AD/LYC/115 - Lycoming Crankshaft Replacement

The AD organises around a small number of concrete regulatory concepts: applicability by engine model and manufacturing/maintenance chronology; a serial-number-driven identification regime; mandatory removal and replacement of certain crankshafts; a prohibition on future installation of listed crankshafts; a defined compliance timeframe; and cross-references to the manufacturer’s mandatory service bulletin and a comparable FAA AD.

Applicability: The AD specifies the engines covered by make and model series (AEIO-360, IO-360, O-360, LIO-360, LO-360) and then describes scope in terms of production and maintenance history , engines manufactured new or rebuilt, overhauled, or that had a crankshaft installed after 1 March 1999 (Applicability). That phrasing makes the AD contingent on a historic cutoff date for crankshaft installation rather than on calendar age alone.

Identification mechanics: The AD delegates identification to Lycoming’s documentation. Operators must check engine and crankshaft serial numbers against Table 1 and Table 2 of Supplement No. 1 to Lycoming MSB No. 566, dated 30 November 2005. The tasks are sequentially specified: if Table 1 lists your engine serial number, use Table 2 to verify whether that engine contains an affected crankshaft; if Table 1 does not list the engine serial number, consult Table 2 directly to see if an affected crankshaft was installed as a replacement (Requirement 1). The AD therefore uses serial-number lookup tables as the definitive determinant of regulatory obligation.

Replacement and prohibition: Where a crankshaft’s serial number appears in Table 2, the AD requires replacement with a crankshaft that is not listed in Table 2 (Requirement 2). Separately, it prohibits the installation, after the AD’s effective date, of any crankshaft whose serial number appears in Table 2 into any engine (Requirement 3; Compliance item 3). The prohibition is prospective and absolute in wording: "Do not install any crankshaft that has a SN listed in Table 2 ... into any engine" (Requirement 3).

Timing: The inspection and replacement obligations are time-limited , to be completed within 50 hours time-in-service or 6 months after the effective date of the AD, whichever is earlier , unless previously accomplished (Compliance items 1-2). The replacement prohibition applies from the effective date forward (Compliance item 3).

Cross-references and context: The AD instructs use of Supplement No. 1 to Lycoming MSB No. 566 (dated 30 November 2005) as the operative identification document and explicitly notes relationship to other Lycoming MSBs (No. 552, No. 553 and No. 566) and CASA ADs AD/LYC/107 and AD/LYC/112 (Requirement Note 2). It also references FAA AD 2006-06-16 Amendment 39-14525 (Requirement Note 3), which it says is referred to by the Lycoming MSB.

Safety rationale: The background statement links the AD to a specific crankshaft failure event in a Lycoming LO-360-A1H6 engine and frames the AD as preventative of in-flight engine failure and possible loss of aircraft (Background). That causal linkage is presented as the reason for the serial-number-based mandatory action.

Administrative provenance: The document ends with the delegate signature "James Coyne, Delegate of the Civil Aviation Safety Authority" and the dates 29 March 2006 (signature) and 11 May 2006 (effective date). The AD carries the identifier AD/LYC/115 and the internal date code 5/2006.

The AD assigns obligations to aircraft owners and operators who use or maintain the affected Lycoming engine series. The formal applicability language makes the set of affected parties those who own or operate engines in the listed series "manufactured new or rebuilt, overhauled, or that had a crankshaft installed after 1 March 1999" (Applicability). This formulation targets engines with a certain manufacturing or maintenance status rather than all engines of those models categorically. Practically, the following groups are implicated:

• Aircraft owners/operators with an installed Lycoming AEIO-360, IO-360, O-360, LIO-360 or LO-360 engine where the engine or its crankshaft falls into the post-1 March 1999 category. The owner or operator is required to check serial numbers and, where necessary, replace crankshafts (Requirement 1-2; Compliance 1-2).

• Maintenance organisations, mechanics and overhaul facilities that perform engine inspections, serial-number verification, removals and installations. The AD prohibits the installation of any crankshaft listed in Table 2 of Supplement No. 1 to Lycoming MSB 566 into any engine after the AD’s effective date, thereby imposing a direct operational constraint on what parts can be installed (Requirement 3; Compliance 3).

• Parts suppliers and sellers dealing in Lycoming crankshafts. The AD’s prohibition on installing listed serial-number crankshafts creates a downstream restriction on circulation and sale for the listed serial-number parts after the effective date.

• Regulatory and airworthiness personnel charged with compliance oversight. CASA’s issuance and the effective date (11 May 2006) define the period when compliance and enforcement expectations apply (signature and effective date).

• Any party that repaired, overhauled, replaced or manufactured crankshafts for these engines. Note 1 addresses engines where Lycoming manufactured, rebuilt, overhauled or replaced the crankshaft before 1 March 1999. The Note states that if Lycoming did that before 1 March 1999 and the crankshaft has not been replaced since, "no further action is required" (Requirement Note 1). Where a crankshaft was installed after 1 March 1999, or where replacements have occurred after that cutoff, the obligations apply.

The AD does not create explicit exceptions beyond Note 1, and it treats earlier Lycoming-serviced crankshafts differently. The instrument also identifies relationships to other Lycoming MSBs and to prior CASA ADs (Requirement Note 2), so owners/operators who have complied with earlier MSBs or ADs will need to confirm whether their earlier compliance satisfies this AD’s specific serial-number checks and replacement prohibition.

Who pays: The AD’s mandatory replacement obligation implies that owners/operators will bear the direct cost of replacing an affected crankshaft and any associated labour and downtime, since the AD commands replacement in Requirement 2 and sets private parties as the ones to check and replace within the specified compliance window. The AD itself does not specify funding or subsidies.

Who decides: The AD places the initial decision task on the owner/operator to check serial numbers against Lycoming’s tables (Requirement 1); where Table 2 lists a crankshaft serial number, there is no discretion , replacement is required (Requirement 2). Installation decisions are constrained by the absolute prohibition (Requirement 3). CASA sets the requirement, Lycoming supplies the identification tables, and the owner/operator and maintenance providers execute the work.

Duties

• Serial number verification: Owners/operators must check the engine serial number and crankshaft serial number against the tables in Supplement No. 1 to Lycoming MSB No. 566 (dated 30 November 2005). The AD instructs a two-step check: if Table 1 lists your engine serial number, use Table 2 to verify whether the crankshaft serial number is listed; if Table 1 does not list your engine serial number, consult Table 2 directly to see if an affected crankshaft was installed as a replacement (Requirement 1). This is a mandatory, affirmative duty to consult the specified manufacturer documentation.

• Mandatory replacement: If a crankshaft’s serial number appears in Table 2 of Supplement No. 1, the owner/operator must replace that crankshaft with one that is not listed in Table 2 to Lycoming MSB 566 (Requirement 2). The obligation is concrete and prescriptive: affected parts must be removed and substituted.

• Prohibition of installation: From the effective date forward, no one may install any crankshaft whose serial number is listed in Table 2 into any engine (Requirement 3; Compliance 3). This is a continuing prohibition on future installation of specific serial-numbered parts.

• Timing obligation: Unless already accomplished, the checks and, where necessary, replacement must be done within "50 hours time-in-service or 6 months after the effective date of this AD, whichever is earlier" (Compliance items 1-2). The AD therefore imposes a short compliance window.

• Use of specified documents: The duties are explicitly tied to Lycoming MSB No. 566 Supplement No. 1 dated 30 November 2005 as the authoritative reference for serial-number identification (Requirement 1).

Rights or entitlements (as implied by the text)

• Note 1 offers a relief-like statement: "If Lycoming Engines manufactured new, rebuilt, overhauled, or replaced the crankshaft in your engine before 1 March 1999, and you haven't had the crankshaft replaced, no further action is required." That is an express carve-out for certain earlier Lycoming-serviced crankshafts (Requirement Note 1). Where that condition is met by an owner/operator, the AD states there is no further action required.

• The AD does not create an explicit right to compensation or funding for replacement costs; it does not grant exemptions except as provided by Note 1. Similarly, the AD does not grant rights to install listed crankshafts after the effective date; instead it imposes a prospective prohibition.

• Operators are entitled to rely on Lycoming MSB Supplement No. 1 as the identification source. The AD makes Lycoming’s tables the operative determiner of obligation and therefore confers a functional reliance right on those documents for compliance.

Execution and record-keeping

• The AD does not set out audit or record-keeping processes in the text supplied, but the requirement to check serial numbers and to replace or not install parts implies that maintenance records and logbook entries will need to reflect compliance in practice. The text does not prescribe the form or content of such entries.

Delegations and decision nodes

• CASA issued the AD and provided the effective date; the instrument authorises no discretionary exemptions within the text supplied. The decision nodes available to owners/operators are: verify serial numbers against the specified tables; where listing occurs, execute replacement within the stated timeframe; avoid installing listed crankshafts after the effective date.

The AD text supplied does not itself state specific penalties, monetary fines or criminal sanctions for non-compliance. It is an airworthiness directive that places mandatory obligations on owners, operators and maintenance providers. The enforcement implications derive from its nature as an AD issued by CASA and from the duties set out (check serial numbers, replace affected crankshafts within the specified timeframe, and avoid installing listed crankshafts after the effective date).

Enforcement mechanisms implied by the text

• Regulatory authority: CASA is the issuing authority (signature by James Coyne, Delegate of the Civil Aviation Safety Authority, dated 29 March 2006). As such, CASA is the body responsible for monitoring, investigating and enforcing compliance with its ADs in the Australian civil aviation regulatory framework. The AD itself sets prescriptive requirements which CASA can expect to be enforced through its normal regulatory powers, though those enforcement powers are not specified in this AD text.

• Operational consequences: Non-compliance with the AD would leave an aircraft operating with a crankshaft that the AD identifies as having a demonstrated failure risk. The AD states the safety hazard , "could result in total engine power loss, in-flight engine failure, and possible loss of the aircraft" (Background). Regulators typically use safety risk as a basis to require rectification; although this AD text does not list penalties, operating an aircraft contrary to an AD will typically expose the operator to regulatory action.

• Maintenance approval and certification: Because the AD requires removal and replacement of a component, an aircraft that has not complied may not meet airworthiness conditions necessary for a valid maintenance release, certificate of airworthiness, or equivalent regulatory approvals. The AD text does not specify these downstream certification mechanisms, but compliance with ADs is typically a condition of continued legal operation in airworthy form.

• Supply-side constraints: The AD’s prohibition on installation of listed crankshafts after the effective date effectively renders those parts unfit for legal installation in Australia in the affected engines. Suppliers or maintenance providers who install such parts would expose themselves and the operator to enforcement scrutiny.

Absence of explicit penalties in the text

• The AD does not include a schedule of fines, sanctioning provisions or an explicit enforcement process. Any penalties, criminal liability or administrative actions therefore are those existing within CASA’s regulatory toolkit rather than newly created by this AD’s text. The AD’s immediate legal force is to set mandatory corrective action; enforcement processes and penalties would be exercised under the enabling aviation safety legislation and CASA’s regulatory powers rather than within this AD document itself.

Cross-reference to FAA AD

• The AD notes that "FAA AD 2006-06-16 Amendment 39-14525 refers" (Requirement Note 3). That reference indicates a parallel FAA action; while the CASA AD is the enforceable Australian instrument, the cross-reference may guide inspectors and maintenance organisations to the technical context used in enforcement. The AD does not set out differing penalties or enforcement measures tied to the FAA AD.

The AD expressly cross-references manufacturer service communications and earlier airworthiness directives, creating an interaction network between CASA’s regulatory instrument, Lycoming’s service material, and an FAA AD. The document does not set out a comprehensive scheme of interaction with all other laws, but from the text we can infer the following interactions and linkages:

Interaction with manufacturer documents

• The AD makes Lycoming Mandatory Service Bulletin No. 566 (Supplement No. 1 dated 30 November 2005) the operative technical reference for determining which engines and crankshafts are affected. The Requirement directs owners/operators to use Table 1 and Table 2 in that Supplement to verify serial numbers (Requirement 1). This is an example of regulatory reliance on manufacturer-provided technical data: compliance with the AD is achieved by acting on the manufacturer’s lists.

Interaction with other CASA ADs and Lycoming MSBs

• The AD explicitly notes that the engine and crankshaft serial numbers in Supplement No. 1 are different from those affected by Lycoming MSBs No. 552, No. 553 and No. 566 and CASA ADs AD/LYC/107 and AD/LYC/112 (Requirement Note 2). That statement indicates that owners/operators who previously complied with those earlier service bulletins or ADs should not assume that those actions necessarily satisfy this AD. The AD therefore modifies or supplements the scope of prior instruments by focusing on a different set of serial numbers.

Interaction with FAA ADs

• The AD notes that FAA AD 2006-06-16 Amendment 39-14525 "refers" (Requirement Note 3). The CASA AD stands on its own as an Australian regulatory requirement for Australian operators, but the reference signals technical equivalence or coordination with FAA action. The AD does not state that compliance with the FAA AD automatically satisfies the CASA requirement; instead it instructs operators to use Lycoming’s Supplement No. 1 and indicates the FAA AD is relevant.

Interaction with maintenance and airworthiness certification regimes

• By imposing mandatory part replacement and a prohibition on installing listed crankshafts, the AD affects what maintenance organisations can lawfully certify. While the AD text does not directly specify how certification or logbook entries are to be handled, in practice, compliance with ADs is intrinsic to maintaining an aircraft in an airworthy condition under aviation safety legislation. The AD’s requirements therefore intersect with obligations under aircraft maintenance, repair and overhaul regulation and with the conditions for legal operation.

No express interaction with civil liability or insurance provisions

• The AD does not mention civil liability, insurance coverage, or tort consequences. However, the safety rationale and mandatory nature of the AD suggest that continuing to operate with a listed crankshaft could have downstream implications for insurance coverage or liability in the event of failure; those implications are not stated in the AD text and would arise under contract and tort law and insurance policy terms outside the AD itself.

No explicit conflict-resolution clause

• The AD does not include a clause resolving conflicts with other instruments. Instead it sets an independent set of obligations tied to Lycoming’s Supplement No. 1 and the effective date. In cases where multiple ADs or service bulletins apply, operators must ensure compliance with each relevant instrument. The Note that serial numbers differ from earlier MSBs and ADs signals that overlapping instruments exist and that a straightforward reliance on past compliance may not be sufficient.

The supplied text provides limited explicit amendment history. The AD identifier includes "5/2006" and the instrument is dated 29 March 2006 with an effective date of 11 May 2006. The document names the related Lycoming Mandatory Service Bulletin (MSB No. 566) and its Supplement No. 1 dated 30 November 2005 as the operative technical reference.

Items in the text that bear on amendment history:

• Issuance date and effective date: The AD was signed on 29 March 2006 by James Coyne, Delegate of CASA, and the AD "becomes effective on 11 May 2006" (signature and effective date lines). These two dates define the AD’s creation and the date from which certain prohibitions apply.

• Reference to Lycoming MSB and supplements: The AD relies on Lycoming MSB No. 566 Supplement No. 1 (dated 30 November 2005) for the identification of affected serial numbers. The presence of that dated Supplement shows the AD is contemporaneous with manufacturer's data from late 2005.

• Relation to other MSBs and ADs: The AD states the engine and crankshaft serial numbers listed in Supplement No. 1 "are different from the engine and crankshaft SNs affected by Lycoming MSBs No. 552, No. 553 and No. 566; and CASA ADs AD/LYC/107 and AD/LYC/112" (Requirement Note 2). That language indicates prior service bulletins and CASA ADs exist which addressed similar issues at an earlier time; the AD therefore functions as a subsequent instrument that targets a different set of serial numbers. The AD does not detail earlier amendment stages for this specific instrument.

• Cross-reference to FAA AD: The AD records that FAA AD 2006-06-16 Amendment 39-14525 "refers" (Requirement Note 3). That suggests the FAA issued a parallel or related directive in 2006; the CASA AD does not include further detail on amendments or changes to its own text subsequent to issuance.

What the supplied text does not record

• There is no record in the supplied AD text of subsequent amendments to AD/LYC/115 itself. The AD text as provided contains the initial requirements, notes and compliance timing, with no later amendment clauses or revision notes inside the body of the text.

• The AD does not include an explicit history section summarising prior or subsequent modifications to AD/LYC/115. Consequently, from the supplied text, the only available amendment-history data points are the signature date (29 March 2006) and the effective date (11 May 2006), together with the associated Lycoming and FAA documents referenced by date.

For compliance and legal certainty, operators and maintenance organisations will need to check CASA’s official AD registry or current regulatory database for any later amendments, but such subsequent changes are not present in the supplied instrument.

The text of AD/LYC/115 supplied contains no litigation history. It does not reference any judicial decisions, legal proceedings, appeals against the AD, or proceedings involving CASA, Lycoming, operators, or third parties. The only legal-administrative information provided in the document is the AD’s issuance by CASA, the effective date, the serial-number checks and replacement requirement, and its cross-references to Lycoming MSB Supplement No. 1 and FAA AD 2006-06-16.

Implications of silence

• Because no litigation or appeal details appear in the AD text, the instrument stands as a regulatory directive without recorded judicial challenge in the supplied material. Any litigation events, appeals to the Administrative Appeals Tribunal, or judicial review instances are not present within this text.

• Where legal challenges to ADs arise, they typically concern procedural fairness, technical sufficiency, or whether the issuing authority stayed within its statutory powers. The supplied AD does not discuss such procedural matters, and no case citations or litigation outcomes are included.

What to do if litigation history is required

• The AD as supplied does not provide a litigation history; users needing authoritative information on whether AD/LYC/115 has been litigated should consult CASA’s records, legal databases, or court registries for any subsequent proceedings. That information is not contained in the instrument itself.

The AD includes multiple potential traps for owners, operators and maintenance providers if the text is not read carefully. The following issues arise directly from the AD’s wording and structure:

1. Serial-number lookup logic and Table dependencies: The AD requires use of Supplement No. 1 to Lycoming MSB No. 566 (dated 30 November 2005) and specifically directs a sequence of checks: consult Table 1 for the engine serial number and then Table 2 for crankshaft serial numbers, or consult Table 2 directly if Table 1 does not list the engine (Requirement 1). The "gotcha" is that compliance turns on referencing the correct Supplement and its specific tables. Using an earlier or different document, or misreading Table 1/Table 2 roles, could lead to incorrect conclusions about whether replacement is required.

2. The 1 March 1999 cutoff and Note 1 ambiguity: The Applicability section describes engines "manufactured new or rebuilt, overhauled, or that had a crankshaft installed after 1 March 1999." Note 1 then states: "If Lycoming Engines manufactured new, rebuilt, overhauled, or replaced the crankshaft in your engine before 1 March 1999, and you haven't had the crankshaft replaced, no further action is required." The interplay between the applicability cutoff and Note 1 can be confusing. Operators must be precise in determining whether a crankshaft was installed or last serviced before or after 1 March 1999 and whether Lycoming performed the work. The condition in Note 1 requires both that Lycoming performed the work before the cutoff and that the crankshaft has not subsequently been replaced.

3. Duplicate compliance text: The Compliance block repeats the same timing for items 1 and 2: "Unless previously accomplished, within 50 hours time-in-service or 6 months after the effective date of this AD, whichever is earlier." The repetition emphasises the short window but could be misread as applying differently. Users should treat both the serial-number check and the physical crankshaft replacement as subject to that timeframe if not already done.

4. Prohibition timing: Requirement 3 states "Do not install any crankshaft that has a SN listed in Table 2 of Supplement No. 1 to Lycoming MSB 566." Compliance item 3 clarifies that this applies "After the effective date of this AD." The gotcha is that parts installed before the effective date may still exist in circulation, but installation after the effective date is forbidden. Operators must reconcile parts inventories and maintenance plans so that prohibited serial-number parts are not fitted post-effective date.

5. Reliance on Lycoming’s Supplement: Because the AD delegates the identification task to Lycoming’s Supplement No. 1, any errors, ambiguities or updates in that Supplement will materially affect compliance outcomes. The AD does not itself include the tables; enforcement and compliance require access to the Supplement as dated (30 November 2005). Operators without that document risk non-compliance through omission.

6. Interaction with prior MSBs and ADs: Note 2 warns that the serial numbers in Supplement No. 1 differ from those in Lycoming MSBs No. 552, No. 553, No. 566 and CASA ADs AD/LYC/107 and AD/LYC/112. The gotcha is assuming compliance with those earlier instruments satisfies this AD. Operators must specifically check the Supplement No. 1 tables.

7. Technical specificity absent in the AD text: The AD describes the safety hazard and the required remedial action but does not detail technical replacement procedures, part numbers for compliant crankshafts, or installation instructions. Maintenance providers must consult Lycoming’s MSB and normal maintenance manuals for technical procedure. Failure to do so could result in improper replacement even where the serial-number swap is undertaken.

8. No explicit record-keeping or certification instructions: The AD does not specify the form of compliance evidence required. Operators must be prepared to document the checks and replacements in maintenance records and to demonstrate compliance to CASA upon inspection, even though the AD does not set out a required certificate format.

9. Cross-border parts circulation: The AD’s prohibition on installing listed crankshafts in Australian operations exists alongside an FAA AD reference. Operators should not assume that parts legal in other jurisdictions remain installable in Australia after the effective date; the AD explicitly forbids installation regardless of external status (Requirement 3; Compliance 3).

10. Timeliness and operational disruption: The 50-hour or 6-month deadline is short. Operators must plan for aircraft downtime, labour scheduling and parts sourcing in that window. The AD does not provide extensions or staged-compliance options within the text supplied.

Read carefully, maintain clear records of serial-number checks, and ensure maintenance providers have the dated Lycoming Supplement available. Failure to attend to these detail points could result in non-compliance or inadvertently continuing to operate with a crankshaft the AD identifies as a risk.

The AD sets a clear, short list of compliance steps. Below is a source-grounded, stepwise checklist that follows the AD’s exact directions and the Notes included in the instrument. The AD’s requirements are quoted or paraphrased from the text supplied; operators should perform these actions using the dated Lycoming document specified.

1. Obtain the operative documents

   • Secure a copy of Supplement No. 1 to Lycoming Mandatory Service Bulletin No. 566, dated 30 November 2005. The AD instructs use of Table 1 and Table 2 within that Supplement as the definitive identification lists (Requirement 1).

2. Determine whether your engine falls within the AD’s applicability

   • Confirm whether your engine is an AEIO-360, IO-360, O-360, LIO-360 or LO-360 series engine. Confirm the engine was "manufactured new or rebuilt, overhauled, or had a crankshaft installed after 1 March 1999" if applicable (Applicability). If the engine does not match these characteristics, the AD text indicates it is outside the stated applicability.

3. Serial-number checking process (Requirement 1)

   • If Table 1 in Supplement No. 1 lists your engine serial number, use Table 2 to verify whether your crankshaft serial number is listed. If Table 1 does not list your engine serial number, consult Table 2 directly to check whether an affected crankshaft serial number was installed as a replacement.
   • Record the engine serial number, crankshaft serial number, the table consulted and the outcome of this check in maintenance records. The AD requires the check but does not prescribe the record format; maintain sufficient documentation to demonstrate compliance.

4. Determine applicability of Note 1 (if relevant)

   • If Lycoming manufactured new, rebuilt, overhauled, or replaced the crankshaft in your engine before 1 March 1999 and the crankshaft has not been replaced since, Note 1 states "no further action is required." Verify documentation from Lycoming or maintenance logs to establish whether Lycoming performed the work and the date of that work. If both conditions are satisfied, log the basis for reliance on Note 1 in the aircraft’s maintenance records.

5. Replacement process where Table 2 lists the crankshaft SN (Requirement 2)

   • If your crankshaft serial number appears in Table 2 of Supplement No. 1, arrange for replacement with a crankshaft that is not listed in Table 2 to Lycoming MSB 566.
   • Use approved maintenance procedures and qualified personnel to perform the replacement. The AD does not provide the technical procedure; consult Lycoming’s MSB No. 566, the engine maintenance manual and applicable maintenance regulations for authorised workscopes and post-installation tests.
   • Ensure the replacement crankshaft’s serial number is checked and documented and that the replacement crankshaft is demonstrably not listed in Table 2.

6. Observe the compliance timeframe (Compliance items 1-2)

   • Where not previously accomplished, perform the serial-number check and any required replacement "within 50 hours time-in-service or 6 months after the effective date of this AD, whichever is earlier." That is the operative compliance window for inspection and for effecting replacement. Plan logistics and parts procurement to meet that window.

7. Do not install listed crankshafts after effective date (Requirement 3; Compliance item 3)

   • From the effective date onward (11 May 2006), do not install any crankshaft whose serial number appears in Table 2 into any engine. Ensure purchasing, stock control and maintenance ordering systems exclude those listed serial numbers. Where parts inventories include such crankshafts, segregate and mark them to prevent inadvertent installation and document their status.

8. Record-keeping and evidence of compliance

   • Although the AD text does not prescribe record formats, operators should record: dates of serial-number checks; the specific entries in Table 1 or Table 2 relied on; any correspondence with Lycoming; invoices and records for replacement parts and labour; and maintenance release entries confirming replacement work. These documents will demonstrate compliance if inspected by CASA.

9. Consider cross-reference materials

   • The AD refers to FAA AD 2006-06-16 (Requirement Note 3) and discloses that the serial numbers here differ from those in Lycoming MSBs No. 552, 553 and 566 and CASA ADs AD/LYC/107 and AD/LYC/112 (Requirement Note 2). Review these materials only to the extent necessary to confirm that the specific serial numbers at issue are the ones from Supplement No. 1. Do not assume prior compliance with earlier MSBs or ADs satisfies this AD.

10. Liaise with Lycoming and CASA where necessary

    • If there is ambiguity about serial-number records, replacement part eligibility, or the provenance of a particular crankshaft, obtain written confirmation from Lycoming or seek clarification from CASA. The AD ties the identification to Lycoming’s tables, so manufacturer clarification may be required where records are incomplete.

11. Safety verification after replacement

    • Carry out any functional tests and inspections required by the engine maintenance manual and Lycoming’s service instructions following crankshaft replacement. The AD requires replacement but does not detail the test regime.

12. Operational planning

    • Plan for aircraft downtime and labour time to effect replacements within the compliance window. The AD does not offer phased compliance or extensions in the text supplied; therefore schedule work so the 50-hour/6-month limit is met.

Following these steps will align an operator’s actions with the AD’s stated obligations: verify serial numbers against Supplement No. 1 tables (Requirement 1); replace any listed crankshaft (Requirement 2); and avoid installing listed crankshafts after the effective date (Requirement 3), all within the AD’s compliance timeframes (Compliance items 1-3).