Airworthiness Directives 2004 - Revocation and Remaking - DHC-6 (Twin Otter) Series Aeroplanes

The instrument rests on three principal legal and administrative concepts as set out in its short text. First, delegated regulatory action. The instrument is signed by a named delegate of the Civil Aviation Safety Authority and explicitly invokes subregulation 39.001(1) of the Civil Aviation Safety Regulations 1998 as the source of authority for the act of revocation and re-making. The act of a delegate is therefore the legal decision-maker within the statutory delegation scheme the instrument invokes.

Second, revocation and re-making as separate instruments. The instrument performs a pair of linked procedural operations: revocation of existing AD instruments listed in Schedule 1, and the creation of replacement AD instruments, each reproduced and attached to this instrument. The text frames these as two elements of one administrative action: revoke first, then make new instruments covering the same matters. The Schedule enumerates each AD by identifier and short title, and the instrument says the re-made instruments are attached.

Third, administrative continuity. The note included in the instrument states that each attached AD is being re-made in exactly the same form as appears in the latest published edition of the Directive. That is an express administrative claim of substantive continuity, signalling that the re-issuance is not intended to alter technical standards, compliance steps, or obligations contained in the published ADs; it is an administrative re-issuance. The inclusion in the Schedule of entries labelled "CANCELLED" indicates the attached package includes instruments that reflect cancellation status where applicable in the latest published edition.

Operationally, the Schedule provides the scope and catalogue of items affected. It lists a long series of ADs for DHC-6 (Twin Otter) series aeroplanes, with short titles describing the subject matter for each AD (for example "Upper Rudder Fairing - Modification AD/DHC-6/1", "Fuel System Crossfeed Thermal Relief - Modification AD/DHC-6/2", through to "Wing Spar Strut Lug AD/DHC-6/73"). Many entries bear amendment numbers, which show that the published ADs had been amended prior to re-making. The instrument does not itself set compliance obligations, times or technical requirements; rather, it re-establishes the separate AD instruments which contain those details.

Taken together, the conceptual effect is administrative housekeeping: the regulatory power under subregulation 39.001(1) is used to revoke a set of existing AD instruments and reissue them as separate, attached instruments that the instrument claims are identical to the latest published editions. The practical import for regulated parties depends on the content of those attached ADs.

The instrument’s scope is the Airworthiness Directives listed in Schedule 1, which are all identified as applying to DHC-6 (Twin Otter) series aeroplanes. That fixes the primary affected population as persons and entities with operational or regulatory responsibility for those specific aircraft. In practical categories, the affected persons will include:

• Registered owners and operators of DHC-6 (Twin Otter) series aeroplanes in Australia for whom CASA directives have legal force. The instrument revokes the listed ADs and remakes them as separate instruments; therefore the operator’s legal obligations, as set out in the attached re-made ADs, will govern continuing airworthiness and required maintenance or modifications.

• Maintenance organisations, licensed aircraft maintenance engineers, and approved repair stations that perform work on DHC-6 aircraft. The ADs listed in Schedule 1 are styled as modifications, inspections, replacements and limitations; such actions typically require maintenance tasks to be programmed into scheduled maintenance, carried out by appropriately authorised persons, and recorded in maintenance releases and aircraft logbooks. The remade ADs will be the operative instruments that specify the technical measures.

• Airworthiness and compliance officers within airlines or charter operators that operate DHC-6 aircraft. They must track the remade AD instruments and ensure compliance is recorded and certified under the applicable regulatory framework. The administrative change may require internal reference updates and re-filing of compliance evidence.

• CASA as regulator and its delegates. The instrument itself is the result of delegated authority and will change the statutory citation and form in CASA’s instrument register. CASA staff administering continuing airworthiness obligations will use the re-made ADs as the regulatory instruments for enforcement, approvals and audit.

• Legal and compliance advisors who advise affected parties on regulatory compliance; they will need to review the attached re-made ADs to advise whether any practical changes to maintenance programmes, approvals, or documentation are necessary.

The Schedule includes AD entries that are annotated "CANCELLED". Where an entry is so annotated, the attached re-made instrument will reflect the latest published edition, which in those cases may be a cancellation. That affects stakeholders who previously relied on a now-cancelled AD: they should verify whether a cancellation means action is no longer required or whether other instruments now cover the same risk. The instrument itself does not list aircraft registration numbers, so the universal effect is on all DHC-6 series aeroplanes to which those ADs apply under CASA’s regulatory regime.

The instrument is silent on geographic scope outside the CASA framework. It does not purport to amend foreign airworthiness directives or the regulatory regimes of other states. The practical effect for operators outside Australia will depend on their national authority’s treatment of CASA ADs; that is beyond the text of this instrument.

The instrument’s short form sets out what it does procedurally; it does not itself articulate the technical duties that regulated parties must follow. Nevertheless, from the instrument’s structure and the attached Schedule the following duty-right framework is implicit and grounded in the instrument:

• Duty to comply with the remade ADs. Clause (b) of the instrument’s operative text states the delegate will make, as separate instruments, each Airworthiness Directive mentioned in Schedule 1 and attached. Those attached ADs are the separate statutory instruments that impose specific duties (inspection, modification, replacement, life-limitation, or prohibition) on owners, operators and maintenance providers. Accordingly, the primary duty is to perform, within the times and methods set out in each attached AD, the actions those ADs require.

• Duty to treat the remade ADs as the operative instruments. The instrument revokes the earlier ADs it lists and replaces them with the attached instruments. That change affects what the regulated party should cite in records, certificates of release to service, and compliance files. The instrument’s note that each AD “is being re-made in exactly the same form” informs the expected continuity of substantive duties, but the formal duty is to comply with the attached instruments as the legal source.

• Right to rely on the instrument’s administrative statement of identity. The instrument’s note gives a stated assurance that the attached ADs reproduce the latest published editions. A regulated party can reasonably expect that compliance obligations remain substantively as they were in the published editions, but the legal right to rely on that assurance is procedural: any dispute about substance would be resolved by reference to the text of the attached re-made ADs and the enabling legislation.

• Duty to check for cancellations and amendments. The Schedule includes items marked “CANCELLED” and many entries include amendment annotations (Amdt X). Those markings indicate variation in status among the listed ADs. Affected parties must examine the attached instruments to determine whether an AD imposes a continuing obligation, has been amended, or has been cancelled. The instrument itself does not elaborate the effect of cancellations beyond annexing the attached instruments.

• Duty to maintain administrative records. Because the instrument revokes and remakes the ADs as separate instruments, operators and maintainers will need to update their compliance records, maintenance logs, and regulatory filings to reflect the current instrument identifiers and dates. The instrument does not specify record-keeping procedures; those are controlled by the Civil Aviation Safety Regulations and by the individual ADs.

Rights that the instrument does not expressly grant or alter include applications for exemptions, approvals for alternative means of compliance, or appeals against CASA decisions. The instrument is silent on appeals, discretionary approvals or specific procedural remedies; the legal availability of those mechanisms will lie in the broader statutory framework under the Civil Aviation Safety Regulations and any administrative law remedies. The instrument’s text anchors duties and rights to the attached ADs and to the enabling subregulation 39.001(1).

The instrument itself is a short revocation/remaking declaration and does not set out penalty provisions or enforcement procedures. It invokes subregulation 39.001(1) of the Civil Aviation Safety Regulations 1998 as the enabling authority for the delegate’s action, but it contains no express provision that creates criminal sanctions, civil penalties, or an enforcement regime. Therefore the enforcement and penalty framework relevant to non-compliance with any requirements arising from this instrument must be found in the Civil Aviation Safety Regulations and in the substantive language of the attached Airworthiness Directives.

Practically, this means:

• The instrument does not itself impose a distinct penalty for failure to comply with it; rather, compliance obligations will flow from the separate ADs that are attached and remade. Any penalty for non-performance of the measures contained in an AD must be determined by reference to the Civil Aviation Safety Regulations and other applicable statutory provisions which govern offences and sanctions for airworthiness and safety breaches.

• The instrument’s revocation of earlier ADs and re-making of replacement AD instruments changes the legal instrument that CASA would rely upon in enforcement. If CASA were to take enforcement action for failure to comply with an AD-listed requirement, the relevant promissory instrument would be the re-made attached AD rather than the previously existing AD. The instrument therefore affects which statutory instrument is cited in notices, infringement proceedings, or prosecutions.

• The instrument contains no statement of administrative discretion or of how CASA will exercise enforcement options. The process for enforcement (notices, rectification directions, infringement notices, civil penalties, or criminal prosecutions) and the procedural rights of the regulated party are not addressed in the instrument’s text and must be sought in the wider CASR framework.

• Where an entry in the Schedule is marked “CANCELLED”, the attached instrument will reflect that status. Enforcement exposure for a previously required action may cease if the AD has been cancelled in the latest published edition and the attached instrument records that cancellation. Regulated parties must therefore review the attached ADs themselves to determine whether non-compliance remains a potential enforcement matter.

Because the instrument provides neither penalty figures nor enforcement steps, stakeholders aiming to understand sanction exposure must consult the Civil Aviation Safety Regulations 1998 for the enforcement scheme and the attached ADs for the specific compliance conditions that, if breached, may attract enforcement action.

The instrument operates expressly within the Civil Aviation Safety Regulations 1998. The delegate invokes subregulation 39.001(1) as the statutory source for revocation and re-making of Airworthiness Directives. Accordingly, its legal effect is as a subordinate instrument under that regulatory framework; it does not purport to displace primary legislation, nor does it repeal or amend the Civil Aviation Safety Regulations themselves.

Interactions that arise from this are principally of an administrative and evidentiary nature:

• Instrumental relationship to CASR. The instrument is a regulatory measure made under authority provided by a specific subregulation of CASR. Therefore the scope of the instrument, including what it may lawfully revoke and remake, is bounded by the powers and limits in CASR. Any interpretive or enforcement matter that depends on the enabling authority must be resolved by reference to CASR’s provisions, which are not reproduced in this instrument.

• Relationship to the separate AD instruments. The instrument reissues the ADs as separate instruments attached to it. Those attached ADs will interact with, and be applied alongside, other CASR obligations on continuing airworthiness, maintenance release processes, certification, and record-keeping. The instrument does not itself specify how conflicts between AD requirements and other CASR requirements are to be resolved; resolution will follow statutory interpretation and the regulatory hierarchy under CASR.

• Impact on administrative records and compliance chains. By revoking listed ADs and remaking them as separate instruments, the instrument alters the formal provenance of the regulatory obligations. Other administrative instruments, approvals, or exemptions that reference the previous AD instruments may need to be reviewed to ensure that cross-references remain accurate. The instrument does not automatically update external documents that cite the old AD instrument numbers.

• Interaction with prior amendment history. Many entries in Schedule 1 include amendment annotations (for example “Amdt 1”, “Amdt 4”, “Amdt 5”), indicating the published ADs have been amended previously. The instrument’s note states that each attached AD reproduces the latest published edition. Therefore, for legal effect, the remade instruments incorporate those prior amendments as they appear in the latest edition. Where a prior instrument has been cancelled as indicated in the Schedule, the attached remade instrument will carry that cancellation status and will therefore interact with other laws and approvals accordingly.

• No stated extra-territorial effect. The instrument makes no claim of extra-territorial operation. Any interaction with foreign regulatory regimes or with aircraft registered in other states will depend on those states’ treatment of CASA ADs and on international agreements; the instrument contains no text to bind other jurisdictions.

Overall, interaction with other laws is mediated through the enabling CASR provisions and through the content of the re-made ADs. Parties seeking to map the full legal consequences must consult CASR, the attached AD instruments, and any other CASA instruments or approvals that reference those ADs.

The instrument itself is a single dated action, signed 20 December 2004 by David Alan Villiers, delegate of the Civil Aviation Safety Authority. It records no prior amendments to the instrument because its subject is the revocation and re-making of a package of Airworthiness Directives rather than a series of iterative amendments to a single statutory instrument.

However, the Schedule lists many ADs with amendment annotations. Those annotations are part of the published ADs’ histories and indicate that individual ADs have themselves been amended before the date of this instrument. For example several entries show “Amdt 1”, “Amdt 2”, “Amdt 3”, “Amdt 4” or “Amdt 5” appended to the AD identifier. Those amendment annotations in Schedule 1 show the administrative history of the underlying AD documents as they stood in their latest published edition prior to re-making.

The instrument’s note, which states that each attached Airworthiness Directive is being re-made in exactly the same form as appears in the latest published edition of the Directive, implies that the remade instruments incorporate those amendment histories up to the latest published edition. In other words, this instrument is not recapturing original AD texts from first issue; it is reissuing the latest, amended editions as separate instruments.

A small number of entries in Schedule 1 are labelled “CANCELLED”. Those entries show that certain ADs had been cancelled in the latest published edition and that the attached set includes that cancellation status. The instrument does not explain the reasons or dates for those cancellations, and it does not include a timeline of when each AD or amendment was originally made. It simply records the current administrative status as at the date of remaking.

Because the instrument is procedural in nature and only reissues the latest published ADs, its own amendment history is a single recorded action. Any further changes to the remade ADs after 20 December 2004 would appear as amendments to those separate AD instruments and would not be reflected in this revocation/remaking instrument unless a subsequent instrument expressly revoked or re-made them again.

The instrument itself contains no record of litigation, court challenges, or administrative appeals. It is a short administrative instrument that revokes and reissues a catalogue of Airworthiness Directives and includes a signature and date. No case names, judicial decisions, or proceedings are referenced in the instrument text.

Because the instrument does not include litigation history, a reader cannot infer from the instrument whether any of the underlying ADs or their contents have been the subject of judicial review, administrative appeals, or enforcement litigation. Any litigation that might relate to the enforcement or interpretation of those ADs would be recorded in external case law or administrative records; those are not reproduced or summarised here.

Practically, potential avenues for dispute would, in the broader legal context, include questions about the validity of the revocation/remaking exercise, the correctness of the enabling power in subregulation 39.001(1), or the legal effect of cancellations and amendments. None of those matters are addressed or decided in the instrument itself. If an affected party wished to challenge the action, the appropriate legal forum and grounds for review would depend on the statutory appeal and judicial review regimes applicable to CASA decisions and to the Civil Aviation Safety Regulations, none of which are contained within this instrument.

In short, the instrument records no litigation history. Those seeking to identify whether any of the ADs listed have been litigated will need to consult court and tribunal records, administrative appeal registers, or CASA’s public records outside the instrument supplied here.

Several practical and legal pitfalls are visible from the instrument’s text and Schedule; they are matters of administrative detail rather than substantive surprise, but they warrant attention because they affect compliance posture.

• Formal instrument identity changes. The instrument revokes the ADs and re-makes them as separate attached instruments. Even though the note claims the re-made ADs are in exactly the same form as the latest published editions, the formal legal instrument that an operator must cite and that regulators will rely on has changed. That affects citations in compliance files, maintenance records and any regulatory correspondence. Operators should not assume that informal references to old instrument pages or URLs remain authoritative.

• Cancellations are listed among re-made items. Several entries in Schedule 1 are annotated “CANCELLED” (for example AD/DHC-6/20, AD/DHC-6/47, AD/DHC-6/59 and AD/DHC-6/68). The presence of a cancellation entry in the Schedule could be misread. The instrument’s text says that each AD mentioned in Schedule 1 is to be revoked and re-made as attached instruments. Where the latest published edition records cancellation, the attached instrument will likely reflect that cancellation. Practitioners should open each attached AD to confirm whether an AD is operative or cancelled rather than rely on the Schedule label alone.

• Amendment numbers in the Schedule. Many AD entries carry amendment annotations (Amdt 1, Amdt 2, Amdt 3, Amdt 4, Amdt 5). Those annotations indicate that the published AD in the latest edition has undergone prior amendment. If a regulated party’s compliance records refer to an earlier edition lacking those amendments, they may be out of compliance even though the work done complied with the earlier text. The remade instruments, per the instrument note, will be in the form of the latest published edition and therefore include those amendments.

• The instrument does not itself include technical requirements. The revocation/remaking instrument is administrative; it does not reproduce the technical obligations, compliance times, or methods. A common mistake would be treating this instrument as the substantive source for technical compliance. That error can be avoided only by consulting each attached remade AD.

• Record-keeping and certification. Because the legal instrument that supports AD requirements is altered, certificate references (for example references in Certificates of Release to Service) may need updating to reflect the re-made instrument identifiers and dates. A lapse in updating such administrative citations could complicate audit trails or enforcement interactions.

• Reliance on the note of identity. The instrument’s note asserts that the attached ADs are identical to the latest published edition. That is an administrative assurance, not a substantive revalidation. If discrepancies exist between a published AD and the attached AD, the text of the attached instrument is the operative legal text. Parties should verify the attached instruments themselves rather than rely solely on the note.

• No penalty text or enforcement process in the instrument. The instrument does not specify penalties, enforcement pathways or appeal processes. Parties must consult CASR and other instruments for those matters. Failing to do so can lead to misapprehension about sanction exposure.

• Scope limited to DHC-6 series. The Schedule is explicit in covering DHC-6 (Twin Otter) series aeroplanes. That specificity means the instrument does not, on its face, affect other aircraft types. Confusion can arise where operators maintain mixed fleets and assume blanket applicability across types.

Being alert to these administrative intersections and confirming the content of each attached AD will reduce compliance risk. Where there is ambiguity, the attached texts are the primary sources to consult.

The instrument’s operative effect is to replace older AD instruments with re-made AD instruments attached to the revocation/remaking instrument. Compliance therefore flows from the requirements, times and methods stated in each attached AD instrument. The following practical checklist sets out concrete steps, grounded in the instrument’s structure, that a responsible operator, maintenance organisation or compliance officer should take.

1. Obtain and read the attached ADs. The instrument expressly makes the ADs “as separate instruments” and attaches them. The attached texts are the legal instruments that specify required actions. Do not rely solely on the Schedule headings or on this revocation/remaking instrument’s note. Verify that the attached AD text is the latest published edition and that any amendment numbers are reflected in the attached text.

2. Confirm operational status and cancellations. For any Schedule entry annotated “CANCELLED”, examine the attached instrument to confirm whether the AD is indeed cancelled. If cancelled, determine whether any residual obligations remain under other ADs or CASR provisions. If an AD remains operative, note the compliance times and methods.

3. Map AD requirements to your fleet. Identify every DHC-6 aircraft you operate or maintain and map the specific ADs applicable to each aircraft by serial number, configuration and modification status. ADs often apply only to certain serial ranges or configurations; the attached ADs will state applicability. Ensure that a cross-reference table is created to show which ADs are applicable to each aircraft.

4. Programme required work. Where attached ADs require inspections, replacements or modifications, schedule those tasks into the maintenance programme and ensure qualified personnel or approved facilities will perform the work within the time limits set. If the ADs specify required parts or modifications, procure parts that meet the AD’s specifications.

5. Record compliance formally. After performing work, make the appropriate entries in the aircraft maintenance logbook and in any regulatory compliance register. Where applicable, issue the Certificate of Release to Service (or equivalent) citing the remade AD instrument identifier and date. Update any maintenance checklists, continuing airworthiness records and SMS (safety management system) documentation.

6. Update cross-references and documentation. Replace citations to the revoked AD instruments in procedural manuals, maintenance control manuals, quality manuals and safety cases with citations to the remade attached ADs. Ensure that internal audit and compliance functions are aware of the re-made instruments and their identifiers.

7. Check for alternative means of compliance or approvals. The instrument does not address alternative methods of compliance or exemptions. If you have previously obtained an approved alternative means of compliance (AMOC) that referenced the old AD instrument, verify whether the approval continues to be valid against the remade instrument and, if necessary, seek re-approval from CASA.

8. Confirm amendment status. The Schedule shows that many ADs carried amendment annotations before re-making. Confirm that the remade attached ADs incorporate those amendments. If there is any discrepancy between the remade attachment and previously held copies, resolve the discrepancy by reference to the attached instrument text.

9. Train personnel and communicate changes. Inform maintenance staff, pilots, compliance teams and relevant subcontractors about the reissued ADs, where to find the attached texts, and what steps are required for compliance. Ensure that contracting documentation with maintenance providers specifies the correct AD instrument identifiers.

10. Retain proof of compliance for audits. Keep dated proof of compliance, including work orders, parts procurement records, certificates, logbook entries and relevant correspondence. Because the instrument changes the formal source document, ensure that proof cites the remade AD instrument.

11. Seek regulatory clarification if needed. If the operator finds any inconsistency between the remade AD and the published edition relied upon previously, or if there is uncertainty about the effect of a cancellation entry, seek clarification from CASA using the normal channels. The instrument does not itself provide dispute mechanisms.

By following these steps, an operator will align its practical maintenance and compliance processes to the legal effect created by the instrument: revoked instruments replaced by separately attached Airworthiness Directives that are, per the instrument’s note, identical to the latest published editions.