The instrument operates as a prescriptive continuing airworthiness directive. Core concepts in the text are:

• Mandatory intervals vs. approved alternatives: The AD sets out mandatory maximum intervals (the AD’s own requirements), preserves the manufacturer’s published TBO as a valid alternative, and recognises approved systems of maintenance under regulation 42M as another alternative. This provides three discrete compliance routes (Requirement 1.1).

• Engine‑family specific regimes: The AD delegates different specific regimes to major engine families:

  • Honeywell TPE331 series: compliance via Honeywell Service Bulletins for TBO, through Honeywell CAM programs, or approved maintenance systems (Requirement 1.2). The AD explicitly disclaims annual utilisation or operation type as requisites to establish TBO for the listed TPE331 sub‑series.
  • Pratt & Whitney Canada PT6A series: bifurcated treatment depending on operational role (aerial agricultural/fire‑fighting v other operations) with different options and mandatory Appendices (Requirements 1.3-1.4).

• ECTM requirement: For PT6A engines that adopt the enhanced or on‑condition programs, the AD requires Engine Condition Trend Monitoring (ECTM) and binds the ECTM approach to specific software/telemetry providers: WebECTM® or CAMP Systems International, "as required under revision 10 of Pratt and Whitney Canada SIL No. GEN‑055" (Appendices A and B, requirement 2). The AD therefore does more than set intervals: it prescribes the monitoring platform and qualification/training expectations for personnel conducting ECTM.

• Prescriptive inspection and servicing tasks: Appendices A and B provide fixed intervals for hot section inspections, fuel nozzle cleaning/flow checks, oil filter element inspection, reduction gearbox chip detector checks, compressor inspections, compressor washes, oil changes for low‑utilisation engines, and the replacement of life‑limited components per AD/ENG/7. Appendix A includes optional extended hot section intervals subject to boroscope checks and sets a 5,000 hour cap as an AD alternative for non‑agricultural PT6A overhaul intervals (Requirement 1.3(b)).

• Reporting and programme review: Both Appendices require a review and revision of the programme at intervals not exceeding two years, with outcomes reported to CASA through the DRS Portal or Form 404 referring to AD/ENG/5 (Appendices A and B, requirement 13 and 12 respectively).

• Transition and continuity: The AD accepts previously issued AMOCs or exclusions promulgated under AD/ENG/5 Amendment 9 for compliance with equivalent AD requirements. The AD also fixes a specific revision of PWC SIL (GEN‑055 Revision 10 dated 13 November 2018) as the relevant reference "as at the commencement of this AD", thereby anchoring the ECTM requirements to that SIL revision.

Mechanically, the AD imposes obligations on operators to either adopt manufacturer published intervals or comply with a CASA AD or an approved system of maintenance. It then overlays detailed tasking and monitoring regimes for PT6A engines that elect the CASA‑enabled paths, and restricts applicability to exclude a small set of aircraft categories. The AD is time‑limited in transition: effective 31 March 2026 with a compliance deadline of 30 June 2026.

The AD applies to "All turbine engines" except those installed in aircraft falling into three narrowly defined excluded categories: aircraft administered by an approved sports aviation body; aircraft with a limited category certificate of airworthiness under CASR regulation 21.189; and aircraft with an experimental certificate under CASR regulation 21.195A (Applicability table). That means the AD will capture the majority of turbine engine installations across the general aviation, commercial, and specialised aerial work fleets in Australia, subject to those exclusions.

Primary parties affected:

• Aircraft operators and owners: Operators whose turbines are within scope must ensure engine maintenance is performed to one of the AD‑approved regimes (manufacturer TBO, AD intervals/Appendices, or an approved system of maintenance under regulation 42M). For PT6A operators, the AD’s specific Appendix programs will be particularly relevant: they must implement ECTM, arrange inspections at the specified intervals, and perform required servicing tasks (Appendices A and B).
• Maintenance organisations and approved maintenance personnel: Organisations certified to hold an approved system of maintenance under regulation 42M can be the vehicle by which operators satisfy the AD’s alternative route; they must configure maintenance data, training, ECTM arrangements and reporting processes to meet Appendix requirements. Personnel conducting ECTM must meet qualification and training expectations set by the Appendix requirements.
• Engine manufacturers and service providers: Honeywell and Pratt & Whitney Canada (PWC) are central. The AD directs operators to "the latest revision" of Honeywell or PWC Service Bulletins and to Pratt & Whitney Canada SIL No. GEN‑055 Revision 10 for ECTM platform requirements (Requirement 1.2, 1.3, 1.4; Appendices). WebECTM® and CAMP are named as the permitted ECTM systems for PT6A program compliance under Revision 10 of SIL GEN‑055.
• CASA as regulator: CASA is the issuer and has set compliance dates and reporting channels. CASA requires submission of program reviews via its DRS Portal or Form 404 per the Appendices.
• Component suppliers and engine shops: The APPENDICES mandate life‑limited components be replaced per AD/ENG/7, and accessory TBOs to follow PWC recommendations. Engine shops will need to schedule capacity for hot section inspections, boroscopes and overhauls if operators elect the AD pathways.

Secondary and economic impacts:

• Operators with high utilisation PT6A agricultural/fire‑fighting fleets will be affected by Appendix B’s on‑condition monitoring and mandated hot section intervals (Appendix B requirement 2). Appendix A sets tighter frequent maintenance tasks for certain PT6A engines electing the 5,000 hour TBO alternative.
• Operators of Honeywell TPE331 engines must follow Honeywell Service Bulletins or the CAM program requirements if they do not elect an approved system of maintenance. The AD’s explicit removal of utilisation and operation type as determinants for TBO for listed TPE331 series disables an operator argument to lengthen TBOs based on usage profile.

Who pays:

• Costs are borne primarily by operators and maintenance organisations: ECTM subscriptions (WebECTM/CAMP), training for ECTM personnel, increased inspection frequency (if electing Appendix A/B), potential earlier replacement of life‑limited parts, and administrative costs for biennial programme reviews and reporting to CASA.

Who decides:

• Operators choose between the three compliance routes (manufacturer TBO, AD intervals, or approved system of maintenance). CASA decides the AD requirements, accepts AMOCs/exclusions previously issued, and receives the two‑year programme review outcomes. Approved system of maintenance decisions occur under regulation 42M (the instrument references that regulation as the statutory vehicle for approved maintenance systems).

Key duties are explicit in the instrument; rights are limited to choices among approved compliance routes and the continued acceptance of previously issued AMOCs/exclusions.

Duties on operators and maintenance providers:

• Select and comply with one of three paths: (a) the AD intervals (including Appendices where relevant), (b) the engine manufacturer’s recommended hours in service (manufacturer TBO) or the manufacturer’s published CAM program for TPE331, or (c) a system of maintenance approved under regulation 42M. Requirement 1.1 sets the choice framework.
• For Honeywell TPE331 series: either overhaul at the periods and requirements of Honeywell’s latest Service Bulletin for the engine model, or inspect under Honeywell CAM program, or comply with an approved system of maintenance (Requirement 1.2).
• For PT6A engines not used for aerial agriculture or fire‑fighting: either follow the latest PWC Service Bulletin for PT6A TBO and hot section frequency, or overhaul not to exceed 5,000 hours time in service subject to Appendix A maintenance requirements, or use an approved system of maintenance (Requirement 1.3).
• For PT6A engines used in agricultural or fire‑fighting operations: either follow the PWC Service Bulletin, or be inspected under an engine on‑condition program having regard to Appendix B, or comply with an approved system of maintenance that includes inspection, overhaul and on‑condition monitoring (Requirement 1.4).
• Implement and maintain Engine Condition Trend Monitoring (ECTM), including data collection, analysis and follow‑up actions, and qualification and training of ECTM personnel, in accordance with WebECTM® or CAMP as required under PWC SIL GEN‑055 R10. Appendices A and B requirement 2 imposes this duty.
• Perform the prescribed inspection and maintenance tasks at the stated intervals in the Appendices (hot section intervals, fuel nozzle cleaning every 460 hours, oil filter and chip detector inspections every 220 hours, compressor checks, compressor washes at set thresholds or trigger points, oil change intervals for engines with <500 hours pa annual use, etc.).
• Replace life‑limited components at manufacturer published life limits per AD/ENG/7 and inspect critical components per the relevant PWC Service Bulletin (Appendices A and B).
• Conduct a maintenance programme review at intervals not exceeding two years, taking into account all major defects and defects that affect engine durability, and report the outcomes to CASA via the DRS Portal or Form 404 referring to AD/ENG/5 (Appendices A and B).

Rights and options:

• Choice among compliance options: operators retain the right to follow manufacturer guidance, adopt the AD’s specified intervals, or use an approved system of maintenance with CASA recognition , the instrument explicitly provides those options (Requirement 1.1).
• Transitional acceptance of existing AMOCs and exclusions: previously issued AMOCs or exclusions to AD/ENG/5 Amendment 9 are stated as acceptable for compliance with equivalent AD requirements in Amendment 10. This preserves pre‑existing regulatory accommodations (last sentence of the Requirements table).
• Use of approved systems of maintenance: operators with an approved system under regulation 42M can use that as their compliance vehicle, implying rights to rely on regulatory approval to meet AD obligations.

Constraints and limits:

• For PT6A ECTM, the AD restricts acceptable ECTM systems to the WebECTM® or CAMP platforms "as required under revision 10" of PWC SIL GEN‑055. That reduces the freedom to select alternative condition monitoring vendors when complying via Appendix A or B.
• The AD fixes certain intervals (e.g., hot section intervals, nozzle cleaning, chip detector/ oil filter inspections) that must be observed if operators elect the CASA‑prescribed pathways.

Recordkeeping, training and reporting obligations:

• The Appendices require qualification and training for personnel conducting ECTM, and the maintenance programme must be reviewed and its outcome reported to CASA via DRS or Form 404 within the two‑year review cycle. These are affirmative duties to establish documented competence and oversight.

Temporal duties:

• The AD becomes effective 31 March 2026 and compliance is required no later than 30 June 2026. Operators therefore must establish whichever compliance route they choose within the prescribed timeline.

The text of this AD does not set out express monetary penalties, infringement notices, or a specific enforcement schedule within the document itself. What the instrument does provide is an affirmative compliance requirement and a regulatory framework (the AD) issued by CASA; it prescribes compliance paths, prescribes inspection and reporting duties, fixes effective and compliance dates, and states that previously issued AMOCs or exclusions to Amendment 9 remain acceptable for equivalent requirements.

From the AD text practitioners can infer the following enforcement‑relevant facts that are expressly stated:

• The AD is issued by a CASA delegate (signature block of David Punshon, Delegate of the Civil Aviation Safety Authority), and it is framed as addressing an unsafe situation that, if not remedied, "could result in loss of power, uncontained release of debris, damage to the engine, and damage to the aircraft." This characterisation supports CASA’s regulatory objective in compelling compliance.
• The AD requires reporting of maintenance programme reviews to CASA via the DRS Portal or Form 404 referring to AD/ENG/5. The existence of a required reporting channel establishes an administrative compliance mechanism that CASA can monitor.

What the AD does not contain and what practitioners should note:

• The AD text supplied does not specify statutory penalty provisions, enforcement instruments, or the consequences of failing to comply (for example, suspension of certificates, fines, or grounds for enforcement action). The AD references regulation 42M of the Civil Aviation Regulations 1988 as the statutory route for an approved system of maintenance, but the AD text does not reproduce enforcement provisions or indicate specific sanctioning powers in the event of non‑compliance.
• The AD refers to AD/ENG/7 for life‑limited components but does not include enforcement details associated with AD/ENG/7.

Practical consequence for operators and maintenance organisations:

• The instrument places affirmative duties and reporting obligations on operators that can be monitored by CASA. In practice, non‑compliance with an AD can lead to CASA intervention via its compliance and enforcement processes, and because ADs implement continuing airworthiness standards, failure to comply may affect the legal permissibility of operating an aircraft. However, any specific enforcement steps or penalties are not articulated in the AD text provided and must be determined by consulting CASA’s wider enforcement policies and the underlying Civil Aviation legislation and regulations.

Action point for practitioners:

• Because the AD itself does not specify penalties, advise clients to consult CASA guidance, the Civil Aviation Act, and the Civil Aviation Regulations for the regulator’s enforcement powers and sanctions associated with non‑compliance with ADs and continuing airworthiness obligations. Ensure reports required by the AD are submitted via the CASA DRS Portal or Form 404 by the timelines specified to avoid regulatory escalation attributable to administrative non‑compliance.

The AD is not a standalone legal code; it operates by reference to other regulatory instruments, manufacturer service information and prior ADs. The AD text explicitly interacts with the following materials and regulatory hooks:

• Civil Aviation Regulations 1988 , regulation 42M: The AD permits compliance via "an approved system of maintenance" under regulation 42M of the Civil Aviation Regulations 1988 (Requirement 1.1). That reference creates a statutory pathway to satisfy the AD: if a system of maintenance is approved under 42M, following that system meets the AD requirement. The AD itself does not reproduce regulation 42M; operators must consult the Civil Aviation Regulations for the detail of approval processes and requirements.

• CASR regulation 21.189 and 21.195A: The AD excludes turbine engines installed in aircraft with a limited category certificate of airworthiness under CASR regulation 21.189 and those with an experimental certificate under CASR regulation 21.195A. It also excludes aircraft administered by an approved sports aviation body. These references carve out small categories of aircraft from the AD’s applicability and require practitioners to cross‑check an aircraft’s certification before applying the AD.

• Manufacturer service information: The AD repeatedly directs operators to the "latest revision" of manufacturer service bulletins and service information letters. For Honeywell TPE331 the AD requires compliance with the latest Honeywell Service Bulletin detailing TPE331 TBO, or the latest Honeywell CAM program. For PWC PT6A engines the AD refers to the latest PWC Service Bulletin detailing PT6A TBO and hot section inspection frequency. The AD also replaces an obsolete reference with a specific Pratt & Whitney Canada Service Information Letter (SIL) , GEN‑055 Revision 10 dated 13 November 2018 , and anchors its ECTM requirements to that revision "as existing at the commencement of this instrument".

• AD/ENG/7: The Appendices require replacement of life‑limited components per the engine manufacturer’s published life limits as set out in AD/ENG/7. That creates dependency on AD/ENG/7 for the timing and identification of life‑limited components.

• CASA administrative processes: The Appendices require reporting of maintenance program reviews to CASA via the DRS Portal or Form 404 referring to AD/ENG/5. That creates an administrative interaction with CASA’s defect reporting and recordkeeping systems.

Implications of these interactions:

• Reliance on manufacturer documents means that the AD imports external technical material into a regulatory requirement. For PT6A ECTM, the AD not only points to the PWC Service Bulletin but also to a specific SIL revision that requires the use of WebECTM® or CAMP. This constrains compliance to named third‑party providers as mandated by the referenced service information letter. The AD explicitly binds to "revision 10" of GEN‑055 "as existing at the commencement of this instrument", which fixes a reference point in time rather than a moving target of "latest available" going forward; that may limit the need to follow later, substantively different SIL revisions unless and until CASA amends the AD.

• Operators relying on an approved system of maintenance must ensure the system is compliant with regulation 42M, linking AD compliance to the approval, content and auditability of that system under the Civil Aviation Regulations.

• The reporting and DRS/Form 404 linkage makes program review outcomes a matter of record with CASA, enabling the regulator to monitor compliance and trends across fleets.

Elements not contained in the AD text:

• The instrument does not restate enforcement powers in the Civil Aviation Act or Regulations, nor does it reproduce detailed application procedures for obtaining or varying an approved system of maintenance under regulation 42M. Those are external and must be consulted directly to understand procedural interactions, approval lead times and administrative processes.

The instrument itself is identified as Amendment 10 to AD/ENG/5, and contains change history comments within its background. The AD’s amendment history, as reflected in the document, is limited to the following points:

• Amendment number: This is AD/ENG/5 Amendment 10 (AD/ENG/5 Amdt 10), dated with a signing block of 18 March 2026 and an effective date of 31 March 2026. The Compliance line states "No later than 30 June 2026" for compliance.

• Specific amendment content: Amendment 10 removes an obsolete reference to Pratt & Whitney Canada SIL PT6A‑122 and replaces it with a reference to Pratt & Whitney Canada SIL No. GEN‑055 Revision 10 dated 13 November 2018. The background text expressly states this amendment "has been issued to remove an obsolete reference to Pratt and Whitney Canada SIL PT6A‑122 and replace it with a reference to Revision 10 (Pratt and Whitney Canada SIL No. GEN‑055 R10 dated 13 November 2018), the latest version of this Service Information Letter as at the commencement of this AD."

• Transitional provision: Amendment 10 clarifies that previously issued Alternative Means of Compliance (AMOCs) or exclusions to AD/ENG/5 Amendment 9 are considered acceptable for compliance with the equivalent requirements of this AD. This preserves continuity for affected operators who had previously secured AMOCs/exclusions.

• Appendix content additions or confirmations: The AD includes two detailed Appendices (A and B) for PT6A engines. These Appendices set out specific ECTM, inspection and review obligations, including a requirement that the ECTM follow the WebECTM® system or CAMP as required under PWC SIL GEN‑055 R10 "as existing at the commencement of this instrument." The inclusion of those Appendix regimes and the anchoring to GEN‑055 R10 are part of the current amendment’s technical content.

What the amendment history in the AD does not provide:

• The AD does not include a long history of prior amendments, nor does the provided text catalogue the specific content of Amendments 1-9. It only references Amendment 9 in relation to the acceptance of previously issued AMOCs or exclusions. For a full trace of earlier changes practitioners must consult the prior AD/ENG/5 amendment texts (Amendments 1-9) and any consolidated history provided by CASA.

Practical note for operators and maintainers:

• Because Amendment 10 explicitly updates the referenced PWC SIL to Revision 10 dated 13 November 2018 and ties ECTM platform requirements to that revision "as at the commencement of this instrument", practitioners must align their PT6A programmes, ECTM vendor selection and training to the requirements of GEN‑055 R10 or an approved system of maintenance. Operators who had compliance arrangements under Amendment 9 via AMOCs or exclusions will not be required to revalidate those, according to the AD text.

The AD text supplied does not include any litigation history, case references, court decisions, or administrative appeals. There are no named judicial proceedings, tribunal matters or enforcement cases recorded in the document itself. The instrument contains no description of prior legal challenges, determinations or contested enforcement actions pertaining to AD/ENG/5 or its earlier amendments.

Implications for practitioners:

• Because no litigation or case law is cited in the AD, practitioners wishing to understand how courts or tribunals have treated ADs, approved systems of maintenance under regulation 42M, or disputes over the adequacy of maintenance programs should undertake independent legal research. The AD does not provide precedential material or a record of judicial interaction.

Recommended due diligence steps:

• Search administrative decisions, Federal Court and state/territory case law databases for any decisions involving CASA AD enforcement, AD/ENG/5 (if earlier litigation exists but is not referenced here), or disputes relating to continuation of airworthiness obligations. The AD itself does not supply that history, so independent legal research is necessary.
• Check CASA’s published enforcement and compliance statements and any public determinations about AD/ENG/5 that may exist on CASA’s website or in its records.

Practical consequence:

• Absent litigation history in the AD, reliance on the instrument requires adherence to the AD’s terms and to the wider statutory and regulatory enforcement framework. Any operational strategy that rests on contesting an AD would need to proceed through the applicable administrative and judicial processes, none of which are described or referenced in this document.

This AD contains multiple specific provisions and reference points that can create practical traps for operators and maintainers if overlooked. The following items are concrete "gotchas" extracted from the AD text:

1. Applicability carve‑outs are narrow but specific:

   • Engines installed in aircraft administered by an approved sports aviation body, aircraft with limited category certificates under CASR 21.189, and experimental certificate aircraft under CASR 21.195A are excluded. Misclassifying an aircraft’s certification status could lead to incorrectly assuming an engine is outside the AD’s reach. Confirm certification status before relying on the exclusion.

2. Fixed SIL reference point:

   • The AD replaces an obsolete PWC SIL reference with Pratt & Whitney Canada SIL No. GEN‑055 Revision 10 dated 13 November 2018 and ties ECTM requirements to that revision "as existing at the commencement of this instrument". Practitioners must not assume "latest" means future revisions; the AD anchors to GEN‑055 R10. If PWC later publishes a different SIL, operators must check whether CASA amends the AD or requires compliance with the later SIL.

3. ECTM vendor constraint:

   • Appendices mandate ECTM "in accordance with the WebECTM® system or CAMP Systems International (CAMP), as required under revision 10 of Pratt and Whitney Canada SIL No. GEN‑055". That narrows acceptable ECTM providers and may require subscription to a named system. Operators using an alternative monitoring provider may need to migrate or secure an approved system of maintenance under regulation 42M.

4. Pro‑rata TBO for partially used PT6A engines:

   • Appendix A, requirement 1 mandates that PT6A engines introduced into the maintenance program with more than 75% of the PWC published TBO already elapsed must be subject to a pro‑rata TBO based on the published TBO. Operators introducing older engines into a program must plan for shortened remaining TBO and potentially immediate maintenance.

5. Training and qualification obligations for ECTM personnel:

   • Both Appendices require qualification and training for personnel conducting ECTM. Delegating ECTM tasks to unqualified personnel risks non‑conformance with the AD.

6. Two‑year review and CASA reporting:

   • The maintenance programme must be reviewed and revised as required at periods not exceeding two years and outcomes must be reported to CASA via DRS or Form 404 referencing AD/ENG/5 (Appendices). Failure to report may constitute an administrative breach.

7. Conflicting choices for PT6A operators:

   • PT6A operators must carefully select between following PWC Service Bulletins, electing the 5,000 hour TBO subject to Appendix A, or an approved system of maintenance. Each choice carries different inspection schedules, vendor requirements and documentation obligations.

8. Inspections with short periodicities:

   • Several inspection items have short intervals: oil filter and chip detector inspections every 220 hours; fuel nozzle cleaning/flow checks every 460 hours; compressor inspections every 220 hours. Organisations must ensure maintenance cycles and scheduling systems can accommodate these cadences, particularly for fleets with high numbers of aircraft or tight maintenance windows.

9. Life‑limited components tied to AD/ENG/7:

   • Life‑limited component replacements are mandated per AD/ENG/7. Operators must cross‑check AD/ENG/7 to identify life‑limited parts and their limits; failure to observe AD/ENG/7 will leave a maintenance programme non‑compliant.

10. Deadline tension:

• The AD becomes effective 31 March 2026 and requires compliance no later than 30 June 2026. Operators needing to establish ECTM arrangements, staff training, or approved systems of maintenance approvals should note the limited transition period and plan capacity accordingly.

11. Previous AMOCs acceptance is limited to "equivalent requirements":

• Although the AD accepts previously issued AMOCs or exclusions to AD/ENG/5 Amendment 9 as acceptable for compliance with equivalent requirements, the phrase "equivalent" requires a careful mapping exercise. Operators should document equivalence to avoid gaps.

12. Distinct regimes for agricultural/fire‑fighting PT6A engines:

• Aviation operations that change role (e.g., an aircraft switching from general charter to agricultural operations) must reassess which PT6A regime applies. Appendix B (agricultural on‑condition program) differs in mandated intervals and monitoring expectations from Appendix A (enhanced program).

These are concrete implementation risks arising from the AD’s text. Each represents a point where oversight, administrative error, vendor choice, timing, or misinterpretation could render an operator non‑compliant with the AD.

Compliance hinges on three sequential steps: (1) determine applicability for each turbine engine and aircraft, (2) select an approved compliance pathway appropriate to the engine family and operations, and (3) implement the specific technical, administrative and reporting measures mandated.

Step 1 , Determine applicability and classification:

• Check whether the turbine engines are installed in aircraft excluded by the AD: aviation administered by an approved sports aviation body; limited category certificate aircraft under CASR 21.189; experimental certificate aircraft under CASR 21.195A (Applicability). If excluded, document the basis for exclusion in maintenance records.
• For engines within scope, identify engine family and model (Honeywell TPE331 series, PWC PT6A series or other turbine engines). Ascertain operational role for PT6A engines (whether conducting aerial agricultural operations or fire‑fighting operations) because Appendices differ by role (Requirements 1.3-1.4).

Step 2 , Choose the compliance route:

• Option A: Manufacturer TBO/CAM , For many operators the simplest route is to adopt the engine manufacturer’s published TBO hours or CAM program. The AD explicitly allows manufacturers’ recommended hours in service as one compliance path (Requirement 1.1), and for TPE331 specifically allows Honeywell Service Bulletin TBO or Honeywell CAM program (Requirement 1.2).
• Option B: AD intervals/Appendices , For PT6A engines, elect the AD’s specified engineering routes: (i) non‑agric PT6A: PWC Service Bulletin or overhaul ≤5,000 hours subject to Appendix A; (ii) agric/fire‑fighting PT6A: follow the PWC Service Bulletin or adopt an on‑condition program having regard to Appendix B (Requirements 1.3-1.4).
• Option C: Approved system of maintenance under regulation 42M , If you already hold a CASA approved system of maintenance, confirm that your system aligns with the AD requirements. If not previously approved, consider seeking approval under reg 42M and document equivalence to AD intervals and monitoring.

Step 3 , Implement technical measures (Appendices A and B when relevant):

• ECTM: If electing Appendix A or B, subscribe to WebECTM® or CAMP as required under PWC SIL GEN‑055 R10 and implement ECTM data collection, analysis, trend monitoring, and defined follow‑up actions. Ensure personnel conducting ECTM have documented qualification and training per Appendix requirements.
• Hot section inspections: Implement hot section inspections at the specified maximum intervals:
  • Appendix A: not to exceed 1250 hours; or 1760 hours subject to boroscope inspections at intervals not exceeding 610 hours.
  • Appendix B: not to exceed 1510 hours. Schedule boroscope inspections where the extended interval option is elected.
• Fuel nozzle and engine accessory servicing: Clean and flow check fuel nozzles every 460 hours; maintain accessory TBOs in line with PWC recommendations.
• Oil filter and chip detector: Inspect the engine oil filter element every 220 hours for contamination and the reduction gearbox chip detector every 220 hours for contamination or continuity.
• Compressor actions: Inspect the 1st stage compressor for FOD, corrosion and contamination every 220 hours; perform compressor power recovery washes in response to trend deviations or at intervals not to exceed 220 hours or 3 calendar months (Appendix A item 9).
• Low utilisation oil change: For engines with annual utilisation <500 hours per annum, change engine oil at intervals not exceeding 12 calendar months.
• Life‑limited components and critical components: Replace life‑limited components in line with AD/ENG/7 and inspect critical components as per the applicable PWC Service Bulletin.
• Engine shop work‑scope: For Appendix B agricultural on‑condition program, ensure shop visit work‑scopes take account of PWC recommendations and minimum modification standards for engine durability (Appendix B item 10).

Step 4 , Administrative actions and recordkeeping:

• Pro‑rata TBO: For PT6A engines with hours in service greater than 75% of PWC published TBO at time of introduction into the program, apply a pro‑rata TBO according to Appendix A item 1.
• Programme review schedule: Perform a documented review of the maintenance program at intervals not exceeding two years, taking into account all major defects and defects affecting engine durability. Record outcomes of the review and submit to CASA using the DRS Portal or via Form 404 referencing AD/ENG/5 (Appendices A and B).
• Maintain evidence of compliance: Keep copies of the relevant manufacturer Service Bulletins, the Pratt & Whitney SIL GEN‑055 R10 (where claimed), ECTM vendor subscriptions, training records for personnel, inspection logs, component replacement records (including references to AD/ENG/7 life‑limited components), and DRS/Form 404 submissions.

Step 5 , Transition and continuity:

• If you have an existing AMOC or exclusion under AD/ENG/5 Amendment 9, map its terms to the Amendment 10 requirements and document equivalence. The AD indicates such AMOCs/exclusions are acceptable for compliance with equivalent requirements.
• Timelines: The AD is effective 31 March 2026; compliance is required no later than 30 June 2026. Schedule required changes (ECTM subscription, training, inspection slots, parts procurement) so that the chosen compliance route is fully operational by the compliance date.

Step 6 , Cross‑reference other ADs and documents:

• Confirm life‑limited components per AD/ENG/7 and ensure AD/ENG/7 compliance is integrated into the maintenance program.
• For Honeywell TPE331 engines rely on the latest Honeywell Service Bulletins or CAM program that apply to the model. Document which revision was used for compliance purposes.

Step 7 , Practical vendor and capacity planning:

• If electing Appendix A/B ECTM requirements, contact WebECTM® or CAMP to confirm onboarding timelines, data collection interfaces and training packages. Budget for subscription costs and data management.
• Plan for maintenance shop availability for hot section inspections, boroscope inspections, nozzle servicing and potential early overhauls in cases subject to pro‑rata TBO.
• Ensure supply chain availability for life‑limited parts and critical components that will be replaced on published life limits.

Step 8 , Legal and compliance checks:

• Seek legal/regulatory advice if there is uncertainty about whether an engine variant or specific operation falls within the AD’s applicability, or if you need to apply for or update an approved system of maintenance under regulation 42M.
• Document the choice of compliance path, technical documents relied upon (service bulletins, SIL GEN‑055 R10 where relevant), and the administrative proof of compliance (DRS/Form 404 receipts, training records).

By following these steps and aligning technical programmes and administrative processes to the specific intervals and reporting obligations set out in the AD and its Appendices, operators and maintenance organisations can create an auditable compliance trail that conforms to the AD’s requirements by the stated compliance date.