{"id":"F2006B08651","name":"AD/CON/75 - Magneto Timing","slug":"ad-con-75-magneto-timing","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51716,"registerId":"commonwealth-F2006B08651-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CON/75 - Magneto Timing","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)  \nTeledyne Continental Motors Piston Engines\n\nAD/CON/75 Magneto Timing 10/96\n\nApplicability: Teledyne Continental Motors (TCM) O-200A, O-200B and Rolls Royce O-200A, O- 200B and O-200C engines.\n\nRequirement: To prevent possible cylinder cracking with a subsequent loss of engine power.\n\n1. (a) For engines fitted with one or more cylinders with a part number lower than 641917, set the engine magneto timing to 24 degrees (plus or minus 1 degree) before top dead centre (BTDC) on both magnetos in accordance with the procedures detailed in TCM Service Bulletin (SB) No. SB94-8, and\n\n    (b) Stamp the engine data plate to reflect a magneto timing of 24 degrees BTDC.\n\n    2. (a) For engines fitted with all four cylinders part number 641917 or higher, the engine magneto timing may be set to 28 degrees (plus or minus 1 degree) BTDC on both magnetos in accordance with the procedures detailed in TCM SB No. SB94-8, and\n\n2. (b) Stamp the engine data plate to reflect a magneto timing of 28 degrees BTDC.\n\nNote: FAA Airworthiness Directive 96-12-06 refers.\n\nCompliance: Requirement 1. Unless previously accomplished, within 50 hours time in service after 12 September 1996 and thereafter at each cylinder replacement.\n\nRequirement 2. Effective 12 September 1996 and thereafter at each cylinder replacement.\n\nBackground: This directive has been issued to require the engine magneto timing to be set in consideration of the status of the cylinders fitted. The requirement addresses reports of cylinder cracking in engines fitted with early model cylinders.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete airworthiness directive with a narrow, specific purpose: correcting magneto timing to prevent cylinder cracking in particular engine models. The scope remains tightly focused on this single safety issue without expansion into broader operational or maintenance requirements."},"complexity_factors":["Short, single-purpose directive (2 main requirements with sub-paragraphs)","Only 2 defined technical terms requiring explanation (BTDC, part numbers)","Simple conditional logic based on cylinder part numbers (binary split: old vs new cylinders)","No cross-references to other legislation beyond a single reference to an FAA directive and a TCM service bulletin","Clear compliance deadlines with straightforward trigger events (50 hours time in service, cylinder replacement)","Limited applicability (specific engine models only)"],"plain_english_summary":"This CASA safety directive requires owners, operators and maintenance engineers of aircraft with Teledyne Continental or Rolls Royce O-200 series piston engines to set magneto timing to specified BTDC values (24° or 28° depending on cylinder design) and record the change, to stop cylinder cracking that can cause sudden engine failure.\n\nIt applies when cylinders are installed or replaced and mandates timely compliance to remove this known in‑flight safety risk."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The directive stays aligned with its stated purpose: prevent cylinder cracking by mandating magneto timing and record-keeping for the listed engines. It does not expand to other engine types or unrelated maintenance actions; it adds timing values, stamping, and recurring checks at cylinder replacement as implementation details rather than a change of substantive scope."},"complexity_factors":["Conditional rule based on cylinder part numbers (part number threshold 641917 distinguishes which timing applies) (Requirement 1(a) / 2(a)).","Two distinct timing settings and narrow tolerances: 24° ±1° BTDC versus 28° ±1° BTDC, requiring precise adjustment and measurement (Requirement 1(a) / 2(a)).","Mandatory permanent marking of the engine data plate to reflect the chosen timing (Requirement 1(b) / 2(b)), creating a documentation/traceability step.","Compliance timing obligations: Requirement 1 must be done within 50 hours time in service after 12 Sep 1996 and at each cylinder replacement; Requirement 2 effective 12 Sep 1996 and at each cylinder replacement (Compliance).","Procedural reliance on an external service bulletin (TCM SB No. SB94‑8) for the correct adjustment method, imposing dependence on that manual and its availability.","Applicability restricted to specific engine models (TCM O‑200A/B and Rolls Royce O‑200A/B/C), which narrows affected population but requires part-number checks (Applicability).","Cross-reference to FAA Airworthiness Directive 96‑12‑06 (Note), indicating harmonisation with or dependence on an external regulator's finding."],"plain_english_summary":"This airworthiness directive requires owners/operators of specified Teledyne Continental and Rolls Royce O-200 engines to set magneto ignition timing according to which cylinder part numbers are fitted, and to update the engine data plate to record the chosen timing. The measure is intended to prevent cylinder cracking and consequent loss of engine power; compliance deadlines include a 50‑hour window for certain engines and repeated action at each cylinder replacement, using the procedures in TCM Service Bulletin SB94‑8."},"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-con-75-magneto-timing","history":"/api/acts/ad-con-75-magneto-timing/history","analysis":"/api/acts/ad-con-75-magneto-timing/analysis","conflicts":"/api/acts/ad-con-75-magneto-timing/conflicts","importantCases":"/api/acts/ad-con-75-magneto-timing/important-cases","documents":"/api/acts/ad-con-75-magneto-timing/documents"}}