AD/DH 83/6 - Inspection of Wooden Structure

The AD rests on a small set of operational and technical concepts drawn from the DHSL Technical News Sheet specified in the AD. First, the AD treats the internal wooden structure of the flying surfaces as a critical, inspectable element whose continued airworthiness cannot be assured without physical inspection of the entire internal structure (Background; Requirement 1(c)). Second, the AD prescribes a combination of physical access measures and inspection criteria: install inspection rings and drainage provisions (Figure 3, Appendix G of the TNS), remove pop‑in panels or cut fabric from inside inspection rings to access structure, then inspect in line with Appendix B, paragraph 6 and Appendix F, page F17, paragraph 2 (Requirement 1(a)-(c); Definitions). Third, remedial options are removal from service or repair “in accordance with approved data” if wooden structure is found to be unserviceable (Requirement 1(d)). Fourth, the AD introduces a repeat inspection regime keyed to usage hours and time (every 200 hours or within 36 months, whichever is earlier), and to specific events such as ground strikes or birdstrikes that leave witness marks (Compliance repeats (i)-(iii)).

The AD also integrates administrative requirements: mandatory defect reporting to CASA through the Service Difficulty Reporting System and compliance with Part 4B - Defect Reporting of CAR 1988 (Requirement 2; Compliance 2). It differentiates initial timeframes by operational status, imposing a shorter initial compliance window for aircraft used for commercial purposes under regulation 206 CAR 1988 (Compliance 1(a)). The AD references and thereby compels following the manufacturer/maintainer technical guidance (the DHSL TNS CT (Moth) No. 32 Issue 3 dated 1 December 2008), making that document operationally obligatory for inspection content, specific areas, and installation details (Definitions; Requirement 1(a), (c); Appendix references).

Mechanically, the AD converts technical guidance in a TNS into mandated maintenance actions, binds initial compliance dates according to commercial use, requires periodic re‑inspection by hours or time, mandates reporting under Part 4B CAR 1988, and requires repairs only under “approved data.” The concept of “approved data” creates a gate between on‑site judgement and formally authorised repair data, while the combination of inspection rings and fabric removal sets up particular maintenance work (possible alteration or recovery) as necessary to comply.

The AD binds the owners and operators of every DH 83 variant in Australia. Applicability is explicit: “This AD applies to all variants of DH 83 aircraft” (Applicability). That language places the obligation on any party responsible for the aircraft’s continuing airworthiness: owners, operators and maintenance organisations who must carry out inspections and repairs. The AD draws a regulatory distinction for timing: aircraft used for commercial purposes as defined by regulation 206 CAR 1988 have a two‑month deadline from the effective date (6 February 2015) to complete the initial actions, whereas non‑commercial aircraft have until 31 December 2015 (Compliance 1(a)-(b)). This imposes a shorter, concentrated deadline on commercially operated DH 83s.

Maintenance providers and certificated engineers carrying out the inspections and repairs are affected practically because the AD prescribes how access is to be achieved (removing pop‑in panels or cutting fabric from inside inspection rings) and requires adherence to inspection criteria set out in the TNS (Requirement 1(a)-(c)). Repairers will need to work with “approved data” for any repair or removal from service (Requirement 1(d)), which implicates whoever approves repairs (manufacturer data or CASA‑approved repair data).

CASA as regulator is an active party: the AD requires defect reports to be submitted to CASA via the Service Difficulty Reporting System and requires compliance with Part 4B - Defect Reporting of CAR 1988 (Requirement 2; Compliance 2). The AD was issued by a CASA delegate, Nicholas Ward (signature block), indicating decision‑making and enforcement originate from CASA.

Third‑party stakeholders include insurers and lessors because a mandatory inspection regime, findings of unserviceable structure, or required repairs can affect airworthiness, insurability and lease obligations. Pilots and operators must accommodate potential aircraft downtime for access work and repairs. The AD’s repeat intervals affect high‑utilisation aircraft more directly: an aircraft that accumulates 200 hours of flying in a short period will trigger more frequent inspections than one flown less, so operators with higher utilisation bear proportionately higher inspection frequency and cost (Compliance repeats (i) and (ii)).

The TNS itself is incorporated by reference, so DHSL (de Havilland Support Ltd) is an indirect but central technical stakeholder because the AD commands following the TNS’s specific figures and appendices (Definitions; Requirement 1(a), (c)). The AD does not create exemptions or carve outs in the text provided; it applies uniformly to all variants (Applicability).

Duties imposed by this AD are concrete and specific. Primary duties on the responsible person (typically owner/operator) include:

• Install inspection rings and drainage provisions as shown in Figure 3 of Appendix G of the DHSL TNS (Requirement 1(a)). This is an affirmative alteration/installation duty where those fittings do not already exist.
• Gain access to the entire internal wooden structure for inspection, by removing all pop‑in panels or cutting away fabric from inside inspection rings where required (Requirement 1(b)). The AD prescribes how access may be achieved rather than leaving it entirely to the maintainers’ discretion.
• Conduct a detailed inspection of the internal wooden structure in accordance with the inspection criteria in Appendix B, paragraph 6, and bearing in mind Appendix F, page F17, paragraph 2 of the TNS (Requirement 1(c)). The inspection content is therefore prescriptive and tied to the TNS.
• Remove all unserviceable wooden structure from service or effect repairs in accordance with approved data (Requirement 1(d)). This creates an obligation to either decommission unserviceable structure or remediate to standards captured by approved data.
• Report all defects discovered to CASA via the Service Difficulty Reporting System and comply with Part 4B - Defect Reporting of CAR 1988 (Requirement 2; Compliance 2). The AD makes reporting mandatory and links it to the statutory defect reporting regime.

Timing duties are explicit: commercial aircraft must comply within two months of the effective date (6 February 2015); other aircraft must comply by 31 December 2015 (Compliance 1(a)-(b)). Inspection repetition duties require re‑inspections every 200 hours or within 36 months, whichever is earlier, and immediate inspection after qualifying strike events, checking both upper and lower wings on the side impacted (Compliance repeats (i)-(iii)).

Rights in the text are implicit rather than expansive. The AD requires repairs “in accordance with approved data,” which implies the right of the maintainer or owner to use repairs that meet the approval pathway; it does not enumerate the approval mechanism but ties the remedy to formally approved technical data (Requirement 1(d)). The AD does not specify administrative appeal rights, waivers, or exemptions in the text provided. Practically, the owner/operator retains the operational discretion to schedule inspections and repairs within the timelines set, and to choose approved repair data, but must meet the inspection content and reporting obligations prescribed.

The AD also fixes responsibility for reporting to CASA, creating a duty to use the Service Difficulty Reporting System rather than an alternative channel (Requirement 2). There is no explicit provision in the AD itself for temporary grounding, but removal of unserviceable wooden structure from service can have the effect of grounding components or the aircraft until repairs are approved and carried out.

The AD text itself does not set out monetary fines or criminal penalties within its language. It mandates actions and cross‑references the statutory defect reporting regime in CAR 1988 by requiring reporting in accordance with Part 4B - Defect Reporting of CAR 1988 (Requirement 2; Compliance 2). It also links the initial compliance windows to regulation 206 of CAR 1988 for “commercial purposes” (Compliance 1(a)). Enforcement therefore operates through CASA’s regulatory framework and the Civil Aviation Regulations 1988 rather than through penalty clauses embedded in the AD text provided.

Because the AD prescribes mandatory remedial and reporting steps and a repeat inspection regime, enforcement mechanisms available to CASA under CAR 1988 (not reproduced in the AD) are the likely avenue for compliance oversight and any enforcement action; the AD requires that operators report defects via the Service Difficulty Reporting System (Requirement 2), creating an administrative trail. The document is issued and signed by a CASA delegate, Nicholas Ward, giving it formal regulatory force as an airworthiness directive (signature block; Background).

The AD sets specific compliance dates and repeat intervals. Failure to meet the AD’s requirements would leave an aircraft non‑compliant with a CASA AD and, by extension, potentially non‑compliant with continuing airworthiness obligations under CAR 1988. The AD itself does not list inspectors, inspectors’ powers, or specific penalties; those matters must be located in CAR 1988 and CASA enforcement policy. Practitioners should therefore consult Part 4B and relevant enforcement provisions of CAR 1988 for the explicit penalties and enforcement procedures that would apply if the AD is breached; the AD’s linkage to that statutory regime indicates reportorial and compliance obligations are enforced under those statutes (Compliance 2).

In practice, enforcement risk includes administrative action, grounding directives, or other regulatory measures that CASA is authorised to take under the CAR 1988 framework. The AD creates an auditable obligation (installation, access method, inspection content, repairs per approved data, and defect reporting), so non‑compliance is verifiable through maintenance records, Service Difficulty Reporting System entries and physical inspection. The AD does not offer a schedule of sanctions in its text.

This AD explicitly interacts with the Civil Aviation Regulations 1988 in two ways. First, it ties the initial compliance deadlines for commercially used aircraft to regulation 206 of CAR 1988, distinguishing commercial‑operation timelines from non‑commercial ones (Compliance 1(a)). Second, it requires that defect reporting be performed “in accordance with Part 4B - Defect Reporting of CAR 1988” and specifies CASA’s Service Difficulty Reporting System as the reporting mechanism (Requirement 2; Compliance 2). Both cross‑references integrate the AD into the broader statutory maintenance and reporting framework.

The AD also imports external technical material by reference. It makes the DHSL Technical News Sheet CT (Moth) No. 32, Issue 3, dated 1 December 2008, operationally mandatory for inspection content, specific inspection areas and installation detail (Definitions; Requirement 1(a), (c)). That means compliance requires following technical guidance that is not fully reproduced in the AD; practitioners must obtain the TNS and follow Figure 3 (Appendix G), Appendix B paragraph 6, and Appendix F page F17 paragraph 2 as the AD directs. The effect is that the AD combines statutory regulatory requirements (CAR 1988 cross‑references) with manufacturer/maintainer technical guidance (TNS).

The AD’s demand that repairs be carried out “in accordance with approved data” creates an interface with approval processes under the civil aviation regulatory regime. Approved data is the legal standard for maintenance modifications and repairs; the AD does not define the approval mechanism but relies on the existing approvals and certification pathways in Australian aviation regulation. Thus the AD prescribes a duty (repair per approved data) that must be discharged through the statutory approval processes governed by CAR 1988 and CASA policy.

No other statutes, authorities, or international rules are cited in the AD text provided. The AD does not provide transitional provisions that alter CAR 1988, nor does it purport to modify existing maintenance approvals; instead it adds a mandatory inspection and reporting obligation within the existing regulatory framework. Practitioners should consult CAR 1988 for enforcement provisions, approvals for alterations and repairs, and the definition of “commercial purposes” in regulation 206, because the AD uses those statutory constructs to determine compliance windows and reporting obligations (Compliance 1(a); Compliance 2).

The AD document identifies itself as "AD/DH 83/6" and as issue "3/2015." It bears a signature by Nicholas Ward, Delegate of the Civil Aviation Safety Authority, and is dated 2 February 2015. The AD states its effective date as 6 February 2015 (signature; effective date). The DHSL TNS it references is CT (Moth) No. 32, Issue 3, dated 1 December 2008 (Definitions).

No amendments, supersessions, revocations, or subsequent issue dates are shown in the extract provided. The document includes a header table indicating the AD number, subject "Inspection of Wooden Structure" and effective date notation “3/2015” but contains no trace of later revisions within the provided text (AD/DH 83/6; 3/2015). The AD’s internal structure records “Requirement” and “Compliance” clauses and sets explicit deadlines; none of those clauses include amendment provisions or sunset clauses beyond the repeat inspection intervals.

Because the AD incorporates external TNS material by reference, any later amendment of that TNS could be relevant to operators, but the AD as provided binds operators to the specified issue of the TNS (CT (Moth) No. 32, Issue 3, dated 1 December 2008) unless and until CASA issues a further AD modifying the reference. The AD does not itself instruct operators to follow future TNS issues; it specifies the exact issue and appendices to be used (Definitions; Requirement 1(a), (c)). Practitioners should check CASA AD registries and DHSL publications for subsequent ADs or TNS revisions to confirm whether this AD has been amended or superseded after the effective date of 6 February 2015; that information is not present in the supplied text.

The supplied AD text contains no references to judicial review, litigation, or case law. It does not mention any appeals, legal challenges, tribunal decisions, or precedential cases. The document is an administrative instrument signed by a CASA delegate and framed as a safety mandate; its text does not report or cite any litigation history.

Given the absence of litigation references in the AD, there is no source‑grounded litigation history to summarise here. Practitioners seeking information on any legal challenges to this AD or to CASA’s use of ADs in general would need to consult court records, tribunal decisions or subsequent CASA documentation; none of that material is reproduced in the AD provided. The AD itself neither records outcomes of disputes nor sets out an internal appeal mechanism in its content.

The AD contains several practical points that can be operational traps if overlooked.

• TNS dependence and version specificity: The AD mandates following DHSL Technical News Sheet CT (Moth) No. 32, Issue 3 dated 1 December 2008 for inspection criteria and installation details (Definitions; Requirement 1(a), (c)). Operators must obtain that exact TNS and apply the appendices and figure referenced. Using a different TNS issue or a subset of the guidance risks non‑compliance with the AD’s prescriptive references.

• Installation obligation where fittings are absent: The AD requires installation of all inspection rings and drainage provisions shown in Figure 3 of Appendix G (Requirement 1(a)). For aircraft lacking those features, compliance requires an alteration/installation. That installation may itself require approved data and perhaps an approval process under CAR 1988.

• Access method and consequential work: The AD permits access to the internal structure by removing pop‑in panels or “otherwise cut away the fabric from inside inspection rings” to facilitate access (Requirement 1(b)). Cutting fabric to gain access can create additional workstreams: recovering or re‑skinning fabric, meeting covering standards, or restoring drain paths. Those downstream works implicate repair approvals and may take the aircraft out of service for longer than a simple inspection.

• Ambiguity about “approved data”: Repairs must be “in accordance with approved data” (Requirement 1(d)). The AD does not define the approval pathway in this text. Practitioners must confirm what documents and approvals qualify as “approved data” under CAR 1988 and CASA policy before commencing repairs.

• Repeat interval linked to hours and events: The inspection repetition is keyed to every 200 hours or within 36 months, whichever is earlier, and to strike events leaving witness marks (Compliance repeats (i)-(iii)). High‑utilisation aircraft will hit the 200‑hour interval faster, increasing inspection frequency and cost. After a qualifying strike event operators must inspect both upper and lower wings on the affected side; failing to inspect both surfaces could breach the AD.

• Different initial deadlines for commercial operators: If an aircraft is used for commercial purposes under regulation 206 CAR 1988, the initial compliance window is compressed to two months from the AD’s effective date (6 February 2015) (Compliance 1(a)). That creates a concentrated scheduling and cost pressure on commercial operators who must meet the tighter deadline.

• Reporting requirement: All defects must be reported to CASA through the Service Difficulty Reporting System (Requirement 2). The AD requires reporting “in accordance with Part 4B - Defect Reporting of CAR 1988” (Compliance 2). Failure to use the specified system or to meet Part 4B’s standards risks regulatory non‑compliance.

• No explicit penalty schedule in the AD text: The AD does not state penalties; it instead links to CAR 1988 for reporting obligations. Operators must therefore determine enforcement risk by reference to CAR 1988 rather than expecting an enforcement schedule in the AD.

• Potential skill scarcity and parts lead times: The AD’s requirement to remove and repair unserviceable wooden structure presumes availability of skilled wood‑structure repairers and approved parts or data. Downtime and increased maintenance costs may result where specialists or approved materials are limited.

• Effective date and retroactivity: The AD’s effective date is 6 February 2015 (effective date). For commercial operators that means adhering to the two month timetable from that date. Non‑commercial operators have until 31 December 2015. Operators who flew frequently and accumulated hours between issuance and compliance dates might already have incurred the need for reinspection sooner than anticipated.

Compliance requires a sequence of concrete steps tied to the AD’s text and the referenced TNS.

1. Confirm applicability and timelines:

   • Verify that the aircraft is a DH 83 variant; the AD applies to all variants (Applicability).
   • Determine whether the aircraft is used for commercial purposes under regulation 206 CAR 1988; commercial aircraft must complete initial actions within two months of 6 February 2015, others by 31 December 2015 (Compliance 1(a)-(b)).

2. Obtain the referenced technical material:

   • Acquire DHSL Technical News Sheet CT (Moth) No. 32, Issue 3, dated 1 December 2008, and review Appendix G Figure 3, Appendix B paragraph 6, and Appendix F page F17 paragraph 2, as these are the required sources of inspection criteria and installation details (Definitions; Requirement 1(a), (c)).

3. Prepare and plan maintenance:

   • Schedule installation of inspection rings and drainage provisions in accordance with Figure 3 of Appendix G where not already fitted (Requirement 1(a)).
   • Plan access work: remove all pop‑in panels or, where necessary, plan for controlled cutting away of fabric from inside inspection rings to facilitate internal access (Requirement 1(b)). Include in the plan the steps needed to restore coverings and drains to approved standards after inspection.

4. Perform the inspection:

   • Conduct a detailed inspection of the internal wooden structure following the inspection content and criteria in Appendix B paragraph 6 and taking into account Appendix F page F17 paragraph 2 (Requirement 1(c)). Document the inspection findings in maintenance logs as required by CAR 1988 and local maintenance practice.

5. Remediate defects:

   • For any unserviceable wooden structure discovered, either remove that structure from service or conduct repairs in accordance with approved data (Requirement 1(d)). Confirm which data qualifies as “approved data” under CAR 1988 and secure any necessary approvals before performing repairs.

6. Report defects:

   • Report all discovered defects to CASA via the Service Difficulty Reporting System in accordance with Part 4B - Defect Reporting of CAR 1988 (Requirement 2; Compliance 2). Retain copies of reports and correspondence.

7. Establish repeat inspection programme:

   • Implement a programme to repeat the inspection at the earlier of: every 200 hours, within 36 months of the previous inspection, or after any ground strike, birdstrike or wing strike leaving witness marks or obvious fabric damage (Compliance repeats (i)-(iii)). For qualifying strikes inspect both the top and bottom wings on the side where the impact occurred.

8. Recordkeeping and approvals:

   • Keep contemporaneous records of installations (inspection rings and drainage), access method, inspection findings, repairs and the approved data relied upon. Record Service Difficulty Reporting System entries and any CAR 1988 Part 4B actions. Ensure repair data and any alterations have the necessary approvals under CAR 1988 before returning the aircraft to service.

9. Engage appropriate personnel and suppliers:

   • Use suitably certificated maintenance personnel experienced in wooden structure inspection and repair. If recovery of fabric or alteration approvals are required, coordinate with CASA and approved design/repair data holders early to avoid delays.

10. Verify ongoing compliance and changes:

    • Monitor CASA publications and the DHSL TNS for any subsequent ADs, TNS revisions or guidance. The AD binds operators to the specified TNS issue; verify whether CASA has issued updates or amendments beyond the AD’s effective date (effective date; Definitions).

Following these steps aligns operational practice with the AD’s prescriptive requirements: installation and access measures, inspection content, remedial action per approved data, mandatory defect reporting to CASA, and a recurring inspection schedule keyed to hours, time and strike events (Requirement 1(a)-(d); Requirement 2; Compliance repeats (i)-(iii)).