AD/B737/338 Amdt 1 - Auxiliary Fuel Tanks

The Directive is compact and driven by a small set of interlocking concepts. The primary regulatory lever is a targeted deactivation requirement for auxiliary fuel tanks installed under particular FAA STCs. The key concepts and how they operate in the text are these.

Applicability: The AD applies only to Model 737 aeroplanes fitted with auxiliary fuel tanks installed in accordance with the listed STCs. The table explicitly maps aeroplane series to STC numbers: 737‑200 with SA1082NW, SA2153WE and SA1054NW; 737‑400 and ‑500 with SA3992NM and SA3980NM. The word “Applicability” and the table are the AD’s jurisdictional gate: if the aeroplane is not fitted with one of those STCs, the textual requirement does not apply as written.

Deactivation and approved procedure: The AD instructs operators to “Deactivate the auxiliary fuel tanks, in accordance with an approved deactivation procedure.” The AD does not reproduce a step‑by‑step method in the Requirement box; rather it mandates adherence to an “approved” deactivation procedure and points to Appendix A for criteria “that should be included in the deactivation procedure.” The approval status of the procedure is material to compliance. The Directive therefore imports a discretionary approval layer into the requirement: a deactivation must be performed according to a procedure that carries whatever approval weight the approving authority gives it.

Residual hardware and safety of continued airworthiness: The AD contemplates that some auxiliary tank components might remain on the aeroplane after deactivation. It requires those remaining components to be “secured” and to have “no effect on the continued operational safety and airworthiness of the aeroplane.” A second constraint is that deactivation “may not result in the need for additional instructions for continued airworthiness.” These two sentences operate as constraints on the method of deactivation: the procedure must both leave the aeroplane safe and must not create new ongoing maintenance instructions.

Reference to related FAA AD and Appendix: The AD explicitly refers to FAA AD 2008‑12‑03 Amdt 39‑15546 (Note 2) and directs readers to Appendix A for deactivation criteria (Note 1). This cross‑reference means the instrument sits in a regulatory network; it imports and signals alignment with a specific FAA action.

Timing and amendment mechanics: The Directive fixes a compliance deadline, “On or before 16 December 2008,” and records that Amendment 1 corrects a typographical error in applicability. The original issue’s effective date (28 August 2008) and the amendment effective date (25 September 2008) are recorded. The Directive was issued following manufacturer fuel system reviews that “identified potential unsafe conditions” and, as the Background explains, “result(s) from fuel system reviews conducted by the manufacturer, which identified potential unsafe conditions for which the manufacturer has not provided corrective actions.”

Risk logic: The AD’s public logic is risk mitigation against potential ignition sources inside fuel tanks that could combine with flammable vapours to cause fuel tank explosions and consequent loss of the aeroplane. The mechanism it deploys is removal of the installed auxiliary tanks’ operational capability by mandated deactivation, rather than immediate design changes or mandated removal.

Together, these concepts define both the scope (what aeroplanes and STCs) and the compliance mechanism (approved deactivation, secured residual parts, no new continued‑airworthiness instructions, deadline), and they anchor the Australian requirement to an identified FAA action and manufacturer review.

The Directive identifies and therefore affects a small, specific set of stakeholders by name or functional role.

Operators and owners of Boeing 737‑200, 737‑400 and 737‑500 aeroplanes fitted with Rogerson auxiliary fuel tanks installed under the listed FAA STCs are the primary duty‑holders. The Applicability table specifies the mapping of aeroplane series to STC numbers (SA1082NW, SA2153WE, SA1054NW for 737‑200; SA3992NM and SA3980NM for 737‑400 and ‑500). If an aeroplane is fitted with one of those STCs, the owner/operator must comply by deactivating the auxiliary tank in accordance with an approved deactivation procedure by the compliance date “On or before 16 December 2008.”

Maintenance organisations, licensed engineers and the entities authorised to produce or approve deactivation procedures are consequentially affected. The AD requires deactivation to be performed “in accordance with an approved deactivation procedure” and points to Appendix A for criteria that “should be included.” That imposes demand for technical labour and an approved procedure. While the AD does not name the approving authority in the text supplied, the requirement for an “approved” procedure inevitably involves an approval process and an entity that issues the approval; the AD’s mechanics make that approval status material to compliance.

Regulators and delegated CASA officials are affected as decision‑makers. The AD records it was issued by a CASA Delegate (James Coyne) and the document references an FAA AD. Regulators will be obliged to accept or set the standards for the “approved” procedure and to monitor compliance against the deadline.

Manufacturers and STC holders are affected in an information and reputational sense. The Background notes that manufacturer fuel system reviews identified potential unsafe conditions and that the manufacturer has not provided corrective actions; the Directive fills that corrective gap by mandating deactivation. STC holders whose installations are named (the five STC numbers) will see their modifications targeted by the AD.

Passengers and insurers bear indirect exposure. The safety rationale,preventing ignition sources inside fuel tanks,relates to systemic risk reduction. While the AD’s text does not address insurance, insurers and lessors will be interested in evidence of compliance and that deactivation has not produced ongoing maintenance needs.

Suppliers of parts and components for deactivation or securing of residual hardware may see demand. The AD permits components to remain so long as secured and benign to safety; suppliers that provide brackets, fasteners or modifications to secure residual hardware could be engaged.

Finally, legal and compliance advisers to affected operators will be engaged to confirm applicability, gather records about STCs fitted to particular aeroplanes, secure or draft an approved deactivation procedure, and certify compliance before the deadline. The AD’s timeline and the “approved” procedure requirement create a clear workstream for those advisory roles.

The AD imposes a discrete set of duties on identified operators and prescribes constraints on method and outcomes. It does not enumerate express rights, but by implication affected parties have rights to seek approval for deactivation procedures and to rely on the effective dates and applicability text.

Primary duties

• Deactivate the auxiliary fuel tanks. The Requirement plainly states: “Deactivate the auxiliary fuel tanks, in accordance with an approved deactivation procedure.” The duty is not to remove every component but to deactivate the tank’s function following an approved procedure.

• Secure any remaining components. The AD requires that “Any auxiliary tank component that remains on the aeroplane must be secured and must have no effect on the continued operational safety and airworthiness of the aeroplane.” That imposes a duty to ensure the residual configuration is physically restrained and does not threaten operational safety.

• Avoid creating continued airworthiness obligations. The AD adds a constraint: “Deactivation may not result in the need for additional instructions for continued airworthiness.” Operators and maintenance providers must choose a deactivation method that does not produce new ongoing inspection or maintenance tasks requiring separate instructions.

Timing duty

• Comply by the fixed deadline. The Compliance provision sets the date: “On or before 16 December 2008.” The Amendment records the instrument’s effective date (25 September 2008 for Amendment 1) and the original issue effective date (28 August 2008). These dates are the temporal boundaries for fulfilling the duties.

Procedural and content constraints

• Use an approved deactivation procedure and include Appendix A criteria. The AD instructs adherence to an “approved” deactivation procedure and directs that Appendix A “provides criteria that should be included in the deactivation procedure.” While the AD does not reproduce Appendix A’s text in the included extract, the AD makes the approval status and Appendix A’s criteria a material element of a compliant deactivation.

Rights and implied entitlements

• Right to rely on the AD’s applicability and table. The Applicability table delimits the AD’s scope; operators not fitting one of the listed STCs can treat the AD as not applying, subject to verifying actual equipment and modification status.

• Right to execute the deactivation in accordance with an approved procedure. The AD contemplates that a procedure will be approved and used. The AD does not specify the approver in the text presented but the obligation is to adopt the approved procedure rather than adhere to any single mandated method.

• Right to preserve aircraft safety and airworthiness. The duties require securing components and avoiding new continued airworthiness instructions, which aligns with the ongoing legal ecosystem that aircraft must remain airworthy. The AD requires actions that preserve continued operational safety and airworthiness, not actions that compromise it.

No expressed compensatory or enforcement rights are set out in the AD text supplied. The document does, however, relocate responsibility for technical conformity (approved procedure, securing components, no new continued‑airworthiness instructions) to operators and their maintenance organisations, effectively placing them in a compliance and certification role for the deactivation outcome.

The text provided is an Airworthiness Directive and contains the mandated requirements, the compliance date and the background rationale; it does not, within the extract supplied, set out specific penalty provisions, fines or the exact enforcement process. The AD is a regulatory instrument of the Civil Aviation Safety Authority, issued by a CASA Delegate, and the compliance instructions and deadlines create enforceable obligations in the regulatory domain,failure to comply would be a regulatory noncompliance in the context of CASA’s airworthiness oversight.

What the AD does state about enforcement‑relevant matters in the supplied text

• Compliance deadline: The AD fixes a compliance date, “On or before 16 December 2008.” A fixed deadline makes monitoring and enforcement administrable: records of compliance must exist by that date.

• Approval requirement: Deactivation must be “in accordance with an approved deactivation procedure.” The approval status of procedures is an enforcement hinge: authorities enforcing the AD will assess whether the procedure used was an “approved” one, as required.

• Safety and continued airworthiness criteria: The AD requires that residual components be secured and that deactivation “may not result in the need for additional instructions for continued airworthiness.” Enforcement will likely focus on whether deactivation satisfies those constraints and whether the aircraft remains airworthy.

What the extract does not state

• The AD extract does not list sanctions, penalty amounts, or specific enforcement mechanisms (such as suspension of certificate, fines, or mandatory grounding) within the excerpt provided.

• It does not specify the approving authority for the deactivation procedure, the process to obtain approval, or documentary evidence that must be retained to demonstrate compliance.

Implications for enforcement in practice (grounded in the AD text)

• Enforcement will be documentary and technical: inspectors will check aircraft modification records, STC fitment, the existence and approval status of the deactivation procedure, and physical evidence that tanks have been deactivated or components secured consistent with the AD’s requirements and Appendix A criteria.

• The AD’s explicit cross‑reference to FAA AD 2008‑12‑03 suggests a harmonised enforcement posture: regulators may treat the FAA AD as relevant technical background when assessing whether a deactivation procedure meets the AD’s intent.

Because the AD is a CASA instrument and the signed delegate is named, the usual administrative enforcement tools of the aviation regulator (oversight, notices, enforcement action under applicable aviation law) are inference‑adjacent to this AD but are not enumerated in the supplied text. Any enforcement action taken would be administered through CASA’s statutory powers rather than the AD text itself.

The AD is a specific safety instrument operating within a network of aviation regulatory instruments. The text explicitly cross‑references external technical material and indicates interaction with manufacturer reviews.

Interaction with FAA AD 2008‑12‑03: Note 2 of the Directive states “FAA AD 2008‑12‑03 Amdt 39‑15546 refers.” That reference makes the CASA AD part of a transnational harmonisation process where FAA findings and directives inform CASA action. It implies that the FAA AD is a relevant technical source for the nature of the unsafe condition and potential remedial actions. The CASA AD adopts the outcome of that process by mandating deactivation in Australia for the same STC installations.

Relationship to manufacturer reviews and corrective action: The Background explains the AD “results from fuel system reviews conducted by the manufacturer, which identified potential unsafe conditions for which the manufacturer has not provided corrective actions.” The AD therefore fills a remedial gap where the manufacturer has not issued a corrective design action; CASA utilises the AD process to mandate operator action. That is an interaction where regulator‑issued mandates can substitute for (or supplement) manufacturer corrective measures when the latter are not forthcoming.

Interaction with STC approvals and modification records: The Applicability is keyed to FAA STC numbers. Those STCs are approvals under U.S. processes that authorised the auxiliary tank installations. Aviation regulatory regimes typically require operators to maintain records demonstrating which modifications are installed. The AD’s applicability and deactivation requirement will interact with regulatory requirements for maintaining modification and airworthiness records, and with obligations under aircraft maintenance rules to record and sign off deactivation actions.

Interaction with continuing airworthiness frameworks: The AD’s instruction that “Deactivation may not result in the need for additional instructions for continued airworthiness” interacts with the continuing airworthiness system: operators and maintenance organisations must ensure that deactivation does not create new continuing‑airworthiness tasks that would themselves require airworthiness approvals or manufacturer/authority instructions. The AD therefore constrains deactivation methods to avoid generating new regulatory obligations.

Interaction with CASA enforcement frameworks and administrative law: Though this AD excerpt does not set out enforcement mechanisms, the instrument will be enforced under CASA’s broader statutory powers and administrative processes. Any applicant for approval of a deactivation procedure will operate within CASA’s approval and oversight procedures, and disputes or enforcement actions arising from alleged noncompliance would follow administrative law channels available against regulatory decisions.

In sum, the AD intersects horizontally with FAA directives and manufacturer technical reviews, vertically with STC and modification recordkeeping and approvals, and procedurally with CASA’s approval and enforcement frameworks. The AD does not purport to amend or replace other legislative instruments in the supplied text; it acts as a targeted operational instruction referencing external technical materials.

The Directive contains a brief record of its issuance and amendment in the supplied text.

• Original issue: The table footnote states “The original issue of this Directive became effective on 28 August 2008.” That is the first effective date recorded for the Directive as initially released.

• Amendment 1: The heading of the supplied text is AD/B737/338 Amdt 1 and the body states “This Amendment becomes effective on 25 September 2008.” The stated purpose of Amendment 1 is narrowly corrective: “Amendment 1 is issued to correct a typographical error in the applicability.” The Amendment therefore did not add new substantive requirements to the Requirement box provided in the extract; it corrected an error in the Applicability text.

• Issuance date and signature: The Directive bears the signature details at the foot: “James Coyne, Delegate of the Civil Aviation Safety Authority” and the date “6 August 2008.” That suggests the administrative act of signing preceded the original effective date noted above.

• Relationship to FAA AD: Note 2 says “FAA AD 2008‑12‑03 Amdt 39‑15546 refers.” This places the AD in a chain of technical directives contemporaneous with mid‑2008 FAA action. The AD’s Background also states the Directive “results from fuel system reviews conducted by the manufacturer,” indicating that its issuance followed manufacturer review findings.

What the supplied extract does not record

• The extract does not provide a history of any further amendments beyond Amdt 1, nor does it list revocation or superseding ADs. Nor does it include the text of the corrected applicability in the amendment markup; it only states the reason.

Practical import of the amendment history

• The Amendment 1 record signals that CASA corrected a drafting error in the Applicability, and that operators should ensure they consult the amended applicability table (the table reproduced in the extract) when determining whether their aeroplane is within scope. The original effective date (28 August 2008) and the amendment effective date (25 September 2008) bracket the administrative timeline in which the typographical correction was implemented, and the compliance deadline (16 December 2008) remained the substantive operational deadline for affected operators.

In short, the AD has at least two recorded administrative steps: the original issue (effective 28 August 2008) and Amendment 1 (effective 25 September 2008), the latter correcting an applicability typographical error. The signing delegate and the referenced FAA AD are also recorded in the same administrative package.

The supplied text contains no litigation history. The Directive does not reference any judicial proceedings, appeals, or case law. It is a regulatory safety directive issued by CASA and signed by a named delegate; the text records administrative steps (original issue, Amendment 1) and technical references (FAA AD and Appendix A) but contains no mention of litigation, contested enforcement outcomes, or judicial review cases.

Given the absence of litigation references in the document, there is no case law or judicial interpretation recorded in the supplied material to use as precedent for interpreting the AD’s provisions. Any judicial or tribunal decisions that might have engaged with this specific AD, with CASA’s exercise of power in this context, or with the technical requirements of auxiliary fuel tank deactivation are not contained in the excerpt provided.

For practitioners seeking to know whether enforcement or interpretation disputes arose from this AD, the AD text itself provides no litigated context. In the absence of litigation references in the source, interested parties must rely on contemporaneous administrative records, CASA enforcement records, or separate legal databases to identify any subsequent judicial or administrative appeals, none of which are supplied in the material given.

The AD’s brevity and its reliance on external materials create a number of practical pitfalls for operators and maintainers. The AD text itself suggests several points where compliance could be misinterpreted or where administrative friction can arise.

Applicability mis‑identification: The AD applies only to aeroplanes equipped “with auxiliary fuel tanks installed in accordance with specified United States Federal Aviation Administration (FAA) Supplemental Type Certificates (STC) as follows.” The table lists five STC numbers mapped to aeroplane series. Because Amendment 1 was issued to correct a typographical error in applicability, operators must be careful to use the amended applicability table provided. Mistakes in identifying whether an aeroplane is fitted with one of the listed STCs would lead to incorrect compliance assessments.

Dependence on “approved” deactivation procedure: The AD requires deactivation “in accordance with an approved deactivation procedure.” The AD excerpt does not specify who approves the procedure, what form the approval must take, or what evidence of approval an operator should keep. That creates an administrative risk: if an operator executes a deactivation using a procedure it believes valid but which the regulator does not accept as “approved,” the operator could be found non‑compliant even if the technical work was competently done.

Appendix A is referenced but not supplied: The AD states that “Appendix A of this Directive provides criteria that should be included in the deactivation procedure,” but the supplied extract does not contain Appendix A. Compliance requires consulting Appendix A. Relying on the Requirement paragraph without Appendix A risks omitting criteria the regulator expects to be addressed.

Securing residual components versus removal ambiguity: The AD allows auxiliary tank components to remain provided they are “secured” and have “no effect on the continued operational safety and airworthiness.” Operators must make engineering judgments about whether remnants can be left in situ or must be physically removed. The phrase “must be secured and must have no effect” is outcome‑based rather than prescriptive about methods; disagreement can arise about sufficiency of securing measures.

No new continuing airworthiness instructions allowed: The AD states “Deactivation may not result in the need for additional instructions for continued airworthiness.” That constraint limits deactivation methods to those that do not create new recurring tasks or inspection regimes. It can be technically challenging to deactivate a system so that it neither requires removal nor creates new inspection or maintenance tasks, and the operator must document this technical position.

Timing and administrative lead times: The compliance date is “On or before 16 December 2008.” The AD became effective in August/September 2008 (original AD effective 28 August 2008; Amendment 1 effective 25 September 2008). That gives a finite window to identify affected aeroplanes, obtain an approved deactivation procedure, schedule maintenance slots, and perform the work. Operators who delay identification of STC fitment risk constrained maintenance availability or non‑compliance.

Cross‑jurisdictional technical references: The AD refers to FAA AD 2008‑12‑03. Operators may rely on the FAA document for technical detail, but must ensure that any FAA‑originated procedure is acceptable to CASA as an “approved deactivation procedure” under the Australian AD. Relying solely on FAA material without domestic approval could cause disagreement.

Recordkeeping and evidence: The AD does not state explicitly what documentary evidence suffices to demonstrate compliance. Operators should not assume that a brief work card entry is adequate; the AD’s approval and Appendix A references imply the regulator will expect a substantive record showing the procedure used, the approval instrument, and evidence that remaining components are secured and harmless to airworthiness.

In short, the main gotchas are: ensure you are consulting the amended applicability; obtain and rely on an approved deactivation procedure (and the approval evidence); consult Appendix A and the FAA AD; ensure the deactivation method does not create new continued‑airworthiness instructions; carefully document the work; and schedule the intervention to meet the December 2008 deadline.

The AD sets a small set of concrete, sequential compliance tasks. The steps below rest directly on language from the AD and on the practical inferences that the Requirement, Applicability, Appendix A reference and Compliance date create. The AD itself should be read alongside Appendix A and FAA AD 2008‑12‑03; those materials are referenced in the Directive.

1. Determine applicability to the individual aeroplane

   • Check the aeroplane’s modification and STC records to confirm whether it is fitted with Rogerson auxiliary fuel tanks installed under one of the listed STCs. The Applicability table specifies: for 737‑200 series SA1082NW, SA2153WE and SA1054NW; for 737‑400 and ‑500 series SA3992NM and SA3980NM. The AD applies only to aeroplanes equipped in accordance with those STCs.

2. Obtain the current Directive text and Appendix A

   • Use the amended AD text (Amendment 1) because Amendment 1 corrected a typographical error in the applicability; the Amendment became effective on 25 September 2008. Appendix A “provides criteria that should be included in the deactivation procedure” and is a required reference for preparing or assessing any deactivation procedure.

3. Secure an approved deactivation procedure

   • The AD requires deactivation “in accordance with an approved deactivation procedure.” Identify the entity that is authorised to approve deactivation procedures under the applicable Australian aviation regulatory processes (the AD itself names a CASA Delegate as issuer, so CASA approval pathways are implicated). Prepare the deactivation procedure to meet the Appendix A criteria and submit it for approval as required.

4. Demonstrate that deactivation will not create new continued airworthiness instructions

   • The AD explicitly prohibits deactivation that “may result in the need for additional instructions for continued airworthiness.” The approved deactivation procedure must therefore include analysis and steps showing that the deactivated state does not generate recurring maintenance tasks, inspections or other continuing airworthiness requirements.

5. Plan and schedule the physical deactivation work

   • Once the deactivation procedure is approved, schedule the maintenance work in time to comply with the deadline “On or before 16 December 2008.” Arrange for appropriately licensed maintenance personnel or organisations to perform the work and for quality assurance sign‑offs.

6. Secure any remaining auxiliary tank components and verify airworthiness impact

   • If components remain on the aeroplane after deactivation, ensure they are physically secured in accordance with the approved procedure and that they have “no effect on the continued operational safety and airworthiness of the aeroplane.” The deactivation report should include photographs, engineering assessments and sign‑offs demonstrating that residual parts are secured and benign.

7. Record and retain documentation of approval and work

   • Keep the approved deactivation procedure, the approval instrument, maintenance work orders, sign‑offs by licensed personnel, and any engineering compliance statements required by Appendix A. The AD’s enforcement hinges on technical compliance and approval status, so documentation is essential.

8. Cross‑reference FAA AD 2008‑12‑03 where relevant

   • Note 2 says “FAA AD 2008‑12‑03 Amdt 39‑15546 refers.” Use that FAA AD as technical background or supporting material where relevant, but ensure that any FAA‑originated methodology is acceptable to CASA as the “approved” deactivation procedure for the Australian AD.

9. Communicate with lessors, insurers and operators’ compliance functions

   • For leased aircraft or those with multiple stakeholders, notify lessors and insurers of planned deactivation and document completion. The AD imposes a regulatory obligation on the operator and evidence of compliance will be important to contractual and insurance relationships.

10. Final verification before putting the aeroplane back into service

    • Ensure a final airworthiness verification is completed demonstrating that the deactivation was performed per the approved procedure, that any remaining components are secured and benign, and that there are no outstanding continuing‑airworthiness instructions resulting from the deactivation.

These steps reflect the AD’s textual demands and the practical steps necessary to demonstrate compliance. The key documentary items to obtain and retain are: the amended AD text (Amdt 1), Appendix A (criteria), the approved deactivation procedure, the approval instrument, maintenance records and engineering assessments showing residual hardware security and lack of impact on continued airworthiness.