{"id":"F2006B08655","name":"AD/CON/79 Amdt 2 - Crankshaft Inspection","slug":"ad-con-79-amdt-2-crankshaft-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51730,"registerId":"commonwealth-F2006B08655-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CON/79 Amdt 2 - Crankshaft Inspection","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/79\n\nAmdt 2\n\n  \nCrankshaft Inspection 11/99\n\nApplicability: 1. O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, IO-550, TSIO-550 and\n\nTSIOL-550 engines detailed by serial number in TCM Mandatory Service Bulletin MSB 99-3C as incorporating a crankshaft that was manufactured or rebuilt by Teledyne Continental Motors (TCM) in the period 1 January 1998 to 31 December 1998, and\n\n    2. GTSIO-520 and GIO-550 engines detailed by serial number in TCM Critical Service Bulletin CSB 99-6A as incorporating a crankshaft that was manufactured by Teledyne Continental Motors (TCM) in the period 1 January 1998 to 31 December 1998.\n\nThis directive is not applicable to engines released new, rebuilt, overhauled or last repaired prior to 1998. Nor is the directive applicable to engines fitted with crankshafts repaired or overhauled by an organisation other than TCM.\n\nNote 1: Copies of TCM MSB 99-3C and CSB 99-6A may be obtained by contacting TCM, an authorised TCM distributor or by accessing the TCM website [www.tcmlink.com](http://www.tcmlink.com/)\n\nRequirement: To prevent the possible fracture of the crankshaft resulting in failure of the engine, inspect the crankshaft in accordance with the procedures detailed in TCM MSB 99- 3C or CSB 99-6A as applicable by engine model.\n\nNote 2: FAA Airworthiness Directive 99-09-17 refers.\n\nCompliance: 1. Applicable O-470, IO-470, TSIO-470, IO-520, TSIO-520, LTSIO-520, IO-550,\n\nTSIO-550 and TSIOL-550 engines:\n\nUnless previously accomplished; effective 4 November 1999:\n\n    Applicable engines with less than 500 hours time in service since installation of a 1998 manufactured or 1998 TCM rebuilt crankshaft; within 10 hours time in service from the effective date of this directive.\n\n    B. Applicable engines with greater than 500 hours time in service since installation of a 1998 manufactured or 1998 TCM rebuilt crankshaft; within 50 hours time in service from the effective date of this directive or at the next periodic inspection after the effective date of this directive, whichever occurs first.\n\n    2. Applicable GTSIO-520 and GIO-550 engines:\n\nUnless previously accomplished; effective 4 November 1999:\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n    Applicable engines with less than 500 hours time in service since installation of a 1998 manufactured crankshaft; within 10 hours time in service from the effective date of this directive.\n\n    B. Applicable engines with greater than 500 hours time in service since installation of a 1998 manufactured crankshaft; within 50 hours time in service from the effective date of this directive or at the next periodic inspection after the effective date of this directive, whichever occurs first.\n\n    3. Spare engines:\n\nPrior to installation in an aircraft.\n\nThis Amendment becomes effective on 4 November 1999.\n\nBackground: This directive was originally issued to require a once only inspection of crankshafts manufactured in 1998. The original requirement reflected advice of seven (7) crankshaft fractures which have occurred in engines fitted with crankshafts manufactured during 1998. An investigation of those fractures has revealed the crankshafts had been damaged during the counterweight bushing installation process.\n\nAmendment 1 added crankshafts rebuilt by TCM during the period of concern. This amendment has been issued to reflect:\n\n    The manufacturer’s revision to the original requirement document. MSB 99- 3C, in part, increases the critical compliance period from 300 to 500 hours, and\n\n    2. The addition of GTSIO-520 and GIO-550 engines. The increase in engine models applicable reflects advice of a crack found in a GTSIO-520 crankshaft also manufactured during 1998.\n\nAmendment 1 of this Directive became effective on 16 June 1999. The original issue of this directive became effective on 12 May 1999.","sortOrder":0}],"analysis":{"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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Yes. The AD has expanded beyond its original, narrowly framed requirement. The original directive required a once‑only inspection of crankshafts manufactured in 1998. Subsequent amendments broadened scope in two concrete ways: (1) Amendment 1 added crankshafts that were rebuilt by TCM in 1998 (so rebuilt crankshafts became subject to the inspection), and (2) this amendment increases the critical compliance threshold (from 300 to 500 hours) and adds the GTSIO‑520 and GIO‑550 engine models after discovery of an additional crankshaft crack. Both changes materially expand which engines and crankshafts are captured and change the compliance timing (see \"Background\" and \"Amendment\" notes)."},"complexity_factors":["Multiple engine model groups listed (10+ models across two groups).","Applicability relies on external manufacturer documents (TCM MSB 99-3C and CSB 99-6A) that contain serial‑number lists and procedures.","Conditional compliance windows based on time‑in‑service (<500 hours = within 10 hours; >500 hours = within 50 hours or next periodic inspection).","Exclusions (engines released/new/repaired prior to 1998; crankshafts repaired by non‑TCM organisations) add conditional logic.","Amendment history: scope expanded from original, including addition of rebuilt crankshafts and extra engine models, and change of the critical hours threshold from 300 to 500.","Cross‑reference to FAA AD and manufacturer service bulletins for technical steps and serial numbers."],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an Airworthiness Directive (AD) requiring owners/operators of certain Teledyne Continental Motors (TCM) piston engines to have the engine crankshaft inspected once, following the inspection steps set out by TCM in two service documents (MSB 99-3C or CSB 99-6A). (See: \"Requirement\" and \"Compliance\".)\n\n**Which engines and crankshafts are covered**\n\n- Covered engines are listed by model groups: O‑470, IO‑470, TSIO‑470, IO‑520, TSIO‑520, LTSIO‑520, IO‑550, TSIO‑550, TSIOL‑550, and certain GTSIO‑520 and GIO‑550 engines. The specific serial numbers are in TCM MSB 99-3C or CSB 99-6A. (See: \"Applicability\".)\n- The directive applies only to crankshafts that were manufactured by TCM in calendar year 1998, and (for most models) to crankshafts rebuilt by TCM in 1998. It does not apply to engines or crankshafts that were released new, rebuilt, overhauled or last repaired before 1998, nor to crankshafts repaired/overhauled by organisations other than TCM. (See: \"Applicability\" and the Note on exclusions.)\n\n**When the inspection must be done (compliance timing)**\n\n- If the 1998 crankshaft has been installed for less than 500 hours: inspection must be carried out within 10 hours time-in-service from the AD’s effective date.\n- If the 1998 crankshaft has been installed for more than 500 hours: inspection must be carried out within 50 hours time-in-service from the AD’s effective date or at the next periodic inspection after the AD’s effective date, whichever comes first.\n- For spare engines with a covered crankshaft, the inspection must be done before the engine is installed in an aircraft. (See: \"Compliance\" paragraphs 1–3.)\n\n**How to carry out the inspection**\n\n- The AD requires the inspection to follow the procedures and acceptance criteria set out in the TCM documents MSB 99-3C (for most models) or CSB 99-6A (for the GTSIO/GIO models). The AD points owners to where those documents can be obtained. (See: \"Requirement\" and Note 1.)\n\n**Why the AD was issued (stated purpose) and what the investigation found**\n\n- The stated aim is to prevent crankshaft fracture and consequent engine failure. The directive follows reports of seven fractures in engines fitted with crankshafts manufactured during 1998; investigators found damage occurred during the counterweight bushing installation process. (See: \"Background\".)\n- Amendment history: the AD originally required a once-only inspection for crankshafts manufactured in 1998. Amendment 1 added TCM‑rebuilt crankshafts and later this amendment (Amdt 2) (a) increases the critical compliance threshold from 300 to 500 hours (following TCM’s revision), and (b) adds the GTSIO‑520 and GIO‑550 models after a crack was found in a GTSIO‑520 crankshaft from 1998. (See: \"Background\" and \"Amendment\" notes.)\n\n**Who pays, who decides, and what behaviour changes**\n\n- Who pays: aircraft owners/operators (or whoever holds responsibility for maintenance) pay for the inspection work, any non‑routine disassembly or non‑destructive testing (if required), and any repair or replacement if defects are found. Downtime and opportunity cost of the aircraft while it is inspected or repaired are also borne by the owner/operator. (Implicit from the AD’s compliance obligations.)\n- Who decides: the Civil Aviation Safety Authority (CASA) issued and enforces the AD; TCM provides the inspection procedures and the list of serial numbers in MSB 99-3C and CSB 99-6A. The owner/operator must determine whether their engine/crankshaft serial number appears in the manufacturer’s documents and then follow that procedure. (See: \"Applicability\", \"Requirement\", and Note 1.)\n- Behaviour change required: owners/operators must check serial numbers, schedule and carry out the one‑time inspection within the specified hours, and avoid installing a spare engine with an uninspected 1998 crankshaft without first complying. Some owners may choose to avoid using TCM‑manufactured or TCM‑rebuilt crankshafts from 1998 when possible. (See: \"Compliance\" and \"Spare engines\".)\n\n**Costs, incentives, trade‑offs and implementation risks**\n\n- Compliance cost and downtime: the AD creates a direct inspection cost and possible repair/replacement cost if cracks or damage are found. Aircraft may be removed from service briefly, creating opportunity costs for operators. (See: \"Compliance\" and \"Requirement\".)\n- Dependence on manufacturer documentation: the AD references TCM MSB 99-3C and CSB 99-6A for procedures and serial numbers, so operators are expected to obtain and follow a manufacturer’s document. That creates a reliance on TCM for the technical steps and the definitive list of affected serial numbers. (See: \"Requirement\" and Note 1.)\n- Scope narrowing by exclusions: where crankshafts were repaired or overhauled by organisations other than TCM, those crankshafts are excluded; that changes which engines carry obligations and could affect repair/overhaul choices going forward. (See: Applicability exclusions.)\n- Enforcement practicality: CASA enforces compliance via its regulatory framework for airworthiness. Practical enforcement depends on operators’ recordkeeping (serial numbers, time‑in‑service) and the ability to verify inspections during audits or after incidents. (Implicit in a compliance regime.)\n\n**Concrete trade‑offs**\n\n- Concentrated benefit / diffuse cost: the safety benefit (reduced risk of crankshaft fracture) is concentrated on operators of affected engines and their passengers; the financial cost is borne by those same operators and by owners of spare engines. The AD does not create a subsidy or compensation for inspection costs. (Based on the AD’s compliance and applicability rules.)\n\n**Implementation note**\n\n- Operators must consult the TCM documents (MSB 99-3C or CSB 99-6A) for the exact serial numbers and the inspection procedure. The AD explicitly points users to those manufacturer documents. (See: Note 1 and \"Requirement\".)\n\n(References in this summary: Applicability; Requirement; Compliance; Background; Amendment notes; Notes 1–2 of the AD.)"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The directive has expanded beyond its original scope. Initially issued to address crankshafts manufactured in 1998 only, Amendment 1 added crankshafts rebuilt by TCM in 1998. Amendment 2 further expanded the scope to include additional engine models (GTSIO-520 and GIO-550) and increased the critical compliance threshold from 300 to 500 hours based on new manufacturer data and discovery of additional cracked crankshafts."},"complexity_factors":["Multiple engine model categories with slightly different compliance rules (Group 1: O-470/IO-470/IO-520/IO-550 series vs Group 2: GTSIO-520/GIO-550)","Nested conditional logic based on 'time in service' thresholds (500-hour cutoff) and effective dates","Cross-references to external manufacturer documents (TCM MSB 99-3C and CSB 99-6A) that are not reproduced in the directive itself","Amendment history creates layered applicability (original issue → Amendment 1 → Amendment 2) with evolving scope","Specific serial number tracking required via manufacturer bulletins","Exclusions based on repair history and manufacturing date (pre-1998 engines, non-TCM overhauls)"],"plain_english_summary":"This Airworthiness Directive orders owners/operators and maintenance organisations to inspect crankshafts on certain Teledyne Continental piston engines that were manufactured or rebuilt by TCM in 1998 after several fractured crankshafts were found. The inspections must follow TCM service bulletins and be done urgently (very short flight‑hour windows for recently installed/suspect units, and before installing spares). It’s a mandatory safety action to prevent in‑flight engine failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-con-79-amdt-2-crankshaft-inspection","history":"/api/acts/ad-con-79-amdt-2-crankshaft-inspection/history","analysis":"/api/acts/ad-con-79-amdt-2-crankshaft-inspection/analysis","conflicts":"/api/acts/ad-con-79-amdt-2-crankshaft-inspection/conflicts","importantCases":"/api/acts/ad-con-79-amdt-2-crankshaft-inspection/important-cases","documents":"/api/acts/ad-con-79-amdt-2-crankshaft-inspection/documents"}}