AD/CESSNA 400/81 Amdt 4 - Engine Mount Beams

The AD rests on a small number of interlocking technical and regulatory concepts, each explicit in the text.

Applicability by model and serial number: The AD defines its scope strictly by model and serial number ranges, specifying Models 402C and 414A and precise serial number ranges for each model. This produces a bounded universe of affected aircraft, rather than a model-wide or type-certificate-wide sweep.

Kit-based design change versus inspection reliance: The AD distinguishes aircraft that already have Cessna Kit SK414-17 incorporated from those that do not. For both classes, the prescriptive route is incorporation of Cessna Kit SK414-19-1 plus a variant kit chosen according to propeller installation and serial-number subsets. Amendment 4 implements a design-change approach promoted by the FAA, expressly to eliminate or reduce recurring inspections where a design fix exists. The AD thus sets a durable engineering solution as the primary compliance path.

Method-specific inspections: The AD prescribes inspection techniques by context. Requirement 3 mandates radiographic inspection in accordance with the Accomplishment Instructions of the Attachment to Service Bulletin MEB85-3, Revised 23 August 1985, as referenced in Service Bulletin MEB85-3 Revision 2 dated 23 October 1987. Where modification parts have been ordered but are not available, Requirement 4 differentiates interim methods: radiography for aircraft with SK414-17 incorporated, fluorescent penetrant inspection for those without.

Quantitative crack-management thresholds: The AD sets hard measurement thresholds for decision-making. For cracks in the top horizontal portion of the beam, the total length bands are: less than 1.75 inches (44.5 mm) , stop-drill each end of each crack with a 0.098 inch drill bit; equal to or greater than 1.75 inches but less than 2.75 inches (70 mm) , obtain and incorporate a manufacturer repair scheme; equal to or greater than 2.75 inches , replace the engine beam with a part number specified in SK414-19B Revised 4 March 1986. Cracks in the left vertical portion of the left engine beam always require obtaining and incorporating a manufacturer repair scheme.

Temporal compliance structure: The AD uses hours time in service referenced to the effective date of 23 April 1998 to set mandatory deadlines. Different requirements have different windows: for aircraft with SK414-17 incorporated, incorporation of kits per Requirement 1 is due within 1,600 hours TIS or at the next engine overhaul, whichever occurs first. For aircraft without SK414-17 incorporated, Requirement 2 is due within 200 hours TIS. Post-modification inspection intervals are long in some cases, for example Requirement 3 requires inspection within 9,600 hours TIS after the modification and thereafter at intervals not to exceed 9,600 hours. Interim inspection intervals where parts are on order are specified at either 1,600 hours or 200 hours depending on the prior kit status.

Linkage to manufacturer materials and FAA AD: The AD repeatedly refers to specific Cessna service kits and a named Service Bulletin for accomplishment instructions, and it notes the related FAA AD 97-26-16. The AD therefore binds operator action to manufacturer-prescribed methods and to a prior FAA mandate, rather than to free-form maintenance judgement.

Remedial hierarchy and continuity: The instrument sets an ordered sequence of remedial options , design fix via kit, radiographic inspection and stop-drilling for small cracks, manufacturer repair schemes for intermediate cracks, and full replacement for large cracks , and provides transitional measures where parts are on order. It explicitly permits continuing repetitive inspections where temporary measures are necessary.

The AD identifies a specific, bounded set of affected parties and responsibilities.

Operators and owners of the specified airframes: Primary direct costs fall on the owners and operators of Cessna Models 402C and 414A within the serial-number bands listed: 402C0001 through 402C0808 for 402C, and 414A0001 through 414A1206 for 414A. These parties are responsible for ensuring compliance with kit incorporation, inspections, repairs and replacements required in Requirements 1 through 5 within the specified time frames after the effective date. The AD’s compliance times are expressed in hours time in service, which directly links operator usage to compliance timing and potential downtime.

Maintenance organisations and accredited engineers: The AD requires particular inspection methods (radiographic or fluorescent penetrant) and specific mechanical operations (stop-drilling with a 0.098 inch drill bit, incorporation of kits and parts to specified part numbers). That allocates workload to maintenance providers with appropriate non-destructive inspection capability and access to Cessna’s service kits and parts. Maintenance providers will need to follow the Accomplishment Instructions in the referenced Service Bulletin MEB85-3 Revision 2 and Service Kit SK414-19B Revised 4 March 1986.

Cessna, as manufacturer and parts supplier: The AD explicitly makes the manufacturer the source of repair schemes where intermediate crack lengths are encountered. When the AD requires "obtain a repair scheme from the manufacturer", Cessna has the operational role of producing and supplying a repair design, and providing the parts specified in SK414-19B. The AD also ties the particulars of replacement part numbers to the instructions in SK414-19B, embedding dependence on manufacturer documentation and inventory.

Regulator and inspectors: The AD is issued under the Commonwealth Civil Aviation Regulations 1998, Part 39 schedule of Airworthiness Directives, placing CASA in the regulatory role to require and, as necessary, enforce compliance. The AD becomes effective on 23 April 1998, creating a statutory timeline for compliance.

Indirectly affected parties: Operators of fleets that perform commuter service are explicitly implicated in the background rationale. The FAA reasoning reproduced in the background states that reliance on critical repetitive inspections for aircraft in commuter service carries an unnecessary safety risk when a design change exists to eliminate the need for them. Although not binding beyond the statement, that rationale means operators using aircraft in commuter contexts will typically be the ones most exposed to the safety and operational trade-offs discussed.

Geographic reach and overlapping jurisdictions: The AD references FAA AD 97-26-16 Amdt 39-10259 and adopts kit changes adopted in response to that FAA AD, which indicates parallel or aligned obligations for aircraft that may operate in or across jurisdictions. Operators that prepare aircraft documentation for multiple regulators will need to reconcile compliance across CASA and FAA requirements where applicable.

The AD prescribes affirmative duties and specifies procedural rights indirectly by reference to manufacturer materials. Duties are explicit and quantified in the Requirements and Compliance sections.

Affirmative duties

• Incorporation of kits: Operators must incorporate Cessna Kit SK414-19-1 plus one of the specified companion kits depending on model, serial-number range and whether SK414-17 has already been incorporated, as described in Requirements 1 and 2. The kits must be incorporated in accordance with the instructions to Service Kit SK414-19B, Revised 4 March 1986.

• Inspection obligations: Requirement 3 mandates radiographic inspection of engine mount beams for cracks in accordance with the Accomplishment Instructions of the Attachment to Service Bulletin MEB85-3 Revised 23 August 1985, as referenced in Service Bulletin MEB85-3 Revision 2 dated 23 October 1987. Where parts have been ordered but are not available, Requirement 4 prescribes interim repetitive inspections, radiographic if SK414-17 is incorporated and fluorescent penetrant if not.

• Repair and replacement actions by threshold: The AD requires specific responses measured against crack location and crack total length: for left-side vertical cracks obtain and incorporate a manufacturer repair scheme; for top horizontal cracks with total length under 1.75 inches stop-drill each end with a 0.098 inch drill bit; for cracks between 1.75 and under 2.75 inches obtain and incorporate a manufacturer repair scheme; for cracks equal to or exceeding 2.75 inches replace the engine beam with the part number specified in SK414-19B Revised 4 March 1986. Requirement 5 further prescribes actions where certain findings occur during interim inspections.

• Timing obligations: The AD sets deadlines in hours time in service measured from the effective date 23 April 1998. Requirement 1 compliance window is within 1,600 hours TIS after 23 April 1998 or at the next engine overhaul, whichever occurs first. Requirement 2 compliance window is within 200 hours TIS after 23 April 1998. Interim inspection intervals (Requirement 4) are either within 1,600 hours TIS and thereafter at intervals not to exceed 1,600 hours, or within 200 hours TIS and thereafter at intervals not to exceed 200 hours, depending on prior kit status. Requirement 3 periodicity after modification is within 9,600 hours TIS after the modification and thereafter at intervals not to exceed 9,600 hours.

Procedural dependencies and rights

• Right to rely on manufacturer repair schemes: Where the AD requires "obtain a repair scheme from the manufacturer", the operator is entitled to receive and implement a manufacturer-provided repair scheme, and must do so. The AD places the content of such schemes outside its text; it delegates substantive repair design to the manufacturer.

• Temporary measures where parts are on order: The AD permits operators to continue to operate subject to repetitive inspections specified in Requirement 4 if parts are on order but not yet available. This creates limited procedural flexibility but also ongoing inspection obligations until parts are fitted.

• Method choice governed by existing configuration: The duty to choose radiographic or fluorescent penetrant inspection methods depends on whether SK414-17 has been incorporated. Operators must determine, document and follow the correct method; the AD does not provide an alternative method.

• Documentation obligation implicit in compliance: While the AD does not set out record-keeping language, compliance with the referenced Service Bulletin instructions and kit installation procedures implies that operators must follow and record the steps required by those materials for subsequent verification.

Limits and non-specified matters

• No penalty schedule within the AD text: The AD does not itself list sanctions or penalty amounts; it references the Commonwealth Civil Aviation Regulations 1998, Part 39 schedule of Airworthiness Directives. Enforcement mechanisms and sanction amounts are therefore determined by the broader regulatory framework to which the AD belongs, not by the AD’s own text.

• Manufacturer-defined repair content: The substance of repair schemes is not specified; the AD compels obtaining and incorporating the scheme but leaves its technical content and the timing of its supply to the manufacturer. This allocates technical decision authority to Cessna where the AD requires a repair scheme.

The AD text does not specify monetary penalties or enforcement mechanisms within its own provisions. Instead, it situates the directive within the Commonwealth of Australia regulatory framework by explicitly referencing the Civil Aviation Regulations 1998, Part 39 - Schedule of Airworthiness Directives, and it shows the AD as issued by the Civil Aviation Safety Authority. The AD states it "becomes effective on 23 April 1998", indicating that the regulatory obligation to comply attaches from that date.

What the document provides

• Regulatory placement: The AD is presented within the Commonwealth of Australia Civil Aviation Regulations 1998 Part 39 schedule, which is the formal mechanism through which CASA issues airworthiness directives. That placement means that enforcement and any sanctions would arise under the powers and processes of CASA and the Civil Aviation Regulations rather than from the AD’s text itself.

• No penalty clauses in the AD: There is no provision in the AD that prescribes fines, imprisonment, or other penalties, nor any administrative sanction details. The AD is prescriptive about technical requirements, compliance times and methods, but not about enforcement sanctions.

What to infer, cautiously and strictly from the source

• Enforcement will be through the regulator: Because the AD is issued under the schedule of Airworthiness Directives in the Civil Aviation Regulations 1998, Part 39, the practical consequence is that CASA is the enforcing authority for the mandatory actions the AD sets out. The AD’s effective date is the statutory trigger for CASA’s regulatory expectation that the affected operators commence compliance in accordance with the stated time frames.

• Compliance verification will track the referenced materials: Verification of whether obligations are satisfied will depend on demonstrating incorporation of the specified Kits in accordance with the instructions to Service Kit SK414-19B Revised 4 March 1986, and on showing inspection and repair work was performed in accordance with Service Bulletin MEB85-3 Revised 23 August 1985 and Revision 2 dated 23 October 1987. Evidence of this will be central for any enforcement action, because the AD ties compliance to those documents.

• Cross-reference to FAA AD: The note that FAA AD 97-26-16 Amdt 39-10259 "refers" indicates a related FAA action. That does not create direct Australian enforcement by the FAA, but it signals that the design-change pathway and technical standards have been subject to parallel regulatory consideration.

Practical enforcement risk areas

• Timing non-compliance and inspection intervals: The AD prescribes narrow inspection intervals for interim measures (as low as 200 hours TIS), and longer post-modification intervals (9,600 hours). Failure to meet those timing obligations is the clearest form of non-compliance the regulator could identify.

• Dependence on manufacturer documentation: Because several remedial steps are conditioned on "obtaining a repair scheme from the manufacturer", disputes could arise about whether an operator implemented a valid scheme, or whether the scheme supplied met the AD’s expectations. Such disputes would be resolved in the regulatory process under CASA’s Part 39 powers.

Absent from the source are detailed enforcement procedures, appeal mechanisms, or penalty schedules. To understand the specific sanctions that could follow non-compliance, an operator must consult the Civil Aviation Regulations 1998, Part 39 and related regulatory materials, which are not reproduced in the AD itself.

The AD expressly situates itself in a web of technical and regulatory instruments, creating linkages that direct operator action and determine which external documents govern method and compliance.

Reference to domestic regulatory framework: The directive is issued under the Commonwealth of Australia Civil Aviation Regulations 1998, Part 39 schedule of Airworthiness Directives. That locates the AD within Australia’s aviation safety regulatory architecture, implying that CASA enforces and implements the requirements under the powers conferred by Part 39. The AD itself does not reproduce Part 39’s enforcement or administrative procedures; rather it functions as the Part 39 schedule entry imposing a technical mandate on specific airframes.

Manufacturer service documentation as normative law by reference: The AD binds operators to execute tasks "in accordance with the instructions to Service Kit SK414-19B, Revised 4 March 1986" and to follow the Accomplishment Instructions in the Attachment to Service Bulletin MEB85-3 Revised 23 August 1985, as referenced in Service Bulletin MEB85-3 Revision 2 dated 23 October 1987. By doing so, it integrates manufacturer service bulletins and kit instructions into the mandatory regulatory requirement. Compliance therefore requires fidelity to the methods and part numbers specified in these manufacturer documents.

Cross-reference to FAA AD: The AD notes that FAA AD 97-26-16 Amdt 39-10259 "refers", and states Amendment 4 is issued in response to a new FAA AD requiring incorporation of engine mount kits that will eliminate the need for ongoing repetitive inspection requirement. This creates an international regulatory cross-reference: CASA’s AD aligns Australian mandatory action with FAA-identified safety concerns and remedial kits. For aircraft that operate between jurisdictions, operators must manage compliance records and technical work to satisfy both CASA and FAA regimes, where applicable.

Interaction with maintenance standards and physical inspection regulations: The AD prescribes particular non-destructive testing techniques, radiography and fluorescent penetrant inspection, and sets precise mechanical operations such as stop-drilling with a 0.098 inch drill bit. These requirements intersect with the regulatory framework controlling maintenance organisation certification, personnel qualifications, and NDT procedures. While the AD does not itself set personnel qualification standards, compliance will require use of appropriately authorised maintenance providers and technicians who operate under the standards required by the Civil Aviation Regulations and by the referenced service documents.

Delegation of technical content to the manufacturer: Where the AD requires operators to "obtain a repair scheme from the manufacturer", it leaves substantive engineering design and repair content to Cessna. That creates a reliance relationship between statutory obligation and manufacturer-supplied remedy. The legal effect is that, for intermediate crack lengths, the AD becomes an obligation to implement the manufacturer’s repair scheme as the chosen method to achieve regulatory compliance.

No explicit interaction with non-aviation laws in the text: The AD does not reference taxation, contract law, consumer law, or employment law. Its operation is confined to the Civil Aviation Regulations framework and the referenced manufacturer service documents. Any contractual or commercial disputes arising from parts supply, downtime or repair costs will therefore play out under general commercial law, but the AD itself does not impose or specify obligations in those domains.

Temporal layering with previous amendments: The AD contains an amendment history that tracks prior versions and the dates they became effective; this history shows a regulatory development path and indicates that previous operators may have complied with different Requirement documents. Operators need to reconcile historic compliance records with the current Requirement 1 through 5 structure.

The AD includes an explicit amendment trail within its text that records previous versions and effective dates. Those entries are the only source-grounded history available in this document.

Chronology provided in the AD

• Original issue: The original issue of this airworthiness directive became effective on 23 June 1981. That establishes the AD’s genesis and the longevity of concern about engine mount beam cracking for the Cessna 400 series.

• Amendment 2: Amendment 2 of this airworthiness directive became effective on 30 June 1985. The AD does not summarise the content changes enacted by Amendment 2; it only records the effective date.

• Amendment 3: Amendment 3 became effective on 31 December 1985. The AD records that Amendment 3 introduced Revision 1 of the Requirement document and noted a related FAA AD. The text therefore documents at least one substantive change to the Requirements and an explicit cross-reference to FAA regulatory material as part of Amendment 3.

• Amendment 4: The present text is Amendment 4, and it has been issued in response to a new FAA AD. The AD describes Amendment 4 as adopting the FAA’s position that incorporation of engine mount kits will eliminate the need for ongoing repetitive inspections in certain circumstances. Amendment 4 became effective on 23 April 1998, which is the effective date now stated in the AD.

What the amendment history shows in practice

• Iterative regulatory response: The record demonstrates an iterative regulatory approach to the same underlying safety problem, namely fatigue cracking of engine mount beams. The history indicates an original AD in 1981, two amendments in the mid-1980s, and a further amendment in 1998 prompted by an FAA action.

• Transition from inspection to design-fix emphasis: The description of Amendment 4’s purpose is informative: it states that the FAA determined reliance on critical repetitive inspections for commuter-service aircraft carried an unnecessary safety risk when a design change exists that could eliminate or reduce those inspections. Accordingly, Amendment 4 shifts the AD’s compliance emphasis toward kit incorporation where possible, rather than indefinite reliance on repeated inspections. That policy shift is recorded as the rationale for Amendment 4.

• Manufacturer documentation updates referenced by amendments: The AD’s Requirements refer to specific revisions of service kits and service bulletin attachments dated in the mid-1980s and 1987, and the current Requirement directs compliance with SK414-19B Revised 4 March 1986 and Service Bulletin MEB85-3 Revised 23 August 1985 and Revision 2 dated 23 October 1987. The amendment history therefore ties the AD’s technical content to documented changes reflected in those dates.

Limitations of the provided history

• No detail on content of Amendments 1 or subsequent minor editorial changes: The AD text does not describe the content of Amendments 1 or 2 beyond effective dates, and it does not reproduce prior versions for direct comparison. Amendment 3’s introduction of Revision 1 of the Requirement document is stated but not reproduced. Users seeking a full textual change log will need to consult archived versions of the AD and the referenced service documents, which are not included in the AD text itself.

• No administrative record of consultations or notices: The AD does not include transcripts of consultations, economic impact assessments or detailed regulatory impact statements that sometimes accompany changes. The AD provides the amendment dates and the technical rationale for Amendment 4 as reported from the FAA, but not expanded domestic policy analysis.

The AD contains no references to litigation, judicial decisions, administrative appeals or contested enforcement actions. The only cross-references in the document are to manufacturer service kits and a related FAA AD, not to case law or tribunal decisions.

What the absence of litigation references means

• No source-grounded judicial record in this AD: Because the AD text does not cite any litigation, there is no direct textual basis in this instrument to report on disputes about its validity, interpretation, or enforcement. The AD’s background and amendment history discuss technical experience and regulatory responses but do not mention court or tribunal outcomes.

• Potential dispute loci implied by the AD’s content: While the AD itself does not record litigation, it sets out factual and procedural conditions that could generate disputes. Those loci for potential disagreement, grounded in the AD’s provisions, include:

  • Identification of applicability: disputes may arise about whether a particular airframe falls within the specified serial-number ranges, or whether SK414-17 has already been incorporated for a given aircraft.

  • Measurement and technical thresholds: the AD’s outcomes turn on precise crack-length measurements (for example 1.75 inches and 2.75 inches). Disagreement about measurement technique, aggregated total crack length, or interpretation of where a crack sits (top horizontal portion versus left vertical portion) could trigger administrative or legal contestation.

  • Adequacy of manufacturer repair schemes: where the AD requires obtaining a repair scheme from the manufacturer, an operator or regulator could dispute whether a given manufacturer repair scheme satisfies the AD’s safety expectations. The AD leaves the technical content of such schemes to the manufacturer, so questions of sufficiency could be litigious.

  • Parts availability and interim compliance: Requirement 4 permits interim inspection regimes where parts are on order but not available. A regulator could accept or reject an operator’s assertion that parts are on order, or could challenge whether the interim inspection regime was correctly carried out, potentially giving rise to dispute.

Procedural disputes would be handled under the administrative and judicial mechanisms provided by the Civil Aviation Regulations and relevant administrative law, but the AD does not detail those processes. The AD’s silence on litigation history means practitioners must look to CASA records, judicial databases and administrative appeal records outside this instrument to discover whether any contested cases have arisen concerning this specific AD.

This section flags specific practical pitfalls and interpretative traps that follow from the AD’s wording and technical structure, as given in the text.

Serial-number and kit-selection complexity: The AD divides the affected population along model lines and into serial-number sub-ranges that map to different kit variants. For example, for aircraft with SK414-17 incorporated, SK414-19-3 applies to 402C0001 through 402C0468 and 414A0001 through 414A0646, while SK414-19-5 applies to later serial numbers. For aircraft without SK414-17, SK414-19-4 applies where SK414-19-3 would otherwise have been specified. Misidentifying serial numbers or applying the wrong kit variant will result in non-compliance. Operators must verify serial numbers meticulously and cross-check which companion kit is required for their precise configuration.

Configuration-dependent inspection method: Requirement 4 prescribes radiographic inspection when SK414-17 is incorporated and fluorescent penetrant inspection when it is not. Choosing the wrong inspection technique is not an optional deviation; it is a default requirement in the AD. Maintenance providers routinely experienced in one NDT method but not the other must ensure they have documented capability for the specific method required by an airframe’s configuration.

Timing divergence tied to SK414-17: The AD sets different compliance windows depending on whether SK414-17 is installed. For aircraft with SK414-17, kit incorporation (Requirement 1) must occur within 1,600 hours TIS or the next engine overhaul, whichever occurs first. For aircraft without SK414-17, Requirement 2 deadlines are within 200 hours TIS. Operators that do not recognise which category they fall into may miss the earlier 200-hour deadline.

Precision of measurement thresholds: The AD’s actions pivot on exact crack-length thresholds: less than 1.75 inches (44.5 mm), equal to or greater than 1.75 inches but less than 2.75 inches (70 mm), and equal to or greater than 2.75 inches. Practically, this requires accurate measurement and, where multiple cracks exist, summing total lengths. Measurement methodology, documentation, and reproducibility will be focal in audits or disputes. The AD prescribes stopping the crack ends with a 0.098 inch drill bit for the smallest band, a seemingly small but specific numerical requirement; using a different bit size could be challenged.

Left engine beam vertical portion special rule: Any crack found in the left side vertical portion of the left engine beam of either nacelle requires obtaining and incorporating a repair scheme from the manufacturer. That is a categorical rule, not subject to the length thresholds that apply to top horizontal cracks. Operators who treat all cracks uniformly may misapply the AD.

Parts ordering does not suspend inspection obligations: When parts have been ordered but are not available, the AD does not excuse inspection obligations. Instead, it prescribes interim inspection regimes under Requirement 4 and, if certain findings occur, specifies follow-up actions under Requirement 5. The "on order" status creates an administrative burden: operators must be able to document that parts were ordered, and then maintain the interim inspection schedule until the parts are installed.

Reliance on manufacturer repair schemes: For cracks in the 1.75-2.75 inch band and for vertical left-side cracks, operators must obtain and incorporate a repair scheme from Cessna. The timing of Cessna’s delivery of that scheme and parts availability can create operational exposure. The AD contemplates termination of interim inspections once parts become available and the modification is incorporated, but it does not specify a maximum delay for the manufacturer to supply repair instructions or parts.

Interpreting "total length of the cracks": The AD speaks of "the total length of the cracks" for the top horizontal portion. Where multiple smaller cracks exist, determining whether to sum their lengths to reach a threshold will require a consistent inspection protocol. The AD does not provide a method for aggregation; practitioners must therefore rely on the referenced Service Bulletin instructions or on documented inspection practices.

Interfacing with overhaul scheduling: Requirement 1 provides the option of meeting the kit incorporation "at the next engine overhaul" as an alternative to within 1,600 hours TIS. That introduces a scheduling decision for operators: whether to bring forward overhaul work to meet the AD sooner or to fit the kit outside the overhaul schedule. Either choice has cost and operational implications.

Documentation and audit trail expectations: Because compliance is tied to specific service kit instructions and service bulletin accomplishment instructions, operators must ensure they keep a clear maintenance record demonstrating that the steps were followed in accordance with the specified revisions and dates. Failure to match the specified revision dates could create disputes on compliance sufficiency.

This section sets out a practical, stepwise compliance checklist derived from the AD’s Requirements and Compliance sections. Each step references the relevant requirement or compliance window from the AD text.

1. Identify affected aircraft precisely

   • Confirm model and serial number against the AD’s applicability: Model 402C serial numbers 402C0001 through 402C0808; Model 414A serial numbers 414A0001 through 414A1206. This establishes whether the AD applies.

2. Determine existing configuration

   • Check maintenance records to establish whether Cessna Kit SK414-17 has already been incorporated. The presence or absence of SK414-17 determines which companion kit variants and which compliance times apply under Requirements 1 and 2.

3. Select the correct kit combination and order parts

   • If SK414-17 is incorporated, comply with Requirement 1: incorporate SK414-19-1 and one of SK414-19-2, SK414-19-3 or SK414-19-5 as mapped by the aircraft’s serial number and propeller unfeathering accumulator configuration.
   • If SK414-17 is not incorporated, comply with Requirement 2: incorporate SK414-19-1 and one of SK414-19-2, SK414-19-4 or SK414-19-5 per serial number and configuration.
   • Order parts specified in instructions to Service Kit SK414-19B Revised 4 March 1986.

4. Schedule the work in accordance with the compliance windows

   • For aircraft with SK414-17 incorporated, fit the required kits within 1,600 hours TIS after 23 April 1998, or at the next engine overhaul, whichever occurs first (Requirement 1 compliance).
   • For aircraft without SK414-17 incorporated, fit the required kits within 200 hours TIS after 23 April 1998 (Requirement 2 compliance).
   • If design or operational constraints make immediate kit installation impractical, proceed to Step 5 for interim inspections.

5. If parts are unavailable, implement interim inspections

   • If parts have been ordered but are not available, implement the interim inspection regime under Requirement 4:
     • For aircraft with SK414-17 incorporated, perform radiographic inspections within 1,600 hours TIS after 23 April 1998 and thereafter at intervals not to exceed 1,600 hours TIS, provided no Requirement 5 provision occurs.
     • For aircraft without SK414-17, perform fluorescent penetrant inspections within 200 hours TIS after 23 April 1998 and thereafter at intervals not to exceed 200 hours TIS, provided no Requirement 5 provision occurs.

6. Perform the required inspections per the referenced Service Bulletin

   • For the mandated radiographic inspections, follow the Accomplishment Instructions section of the Attachment to Service Bulletin MEB85-3 Revised 23 August 1985, as referenced in Service Bulletin MEB85-3 Revision 2 dated 23 October 1987. This directs inspection scope, NDT procedure, and recording requirements.

7. Apply the AD’s crack-threshold remedial rules

   • For cracks in the left side vertical portion of the left engine beam of either nacelle, obtain and incorporate a repair scheme from the manufacturer (Requirement 3(a) and 5(b)).
   • For top horizontal portion cracks:
     • If total crack length is less than 1.75 inches (44.5 mm), stop-drill each end of each crack using a 0.098 inch drill bit, and continue inspections as required (Requirement 3(b), 5(c)).
     • If total crack length is equal to or greater than 1.75 inches but less than 2.75 inches (70 mm), obtain and incorporate a repair scheme from the manufacturer, then continue inspections as required (Requirement 3(c), 5(d)).
     • If total crack length is equal to or greater than 2.75 inches, replace the engine beam with a part number specified in the instructions to Service Kit SK414-19B Revised 4 March 1986, and thereafter inspect as per Requirement 3 (Requirement 3(d), 5(e)).

8. Termination of interim inspections after parts availability

   • If parts become available and are fitted, terminate the repetitive inspections required by Requirement 4, incorporate the required modification kits under Requirement 1 or 2, and inspect the engine mount beams as specified in Requirement 3 (Requirement 5(a)).

9. Post-modification inspection interval

   • After the modification required by Requirement 1 or 2 is incorporated, perform the radiographic inspection required by Requirement 3 within 9,600 hours TIS after the modification and thereafter at intervals not to exceed 9,600 hours TIS. Ensure the inspection method and frequency match the AD’s post-modification schedule.

10. Record-keeping and proof of compliance

    • Maintain maintenance records that show:
      • Serial-number verification and configuration check for SK414-17 status.
      • Procurement records showing parts were ordered when applicable.
      • Records of inspections performed, specifying the method (radiography or fluorescent penetrant), dates, technician or NDT provider, measurement results including total crack lengths and the measurement methodology used, and the instrument calibration or standards referenced.
      • Details of stop-drilling operations including drill bit size used (0.098 inch), and drawings or photos showing repair locations.
      • Manufacturer repair schemes obtained and records proving incorporation.
      • Part numbers used for any beam replacement per SK414-19B Revised 4 March 1986.

11. Coordinate with manufacturer and regulator

    • Obtain any required repair schemes from Cessna promptly where the AD requires it, and document communications and implementation.
    • Be prepared to demonstrate compliance to CASA under the Civil Aviation Regulations 1998, Part 39, as the AD is issued under that framework.

12. Reconcile with prior compliance history

    • If aircraft were subject to earlier amendments (Amendments 2 or 3) or were maintained under previously issued Requirement documents, verify that the current Requirement 1-5 structure is met; if different actions were taken earlier, document how they satisfy or differ from the current AD’s requirements.

Practical tips directly from the AD text

• Use the specified drill bit size, 0.098 inch, for stop-drilling small cracks; deviations may be questioned during compliance checks.
• Use the exact Service Bulletin revisions referenced: Attachment to Service Bulletin MEB85-3 Revised 23 August 1985 and Service Bulletin MEB85-3 Revision 2 dated 23 October 1987 for inspection methods; use Service Kit SK414-19B Revised 4 March 1986 for kit instructions and replacement part numbers.
• Track hours time in service carefully relative to the effective date 23 April 1998, because most compliance windows are not calendar-based but usage-based.

Following these steps will align an affected operator with the AD’s mandatory technical requirements as written and provide the documentary trail that will be required for regulatory verification.