Civil Aviation Order 100.23 (Airworthiness Authorities — General) Instrument 2007

The central concept is the "authority" itself, defined in the Order as meaning an "airworthiness authority." Under regulation 2 of CAR, an airworthiness authority is an authority granted under regulation 33B, which empowers CASA to issue authorities to persons to exercise privileges in relation to the maintenance, repair, or modification of aircraft. The Order classifies these authorities into three distinct classes: Maintenance Authority (governed by CAO 100.24), Non-Destructive Testing Authority (CAO 100.27), and Aircraft Weight Control Authority (CAO 100.28). Each class may also be "rated" - a rating is an endorsement on the authority that limits or specifies the types of aircraft, components, or processes the holder may work on. The actual rating categories are not set out in this Order; they are defined in the relevant class-specific Orders. A critical concept introduced by the 2026 amendment is the "relevant Order", defined in section 1B as the Civil Aviation Order mentioned in section 1 for the class of authority sought. This means that when applying for a Maintenance Authority, the "relevant Order" is CAO 100.24; for a Non-Destructive Testing Authority, it is CAO 100.27; for an Aircraft Weight Control Authority, it is CAO 100.28. The Order also introduces the concept of "examination" but treats it flexibly: there are no regular periodic examinations (section 3.2), and examinations are arranged individually for each applicant. The examiner has discretion to allow a re-sit of a failed examination and may impose conditions for that re-sit (section 3.1). The holder of an authority can also be required to undergo an examination at any time in respect of any rating endorsed on the authority (section 3.3). Another key concept is the "disability" provision in subsections 2.2 and 4.4. Subsection 2.2 allows CASA to refuse issue of an authority if the applicant has a disability that is "likely to affect" the applicant's technical skill or judgment. Subsection 4.4 imposes a duty on an existing holder who develops such a disability: they must not exercise the privileges of the authority. The Order does not define "disability" or give examples, nor does it specify what standard of proof CASA must meet when forming an opinion. The concept of "public interest" in subsection 5(b) as a ground for withdrawal or cancellation is similarly undefined. The Order also uses the concept of "notice of change of address" in subsection 4.3: the holder must notify CASA in writing of any change of address so that CASA can communicate with the holder about the authority. This is a relatively low burden but creates a potential trap: if CASA sends a notice to the last notified address and the holder does not receive it, the holder may be unaware of a requirement or cancellation.

The primary persons affected are individuals who seek to perform airworthiness functions on Australian registered aircraft, specifically in the areas of maintenance (including repair and modification), non-destructive testing, and aircraft weight control. This includes licensed aircraft maintenance engineers, maintenance organisations (through their authorised persons), non-destructive testing specialists, and weight control engineers. The Order also affects employers of such persons, as they must ensure their employees hold the appropriate authority and comply with the conditions, particularly the disability obligation in subsection 4.4. CASA itself is affected: it must process applications, conduct examinations, issue authorities, and exercise discretion in refusing, withdrawing, or cancelling authorities. The Order also indirectly affects aircraft owners and operators who rely on the work done by authority holders for the airworthiness of their aircraft. If an authority is withdrawn or cancelled, the holder's employer may be unable to continue using that person for certain tasks, potentially disrupting maintenance schedules. The Order does not affect corporate entities directly, as airworthiness authorities are issued to individuals, not companies. However, Part 145 maintenance organisations under the Civil Aviation Safety Regulations 1998 (CASR) may require their personnel to hold airworthiness authorities under CAR, creating a cross-regulatory effect. The age requirement (at least 21 years of age, unless otherwise approved in subsection 2.3(a)) affects younger applicants. This is a notable barrier: an 18-year-old with exceptional skills cannot be issued an authority without CASA's specific approval. The English language requirement in subsection 2.3(b) affects applicants whose first language is not English, although the standard ("able to read, write and speak the English language") is not further defined. The disability provisions in subsections 2.2 and 4.4 affect persons with any physical or mental condition that might impair technical skill or judgment, including conditions that emerge during the validity period. The holder must self-assess and refrain from exercising privileges if such a disability arises. This creates potential legal exposure for the holder if they continue to work while arguably impaired. The Order also affects applicants who fail examinations: the examiner has discretion to allow a further attempt, so there is no guarantee of a re-sit. This creates uncertainty for candidates who may have invested significant time and money preparing. The public interest ground for cancellation (subsection 5(b)) could theoretically affect any authority holder, creating a broad and unpredictable risk that CASA could revoke an authority without cause beyond the Director's opinion that it is in the public interest.

The Order imposes several duties on applicants and holders. The initial duty is to apply using the correct form (subsection 2.1). The forms are prescribed by CASA and differ by class: an "Application for Initial Issue or Amendment to Scope of a Maintenance Authority" for maintenance; an "Application for Initial Issue of, or Additional Method to, a Non-Destructive Testing Authority" for NDT; and an "Application for Initial Issue or Amendment of an Aircraft Weight Control Authority" for weight control. The applicant must also provide full details of any specified experience or qualifications if the relevant Order requires them (subsection 2.1A). This duty is ongoing: if the relevant Order is updated and adds new experience or qualification requirements, the applicant must meet them at the time of application. The applicant has the right to have their application considered by CASA, but the Order does not set a time limit for CASA's decision. There is a duty to attend an interview if required (subsection 2.4) and to sit and pass any required examinations (subsections 2.3(d) and 3.1). The holder has a right to have their authority renewed upon application, subject to "such of the conditions relating to an original issue as are appropriate" (subsection 4.2). This is not an automatic right to renewal; CASA can impose conditions that may be more onerous than initial issue. The holder has a duty to notify CASA of any change of address in writing (subsection 4.3). This is a positive duty: if the holder fails to notify and CASA sends a communication to the old address, the holder cannot claim ignorance. The holder also has a duty under subsection 4.4: if the holder has a disability likely to affect technical skill or judgment, they must not exercise the privileges of the authority. This is a self-executing prohibition; there is no requirement for CASA to confirm the disability first. The holder has a right to request cancellation of their own authority (subsection 5(d)), but the Order does not say CASA must act on that request. The holder also has a right to be examined at any time on any rating (subsection 3.3), but this is actually an obligation: the holder may be required to undergo such an examination, and failure to do so could lead to withdrawal or cancellation. The applicant has a right to make a further attempt at an examination after a failure, but only at the examiner's discretion and subject to conditions the examiner specifies (subsection 3.1). There is no right to a particular number of re-sits. The applicant has a right to apply for an "approval to the contrary" to the age requirement (subsection 2.3(a)) and to the examination requirement (subsection 3.1 "subject to approval to the contrary"), but no criteria for such approvals are specified. The holder of an authority has no right to a hearing or appeal before withdrawal or cancellation under subsections 5(a)-(c), nor any right to compensation if the authority is cancelled in the public interest.

The Order itself does not create offences or prescribe penalties. Instead, it sets out grounds for administrative action: withdrawal or cancellation of the authority. The enforcement mechanisms are located in the enabling Act and regulations. Regulation 33B of CAR, read with the Act, makes it an offence to exercise privileges of an airworthiness authority without holding a valid authority. Additionally, the holder who fails to comply with subsection 4.4 (not exercising privileges while having a disability likely to affect technical skill or judgment) is potentially committing an offence under the Act or regulations if they continue to exercise those privileges. The Order's enforcement is primarily through non-renewal or cancellation. Subsection 5 allows withdrawal or cancellation in four circumstances: (a) the reason for issue no longer exists; (b) the Director is satisfied that withdrawal or cancellation is in the public interest; (c) the holder is no longer considered competent by the Director; or (d) at the holder's request. The first three grounds are entirely within the Director's discretion. There is no requirement for prior warning, a hearing, or a statement of reasons in the Order. The public interest ground is particularly broad and undefined; it could encompass anything from a change in CASA policy to a media report about the holder. The "no longer considered competent" ground is also subjective. The Director's decision is likely subject to judicial review under the Administrative Decisions (Judicial Review) Act 1977 (ADJR Act) or the common law, but the Order provides no internal merits review mechanism. The note to the Order indicates it is made under regulation 33B of CAR, which is itself a regulation under the Civil Aviation Act 1988. That Act contains general enforcement powers for CASA, including the ability to impose conditions, suspend, or vary authorities. The Order's cancellation process is separate from any criminal prosecution that might arise from non-compliance with the Act or regulations. For example, a holder who continues to work with a disability could be prosecuted under section 20AA of the Civil Aviation Act (reckless operation of aircraft endangering life) or under CAR for breach of maintenance conditions. The Order's disability provision (subsection 4.4) creates a strict duty on the holder; there is no requirement for CASA to prove that the holder actually caused harm. The holder could also face civil liability for negligence in tort if they perform work while disabled and cause damage. The Order does not specify who within CASA has authority to withdraw or cancel; it refers only to "the Director." In practice, that power may be delegated. The absence of a defined procedure for withdrawal (e.g., written notice, opportunity to respond) creates procedural uncertainty for holders.

This Order operates within a broader regulatory framework for aviation safety in Australia. It is made under regulation 33B of the Civil Aviation Regulations 1988 (CAR), which itself is subordinate to the Civil Aviation Act 1988. The Act gives CASA the function of developing and promulgating appropriate aviation safety standards. The Order interacts with three specific other Civil Aviation Orders: CAO 100.24 (Maintenance Authority), CAO 100.27 (Non-Destructive Testing Authority), and CAO 100.28 (Aircraft Weight Control Authority). Those Orders contain the technical requirements for each class, including experience, knowledge, and examination syllabi. This Order is the procedural gateway: an applicant must meet the general eligibility criteria here before the class-specific requirements are applied. The Order also interacts with the Civil Aviation Safety Regulations 1998 (CASR), particularly Part 66 (Aircraft Maintenance Personnel Licensing) and Part 145 (Approved Maintenance Organisations). However, the relationship is complex. CASR Part 66, implemented progressively from the 2000s, introduced a new licensing system for maintenance engineers (LAME licences) that replaced the CAR-based airworthiness authorities for many functions. But this Order remains in force for certain specialised functions that are not yet covered by CASR, such as non-destructive testing and weight control. For maintenance authorities, the interplay depends on the transition arrangements. The Civil Aviation Act section 98 allows regulations to prevail over orders. CASA has policy statements on the transition. The Order's disability provisions (subsections 2.2 and 4.4) interact with the Disability Discrimination Act 1992 (DDA). The DDA prohibits discrimination on the ground of disability in employment and other areas. CASA's refusal to issue an authority based on a disability, or its withdrawal under subsection 5, could be challenged as discriminatory. However, the DDA provides an exception for genuine occupational requirements that are necessary for safety. That exception would likely apply to airworthiness decisions, but it would need to be justified in each case. The Order interacts with administrative law: decisions under the Order (refusal, cancellation) are likely reviewable under the ADJR Act. The Order does not contain a privative clause ousting review. The public interest ground in subsection 5(b) would be difficult to justify in review unless CASA can articulate a specific reason. The Order's age requirement (subsection 2.3(a)) of 21 years interacts with the Age Discrimination Act 2004, but again, a safety exception may apply. The Order interacts with state and territory workers' compensation laws: if a holder develops a disability and continues to work in breach of subsection 4.4, they may be denied compensation for an injury that results. The Order also interacts with employment law: an employer who requires an employee to hold an authority and then directs the employee to work despite a disability may be vicariously liable for breaches. The Order does not interact with privacy law directly, but CASA's handling of disability information would be subject to the Privacy Act 1988.

The Order was originally made as "Civil Aviation Order 100.23 Instrument 2007" and registered on the Federal Register of Legislative Instruments (FRLI) on 17 December 2007, commencing 18 December 2007. The original instrument replaced the previous section 100.23 of the Civil Aviation Orders (which had been in force for many years as a numbered section within the consolidated orders). The first amendment was "CAO 100.23 2009 No. 1", registered on 28 May 2009 and commencing 29 May 2009. It added a new subsection 6 to the Order. The content of that subsection is not specified in the compilation table, but it was later repealed. The second amendment was "CAO 100.23 2011 No. 1", registered on 22 June 2011 and commencing 27 June 2011. It repealed subsection 6 entirely. The most recent amendment at compilation date is the "Civil Aviation Orders 100.23 and 100.24 Amendment Instrument 2026", registered on 25 March 2026 and commencing 26 March 2026. This is a significant amendment that restructured the Order. It inserted a new subsection 1A (Name of instrument), a new subsection 1B (Definitions), and amended subsections 1, 2, 3, and 4. The amendment instrument also amended CAO 100.24 concurrently. Prior to this amendment, the Order did not have a formal definitions section. The new definitions section 1B clarifies that "authority" means airworthiness authority, and introduces the concept of "relevant Order" to cross-reference the class-specific Orders. The amendment updated the references in subsection 1 to list the three classes and their governing Orders. Subsection 2 was amended to replace the requirement to submit an application "to CASA" and to refer to specific application forms by name rather than by generic description. Subsection 2.1A (providing details of experience or qualifications) was added. Subsection 3 was amended to make it clearer that examinations will be arranged individually and that the holder may be required to undergo an examination on any rating. Subsection 4 was amended to update the language on validity period and notification of change of address. The 2026 amendment appears to be a consolidation and formalisation of the Order, not a change of policy. The note to the Order includes a table of amendments showing the history. The compilation number at the time of preparation is No. 3.

The source document does not name any court cases. However, the Order itself has been in operation since 2007 (and its predecessor since earlier decades). There is no reference to any litigation in the text. That does not mean no litigation has occurred, but the instrument as compiled does not record any. The broader regulatory context suggests that decisions made under this Order could be subject to judicial review. Possible types of litigation include: challenge to a refusal to issue an authority on disability grounds under the Disability Discrimination Act 1992; challenge to a cancellation on public interest grounds under the ADJR Act; challenge to an examination decision or condition imposed by an examiner; and tort claims by third parties against a holder who exercised privileges while disabled. The broad discretion given to the Director creates fertile ground for review, but also makes it difficult for an applicant to succeed unless the decision was irrational or procedurally unfair. The public interest ground in subsection 5(b) is particularly vulnerable to challenge because it is not defined and could be applied arbitrarily. A court might read it down to require a genuine and identifiable risk to aviation safety. The absence of an internal review mechanism may increase litigation risk. The Order's interaction with the transition from CAR to CASR may also generate litigation if CASA cancels an authority under the Order as part of a policy to move to the new system. The limitation period for ADJR applications is 28 days from the decision. The practical reality is that litigation is expensive and the decision to pursue review often depends on the commercial value of the authority. Maintenance authorities for high-value aircraft would be more likely to justify legal action. The holder's duty under subsection 4.4 to not exercise privileges while disabled could also lead to professional discipline proceedings by CASA or to civil proceedings if the holder causes damage and argues ignorance of the disability. No case law is cited in the Order text, and none is implied.

Several provisions in the Order contain traps for the unwary. The most significant is the disability duty in subsection 4.4: "The holder of an authority who has a disability, that is likely to affect the holder's technical skill or judgment, must not exercise the privileges of the authority." The holder bears the entire burden of assessing their own condition. There is no requirement for CASA to first determine or confirm the disability. If a holder develops a condition like deteriorating eyesight, hearing loss, or a neurological issue, they must immediately stop exercising privileges. Continuing to work could be a breach of the Order and an offence under the Act. The holder cannot rely on their employer's assessment. The term "disability" is not defined, so it could include temporary conditions such as a concussion, severe fatigue, or even the side effects of medication. A holder who is unsure about their condition should consider not exercising privileges until they are certain. The second trap is the public interest ground for withdrawal or cancellation in subsection 5(b). This gives CASA an extremely broad power to cancel an authority without cause. "Public interest" is not defined, and the Director does not need to give a reason for being satisfied. This creates uncertainty for holders, particularly if CASA changes policy or decides to revoke all authorities of a certain type as part of a transition to CASR. There is no compensation for cancellation, even if the holder has invested years in training. The third trap is the age requirement in subsection 2.3(a): "unless otherwise approved, an applicant must be at least 21 years of age." Younger applicants cannot apply unless they obtain an approval, and the criteria for approval are not stated. This may disproportionately affect apprentices and trainees who complete training before age 21. The fourth trap is the lack of periodic examinations but the ability of CASA to require an examination at any time on any rating (subsection 3.3). This means the holder must always maintain their knowledge and skills, and CASA can test them at any time without notice. Failure to pass could lead to cancellation. The fifth trap is the obligation to notify CASA of any change of address in writing (subsection 4.3). This is a duty, not a request. If the holder moves and forgets to notify, any communication from CASA is deemed to have been received at the old address. CASA could cancel the authority for failure to respond to a notice sent to the old address. The sixth trap is that the Order does not provide any right to a hearing or reasons before withdrawal or cancellation. A holder may discover their authority has been cancelled only when they try to exercise privileges. The seventh trap is that the Order does not state the consequences of failing to pass an examination on a re-sit. The examiner may impose conditions, but if the applicant fails repeatedly, there is no specified limit on attempts, but the examiner can refuse further attempts. The eighth trap is that the "relevant Order" (CAO 100.24, 100.27, or 100.28) may change during the validity of an authority. The renewal process subjects the holder to "such of the conditions relating to an original issue as are appropriate" (subsection 4.2). This means that if class-specific requirements become stricter, the holder may not be renewed unless they meet the new standards.

Compliance with the Order requires attention to both the initial application process and ongoing duties. For initial application, the applicant must first identify the correct class of authority and the relevant class-specific Order. The applicant must obtain the correct application form from CASA's website or office. The three forms are: Application for Initial Issue or Amendment to Scope of a Maintenance Authority; Application for Initial Issue of, or Additional Method to, a Non-Destructive Testing Authority; and Application for Initial Issue or Amendment of an Aircraft Weight Control Authority. The applicant must complete the form fully and submit it to CASA. If the relevant class Order specifies particular experience or qualifications, the applicant must provide full details of those with the application form. This may include certified copies of certificates, logbooks, or employment records. The applicant must be at least 21 years of age, unless they seek and receive CASA approval to be younger. The applicant must be able to read, write, and speak English to a standard that CASA considers sufficient for aviation safety. The applicant must possess such experience as the Director requires; this is typically specified in the class Order. The applicant must pass such examinations as the Director requires. To prepare, the applicant should obtain the syllabus from CASA, attend a training course if available, and arrange an examination with CASA. Examinations are arranged individually, so the applicant should contact CASA early to schedule. If the applicant has a disability that might affect technical skill or judgment, they may be refused. It may be prudent to seek medical advice and discuss any condition with CASA before applying. After issue, the holder must comply with ongoing duties. The holder must notify CASA in writing of any change of address promptly. The holder must monitor their own health: if they develop any disability (physical, sensory, or cognitive) that is likely to affect technical skill or judgment, they must immediately stop exercising the privileges of the authority. The holder should consider having regular medical checks, especially for vision and hearing, and should document any health events. The holder may be required to undergo an examination on any rating at any time; they should keep their knowledge current through continuing education. The holder must renew the authority before expiry; the Order says the period generally does not exceed 2 years, so the holder should check the expiry date and apply for renewal well before that. Renewal is subject to conditions appropriate for an original issue, so the holder may need to meet any updated requirements. The holder should keep copies of all correspondence with CASA, including notification of address changes. If the holder wishes to surrender their authority, they can request cancellation in writing under subsection 5(d). The holder should be aware that CASA can withdraw or cancel the authority if the reason for issue no longer exists, if the Director considers it in the public interest, or if the holder is no longer considered competent. There is no right to a hearing, so the holder should maintain competency and avoid any action that could lead to a public interest finding. The holder should also ensure their employer is aware of the disability obligation, so the employer does not pressure them to work while unfit. The holder should keep a personal record of any health conditions and decisions to refrain from work, in case of later investigation.