Part 66 Manual of Standards

Several recurring, organising concepts determine how the MOS operates in practice.

Categories and subcategories of licence. The MOS operates around four licence categories (A, B1, B2 and C) and subcategories for combinations of aeroplanes, helicopters, turbine and piston engines (A1/A2/A3/A4 and B1.1/B1.2/B1.3/B1.4). Section 66.A.1 sets this out and links the subcategories to engine and aircraft types.

Privileges and scope of certification. Section 66.A.20 describes which maintenance tasks a licence holder may certify or may issue a CRS for, subject to limits such as whether the maintenance was personally performed, whether it was base maintenance on a large aircraft, and whether the task is listed in the applicable Part 145 Appendix II tasks. The section separates tasks by category and distinguishes mechanical, powerplant, structural, electrical and avionic designations. Table 1 (in 66.A.20) maps ATA chapters to the B1 (mechanical/powerplant/structural) and B2 (avionic/electrical) designations, and sets conditions or limitations for particular systems.

Modular licences and exclusions. The MOS recognises modular B1 and B2 licences (defined in 66.5) which are B1/B2 licences issued subject to the exclusion of at least one system or subset. Sections 66.A.35 and Appendix VII specify which systems or subsets may be excluded and provide identifiers for exclusions. Section 66.A.70 describes the process for removing exclusions , by meeting knowledge, training and assessment requirements (66.A.25; 66.A.45; 66.A.50; 66.A.55) and, where relevant, holding prescribed units of competency (Appendix VIII mentioned in 66.A.70(e)).

Knowledge, units of competency and examination standards. Section 66.A.25 sets out the basic knowledge requirements, including that applicants demonstrate module knowledge by examination conducted by CASA or an MTO, with the levels of knowledge set out in Appendix I. Where training is provided by an MTO, applicants must hold the units of competency listed and coded in Appendix IV (or Appendix X for modular licences), or their current VET equivalents on training.gov.au (66.A.25(eb),(ec),(ed)). The MOS includes a 10‑year currency rule for the knowledge and experience used to support an application (66.A.25(ea); 66.A.30(ec)).

Practical experience and logbooks. Section 66.A.30 establishes minimum practical maintenance experience periods for licences and for adding categories or subcategories. It requires evidence in CASA logbooks (Basic Practical Experience Logbook, Modular Licence Basic Practical Experience Logbook). Table 3 and Table 3A set detailed experience (and task list) requirements for adding categories or removal of exclusions on modular licences.

Type training and ratings. Sections 66.A.45 to 66.A.55 address type/task training, specifying that type ratings are issued by CASA following approved training and assessment, or on the basis of RPL comparisons where aircraft are of the same manufacturer and differences do not require further training (66.A.45(c)). Practical type training must be fixed in content and duration, supported by syllabuses and records, and retained for five years (66.A.50).

Requalification and currency. Section 66.A.23 gives concrete requalification thresholds: a licence holder is taken to comply with paragraph 66.120(2)(b) of CASR if in the preceding two years the holder has either had six months continuous employment exercising privileges or accumulated 550 hours doing so (66.A.23(a)). For requalification under 66.120(2)(c), the MOS provides three alternative routes for A, B1 and B2: carrying out at least 100 days of maintenance with evidence, an MTO report certifying assessment, or assessment by an AMO or CAR 30 organisation following a CBT‑based process (66.A.23(b)).

Delegated delivery and CASA approval. The MOS allocates roles to MTOs, AMOs and COA holders for delivering training and assessment (66.A.45(h); 66.A.50(b); 66.A.55(ca)). Where AMOs provide training they must have relevant permissions in their exposition and CASA must approve practical training where required (66.A.50(b)). CASA retains the authority to issue type ratings, perform RPL assessments and remove/endorse exclusions (66.A.45(c); 66.A.70).

Cross‑instrument references. The MOS is integrated with other regulatory regimes by reference to CASR (various regulations), CAR 1988 (regulation 31 legacy references in 66.5), Part 145 MOS Appendix II tasks, Part 147 MOS recognition of prior learning (147.A.07 referenced in 66.5), CAO and AAC materials, and VET unit equivalence on training.gov.au (66.A.25(ed)). Certain embedded notes are signposted as having legal effect , for example, where a Note states “This is a rule” the content has legal force for the cell in question (66.A.4(d); Table 3A notes 1, 2 and 4).

Primary decision maker and regulator. CASA is the entity that will approve applications, issue type ratings and perform RPL assessments under the MOS. The instrument repeatedly assigns responsibilities to CASA for issuing ratings and considering assessments (for example 66.A.10 requires applications to be made in a CASA‑approved form; 66.A.45(c) and (g) set out circumstances where CASA issues a type rating or conducts RPL).

Licence applicants and holders. Anyone who applies for or holds a Part 66 licence is affected. That includes applicants for Category A, B1, B2 and C licences, modular licence applicants, holders seeking removal of exclusions, and licence holders seeking additional type ratings or requalification (66.A.1; 66.A.25; 66.A.30; 66.A.70). The MOS also contains transitional privileges for people who held AME licences under CAR 1988 and were issued Category B1 licences on that basis, allowing certain limited privileges (66.A.20(5A); 66.A.21).

Maintenance training organisations and assessors. MTOs are central to the MOS. They conduct knowledge examinations (66.A.25(b)/(ba)), assess and certify units of competency and RPL (66.6; 66.A.25(eb),(ec)), provide PCT and other practical training (66.A.50(b); 66.A.55(a),(c)), and must retain training records for five years (66.A.50(d)). MTOs must also be able to provide statements of attainment and other documentary evidence that applicants hold units of competency (66.6). MTO course content and assessment plans must align with Appendix requirements.

Approved maintenance organisations and COA holders. AMOs and civil aviation order (CAR 30) COA holders can deliver certain type or excluded system training where permitted in their expositions and subject to CASA approval (66.A.45(h); 66.A.50(b); 66.A.55(ca)). AMOs also play a role in requalification and assessing licence holders under 66.A.23(b)(3).

Employers and maintenance organisations where OJT occurs. Organisations carrying out OJT must be approved by CASA to undertake such training activities and must supervise and assess OJT using approved assessors; OJT must be supported by a detailed syllabus and recorded in logbooks/worksheets (66.A.55(c)(1)-(3); 66.A.55(d)). Employers therefore must prepare syllabuses, allocate approved assessors, and ensure assessments meet CASA standards.

Manufacturers and external trainers. The MOS allows AMOs or COA holders to arrange for the aircraft or engine manufacturer to provide training and assessment for a type in some circumstances (66.A.45(h)(3)). This brings manufacturers into the delivery chain for type training where agreed and approved.

Existing AME and legacy licence holders. Persons who held an AME licence under CAR 1988 and qualified under specific earlier regulations are given transitional privileges in sections such as 66.A.21 and 66.A.20(5A). Those persons must confirm whether their previous ratings map to Part 66 privileges or whether they must undertake additional training or assessments.

Applicants with foreign or military qualifications. Recognition of prior learning (RPL) is explicitly accommodated, with the MOS referencing that RPL may be prescribed by CASA, a Part 147 MTO or a Part 145 AMO (66.5 RPL definition); Appendix V and VI list recognised and excluded States for purposes of cross‑jurisdictional qualifications (66.A.60; 66.A.65).

Persons and organisations that hold records or provide evidence. The MOS imposes documentary duties on MTOs, AMOs and applicants to supply evidence , statements of attainment, logbook entries and MTO/AMO reports , and to retain records (66.6; 66.A.50(d); 66.A.23(b)(2)). The Basic Practical Experience Logbook and the Modular Licence Basic Practical Experience Logbook (66.5 definitions; 66.A.30) are instruments by which experience is evidenced, and they are referenced as available on CASA’s website.

Who pays and who decides. The principal decision‑maker for endorsements, type ratings, RPL and removal of exclusions is CASA, which must receive the completed application and supporting documentary evidence (66.A.10; 66.A.70). The practical and financial burden of meeting the MOS’s training and experience requirements falls on the applicant, employers that provide OJT, and MTOs/AMOs that design and deliver courses. The MOS sets who decides (CASA, MTOs and AMOs) and what those decision points require.

Duties imposed on applicants and training/maintenance organisations are specific and prescriptive in several areas.

Application form and documentary requirement. An application for an aircraft engineer licence or for variation of a licence must be made in the form approved by CASA (66.A.10). That creates a procedural duty to follow CASA’s form and any specified documentary attachments.

Knowledge demonstration and unit‑holding. Applicants for Category A, B1, B2 or modular licences must demonstrate knowledge by examination conducted by CASA or an MTO (66.A.25(b); (ba)). Where training was provided by an MTO, the applicant must hold the units of competency listed in Appendix IV (or Appendix X for modular licences) that are marked “X”, or their VET equivalent on training.gov.au (66.A.25(eb),(ec),(ed)). For Category C applicants without prior B1/B2 licences, the MOS requires the same examination standards as for B1/B2 unless the applicant holds a specified academic degree (66.A.25(da)-(db)).

Practical experience and logbook duties. Applicants must have practical experience of specified lengths (66.A.30(a)), and for self‑study applicants must document experience in the Basic Practical Experience Logbook or the Modular Licence Basic Practical Experience Logbook (66.A.30(aa); (a)(4)(ii)). Experience used to support applications must have been gained within specified periods, commonly the last 10 years (66.A.25(ea); 66.A.30(ec)). When applying to add a category, the applicant must have the minimum period of maintenance experience set out in Table 3 (66.A.30(b)) and when seeking a modular removal of exclusion must follow Table 3A (66.A.30(ba)).

Assessment and reporting duties of MTOs and AMOs. An MTO must assess persons as competent in units of competency and provide statements of attainment or similar documents (66.6). MTOs must design and conduct practical training, assessments and PCT in accordance with section 66.A.50 and Appendix III, and must retain records of practical training for at least 5 years (66.A.50(b),(d)). Where OJT is used, it must be supervised and assessed by approved assessors and approved by CASA (66.A.55(c)(1)-(3); 66.A.55(d)).

CASA decision and endorsement powers. CASA must issue a type rating following satisfactory completion of approved or CASA‑approved training or as the result of an RPL assessment comparing two types of the same manufacturer, in specified circumstances (66.A.45(c); 66.A.45(d)). Exclusions annotated on a licence may be removed only after the applicant gains the basic knowledge and competency (66.A.70(b)) and completes the specific training and assessment called for by 66.A.45(d), 66.A.50 and 66.A.55 as applicable (66.A.70(c)). CASA therefore controls endorsements and the final authority for ratings and exclusion removals.

Privileges conferred. The MOS sets out specific rights (privileges) for licence holders. Examples include:

• Category A subcategory holders may perform maintenance certification and issue CRS for tasks they personally carried out and that are of a kind mentioned in Part 145 Appendix II (66.A.20(a)1-2).
• Category B1 licence holders (subject to exclusions) may perform maintenance certification on systems designated in Table 1 and replace avionic LRUs that require only simple tests to prove serviceability (66.A.20(a)4).
• Category B2 licence holders may perform certification for avionic and electrical systems and instrument/electrical subsystems of other systems, and may replace avionic LRUs requiring simple tests unless an LRU exclusion is annotated (66.A.20(a)6).
• Category C licence holders may issue CRS for base maintenance carried out on large aircraft endorsed on their licence, for the aircraft in its entirety (66.A.20(a)8).

Limitations and conditional rights. Many privileges are expressed subject to conditions: for example, Category B1/B2 are restricted from issuing CRS for base maintenance on large aircraft (66.A.20(a)5 and 7), avionic LRU replacement is limited to LRUs requiring only simple tests (definition of simple test and 66.A.20(a)4(ii)(B); 66.5). For modular licences the scope is explicitly curtailed by exclusions annotated on the licence and those exclusions are applied to the aircraft in its entirety (66.A.70(a)).

Requalification options as rights and duties. Licence holders have the right to requalify under alternative methods set out in 66.A.23(b): performing 100 days of maintenance with evidence, obtaining an MTO report within 28 days, or being assessed by an AMO or CAR 30 organisation under CBT standards. Each option imposes documentary and assessment duties on the licence holder or providers.

Recordkeeping duties. Organisations that conduct practical training must retain records for at least five years (66.A.50(d)). MTOs must issue statements of attainment when they assess units of competency (66.6). Applicants must maintain and present logbook evidence where self‑study is used (66.A.30(aa)).

The MOS itself is a Manual of Standards; it prescribes the standards and processes by which CASA and approved organisations assess compliance with CASR Part 66. The MOS text provided does not list criminal or civil penalties within its own clauses. Instead the MOS operates as a standards instrument that supports the CASR regulatory framework. That framework provides CASA the statutory powers to grant, vary, suspend or revoke licences and to take enforcement action under CASR and other aviation safety legislation. Practical enforcement mechanisms implicit in the MOS and the Act include the following institutionally grounded controls.

CASA’s gatekeeping functions. CASA controls issuance of type ratings and endorsements (66.A.45(c), 66.A.10), performs RPL assessments (66.A.45(c)(2) and (3)), approves practical training and OJT syllabuses (66.A.50(b); 66.A.55(c)(3)), and decides whether exclusions can be removed (66.A.70(c)). CASA’s exercise of those powers enables it to deny or withhold endorsements where the MOS requirements are not met.

Loss or inability to exercise privileges. Non‑compliance with the MOS’s requirements for examinations, units of competency, practical experience, training and assessments will prevent an applicant from obtaining the licences, endorsements or removal of exclusions they seek. Conversely, licence holders who do not meet the requalification conditions set out in 66.A.23 risk losing the ability to rely on their privileges in the period the regulatory criteria are unmet.

Organisational approvals and compliance obligations. AMOs and MTOs must maintain expositions and course plans consistent with Part 145 and Part 147 MOS requirements (66.A.45(h); references to 145.025 and 145.A.37). Failure to operate within approved expositions or to retain required training records (66.A.50(d)) may expose an organisation to CASA compliance action under Part 145/147 approval regimes.

Indirect enforcement via related instruments. The MOS specifically references other regulatory instruments as the legal loci for enforcement: for example, Part 145 MOS Appendix II tasks and Part 147 MOS RPL provisions (66.5; 66.A.25). Sanctions for contravening regulatory requirements such as operating without appropriate approvals, making false statements in applications or issuing invalid certificates of release to service flow from the CASR and related statutory provisions rather than from the MOS text itself.

Summary of enforcement landscape. The MOS allocates duties, sets documentary standards, defines the processes for CASA decisions and requires approved organisations to maintain records and to operate within expositions. The immediate operational consequence of failing those duties is administrative: inability to obtain licence endorsements, refusals of CASA approvals, and the resulting inability to lawfully certify maintenance or issue CRS. More formal enforcement (fines, suspensions) derives from the CASR and the enforcement powers it confers on CASA and is not restated in the MOS clauses provided.

The MOS is an instrument subordinate to the Civil Aviation Safety Regulations 1998 (CASR 1998). It repeatedly cross‑references provisions of CASR and other aviation instruments, and establishes standards and procedural detail that operate within that broader regulatory architecture.

CASR 1998. The MOS is expressly the Manual of Standards for Part 66 of CASR 1998 (66.1(b)). Many MOS provisions implement or give effect to specific CASR provisions: for example, the MOS identifies type‑rated aircraft for paragraph 66.015(2)(e) of CASR (66.A.4), addresses the scope of regulation 66.026 exclusions (66.A.35), recognises States under regulation 66.030 (66.A.60), and deals with excluded States for regulation 66.060 (66.A.65). The MOS therefore supplies the technical content and acceptable means by which CASR’s broader regulatory requirements are met.

CAR 1988 and legacy AME provisions. The MOS incorporates earlier CAR 1988 AME licence references and CAOs for legacy licence holders, by defining “regulation 31” to include various CAR 1988 provisions and related CAOs and advisory circulars as they existed before 27 June 2011 and before 27 June 2015 where referenced (66.5). Transitional privileges for those who held AME licences under CAR 1988 are provided in 66.A.21 and 66.A.20(5A).

Part 145 and Part 147 Manual of Standards. The MOS interacts strongly with Part 145 (approved maintenance organisations) and Part 147 (maintenance training organisations). It incorporates Part 145 Appendix II for Category A tasks (66.A.20(a)1-3) and uses Part 147 RPL standards (147.A.07 referenced in 66.5). It also requires AMOs to use their expositions to provide certain training if permitted (66.A.45(h); 66.A.70(c) referencing 145.025).

Civil Aviation Orders and advisory circulars. The MOS references CAOs and Airworthiness Advisory Circulars (AAC) as part of the definition of regulation 31 for legacy matters (66.5), and references CASA advisory material (e.g., Advisory Circular 147‑1 for PCT) as guidance that CASA will consider when approving PCT courses (66.5 Practical consolidation training note).

Australian VET system. The MOS links to the national register of vocational education and training (training.gov.au) to define equivalence and to require that units of competency listed in appendices or their current equivalents be held by applicants trained by MTOs (66.A.25(ed)). CASA commits to updating the appendices to reflect new unit numbering and titles (66.A.25(ed) note).

Acts Interpretation Act 1901. The instrument engages the Acts Interpretation Act in transitional contexts, excluding application of paragraph 7(2)(c) of that Act to specified persons in relation to repealed sections (66.A.56). That shows how the MOS coordinates interpretation across instruments when amendments occur.

Regulatory sequencing and approval dependencies. The MOS both prescribes training/assessment detail and requires approvals/decisions by CASA and approved organisations. For example, practical training conducted by an AMO must be first approved by CASA (66.A.50(b)), and exclusion removals require evidence from an MTO to CASA as specified in other sections (66.A.30(ba) note and 66.072 of CASR referenced). This creates layers of dependency: an applicant may meet MOS training requirements but still need CASA approval for certain practical elements or endorsements.

“Legal effect” notes within the MOS. Some internal Notes are explicitly elevated to the status of rules. Section 66.A.4(d) explains that if a Note in Appendix IX contains “This is a rule.” the contents of that Note have legal effect for that cell. Table 3A includes Notes 1, 2 and 4 stating “This is a rule.” The MOS therefore contains embedded normative directives that are not mere guidance but act as rules when so annotated.

In short, the Part 66 MOS is a standards instrument that sits within a network of aviation instruments. It defines technical content, while CASR and other instruments provide enforcement, approval powers and the statutory backstop. Implementers must consult the MOS together with Part 145, Part 147, CAOs, AMC/GM and training.gov.au to ensure full compliance.

The MOS text contains multiple internal references to amendment instruments and dates. Several of the references identify the way the MOS has been or will be adjusted by later instruments, and they indicate areas where transitional arrangements apply.

References to 2011 and 2015 legacy rules. The definition of “regulation 31” at 66.5 expressly incorporates CAR 1988 regulation 31 as in force immediately before 27 June 2011, and additional CAOs and associated Specification instruments and AAC material as in force or existing immediately before 27 June 2015 (66.5 definition items 1-4). That language preserves legacy regulatory materials for specified transitional purposes.

Part 66 Manual of Standards Amendment Instrument 2018 (No. 1). Section 66.A.100 is a transitional provision explicitly tied to the Part 66 MOS Amendment Instrument 2018 (No. 1). It provides that, where the 2018 instrument replaced a unit of competency in Appendix IV with a new version, persons who held the previous unit are taken to hold the new unit. The section defines commencement day as the day on which the relevant instrument commences and preserves the unit‑equivalence for holders affected by the 2018 changes (66.A.100).

Part 66 Manual of Standards and Part 147 Manual of Standards Amendment Instrument 2023 (No. 1). The definition of “category B1 modular licence” and “category B2 modular licence” in 66.5 refer to licences granted after the commencement of the Part 66 MOS and Part 147 MOS Amendment Instrument 2023 (No. 1). That indicates the MOS has been updated to accommodate modular licences introduced or refined by the 2023 instrument.

Part 66 Manual of Standards Amendment Instrument 2024 (No. 1). Multiple sections reference the Part 66 Manual of Standards Amendment Instrument 2024 (No. 1). Section 66.A.20 contains a Note that repealed paragraphs 66.A.25(i), 66.A.30(f), and 66.A.45(j) were repealed by the 2024 instrument and preserves a transitional grandfathering clause for persons who satisfied the repealed paragraphs on or before 30 June 2021 (66.A.20(5A)). Section 66.A.56 records that sections 66.A.56 and 66.A.57 were repealed by the 2024 instrument and provides limited transitional non‑application of paragraph 7(2)(c) of the Acts Interpretation Act 1901 for affected persons. Section 66.A.56 also specifies that the section is itself repealed 28 days after commencement of the 2024 instrument (66.A.56(e)). These entries show that the MOS includes internal transitional mechanisms to smooth the effect of substantive changes made in the 2024 instrument.

Other dates and transitional markers. The MOS contains other dated references relevant to transition: for example, it treats AME licences as characterised by their state “as in force immediately before 27 June 2011,” and elsewhere references 15 December 2015 for instruments in force immediately before that date (66.5). It also treats applications and experience as time‑bounded by 10‑year currency rules (66.A.25(ea); 66.A.30(ec)) and sets 30 June 2021 as a cut‑off for certain grandfathered qualifications (66.A.20(5A)).

CASA updates to appendices. The MOS anticipates administrative updating: it states that CASA will update Appendix IV or Appendix X as soon as possible to include new numbering and titles of current VET units published on training.gov.au (66.A.25(ed) note). That is an administrative amendment mechanism rather than a legislative amendment.

Net effect. The MOS text demonstrates that it has evolved through a sequence of amendments (2018, 2023, 2024 instruments are cited), and it contains built‑in transitional provisions for persons affected by those changes. The MOS also embeds administrative processes by which CASA keeps appendices and unit references current. Where the MOS indicates “This is a rule” in notes, those items have been given legal effect as part of the MOS structure (66.A.4(d); Table 3A notes). Users should consult the specific amendment instruments for full text and precise commencement dates when assessing the historical sequencing of changes.

The MOS text provided does not include any litigation history, judicial decisions, or references to court cases. It is purely a standards instrument that prescribes technical and procedural requirements. There are no cases named in the MOS excerpt to form part of a litigation history.

If one requires precedents or disputes about interpretation, enforcement or the application of Part 66 standards, those would need to be sought in the decisions and records of tribunals and courts where CASA regulatory decisions have been challenged. The MOS itself does not cite any tribunal or court determinations, nor does it summarise litigation. Practitioners relying on case law should therefore search court and tribunal databases for judicial review or administrative decisions that cite Part 66 MOS provisions, CASR Part 66, or relevant Part 145/Part 147 instruments.

This section collects practical traps and points of specificity that commonly arise when applying the MOS text.

“This is a rule” notes can have legal effect. Certain Notes embedded in tables are elevated to legal effect where the MOS marks them “This is a rule.” Section 66.A.4(d) explains that when such a Note appears within Appendix IX its contents have legal effect for that table cell. Table 3A also contains Notes 1, 2 and 4 labelled “This is a rule.” Do not treat Notes as guidance by default; check the cell-specific text for legally binding content.

Modular licences hold special mechanics and constraints. A modular B1/B2 licence is a B1/B2 licence granted subject to the exclusion of at least one aircraft system or subset (66.5). Exclusions on modular licences apply to the aircraft in its entirety (66.A.70(a)), and removal of exclusions requires meeting specified knowledge (66.A.25), training and assessment (66.A.45(d); 66.A.50; 66.A.55) and, in some cases, holding particular units of competency listed in Appendix VIII before removal (66.A.70(e)). For modular licence holders, the Table 3A task lists may substitute for a period of experience where specified (66.A.30(ba)). CASA must also receive evidence from an MTO that the holder has successfully completed training and assessment required for the system or subset under section 66.A.25 before removing an exclusion (66.A.30(ba) note reference to section 66.072 of CASR). Failure to provide the right evidence will stop removal.

Currency windows and 10‑year limits. The MOS imposes currency limits on the use of training and experience to support applications. Knowledge and practical experience that supports an application must, in most cases, have been gained during the 10‑year period before application (66.A.25(ea); 66.A.30(ec)). Applicants relying on older training or experience need to ensure they meet the currency rules or seek requalification.

Different requirements for modular and non‑modular routes. The knowledge and unit obligations differ depending on whether the licence is modular. Section 66.A.25(eb) requires that applicants trained by MTOs hold units listed for the category/subcategory in Appendix IV, but 66.A.25(ec) directs modular licence applicants to Appendix X units. Practitioners must check the correct appendix for the licence type sought.

Simple test and avionic LRU replacement boundaries. The MOS allows B1 and B2 licence holders to replace avionic LRUs that only require “simple tests” to verify serviceability (definition of simple test in 66.5 and the privileges in 66.A.20(a)4(ii)(B) and 6(ii)(D)). The definition of simple test is precise: outcome must be a unique go/no‑go indication or parameter and not require interpretation or interdependent value analysis (66.5 simple test). Work that requires specialised external testing, interpretation, or multiple LRU changes in pursuit of a system fault falls outside that scope (see definition of troubleshooting and avionic LRU). Misclassifying tests as simple when they require interpretation or specialised equipment creates compliance risk.

Requalification thresholds are strict and documentary. For requalification in the preceding two years, 66.A.23(a) takes a bright line: six months continuous employment exercising MOS privileges or at least 550 hours within periods totalling six months. Alternative requalification under 66.A.23(b) involves 100 days of maintenance with retained evidence, MTO assessment within 28 days specifying how the assessment was conducted, or AMO/CAR 30 assessment following CBT standards. Practitioners need documentary evidence and timely assessments; informal assurances from employers without the specified documentation will not meet MOS standards.

Limits on B1/B2 issuing CRS for base maintenance on large aircraft. Sections 66.A.20(a)5 and 7 limit B1 and B2 holders from issuing CRS for base maintenance carried out on large aircraft. Category C holders can issue CRS for base maintenance on large aircraft for the aircraft in its entirety if appropriately endorsed (66.A.20(a)8). Misunderstanding these limits is a common operational error.

Vendor/manufacturer training and CASA approval. The MOS allows AMOs or COA holders to arrange for manufacturers to provide training (66.A.45(h)(3)), but it also requires CASA approval for practical training where conducted by a maintenance organisation, and PCT can only be delivered by an MTO approved for PCT (66.A.50(b)). Training delivered by manufacturers that is not integrated with CASA‑approved course plans or MTO/AMO expositions may not be accepted for endorsements.

Record retention obligations. Practical training records must be retained by the training organisation for at least five years (66.A.50(d)). Applicants who rely on training delivered outside of this timeframe may face evidentiary gaps.

Transitional clauses and repeals. The MOS contains transitional provisions tied to specific amendment instruments and dates (66.A.20(5A); 66.A.56; 66.A.100). Individuals and organisations that rely on grandfathering should check the exact commencement dates and whether they have met application or removal deadlines referred to in those transitional rules. For example, 66.A.56 is itself to be repealed 28 days after the commencement day of the relevant 2024 instrument (66.A.56(e)).

Cross‑references to other MOS and standards. The MOS frequently defers to AMC/GM for CASR Part 66, Part 145 and Part 147 MOS materials, CAOs and advisory circulars (66.5; 66.A.25 notes). Practitioners should not treat the MOS as a full stand‑alone compliance manual; compliance requires cross‑checking the referenced parts, appendices and external guidance.

This section sets out an operational compliance checklist for applicants, MTOs, AMOs and employers based on the MOS text.

1. Identify the licence category and subcategory required, and the aircraft types intended to work on.

   • Consult 66.A.1 to select Category A, B1, B2 or C and any relevant subcategory (A1-A4/B1.1-B1.4).
   • Use Appendix IX and section 66.A.4 to determine type‑rated aircraft and whether a specific type rating is required for the type(s) in question.

2. Determine knowledge modules and unit requirements.

   • For non‑modular applications, consult Appendix I (Part 2 and Part 3) and 66.A.25(b) to identify modules and submodules to be examined.
   • For modular licences or modular extension/removal of exclusions, consult Part 2A of Appendix I and Appendix X as required by 66.A.25(ba) and (ec).
   • If trained by an MTO, ensure the applicant holds all units of competency listed in Appendix IV (non‑modular) or Appendix X (modular) that are marked “X”, or their current equivalents on training.gov.au (66.A.25(eb),(ec),(ed)). Record or obtain statements of attainment.

3. Satisfy practical experience minima and logbook requirements.

   • For initial licences, meet the periods in 66.A.30(a) or if applying for a modular licence, follow 66.A.30(a)(4) and keep the Modular Licence Basic Practical Experience Logbook as evidence.
   • For adding a category/subcategory to an existing licence, use Table 3 to identify minimum periods (66.A.30(b)) and ensure experience is from a representative cross‑section of maintenance tasks (66.A.30(c)).
   • For modular removal of at least one exclusion, use Table 3A and complete task lists or experience periods specified (66.A.30(ba); Table 3A). Where task lists can substitute for minimum periods, complete them as instructed.

4. Meet currency and recency rules.

   • Ensure knowledge examinations were passed within the 10‑year period where required (66.A.25(ea)).
   • Ensure practical experience used to support an application was gained within the applicable 10‑year window (66.A.30(ec)).
   • For requalification, track employment and hours carefully: 6 months continuous employment or 550 hours in the preceding two years (66.A.23(a)); or alternative requalification routes such as 100 days of maintenance with documentary evidence or an MTO/AMO requalification assessment (66.A.23(b)).

5. Plan and document required training and assessments.

   • Arrange theoretical and practical training with an appropriately approved MTO or AMO as required by 66.A.45(d) and 66.A.50. Ensure practical training has a fixed content and duration and is supported by a detailed syllabus or worksheets/logbook (66.A.50(b),(c)).
   • For PCT, ensure the MTO is approved to conduct PCT and seek CASA approval where necessary (66.A.50(b)).
   • If OJT will be used, confirm the organisation is approved to manage OJT, that approved assessors will supervise it, and that CASA approval is obtained where required (66.A.55(c)(1)-(3); 66.A.55(d)).

6. Prepare documentary evidence for CASA.

   • Complete the CASA‑approved application form required by 66.A.10.
   • Gather statements of attainment, logbook entries (Basic or Modular), MTO or AMO assessment reports, and any RPL evidence generated under Part 147/Part 145 processes (66.6; 66.A.25; 66.A.30(eb),(ec)).
   • If seeking removal of exclusions, provide the MTO’s evidence that the holder has successfully completed the training and assessment required under 66.A.25 and section 66.072 of CASR where referenced (66.A.30(ba) note).

7. For type ratings:

   • Ensure completion of the relevant Category B1, B2 or C aircraft type training approved by CASA or conducted by an appropriately approved MTO (66.A.45(c)(1); 66.A.45(d)).
   • Complete the theoretical examination in accordance with Appendix III and the practical training specified in 66.A.50 and 66.A.55 as applicable.
   • If relying on RPL for obtaining a different type rating for aircraft of the same manufacturer, be prepared for CASA to perform a comparative RPL assessment (66.A.45(c)(2)-(3)).

8. Maintain records and retention requirements.

   • Training organisations must retain practical training records for at least five years following completion (66.A.50(d)).
   • Applicants and licence holders should maintain logbooks and documentary evidence of experience and assessments to provide to CASA when requested.

9. Check recognised and excluded States lists.

   • If relying on foreign qualifications or overseas experience, consult Appendix V (recognised States) and Appendix VI (excluded States) to determine admissibility under the MOS (66.A.60; 66.A.65).

10. Be aware of special limits and exclusions.

• Verify whether an intended privilege is limited by an exclusion annotated on a modular licence, an LRU or avionics exclusion, or by the distinction between base maintenance and non‑base maintenance on large aircraft (66.A.20; 66.A.35; 66.A.70).
• Confirm whether intended tasks require more than “simple tests” and thus fall outside the LRU replacement permissions for B1/B2 (66.5 definition of simple test; 66.A.20).

11. Keep up to date with appendix and unit numbering changes.

• CASA updates Appendix IV and Appendix X to reflect current VET unit numbering and titles; check CASA’s website and training.gov.au for the current unit identifiers (66.A.25(ed) note).

12. Where in doubt, seek CASA clarification or pre‑approval.

• Because CASA has the final authority to issue type ratings, perform RPL, and approve OJT/practical training, early engagement with CASA or an appropriately approved MTO/AMO can reduce the risk of rejected applications or wasted expense.

This compliance roadmap translates the MOS requirements into a sequence of actions that applicants, training providers and maintenance organisations can follow. Each step maps back to MOS clauses cited above. Practitioners should ensure that training course plans, expositions and assessment records are drafted to reflect the MOS detail, and that all documentary evidence is in place before lodging applications with CASA.