{"id":"F2006B11201","name":"AD/LYC/109 Amdt 2 - Crankshaft Gear Bolt","slug":"ad-lyc-109-amdt-2-crankshaft-gear-bolt","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56911,"registerId":"commonwealth-F2006B11201-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LYC/109 Amdt 2 - Crankshaft Gear Bolt","content":"![](image.001.png)\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nLycoming Pistons Engines\n\nAD/LYC/109\n\nAmdt 2\n\n  \nCrankshaft Gear Bolt 13/2003\n\nApplicability: 1. Except as described in Part 2 of this Applicability section:\n\nTextron Lycoming O-540, IO-540, AEIO-540, TIO-540 and LTIO-540 series engines; either\n\n    Factory new, factory rebuilt and factory overhauled engines listed by serial number in Textron Lycoming Mandatory Service Bulletin (MSB) 554 and Supplements to Textron Lycoming Mandatory Service Bulletin (MSB) 554; or\n\n    b. Engines that have had a crankshaft gear bolt part number (P/N) STD-2209 installed at Textron Lycoming Williamsport in the period 27 November 1996 to 10 November 1998; or\n\n    c. Engines fitted with a crankshaft gear bolt P/N STD-2209 that was supplied originally by Textron Lycoming during the period 27 November 1996 to 10 November 1998 and installed during field maintenance or at a field overhaul since 27 November 1996.\n\n    2. This directive is not applicable to Textron Lycoming O-540, IO-540, AEIO-540, TIO-540 and LTIO-540 series engines:\n\n    Incorporating single drive dual magnetos; or\n\n    b. O-540-F model engines:\n\n    Having had crankshaft gear bolt P/N STD-2209 replaced in accordance with AD/LYC/104 or FAA AD 99-03-05; or\n\n    ii. Listed by serial number in Table 1 of MSB 554; and\n\n    iii. Where the crankshaft gear bolt has not been subsequently replaced with a bolt supplied by Textron Lycoming during the period 27 November 1996 to 10 November 1998; or\n\n    c. Engines fitted with a Superior Air Parts FAA approved PMA crankshaft gear bolt P/N SL-STD-2209; or\n\n    d. Engines fitted with a crankshaft gear bolt included in Textron Lycoming gear bolt replacement kit 05K19987; or\n\n    e. Engines fitted with a crankshaft gear bolt P/N STD-2247; or\n\n    f. Engines that are supported by CASA recognised supply documentation detailing that Textron Lycoming did not originally supply the currently installed crankshaft gear bolt during the period 27 November 1996 to 10 November 1998.\n\nNote 1: Superior Air Parts PMA bolts may be identified by the letters SL on the bolt head.\n\nNote 2: Refer to CASA CAAP 42W-1(2) for CASA recognised supply documentation.\n\nRequirement: In accordance with Textron Lycoming MSB 554, replace the crankshaft gear bolt P/N STD-2209 with a bolt:\n\n    Included in Textron Lycoming gear bolt replacement kit 05K19987; or\n\n    ii. A bolt P/N SL-STD-2209 manufactured by Superior Air Parts under an FAA PMA approval; or\n\n    iii. A bolt P/N STD-2209 supplied by Textron Lycoming other than during the period 27 November 1996 through 10 November 1998; or\n\n    iv. A bolt P/N STD-2247.\n\nNote 3: FAA Airworthiness Directive 2002-23-06 refers\n\nCompliance: Unless previously accomplished; within 10 hours time in service or prior to 31 December 2003, whichever occurs first.\n\nThis Amendment becomes effective on 25 December 2003.\n\nBackground: This directive was originally issued to require certain crankshaft gear bolts to be removed from service. This amendment has been issued to amend the applicability to include engines detailed by serial number in Supplement 5 to MSB 554. The amendment also includes; the fitment of a bolt P/N STD-2247 provides a further terminating action for the requirements of this directive.\n\nAmendment 1 of this Airworthiness Directive became effective on 27 November 2002.\n\n![Signature of Jim Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJim Coyne\n\nDelegate of the Civil Aviation Safety Authority 12 November 2003\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 3 December 2003.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":false,"description":"This Amendment 2 refines and slightly expands the original AD’s reach by adding engines listed in Supplement 5 to MSB 554 and by recognising an additional terminating action (bolt P/N STD-2247). Those changes stay within the AD’s original corrective purpose — removing or replacing suspect crankshaft gear bolts — rather than changing the fundamental policy objective. Therefore the scope has not grown significantly beyond the original purpose; it has been adjusted and clarified (applicability expanded and an additional compliant replacement option added)."},"complexity_factors":["Multiple engine models listed (O-540, IO-540, AEIO-540, TIO-540, LTIO-540) increasing applicability matrix","Several distinct applicability paths (serial-number lists in MSB 554 and Supplements; bolts installed at Williamsport in a defined date range; bolts supplied originally during that period but installed later)","Part 2 contains multiple, specific exceptions (engine configurations, model-specific conditions, prior AD-compliant replacements)","Four different acceptable terminating actions (kit 05K19987, Superior PMA SL-STD-2209, STD-2209 supplied outside the suspect period, STD-2247)","Cross-references to external documents: Textron Lycoming MSB 554 and its Supplements, FAA ADs (2002-23-06 and earlier), CASA CAAP 42W-1(2)","Time-limited compliance window (10 hours time-in-service or a calendar date) creates urgency and operational scheduling complexity","Identification requirements that may require documentary proof of supply or physical inspection (bolt head marking 'SL')","Serial-number lists are not reproduced in the AD but exist in external Supplements — requires cross-checking and additional steps for operators","Amendment history (original AD, Amendment 1, Amendment 2) requiring operators to reconcile prior directives and prior compliance actions"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- This is an Airworthiness Directive (AD) that requires owners/operators of certain Textron Lycoming O-540 series piston aircraft engines to replace a particular crankshaft gear bolt (part number STD-2209) when that bolt was installed or supplied during the period 27 November 1996 to 10 November 1998.  \n- The replacement must be carried out following the instructions in Textron Lycoming Mandatory Service Bulletin (MSB) 554.  \n- Acceptable replacement bolts are: a bolt from Textron Lycoming kit 05K19987, a Superior Air Parts bolt P/N SL-STD-2209 (an FAA-approved PMA — Parts Manufacturer Approval), a STD-2209 bolt supplied by Textron Lycoming but supplied outside the suspect 1996–1998 period, or a bolt P/N STD-2247.  \n- Compliance deadline: within 10 hours time-in-service after the AD applies, or by 31 December 2003, whichever comes first.  \n- The AD lists multiple narrow exceptions (engines not affected), and points to MSB 554 (and its Supplements) for serial-number lists and further detail.  \n\n**Who it affects**\n\n- Aircraft owners/operators and maintenance organisations who operate Textron Lycoming O-540, IO-540, AEIO-540, TIO-540 and LTIO-540 series engines that either:  \n  - appear by serial number in MSB 554 and its Supplements; or  \n  - had a STD-2209 crankshaft gear bolt installed at Textron Lycoming Williamsport between 27 Nov 1996 and 10 Nov 1998; or  \n  - have a STD-2209 supplied originally by Textron Lycoming during that same period and installed later in the field.  \n- The AD excludes several engine configurations and situations (for example, engines with single-drive dual magnetos, certain O-540-F engines that have already had the bolt replaced under earlier ADs or that are listed in Table 1 of MSB 554 and have not had the suspect bolt re-fitted, engines fitted with Superior PMA SL-STD-2209, engines fitted from replacement kit 05K19987, engines fitted with STD-2247, or where recognised supply documentation shows Textron did not supply the bolt in that period).\n\n**Why it matters (purpose claims and practical effects)**n\n- The stated purpose (Background) is to remove potentially unsafe crankshaft gear bolts from service. The AD’s corrective mechanism is mandatory replacement of the suspect bolts (Requirement).  \n\n- Who pays and who decides: CASA (through its delegate) mandates the action; aircraft owners/operators pay for the replacement parts, labour and downtime. Maintenance organisations decide how to schedule the work and verify parts.  \n\n- Behaviour changes required: owners/operators must identify affected engines (by serial number or supply/installation date), inspect or confirm the bolt P/N, obtain an approved replacement part, and have the replacement carried out within the tight compliance window (10 hours TIS or by the specified date). Records/supply documentation may need to be checked or produced (the AD references CASA CAAP 42W-1(2) for recognised supply documentation).  \n\n- Effects on private enterprise and the market: the AD permits a Superior Air Parts PMA part (SL-STD-2209), which allows an aftermarket supplier to compete with Textron Lycoming for the replacement market. Accepting multiple terminating actions (including STD-2247 and the replacement kit) gives operators options in sourcing parts and reduces a sole-source dependency.  \n\n**Costs, incentives, trade-offs and implementation risks**\n\n- Direct costs: parts, labour and aircraft downtime. If many engines are affected, total industry costs can be meaningful; for individual owners the cost is discrete but unavoidable once identified.  \n- Scheduling and opportunity cost: the 10-hour TIS window is short and may force operators to bring aircraft forward for maintenance sooner than planned, displacing other work.  \n- Supply risk: availability of approved replacement bolts (especially if operators wait) could constrain compliance and raise replacement prices temporarily.  \n- Identification and documentation burden: operators must determine whether a bolt was supplied/installed in the suspect period; where original supply records are missing, additional investigation or physical inspection (bolt head marking — Superior PMA bolts are marked “SL”) is necessary. The AD points to CASA guidance for what counts as recognised supply documentation.  \n- Regulatory cross-references and duplication: the AD refers to Textron Lycoming MSB 554 (and Supplements), FAA AD 2002-23-06, and earlier ADs (e.g. AD/LYC/104, FAA AD 99-03-05) — operators must reconcile these references when planning compliance.  \n\n**Concentrated benefits and diffuse costs**\n\n- Concentrated benefits: suppliers of approved replacement bolts (including Superior Air Parts and kit suppliers) will receive direct sales from required replacements.  \n- Diffuse costs: the maintenance cost and downtime are spread across many aircraft owners/operators.  \n\n**Implementation and enforcement**\n\n- CASA enforces compliance via its airworthiness regulatory powers; maintenance records showing the replacement and the part installed will be the primary compliance evidence.  \n- The AD allows certain alternatives (specified part numbers and kits) as terminating actions, which gives maintenance providers a clear compliance path.\n\n**Source-identified change**\n\n- The AD itself states that this Amendment 2 extends the applicability to include engines listed by serial number in Supplement 5 to MSB 554 and adds STD-2247 as an additional terminating action (Background). These are the concrete scope changes made by this amendment.\n\n(References in the AD: Applicability; Requirement; Compliance; Background; Notes regarding identification and recognised documentation.)"},"kimi_summary":{"content_quality":"ok","complexity_score":6,"scope_assessment":{"changed":true,"description":"The original directive (implied by the Background) required removal of certain crankshaft gear bolts. Amendment 2 expands the scope beyond the original applicability to include engines detailed by serial number in Supplement 5 to MSB 554 — effectively adding more engines to the mandatory replacement pool. It also adds a new terminating action option (bolt P/N STD-2247), broadening the compliance pathways while maintaining the core safety objective."},"complexity_factors":["Multiple nested exemption criteria in Part 2 of the Applicability section (6 separate exemption categories with sub-clauses)","Date-range dependencies requiring historical tracking of parts (27 November 1996 to 10 November 1998)","Cross-references to external documents: Textron Lycoming MSB 554 and its Supplements (1-5), FAA AD 99-03-05, FAA AD 2002-23-06, CASA CAAP 42W-1(2), and previous CASA AD/LYC/104","Four alternative compliance pathways in the Requirement section with specific part numbers and sourcing conditions","Dual-threshold compliance deadline (flight hours OR calendar date, whichever is earlier)","Serial number tracking requirements for factory engines listed in manufacturer bulletins","Documentation requirements for exemption eligibility (CASA recognised supply documentation)"],"plain_english_summary":"This AD requires replacement of potentially unsafe Lycoming crankshaft gear bolts (P/N STD-2209) installed between 27 Nov 1996 and 10 Nov 1998 on certain O‑540, IO‑540, AEIO‑540, TIO‑540 and LTIO‑540 engines. It affects owners/operators of those engines because bolt failure can lead to catastrophic engine loss. Exemptions include engines already compliant, those with approved replacement bolts/kits or single‑drive dual magnetos. Replacement is required within 10 flight hours or by 31 Dec 2003."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-lyc-109-amdt-2-crankshaft-gear-bolt","history":"/api/acts/ad-lyc-109-amdt-2-crankshaft-gear-bolt/history","analysis":"/api/acts/ad-lyc-109-amdt-2-crankshaft-gear-bolt/analysis","conflicts":"/api/acts/ad-lyc-109-amdt-2-crankshaft-gear-bolt/conflicts","importantCases":"/api/acts/ad-lyc-109-amdt-2-crankshaft-gear-bolt/important-cases","documents":"/api/acts/ad-lyc-109-amdt-2-crankshaft-gear-bolt/documents"}}