent propeller separation and catastrophic accidents."},"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":"The Directive was amended to align with the manufacturer’s latest Service Bulletin (No. 465C) and to remove a direct ECI procedure from the text. ECI must now be performed using a procedure approved by the Authority, and Service Bulletin No. 465C is identified as providing the terminating action (Background; Requirement 3; Note 2)."},"complexity_factors":["Multiple inspection methods offered (visual, Magnetic Particle Inspection, Eddy Current Inspection) create choice and procedural variation (Requirement 1–3).","Very short, recurring inspection intervals increase operational and maintenance burden (Compliance: within 25 hours and repeated intervals).","Applicability is narrow and conditional — specific engine models plus installation in aircraft certificated/approved for aerobatics — requiring accurate identification of affected aircraft (Applicability).","Terminating action (replacement with a solid flange) is prescribed but requires following Service Bulletin No. 465C; this shifts costs to owners/operators and concentrates benefit in reduced inspection burden only after replacement (Note 2; Background).","Regulatory discretion introduced by requiring Authority approval for ECI procedures (Requirement 3; Background), which may produce variability in accepted methods and timing.","Cross-references to manufacturer Service Bulletin and FAA AD increase dependence on external documents for compliant procedures (Requirement; Note 1; Background).","Amendment deleted a previously detailed ECI procedure and deferred to Authority approval, potentially creating short‑term implementation ambiguity until approvals are issued (Background)."],"plain_english_summary":"Requires owners/operators of Lycoming O-360/IO-360/AIO-360/AEIO-360 engines with a light flange crankshaft in aerobatic-approved aircraft to inspect the propeller attachment flange regularly (visual, magnetic-particle, or an Authority‑approved eddy‑current method) and allows replacement with a solid flange as a terminating action. Inspections and any replacement costs fall to aircraft owners/operators; the regulator must approve any ECI procedure and the manufacturer’s Service Bulletin supplies the detailed inspection and terminating-action instructions."}},"importantCases":[],"_links":{"self":"/api/acts/ad-lyc-76-amdt-6-propeller-attachment-flange","history":"/api/acts/ad-lyc-76-amdt-6-propeller-attachment-flange/history","analysis":"/api/acts/ad-lyc-76-amdt-6-propeller-attachment-flange/analysis","conflicts":"/api/acts/ad-lyc-76-amdt-6-propeller-attachment-flange/conflicts","importantCases":"/api/acts/ad-lyc-76-amdt-6-propeller-attachment-flange/important-cases","documents":"/api/acts/ad-lyc-76-amdt-6-propeller-attachment-flange/documents"}}