AD/DC3/29 Amdt 4 - Lower Centre Section Skin and Structure

The AD targets fatigue and structural integrity risks in the lower centre wing structure of DC3 aircraft by defining inspection and modification measures at two critical wing stations: WS 94.25 and WS 127.75. The main technical concepts in the AD are:

• Wing stations and critical locations: The AD identifies a band between approximately WS 90 and WS 130 as the region of concern and singles out WS 94.25 and WS 127.75 as critical locations where reinforcing doublers must be fitted or inspected (Requirement Paras 1-3; Background).

• Access and visibility: The AD requires incorporation of access holes in the landing gear drag strut tunnels per McDonnell Douglas Service Rework Drawing SRD03548001 Revision A to enable visual and radiographic inspection of internal structural elements (Requirement Para 2.a; Note 2). The AD accepts that existing access holes need not be redone provided they allow the necessary inspection reach and visibility (Note 2).

• Inspection modalities: The AD mandates both visual and radiographic inspections. It prescribes specific McDonnell Douglas SRD documents for procedure reference (SRD SR03578001 and SRD SR03578002 Revision A) and accepts an alternative radiographic technique (DCA NCI/R/8) subject to an explicit supplementary film placement for exposures 4 and 5 (Requirement Para 2.b; Note 3).

• Structural modification: Where preventive or repair doublers are absent at either WS 94.25 or WS 127.75, the AD requires modification to incorporate wing skin doublers at both stations according to SRD SR03578003 (Requirement Para 2.c). The AD stresses that doublers actually installed must conform to the specified Service Bulletins (SB 229, SB 263 up to Revision 8) and SRD SR03578003, and flags that alternative designs are permissible only with CAR 35 design authorisation approval (Requirement Para 2 and Note 1).

• Regulatory framing: The AD is issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998 (CAR 1998) and is part of CASA’s Schedule of Airworthiness Directives (cover page and Background). It explicitly revokes the previous amendment (Amdt 3) to close an identified wording ambiguity and to clarify that both named wing stations are required (front matter; Background).

These concepts structure the compliance obligations: ensure access, apply both non-destructive test (radiography) and visual surveillance, and install prescribed reinforcements at two specific structural locations. The AD links these technical prescriptions to explicit reference documents (SB 229, SB 263 up to Revision 8, SRD SR03578001/SRD03578002 Rev A/SRD03578003/SRD03548001 Rev A), making compliance documentary as well as physical.

The AD states its Applicability as "All models" of Douglas DC3 series aeroplanes, thereby placing primary compliance responsibilities on operators and owners of any DC3 under Australian regulatory purview (Applicability). Practically, the following parties are directly affected:

• Aircraft operators and owners of DC3 series aeroplanes. They must schedule and fund the inspections, implement any required access-hole incorporation, perform or contract radiographic and visual inspections, and carry out the wing-skin doubler modifications where required (Requirement Paras 1-3; Compliance).

• Maintenance organisations and licensed maintenance personnel who will perform the visual and radiographic inspections and carry out structural modifications to the wing. They must follow specific McDonnell Douglas service data or equivalent approved procedures (Requirement Paras 2.b and 2.c; Notes).

• Design approval holders with an appropriate CAR 35 design authorisation. The AD permits alternative doubler designs only where the alternative has been assessed and approved as at least equivalent by the holder of an appropriate CAR 35 design authorisation (Note 1). That places decision-making power and legal responsibility for equivalence assessments on CAR 35 design authors.

• CASA and the delegated authority who issued the AD. The instrument is issued under subregulation 39.1(1) of CAR 1998 and is signed by the CASA delegate; enforcement and oversight actions would be initiated by CASA inspectors if aircraft are non‑compliant (front matter; Background; signature).

• Holders of the referenced McDonnell Douglas Service Bulletins and Service Rework Drawings (SB 229, SB 263 up to Revision 8, SRD SR03578001/SRD03578002 Rev A/SRD SR03578003/SRD03548001 Rev A). These documents provide the technical specifics required for compliance; operators and maintainers must obtain and follow them (Requirement Paras 2-3).

• Regulatory counterparts noted in the AD: the AD references FAA AD 92-06-15 and Transport Canada AD CF-92-15 (Background; Note 4). While those are references and do not create obligations under the Australian AD, operators who fly DC3s in multiple jurisdictions will need to track those foreign ADs as part of their global continuing airworthiness management.

Who pays: the AD makes no funding provision; costs for inspections, radiography, incorporation of access holes, and installation of doublers fall to aircraft owners and operators and their maintenance providers. Who decides: CASA sets the requirement; a CAR 35 design authorisation holder may approve alternatives; maintainers and operators implement the work consistent with the AD and referenced McDonnell Douglas data.

Key duties imposed by the AD are concrete, time‑specified and document-referenced. They are as follows:

• Duty to inspect accessible components inside the main landing gear bay and via drag strut tunnel access holes between approximately WS 90 and WS 130. The inspection is a visual check of the front face of the wing front spar, the lower spar cap and lower wing skin and doublers (Requirement Para 1). The initial and recurring timing obligations for these inspections are set out in the Compliance section: before exceeding 500 hours TIS since last AD inspection and at intervals not exceeding 500 hours; additionally before further flight following severe turbulence or a heavy landing (Compliance for Para 1).

• Duty to incorporate access holes when necessary. For aircraft not modified with doublers at both critical stations, operators must incorporate access holes in accordance with SRD03548001 Revision A (Requirement Para 2.a). Compliance timing: those access holes must be incorporated no later than the next inspection under Requirement Para 2.b (Compliance for Para 2.a).

• Duty to perform specified visual and radiographic inspections per the McDonnell Douglas SRDs. The AD instructs operators to inspect using visual and radiographic procedures in SRD SR03578001 or SRD SR03578002 Revision A, whichever is applicable (Requirement Para 2.b). Compliance timing: initial inspection before exceeding 900 hours TIS since the last inspection under the prior AD or within 100 hours after the AD issue date, with recurring intervals not exceeding 900 hours (Compliance for Para 2.b).

• Duty to modify the wing by installing wing skin doublers at both WS 94.25 and WS 127.75 according to SRD SR03578003, where the doublers are not already installed (Requirement Para 2.c). Compliance timing: modification must be completed before exceeding 900 hours TIS after 27 April 1995 or within 100 hours after the AD issue date, whichever is later (Compliance for Para 2.c).

• For aircraft already modified with doublers per SB 229, SB 263 and/or SRD SR03578003, the duty is to conduct visual inspection per SRD03578001 or SRD03578002 Rev A at specified intervals (Requirement Para 3 and Compliance for Para 3).

Key rights and clarifications the AD grants or records:

• Acceptance of alternative designs for doublers only where assessed and approved as at least equivalent by a CAR 35 design authorisation holder. This provides operators a path to alternative technical solutions subject to formal design approval (Note 1).

• Carve-outs for prior compliant work: aircraft that have been modified previously in the manner intended by the earlier amendment , that is, correct doubler installation and detailed visual and radiographic inspection at both WS 94.25 and WS 127.75, left and right , do not require additional work due to this amendment. The AD expressly states that aircraft in full compliance with the intent of the previous issue need no additional work under Amdt 4, though ongoing inspection remains required (Background).

• Access-hole rework is not required where existing access holes provide necessary access and visibility (Note 2). This is a rights-of-exemption style provision limited to accessibility and visibility, not to substantive inspection or modification requirements.

• Specified alternative radiographic technique. The AD provides a permitted alternative radiographic method (DCA NCI/R/8) provided the additional film placement requirement for exposures 4 and 5 is met (Note 3). This both constrains and enables radiographers who might prefer an alternative technique but must add film in specified locations.

Duties are time-bound and documented; rights are limited to equivalence approvals and exemptions for past-conforming access. The AD assigns evaluative authority for alternative designs to CAR 35 design authorisation holders and enforces conformity to specified McDonnell Douglas data for mandated structural doublers.

The AD text itself does not state specific monetary or criminal penalties. The directive is presented as an instrument issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998 (CAR 1998) and is part of CASA’s Schedule of Airworthiness Directives (front matter; Background). As such, the AD is a mandatory continuing-airworthiness requirement, and failure to comply would put an aircraft outside the AD’s requirements. The AD does not itemise the enforcement mechanisms that CASA might apply for non‑compliance within the text provided.

What the AD does state that bears on enforcement and compliance risk:

• The AD is presented as a requirement that the delegate "considers necessary to correct the unsafe condition" and it specifies that the action must be taken "in the circumstances mentioned in the requirement section; in accordance with the instructions set out in the requirement section; and at the time mentioned in the compliance section" (front matter). That framing indicates the AD is intended to be mandatory, not advisory.

• The directive revokes a prior amendment (Amdt 3) and clarifies an ambiguity that allowed some aircraft to escape intended requirements (Background). The explanation of the loophole indicates CASA intends the AD to be enforceable against aircraft that lack the prescribed modifications and inspections.

• The AD references required McDonnell Douglas service data (SB 229, SB 263 up to Revision 8, SRD documents) and ties compliance to those documents. In practical enforcement, CASA inspectors would look for evidence of adherence to the specified service information and to the intervals prescribed in the Compliance paragraphs.

Missing items in the AD text regarding penalties:

• There is no enumeration of fines, suspension powers, certificates actions, or criminal offences in the AD wording supplied. The AD therefore does not itself define the specific penalty regime; enforcement would occur under the broader statutory and regulatory framework of CAR 1998 and CASA’s enforcement policies, which are not reproduced in the AD text.

• The AD includes no dispute-resolution procedure, no provision for temporary exemptions in the text, nor an express appeals mechanism. It does, however, allow for design approval of alternative doublers via CAR 35 design authorisation holders (Note 1), which serves as a formal engineering pathway to lawful deviation.

In practice, compliance with the AD will be monitored through maintenance records, inspection reports, radiographic evidence, and manifesting of physical modification work, and CASA retains regulatory oversight authority. The AD’s silence on explicit penalties in the text supplied does not negate enforceability under CAR 1998, but it does require consultees to look to the parent regulations for details of sanctions and enforcement processes.

The AD is explicitly issued under subregulation 39.1(1) of the Civil Aviation Regulations 1998 (CAR 1998) (front matter). That situates the AD within the CAR 1998 legislative framework as a continuing airworthiness obligation. The AD also cross-references other regulatory and standards frameworks as follows:

• CAR 35 design authorisation: The AD accepts alternative doubler designs only where they "have been assessed and approved as at least equivalent to the above data, by the holder of an appropriate CAR 35 design authorisation" (Note 1). This creates an interoperability point between AD compliance and the CAR 35 design approval process. A CAR 35 holder who signs an equivalence assessment effectively makes a regulatory determination enabling an alternative solution to be used in place of the specific McDonnell Douglas data referenced in the AD.

• McDonnell Douglas service data as incorporated technical standards: The AD makes compliance conditional on following McDonnell Douglas Service Bulletins (SB 229, SB 263 up to Revision 8) and Service Rework Drawings (SRD SR03578001, SRD SR03578002 Revision A, SRD SR03578003, SRD03548001 Revision A) (Requirement Paras 2 & 3). Those documents are private-sector technical data, which the AD incorporates by reference as technical standards for mandatory works. Therefore, the AD harmonises regulatory obligation with manufacturer-provided engineering data.

• International airworthiness directives: The AD cites FAA AD 92-06-15 and Transport Canada AD CF-92-15 as references (Background; Note 4). This indicates cross-referencing of regulatory action among international civil aviation regulators. The AD does not automatically import obligations from those foreign ADs, but it situates CASA's action within a broader international response to the same unsafe condition.

• Commonwealth Gazette notification: The AD notes it is notified in the Commonwealth of Australia Gazette (14 June 2000) and specifies its effective date (becomes effective 13 July 2000) (front matter; end note). That Gazette notification is the formal publication channel to alert regulated parties.

• Interaction with historical ADs: The AD revokes AD/DC3/29 Amdt 3 and clarifies its intent (front matter; Background). The Compliance section makes reference to timing measured from earlier AD inspections and dates (e.g., "before exceeding 900 hours time in service since last inspected in accordance with the previous issue of this AD" and specific calendar references such as "after 27 April 1995" and "after 1 September 1969") which ties current obligations to prior regulatory action and recordkeeping.

• Evidentiary and recordkeeping consequences: By prescribing inspection intervals and specific inspection techniques (visual and radiographic per named SRDs) the AD imposes technical recordkeeping demands. While it does not itself prescribe documentation formats, compliance will require operators to retain evidence (inspection reports, radiographic records, modification records) that can be inspected under CAR 1998 enforcement activity.

In short, the AD operates as a technical regulatory instrument under CAR 1998, incorporating private technical data and connecting to CAR 35 design authorisation for approved alternatives. It references international ADs, which signals international coordination but does not itself create foreign-law obligations. To determine enforcement, sanctions and procedural recourse, stakeholders must consult CAR 1998 and CASA enforcement policy outside the AD text.

The AD is presented as Amendment 4 to AD/DC3/29. The document records specific historical steps and reasons for amendment. Relevant points from the AD text:

• Amdt 4 revokes AD/DC3/29 Amdt 3 and issues the new requirements under subregulation 39.1(1) of CAR 1998 (front matter). The delegate’s signature and dates are recorded: signed 15 May 2000 by William Ronald Smith (Delegate of CASA) and the AD becomes effective on 13 July 2000, with Gazette notification dated 14 June 2000 (signature and final line).

• The Background summarises prior activity: earlier issues of the AD had promulgated inspection and modification in accordance with early versions of the McDonnell Douglas reference documents. Amendment 3 (Amdt 3) introduced an additional modification to improve access for inspection, revised inspection procedures, and required mandatory incorporation of preventive doublers at the two critical wing stations. That amendment was prompted by an in‑flight wing separation in Canada and intended to align the Australian AD with McDonnell Douglas and FAA recommendations. FAA AD 92-06-15 is referenced (Background).

• Amdt 3 became effective on 27 April 1995 (Background). Amdt 4 records that subsequent to Amdt 3 the Authority became aware that the wording of Amdt 3 created an ambiguity that allowed aircraft modified per SB 229 to escape compliance with some paragraphs of the AD, because SB 229 specified modification at WS 127.75 only but not at WS 94.25. This meant some aircraft in service lacked the WS 94.25 modification and were not receiving the intended detailed visual and radiographic inspection at either location (Background).

• Amdt 4 addresses that loophole by making clear that both wing stations (WS 94.25 and WS 127.75) are critical, that modification and inspection at both locations are required, and that the modifications must conform to the specified data (Requirement Paras 2-3; Background). The AD also notes some aircraft have doublers that do not appear to conform to the SB or SRD specifications (Background).

• The AD archives references to Transport Canada AD CF-92-15 (Note 4) suggesting a cross-jurisdictional cognisance of the unsafe condition.

• The Compliance section references earlier dates, including a compliance trigger that requires modification before exceeding 900 hours time in service after 27 April 1995 or within 100 hours after the AD issue date, whichever is later (Compliance for Para 2.c). For Requirement Para 3, inspection intervals reference an initial benchmark "after 1 September 1969" or since last inspection under the previous issue of the AD (Compliance for Para 3).

In sum, the amendment history laid out in the AD explains that Amdt 4 was issued to close an ambiguity introduced by Amdt 3, to reassert the requirement for doublers at both WS 94.25 and WS 127.75, and to require conformity to the specified McDonnell Douglas data. The AD documents the chain of events, associated foreign AD references and effective dates, and provides the specific remedial clarifications being imposed by Amdt 4.

The AD document itself does not record any litigation concerning this directive or its earlier amendments. The Background section recounts operational events and regulatory responses , specifically mentioning "an in-flight wing separation in Canada" as the prompt for the changes first introduced in Amendment 3, and referencing FAA AD 92-06-15 and Transport Canada AD CF-92-15 , but it does not report any legal proceedings or disputes about the AD or its enforcement (Background; Note 4).

What the document does provide that bears on potential dispute drivers:

• Ambiguity in the wording of Amdt 3 is acknowledged in the Background. That ambiguity allowed aircraft modified only at WS 127.75 under SB 229 to avoid compliance with Paragraphs 2.a, 2.b or 2.c of Amdt 3. The Authority characterises this as a loophole permitting some aircraft to escape the AD’s intent; Amdt 4 was issued to close that loophole. The existence of such an ambiguity could be a locus for compliance disputes or administrative review claims in principle, but none are recorded in this AD document.

• The AD states some aircraft have had doublers installed that "do not appear to conform to the SB or SRD specifications" (Background). Non‑conforming installations could be the factual basis for enforcement action or dispute if an operator claimed compliance while the physical work deviated from the specified engineering data. The AD does not record any examples of enforcement outcomes or litigation, however.

• The AD provides a formal approval pathway for alternatives through CAR 35 design authorisation holders (Note 1). Where a CAR 35 holder has approved an alternative as equivalent, disputes about whether that approval is valid or sufficient could arise, but again the AD text does not record such disputes.

Because the AD does not contain or reference any litigation, practitioners must look beyond the AD text to court and tribunal records or CASA enforcement decisions for any recorded litigation history. The AD, as supplied, is silent on legal challenges, appeals, or judicial review outcomes relating to this AD or previous amendments.

The AD contains multiple technical and procedural traps that can create compliance pitfalls if overlooked. These "gotchas" are grounded in the AD text and its interaction with service data.

• Ambiguity closed but still present risk in records: Amdt 4 exists because Amdt 3’s wording allowed SB 229-modified aircraft (which modifies WS 127.75 only) to evade the intended requirement to modify at WS 94.25 as well. Operators who relied on SB 229 alone may think they are compliant when the AD requires doublers at both WS 94.25 and WS 127.75 (Background; Requirement Para 2). The AD states that aircraft "in full compliance with the intent of the previous issue" need no additional work, but operators must be able to demonstrate that their existing doublers conform to the SB/SRD and that both stations were addressed (Background).

• Compliance timing references earlier AD inspections and historical dates: The Compliance paragraphs measure deadlines relative to prior inspections under earlier ADs ("before exceeding 500 hours time in service since last inspected in accordance with the previous issue of this AD"; "before exceeding 900 hours time in service since last inspected in accordance with the previous issue of this AD"; and "before exceeding 2000 hours time in service after 1 September 1969") (Compliance). Operators with incomplete or unclear maintenance records risk miscalculating compliance intervals or initial deadlines.

• Access holes: The AD requires incorporation of access holes per SRD03548001 Rev A (Requirement Para 2.a), but Note 2 allows previously modified aircraft to avoid re‑modification provided the existing access and visibility are adequate. That creates an evidentiary risk: inspectors and operators will need to agree on adequacy of access. Lack of documentary proof or ambiguity in the access hole construction could generate disputes about whether rework is required.

• Radiographic alternative constraints: The AD permits the radiographic technique DCA NCI/R/8 as an alternative but requires additional film placement on the lower wing skin for exposures 4 and 5 to inspect the lower spar between the drag strut fairing and the nacelle centreline (Note 3). If a radiographer follows DCA NCI/R/8 without placing that extra film, the inspection may fail to meet the AD’s procedural requirements.

• Conformity of doublers: The AD notes that some doublers "do not appear to conform to the SB or SRD specifications" (Background). Operators may have older or improvised doublers; absence of explicit approval documentation (for alternative designs) could leave such doublers non‑compliant. Note 1 permits alternatives only if approved by a CAR 35 design authorisation holder; informal or undocumented modifications will therefore be problematic.

• Multiple reference documents and revisions: The AD references several documents (SB 229, SB 263 up to Revision 8, SRD SR03578001, SRD SR03578002 Revision A, SRD SR03578003, SRD03548001 Revision A). Non-obvious differences between revisions or between SBs and SRDs can matter for compliance. The AD accepts SB 263 "any revision up to and including Revision 8" in Requirement Para 2, which implies later revisions would need separate consideration; operators must ensure they are using the correct revision level.

• Different inspection intervals depending on modification status: Requirement Para 1 inspections are at 500‑hour intervals; Requirement Para 2.b inspections are at 900‑hour intervals; Requirement Para 3 inspections are at 2000‑hour intervals. Operators must map which interval applies to which aircraft depending on modification status. Misapplying the wrong interval is a compliance error (Compliance).

• Dates and retroactivity: The AD sets some compliance deadlines relative to 27 April 1995 (Requirement Para 2.c Compliance) and references 1 September 1969 for Requirement Para 3. Those historical dates can be confusing in recordkeeping and in assessing whether an aircraft is "already in compliance" under the AD’s carve-out. Operators must have accurate historical modification records to establish whether they fall into an exempted cohort or require immediate action.

• International flight implications: The AD references FAA and Transport Canada ADs but does not integrate their substance. Operators flying internationally must ensure compliance with CASA’s AD for Australian registration and also track foreign ADs for operations under other jurisdictions. The AD does not specify cross-acceptance of compliance evidence from foreign regulators.

• No penalty text in AD: Because the AD does not set forth specific penalties, operators should not assume a lack of sanction. Enforcement will be under CAR 1998; absence of penalty details in the AD does not provide relief if CASA determines non-compliance.

Each of these points requires specific documentary and technical evidence to demonstrate compliance: inspection reports, radiographs with the extra film exposures if the alternative technique was used, design approval documentation for any alternative doubler, and records showing the date and content of past modifications.

The AD establishes a prescriptive, document-referenced pathway to compliance. The following is a practical compliance checklist rooted in the AD text and the specified service data; this is a procedural translation of the AD’s requirements and timings.

1. Ascertain applicability and historical status

   • Confirm the aircraft is a Douglas DC3 series aeroplane (Applicability: All models).
   • Gather maintenance and modification records for the lower centre wing skin and structure, specifically any work at WS 94.25 and WS 127.75, and any prior inspections performed under earlier versions of AD/DC3/29. Confirm whether SB 229, SB 263, or SRD SR03578003 work has been recorded.

2. Determine which requirement paragraph applies

   • If the aircraft already has preventive or repair doublers at both WS 94.25 and WS 127.75 installed in accordance with SB 229, SB 263 (up to Revision 8) or SRD SR03578003, then Requirement Para 3 applies: perform the visual inspections per SRD03578001 or SRD03578002 Revision A at the 2000‑hour interval specified (Requirement Para 3; Compliance for Para 3).
   • If the aircraft has not been modified with doublers at both WS 94.25 and WS 127.75 in accordance with the referenced data, Requirement Para 2 applies: incorporate access holes per SRD03548001 Rev A, perform visual and radiographic inspections per SRD SR03578001 or SRD SR03578002 Rev A (or DCA NCI/R/8 with additional film as allowed), and modify the wing to incorporate wing skin doublers at both WS 94.25 and WS 127.75 per SRD SR03578003 (Requirement Para 2; Notes; Compliance).

3. Incorporate access holes if required

   • If doublers are not installed at both stations, embody access holes as per MD SRD03548001 Rev A (Requirement Para 2.a).
   • If access holes exist, verify they provide sufficient access and visibility; if so, Note 2 allows them to remain without re-modification. Document the sufficiency assessment.

4. Conduct visual and radiographic inspections

   • Follow the procedures in SRD SR03578001 or SRD SR03578002 Revision A, whichever is applicable (Requirement Para 2.b).
   • If using the alternative radiographic Technique DCA NCI/R/8, ensure that for exposures 4 and 5 additional film is placed on the lower wing skin to inspect the lower spar between the drag strut fairing and the centre line of the nacelle (Note 3).
   • Maintain inspection reports and radiographs as evidence.

5. Modify to incorporate wing skin doublers where absent

   • Where doublers at both WS 94.25 and WS 127.75 are not present and conforming, install wing skin doublers per SRD SR03578003 (Requirement Para 2.c).
   • If considering an alternative doubler design, secure written approval from a holder of an appropriate CAR 35 design authorisation certifying the design as at least equivalent to the specified SB/SRD data (Note 1). Retain the CAR 35 approval documentation.

6. Apply the correct inspection intervals and deadlines

   • For Requirement Para 1 inspections: initial before exceeding 500 hours TIS since last inspection under the prior AD and thereafter every 500 hours; also inspect before further flight after severe turbulence or heavy landing (Compliance for Para 1).
   • For Requirement Para 2.b radiographic/visual inspections: initial before exceeding 900 hours TIS since last inspection under the prior AD or within 100 hours after the AD issue date, then every 900 hours (Compliance for Para 2.b).
   • For Requirement Para 2.c modification: complete before exceeding 900 hours TIS after 27 April 1995, or within 100 hours after the AD issue date, whichever is later (Compliance for Para 2.c).
   • For Requirement Para 3 visual inspections: initial before exceeding 2000 hours TIS after 1 September 1969 or before exceeding 2000 hours since last inspection under the prior AD, then every 2000 hours (Compliance for Para 3).
   • Reconcile historical records to know which interval is applicable.

7. Recordkeeping and documentation

   • Keep complete records demonstrating when inspections were made, the procedures used (reference the specific SRD or radiographic technique), radiographs (including extra film exposures if DCA NCI/R/8 was used), descriptions and work orders for any access hole incorporation, and as‑fitted drawings for installed doublers.
   • If relying on prior installations or access holes per Note 2, retain documentary proof that the installation was in full compliance with the intent of the previous AD or with the specified SB/SRD.

8. Interaction with approvals and foreign ADs

   • If an alternative design is to be used, obtain CAR 35 design authorisation approval and maintain that documentation.
   • If operating internationally, monitor FAA AD 92-06-15 and Transport Canada AD CF-92-15 for additional obligations in other jurisdictions; ensure records satisfy both CASA and foreign regulator expectations where applicable.

9. Prepare for inspection by CASA

   • The AD is issued under CAR 1998; CASA inspectors may request to see evidence of compliance. Ensure paperwork and physical evidence (radiographs, pictures of access holes, as‑fitted drawings) are available.

10. Budgeting and contracting

• Allocate funds for access-hole incorporation, radiographic inspections (including lab fees for film or digital imaging), and the structural modification to install doublers. Engage maintenance organisations experienced with the specific SRD/SB procedures and radiographic work.

By following these steps and keeping documentary proof tied to the AD’s specified service data and intervals, operators will have a defensible compliance posture. Any deviation or alternative design must be supported by CAR 35 design authorisation evidence as the AD requires.