AD/B747/85 Amdt 5 - Corrosion Prevention and Control Program

The directive rests on a small set of interlocking concepts, each drawn from the AD text. These are: adoption by reference, corrosion‑severity classification and reporting thresholds, alternative means of compliance for a sub‑type, and administrative mapping of foreign regulator contact points to CASA Field Offices.

Adoption by reference: The AD directs Australian operators to carry out work "in accordance with the technical requirements of FAA AD 90‑25‑05 R1 Amdt39‑15327." That means the FAA AD , including its inspection intervals, procedures, corrective actions and any compliance deadlines contained in that FAA instrument , is the technical standard CASA expects Australian operators to meet. The AD explicitly ties associated Boeing documentation to the FAA AD, noting "Boeing Document D6‑36022 Rev D, or later FAA approved revision, is associated with FAA AD 90‑25‑05 R1" and that Boeing Document D621U400‑MRB (Dec 2007 or later FAA‑approved revision) may serve as an AMOC for the 747‑400 series. Those two document references form the technical underpinning of the CPCP requirement in the Australian directive.

Corrosion classification and reporting thresholds: The AD sets three reporting outcomes according to corrosion severity: Level 1 requires no reporting; Level 2 allows consolidation with a sixty‑day corrective action report, submitted to the local CASA Field Office under a single "SDR"; Level 3 must be reported by "SDR." The AD does not define "SDR" within the text provided; it uses the acronym as the vehicle for reporting. The AD therefore separates surveillance and reporting obligations by tangible severity thresholds rather than a single universal reporting duty.

Alternative means of compliance (AMOC) and scope limitation: The AD recognises a specific Boeing document as an approved alternative means of compliance, but limits that recognition to Model 747‑400 series aircraft only. Note 2 states that D621U400‑MRB (Rev Dec 2007 or later FAA‑approved revision) is "an approved alternative means of compliance to FAA AD 90‑25‑05 R1 for Boeing Model 747‑400 series aircraft only." That creates a fleet‑segment specific compliance pathway distinct from the main FAA AD requirements.

Administrative substitution of authority: The FAA AD's internal references to US FAA officials are domesticated. The AD instructs that references to "Administrator FAA, FAA Principal Inspector (PI), or Manager Seattle Aircraft Certification Office (ACO)" in the FAA AD "shall be read as Civil Aviation Safety Authority Field Office." That maps decision and contact points in the referenced foreign instrument onto CASA Field Offices for implementation and enforcement purposes.

Background and effective date: The AD explains its origin as in response to the Country of Origin Airworthiness Authority's requirement to implement a CPCP "to prevent the degradation of the structural capabilities of the affected aircraft." The compliance trigger is the effective date: this Amendment becomes effective on 2 September 2009.

These main concepts frame the operator's obligations. The directive does not itself contain inspection steps, intervals or corrective‑work specifications; those are contained in the FAA AD and in the Boeing documents that the AD references as associated material or AMOC. The AD does, however, modify reporting mechanics and the domestic contact point language, which changes administrative workflows for Australian operators and CASA.

The AD applies to a defined list of Boeing 747 variants. The Applicability statement identifies the following models: "Model 747‑100, ‑100B, ‑100B SUD, ‑200B, ‑200C, ‑200F, ‑300, ‑400, ‑400D, ‑400F, 747SR, and 747SP series aircraft." Any Australian‑registered aeroplane of those variants falls within the directive's scope and therefore must be managed under the CPCP obligations adopted by this AD. The AD does not add other types or serially exclude specific airframes; it records the models by type designation.

Who pays: The AD places technical obligations on operators and/or maintenance organisations responsible for the listed aeroplanes because they must implement the FAA AD's technical requirements and follow the AD's reporting instructions. The AD itself does not allocate cost recovery or funding; it imposes compliance requirements that have cost implications (inspection, labour, parts, reporting) for those entities that operate or maintain the affected 747 types in Australia. The directive does not identify a central fund or Commonwealth subsidy to meet those costs; therefore the practical effect is that the operator or the entity that assumes maintenance responsibility must resource implementation.

Who decides: The AD maps decision and contact points to CASA Field Offices by instructing that references in the FAA AD to US FAA officials "shall be read as Civil Aviation Safety Authority Field Office." That means approval, clarification, and communications that the FAA AD otherwise places with FAA administrators are domestically handled through CASA Field Offices. For Model 747‑400 series aircraft, the AD recognises a Boeing document as an AMOC; decisions regarding the acceptability of that AMOC are framed by the AD's own wording that the document "is an approved alternative means of compliance," but the text also ties the status of that Boeing document to later "FAA approved revision(s)." The AD therefore creates a hybrid decision regime: CASA is the local contact and enforcement body, but the technical provenance and acceptance of Boeing document revisions is tethered to FAA approvals as recorded in the AD notes.

What behaviour changes: Operators must perform the CPCP measures and report corrosion as set out in the referenced FAA AD and in the AD's reporting instructions. The AD requires reporting of Level 3 corrosion by "SDR" and allows consolidation of Level 2 corrosion reporting with a single sixty‑day corrective action submission to the local CASA Field Office. Level 1 corrosion "need not be reported" under the AD. The AD thus alters reporting workflows: more serious corrosion triggers immediate SDR reporting, while lesser but still significant corrosion can be included in a consolidated corrective action report.

Geographic and fleet segmentation: The AD is limited to the listed Boeing 747 models and domestic implementation is tied to CASA Field Offices. It does not extend to other aircraft types or to Boeing 747 variants outside the listed types. It also distinguishes the Model 747‑400 series for AMOC purposes.

Duties imposed by the AD are principally operational and administrative. The AD's central operational duty is to "Action in accordance with the technical requirements of FAA AD 90‑25‑05 R1 Amdt39‑15327." That duty imports inspection, maintenance, preventive and corrective actions set out in the FAA AD; the AD itself does not reproduce those technical procedures, so compliance requires consulting the FAA AD and the associated Boeing documents referenced in the AD.

Reporting duties: The AD sets a three‑tier reporting duty. For corrosion findings:

• Level 1 corrosion: "need not be reported." The absence of a reporting duty does not alter the duty to address corrosion under the FAA AD's technical requirements; it only removes an additional reporting obligation for Level 1 in the domestic directive.
• Level 2 corrosion: "may be consolidated with a sixty day report of corrective action, and submitted to the local CASA Field Office under cover of a single SDR." This creates a duty to compile corrective action and, if desired, consolidate multiple Level 2 findings into a single report that includes a sixty‑day corrective action statement, filed under one SDR to the local CASA Field Office.
• Level 3 corrosion: "shall be reported by SDR." This is an affirmative duty to lodge an SDR specifically for Level 3 corrosion findings.

Rights and administrative interfaces: The AD instructs that any reference in the FAA AD to certain FAA officials "shall be read as Civil Aviation Safety Authority Field Office." Practically, that gives operators and maintenance organisations a single domestic point of contact , CASA Field Office , for requests for relief, AMOC clarifications, technical queries or enforcement correspondence. The AD also recognises an AMOC for a fleet subset, giving Model 747‑400 operators a documented alternative compliance route (Boeing D621U400‑MRB, Rev Dec 2007 or later FAA‑approved revision). The AD thus implicitly provides a right to use that AMOC for eligible aircraft, subject to the AMOC being a later FAA‑approved revision as noted.

Scope of the AMOC and document association: Note 1 and Note 2 in the AD set the relationship between the FAA AD and Boeing documentation. Note 1: "Boeing Document D6‑36022 Rev D, or later FAA approved revision, is associated with FAA AD 90‑25‑05 R1." Note 2: "Boeing Document D621U400‑MRB, at Revision: Dec 2007, or later FAA approved revision, is an approved alternative means of compliance to FAA AD 90‑25‑05 R1 for Boeing Model 747‑400 series aircraft only." Those notes create two discrete technical references with different roles: one as associated material across the fleet and the other as an AMOC limited to the 747‑400 subset.

Compliance obligation language: The AD closes the operative obligations with "Compliance: As specified in the Requirement document." That language confines the duty to the contents of the referenced FAA AD and its associated documents. The AD does not set alternative domestic compliance steps beyond the reporting modifications and AMOC recognition quoted above.

Delegated authority and signature: The AD is signed by "David Villiers, Delegate of the Civil Aviation Safety Authority" and dated 26 August 2009. This identifies the CASA delegate as the authorising officer for the AD.

The AD itself, as provided in the text, does not include explicit penalty clauses or a specified enforcement schedule within its four corners. Instead, it establishes compliance obligations by adopting the technical requirements of FAA AD 90‑25‑05 R1 and by prescribing domestic reporting rules. The AD states "Compliance: As specified in the Requirement document," and identifies CASA Field Offices as the domestic contact point for reporting and for replacing references to FAA officials. Enforcement mechanisms, including penalties for non‑compliance, are not articulated in the AD text supplied; the instrument focuses on technical obligations and reporting mechanics rather than on sanctions.

Because the AD imports the FAA AD's technical requirements by reference, the practical enforcement pathway operates through CASA's oversight and regulatory powers, as signalled by the substitution of CASA Field Offices for the FAA official references. The AD requires Level 3 corrosion to be reported by SDR and Level 2 corrosion to be included in a sixty‑day consolidated corrective action report "submitted to the local CASA Field Office under cover of a single SDR." Those reporting duties create an administrative trail that CASA may use to monitor compliance and to identify non‑compliance with the technical requirements in the FAA AD. The AD does not set out timeframes for CASA responses, nor does it specify sanctioning options for breaches.

The AD’s effective date , 2 September 2009 , is the point at which operators of the listed types are required to ensure actions are taken in line with the FAA AD technical requirements and the AD’s reporting rules. The AD’s Background notes refer to the Country of Origin Airworthiness Authority’s requirement to implement a CPCP "to prevent the degradation of the structural capabilities of the affected aircraft." That rationale supports CASA’s imposition of the technical standard domestically and justifies oversight activity.

Because this AD is an administrative instrument that imports a foreign airworthiness directive, operators should expect enforcement to occur through CASA's usual regulatory toolkit for airworthiness directives and maintenance oversight. The AD text does not itself invoke or reproduce CASA enforcement provisions, civil penalties or criminal sanctions. If a regulated entity needs precise information about penalty exposure or enforcement processes, the AD as supplied directs them instead to comply "as specified in the Requirement document" and to interact with local CASA Field Offices for reporting and further instruction.

The AD interacts with other instruments and regulatory material by adoption and reference. Its primary interaction is with the FAA AD it incorporates: "Action in accordance with the technical requirements of FAA AD 90‑25‑05 R1 Amdt39‑15327." That adoption by reference makes the FAA AD the operative technical standard for Australian‑registered aircraft of the listed 747 types to the extent the FAA AD contains measures; the CASA AD modifies only certain administrative elements (reporting channels and domestic contact points) and recognises specified Boeing documents as associated material or as an AMOC for a subset of the fleet.

The AD explicitly ties Boeing documents to the FAA AD. Note 1 states that "Boeing Document D6‑36022 Rev D, or later FAA approved revision, is associated with FAA AD 90‑25‑05 R1." Note 2 states that "Boeing Document D621U400‑MRB, at Revision: Dec 2007, or later FAA approved revision, is an approved alternative means of compliance to FAA AD 90‑25‑05 R1 for Boeing Model 747‑400 series aircraft only." Those notes create a dependency between the AD, the FAA AD and Boeing technical documents. The AD therefore interacts operationally with manufacturer maintenance data and with foreign regulator approvals , a regulatory regime where domestic legal obligation references foreign technical instruments and manufacturer material.

Administrative substitution: The AD instructs that references in the FAA AD to "Administrator FAA, FAA Principal Inspector (PI), or Manager Seattle Aircraft Certification Office (ACO)," should be read as "Civil Aviation Safety Authority Field Office." This substitution is an internal mapping of foreign official roles to domestic contact points. It interacts with statutes or administrative rules governing CASA’s field offices by designating CASA as the domestic authority for enquiries and reports associated with the FAA AD's implementation. The AD does not itself cite the enabling CASA statute, but it operates within CASA's regulatory mandate by imposing an AD on Australian‑registered aircraft.

Reporting mechanism interaction: The AD requires use of "SDR" for Level 3 corrosion and for consolidating Level 2 corrosion reporting. The acronym "SDR" is used without definition in the provided text, but the AD’s instruction to submit consolidated Level 2 reports "to the local CASA Field Office under cover of a single SDR" creates a procedural interaction between the technical inspection regime and the domestic reporting systems that CASA operates. That procedural linkage situates the AD within CASA’s broader reporting and maintenance oversight framework.

AMOC and foreign approvals: The AMOC note ties acceptance of Boeing Document D621U400‑MRB to FAA approval status ("or later FAA approved revision"). The AD thus preserves a role for FAA approvals in determining which Boeing document revisions are acceptable as alternative compliance means; CASA’s recognition is therefore conditional on FAA approval as recorded in the AD. This creates a cross‑jurisdictional interplay: CASA relies on the FAA's approval of Boeing revisions as a predicate for domestic AMOC recognition, while CASA remains the domestic contact and enforcer.

No domestic legislative cross‑references in the AD text: The supplied directive does not cite or amend any Australian Acts, regulations or CASA legislative instruments beyond itself. It functions as a standalone AD that imports foreign technical standards and clarifies local reporting and contact points.

The AD records a short amendment history across five amendments. The background summarises what each amendment introduced:

• Amendment 1: "introduced a note which specified the reporting requirements when corrosion is found as a result of the CPCP." That is the origin of the corrosion reporting categories and the associated reporting mechanics that the AD uses to distinguish Level 1, Level 2 and Level 3 corrosion reporting.

• Amendment 2: "introduced a method of compliance other than the Country of Origin AD to address current in‑production aircraft." This indicates that a domestic alternative means of compliance was recognised to account for in‑production aircraft differences, although the exact content of that AMOC is not reproduced in the supplied text.

• Amendment 3: "clarified the alternative means of compliance for Model 747‑400 aircraft." The supplied text notes that Amendment 3 provided clarification specific to the 747‑400 family; the current AD (Amendment 5) continues to identify a Boeing D621U400‑MRB document as an AMOC for the 747‑400 series.

• Amendment 4: "clarified the applicability of the existing AD by specifying which Model 747 aircraft are affected, because certain new variants that have not yet been certified would have been subject to the requirements of this Directive." Amendment 4 therefore narrowed or clarified the aircraft types to avoid unintended inclusion of as‑yet‑uncertified variants; the Applicability line in the supplied AD is the concrete outcome of that clarification.

• Amendment 5 (the current amendment): "is issued to allow use of later revisions of Boeing Document D621U400‑MRB as an AMOC to FAA AD 90‑25‑05 R1." The current amendment explicitly authorises later FAA‑approved revisions of the D621U400‑MRB document to be used as an AMOC for the 747‑400 series.

The AD also provides two notes tying Boeing documents to the FAA AD and AMOC: Note 1 identifies Boeing D6‑36022 Rev D (or later FAA‑approved revision) as associated with the FAA AD; Note 2 identifies Boeing D621U400‑MRB (Rev Dec 2007 or later FAA‑approved revision) as an approved AMOC for 747‑400 series aircraft only. Note 3 instructs that references to certain FAA officials in the FAA AD shall be read as CASA Field Office.

The signature block records the delegate and date: "David Villiers, Delegate of the Civil Aviation Safety Authority" dated 26 August 2009, and the AD "becomes effective on 2 September 2009." The amendment history in the AD text therefore shows an evolution from the initial CPCP requirement through progressive clarifications of reporting, applicability and acceptable alternative compliance documents, culminating in Amendment 5’s allowance for later revisions of the recognised Boeing AMOC.

The supplied AD text contains no record of litigation, judicial review or court decisions related to this directive. There are no cases, appeals, or legal challenges mentioned in the AD or in the background and amendment notes provided. The AD is framed as an administrative aviation safety instrument, signed by a CASA delegate, without any appended litigation record.

For readers concerned about legal risk or precedent, the absence of litigation history in the AD text means two things in the source‑grounded record: (1) the directive itself does not disclose any challenges or judicial findings that interpret its requirements; and (2) any interpretation, enforcement dispute or statutory challenge that may exist elsewhere is not recorded in this AD. The AD therefore provides only its own terms and the notes described; it does not cite case law or court interpretations that would clarify contested points such as the scope of the AMOC, the meaning of "SDR," or the interaction between FAA approval and CASA acceptance.

Given the AD imports a foreign instrument (FAA AD 90‑25‑05 R1) and binds Australian‑registered aircraft to that instrument’s technical requirements, potential legal issues that might arise in practice , such as disputes over whether a particular Boeing document revision constitutes a valid AMOC, or whether a specific corrosion finding meets the AD's Level 2 or Level 3 thresholds , would be matters for CASA administrative processes and, if contested, for judicial review outside the AD text. Those jurisdictional and interpretive issues are not documented in the supplied text.

Practitioners needing to assess judicial or administrative interpretations should therefore place reliance on other sources (regulatory correspondence, CASA guidance, or court records). The AD as supplied does not provide litigation guidance or a record of prior adjudication.

Operators and maintainers should note a number of practical pitfalls that follow directly from the AD text as supplied.

1. The AD adopts a foreign AD by reference rather than reproducing technical steps. The Requirement states simply: "Action in accordance with the technical requirements of FAA AD 90‑25‑05 R1 Amdt39‑15327." Operators must therefore obtain and follow the FAA AD and its associated Boeing documents to know what inspections, intervals and corrective actions are required. Failing to consult the FAA AD will leave an operator without the procedural details the CASA AD expects to be followed.

2. Reporting distinctions are severity‑based and not intuitive. The AD gives different reporting requirements by corrosion level: Level 1 "need not be reported"; Level 2 "may be consolidated with a sixty day report of corrective action ... under cover of a single SDR"; Level 3 "shall be reported by SDR." Two pitfalls arise. First, some personnel may misread "need not be reported" as meaning "no action required," but the AD imports the FAA AD's technical requirements, which will generally require corrective action irrespective of reporting thresholds. Second, the consolidation option for Level 2 requires a sixty‑day reporting window and submission "under cover of a single SDR" to the local CASA Field Office , missing that consolidated timing or the single‑SDR instruction could result in separate, fragmented reports and additional administrative burden.

3. "SDR" is used but not defined in the supplied AD text. The AD directs that Level 3 corrosion "shall be reported by SDR" and that Level 2 reports "under cover of a single SDR" are acceptable. Because the AD does not define the term within the text provided, assuming a particular procedural or electronic channel for SDR without confirming CASA's accepted method may cause misfiling. Operators should confirm with the local CASA Field Office which SDR mechanism and format is required.

4. The AMOC is fleet‑segment limited and linked to FAA approval of later revisions. The AD permits Boeing Document D621U400‑MRB (Rev Dec 2007 or later FAA‑approved revision) as an AMOC "for Boeing Model 747‑400 series aircraft only," and Amendment 5 allows "later revisions" to be used as the AMOC. Two practical risks follow. First, the AMOC is not available to non‑747‑400 variants; attempting to apply that AMOC to other 747 types would not be consistent with the AD. Second, the AD conditions acceptance on FAA approval of later revisions. Operators relying on a later Boeing revision should confirm that the particular revision has FAA approval as required by the AD, and that CASA recognises that FAA approval in practice.

5. References to FAA officials are replaced by CASA Field Offices. The AD states that references in the FAA AD to US FAA officials "shall be read as Civil Aviation Safety Authority Field Office." If an operator follows the FAA AD's procedural instruction verbatim and attempts to contact an FAA official, they must instead direct the correspondence to the appropriate CASA Field Office. Misrouting technical queries or AMOC applications to FAA contact points could delay approvals or responses.

6. Applicability boundaries matter. Amendment 4 clarified applicability "because certain new variants that have not yet been certified would have been subject to the requirements of this Directive." The AD lists specific 747 models. Operators should confirm type designation against the list to determine applicability. Mistaking a variant or sub‑variant for a listed model could lead to unnecessary compliance or, conversely, to non‑compliance.

7. The AD does not state enforcement penalties within its text. The absence of express penalties in the AD might prompt questions about enforcement expectations; however, reporting duties and technical compliance obligations remain. Operators should not assume that the lack of penalty language reduces enforcement risk; instead, they should consult CASA Field Offices for clarification on enforcement practice.

8. Effective date versus signature date. The AD is signed 26 August 2009 and "becomes effective on 2 September 2009." Operational planning must reflect the effective date, not merely the signature date.

Each of these points is derived from the AD text supplied. They identify administrative, procedural and interpretive risks inherent in implementing a domestically issued AD that imports foreign technical material and modifies only reporting and contact mechanics.

Compliance under this AD requires concrete, document‑based steps because the AD imports technical content by reference and prescribes certain domestic reporting mechanics. Follow these source‑grounded steps:

1. Confirm applicability. Check that the aeroplane is one of the listed models: Model 747‑100, ‑100B, ‑100B SUD, ‑200B, ‑200C, ‑200F, ‑300, ‑400, ‑400D, ‑400F, 747SR, or 747SP series aircraft. If the aircraft is not on that list, the AD as supplied does not apply.

2. Obtain the referenced FAA AD. The Requirement is express: "Action in accordance with the technical requirements of FAA AD 90‑25‑05 R1 Amdt39‑15327." Obtain that FAA AD and any associated service information it mandates. The FAA AD will contain the inspection tasks, intervals, damage thresholds, and corrective action requirements that CASA expects followed.

3. Obtain the associated Boeing documents. Note 1 indicates "Boeing Document D6‑36022 Rev D, or later FAA approved revision, is associated with FAA AD 90‑25‑05 R1." Acquire the currently applicable revision that is FAA‑approved and treat it as associated technical material for implementation.

4. For Model 747‑400 series aircraft, identify whether the Boeing Document D621U400‑MRB applies as an AMOC. Note 2 states that the D621U400‑MRB (Revision: Dec 2007, or later FAA‑approved revision) "is an approved alternative means of compliance to FAA AD 90‑25‑05 R1 for Boeing Model 747‑400 series aircraft only." If you plan to use that AMOC, confirm that the revision you intend to use is FAA‑approved, and record the revision date, because acceptance is conditioned on FAA approval.

5. Implement the technical CPCP requirements. Carry out inspections, corrosion control measures and corrective actions as documented in the FAA AD and its associated Boeing documents. The AD’s "Compliance" line is explicit: "As specified in the Requirement document." The AD does not substitute or relax the technical standards contained in the FAA AD.

6. Follow the AD’s reporting protocol. Apply the AD’s corrosion classification reporting rules exactly as written:

   • Do not report Level 1 corrosion (the AD: "need not be reported").
   • For Level 2 corrosion, consolidate corrective actions into a sixty‑day report and "submit[ ] to the local CASA Field Office under cover of a single SDR."
   • For Level 3 corrosion, "shall be reported by SDR." Confirm with the local CASA Field Office what constitutes an "SDR" for CASA reporting purposes and the preferred format and channel for submission.

7. Route enquiries and submissions to the local CASA Field Office. The AD instructs that references in the FAA AD to "Administrator FAA, FAA Principal Inspector (PI), or Manager Seattle Aircraft Certification Office (ACO)" "shall be read as Civil Aviation Safety Authority Field Office." Use CASA Field Office contacts for clarifications, to submit reports, and to request any necessary approvals.

8. Keep records and version control. Because the AD allows "later FAA approved revision" of the Boeing documents to be used as associated material or AMOC, document the specific revision you rely on and whether it has FAA approval. Retain records of inspection findings, classification determinations (Level 1/2/3), SDR filings, and sixty‑day corrective action reports. These records will evidence compliance with both the FAA AD technical requirements and CASA reporting obligations under the AD.

9. Observe the effective date. The AD "becomes effective on 2 September 2009." Ensure that all affected aircraft under your control have CPCP actions and reporting arrangements in place from that date forward, as appropriate to the inspection schedule and findings.

10. Clarify unanswered procedural items with CASA. The AD uses procedural terms (for example "SDR") without definition in the supplied text. If there is any uncertainty about the reporting method, acceptable consolidation, or the status of a Boeing revision, seek clarification directly from the local CASA Field Office.

These steps derive directly from the AD text: the Requirement line, the three reporting instructions, the two Boeing‑document notes, the instruction to read FAA official references as CASA Field Office, and the Compliance and effective‑date statements. Practitioners should treat the FAA AD and the named Boeing documents as the technical source documents for inspections and corrective works, and the CASA Field Office as the point of contact for reporting and administrative correspondence.