AD/B747/387 - AN-26 Insulation Blankets

The AD rests on a narrow set of technical and procedural concepts stated in the text.

• Applicability: It applies to specified Boeing 747 models and serial numbers, with serials for many models defined in Boeing Special Attention Service Bulletin 747-25-3429, and a listed set of 747-400 serial numbers (Applicability). The directive therefore combines document-referenced serial-number definitions with an explicit enumerated list for some 747-400 airframes.

• Hazard and safety objective: The stated hazard is that certain insulation blankets made from ORCON Orcofilm AN-26 may ignite or propagate fire when an ignition source such as electrical arcing occurs; the AD’s objective is to "ensure that insulation blankets constructed of AN-26 are removed from the fuselage" because such blankets "could ignite and propagate a fire" (Background). The AD therefore targets flammability properties and their interaction with ignition sources.

• Identification and scope-limiting test: The AD permits a negative identification outcome to relieve a particular blanket from replacement. That identification must be done by "an identification method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA or in accordance with Appendix A of Boeing Special Attention Service Bulletin 747-25-3429" (Requirement: 1.b). Thus the AD creates a gatekeeper function for the Manager, Seattle ACO, whose approvals determine which parts actually require replacement.

• Two paths for compliance: Operators may comply either by (a) removing and installing new blankets using an FAA‑approved method and ensuring the replacements meet 14 CFR 25.856(a), or (b) removing and replacing in accordance with Boeing Special Attention Service Bulletin 747-25-3429 Accomplishment Instructions (Requirement: 1). The AD therefore delegates technical compliance either to a documented Boeing service bulletin procedure or to FAA-approved alternative methods.

• Ongoing installation restriction: After the effective date, "No person may install any insulation blanket constructed of AN-26 as a replacement unless it has been modified to comply with 14 CFR 25.856(a)" (Requirement: 2). The AD thus imposes a forward-looking constraint on parts used in maintenance.

• Temporal compliance window: The main replacement obligation must be completed "within 96 months after the effective date of this Airworthiness Directive" (Compliance: 1). The installation prohibition applies "after the effective date" (Compliance: 2). The AD therefore sets a multi-year compliance period rather than immediate grounding.

• Exempting part‑marks: The AD provides a material exclusion based on part-marking: insulation material that is part-marked with a date of manufacture indicating it was manufactured before July 1981 or after December 1988 is declared "not constructed of AN-26" (Note 1). This allows identification based on markings when present.

• Cross-reference to other instruments: The AD explicitly references 14 CFR 25.856(a) as the flammability standard for replacement insulation, Boeing Special Attention Service Bulletin 747-25-3429 for serials and replacement procedures, Appendix A of that bulletin for an identification method, and FAA AD 2008-23-09 (Notes). The AD therefore operates in a network of technical standards and FAA approvals.

The AD directly addresses owners and operators of the specified Boeing 747 series aeroplanes identified in the Applicability table, since the measures apply to those aircraft. The text uses general phrases such as "No person may install..." and "remove all insulation blankets ... and install new insulation blankets" (Requirement: 1 and 2), which draws duties to the persons performing maintenance, installation, and continued airworthiness. Practically this group will include aircraft owners, aircraft operators, maintenance organisations (MROs), approved maintenance engineers, and any persons performing modification or repair work on affected aircraft.

The AD also affects suppliers and parts management functions because it forbids installation of AN-26 constructed insulation blankets as replacement parts unless the AN-26 has been "modified to comply with 14 CFR 25.856(a)" (Requirement: 2). That restriction affects inventory decisions, procurement of replacement insulation, and acceptance of parts for return-to-service.

Because the AD ties some determinations and approvals to the Manager, Seattle Aircraft Certification Office (ACO), FAA, it also affects the FAA’s Seattle ACO and Boeing insofar as Boeing’s Special Attention Service Bulletin and Appendix A are invoked for serial-number definition and identification methods. The reference to FAA AD 2008-23-09 and to 14 CFR 25.856(a) means that international technical standards and US regulatory criteria are operative for compliance; entities responsible for compliance must therefore coordinate with or use methods that have FAA Manager approval or follow Boeing SB Appendix A.

The AD’s effective date and compliance window affect scheduling and maintenance planning: the directive becomes effective on 15 January 2009 and requires removal/replacement within 96 months. This timing imposes resource allocation decisions on the affected parties: owners/operators must plan inspections, identification activities, and the removal/installation work within the 8‑year window, or ensure that replacement parts installed after the effective date comply with the stated flammability requirement.

Finally, the AD identifies specific fuselage locations (crown area; behind flight deck panels and circuit breaker panels; sidewalls, lavatories, closets, galleys; cargo compartment areas; air ducting; waste and water tubing; underside of floor panels) where the affected insulation may be installed (Requirement: 1.a(i)-(vii)). This spatial list determines which maintenance tasks, access panels, and structures will be subject to inspection and replacement. The AD therefore affects maintenance planners and technicians who must access those compartments and carry out the work.

Duties imposed by the AD are explicit and procedural.

• Removal and replacement duty: The central duty is to "remove all insulation blankets from the pressurized areas of the fuselage and install new insulation blankets" using an FAA‑approved method with replacements that "must comply with 14 CFR 25.856(a)" (Requirement: 1.a). The alternative duty is to "remove the existing fuselage insulation blankets and install new insulation blankets, in accordance with the Accomplishment Instructions of the Boeing Special Attention Service Bulletin 747-25-3429" (Requirement: 1.b). Compliance must occur "within 96 months after the effective date" (Compliance: 1). These provisions place an affirmative obligation on the persons responsible for the affected aeroplanes to perform removal and replacement work.

• Installation prohibition: The AD imposes a continuing duty not to install AN-26-constructed insulation blankets as replacements after the effective date unless those blankets "have been modified to comply with 14 CFR 25.856(a)" (Requirement: 2). This is a forward-looking constraint affecting the choice of parts and materials in maintenance.

• Identification duty: The AD creates a conditional right to avoid replacement for blankets proved not to be AN-26, but that depends on using "an identification method approved by the Manager, Seattle ACO, FAA or in accordance with Appendix A of Boeing Special Attention Service Bulletin 747-25-3429" (Requirement: 1.b). A person seeking to rely on a negative identification result must therefore use one of those specified methods or obtain Manager approval.

• Right to use Boeing SB Accomplishment Instructions: The AD expressly permits compliance by following Boeing Special Attention Service Bulletin 747-25-3429 Accomplishment Instructions (Requirement: 1.b). That gives operators a standardised procedural pathway for the replacement work.

• Material-marking exception: A person may rely on part-marking showing a manufacture date "before July 1981 or after December 1988" to determine that material "is not constructed of AN-26" (Note 1). That provides a narrow evidentiary right to avoid replacement where part marks are present and fall in those date ranges.

• Reference and reliance rights: The AD refers to and relies on other texts (14 CFR 25.856(a), Boeing Special Attention Service Bulletin 747-25-3429, Appendix A, FAA AD 2008-23-09). The duty-holder has the right to follow those referenced documents and to use FAA Manager approvals where specified.

Who decides: The AD delegates technical determinations and approvals to two bodies: the Manager, Seattle ACO, FAA (for approval of identification methods and of replacement methods when an alternative is proposed), and Boeing via the Accomplishment Instructions and Appendix A of Boeing Special Attention Service Bulletin 747-25-3429 (Applicability; Requirement: 1.b). The AD therefore assigns decision-making power over key technical gateways to the FAA Manager and to Boeing’s published service bulletin.

Operational rights not specified: The AD does not set out remediation funding mechanisms, compensation, or penalties in this text. It does not state any rights of appeal or review within the instrument itself. The AD also does not specify record-keeping details in this text; however, the compliance duties implicitly require operators to be able to demonstrate completion within the 96‑month window and to show that installed parts meet the stated flammability standard.

The AD text sets mandatory technical requirements and a compliance timeframe but does not specify civil or criminal penalties, enforcement procedures, or administrative sanction mechanisms within the published text. The instrument states that the AD "becomes effective on 15 January 2009" and sets the compliance deadline at "within 96 months after the effective date" for the replacement obligation (Compliance: 1). It further requires that after the effective date, "No person may install any insulation blanket constructed of AN-26 as a replacement unless it has been modified to comply with 14 CFR 25.856(a)" (Requirement: 2). Those are mandatory commands in the instrument.

The AD assigns approval authority to the Manager, Seattle ACO, FAA for identification methods and approved replacement methods (Requirement: 1.a and 1.b). Those approvals are a direct source of discretionary decision-making: whether an identification method or alternative compliance method is acceptable turns on the Manager’s approval. The AD therefore creates an administrative checkpoint where compliance may depend upon obtaining an FAA-approved method or following Boeing’s Accomplishment Instructions.

Because the directive text itself does not state enforcement mechanisms or penalties, the AD leaves unsettled in-text how non-compliance will be addressed or what sanctions may apply. The AD does, however, create obligations that must be met by the persons responsible for the affected aircraft. The practical effect is that operators will need to implement the required actions to restore regulatory compliance with this AD by the deadline. The AD’s reference to 14 CFR standards and FAA approvals introduces an external legal and regulatory framework that govern technical acceptability; compliance may be demonstrated through adherence to those referenced materials or by obtaining FAA Manager approvals as required by the AD.

The instrument is signed and dated by David Villiers, Delegate of the Civil Aviation Safety Authority, and carries an effective date, which signals that it is an operative regulatory instrument. The AD text does not provide a procedural route for contesting the AD or state how CASA will evidence or record compliance in this text. Because the AD relies on approvals from the Manager, Seattle ACO, FAA and on the Boeing service bulletin, the mechanics of enforcement and audit will involve those documentary references and approvals in practice, but the AD itself does not specify enforcement steps, penalties, or monitoring protocols in its published content.

This AD explicitly cross-references and relies on non-Australian technical and regulatory instruments and a Boeing service bulletin, introducing cross‑jurisdictional regulatory interaction.

• 14 CFR 25.856(a): The AD requires that replacement insulation blankets "must comply with 14 CFR 25.856(a)" (Requirement: 1.a). 14 CFR 25.856(a) is the referenced flammability standard for transport category aeroplane materials in the United States. By mandating compliance with that US regulatory standard, the AD imports a technical performance criterion for replacement materials.

• Boeing Special Attention Service Bulletin 747-25-3429 and Appendix A: The AD makes Boeing Special Attention Service Bulletin 747-25-3429 operative for two purposes: defining serial-number applicability (Applicability) and as an alternate compliance route, where operators may "install new insulation blankets, in accordance with the Accomplishment Instructions of the Boeing Special Attention Service Bulletin 747-25-3429" (Requirement: 1.b). Appendix A of that Boeing SB is specified as an approved identification method alternative to FAA Manager-approved methods. The AD therefore makes Boeing’s service bulletin part of the compliance ecosystem.

• Manager, Seattle Aircraft Certification Office (ACO), FAA approvals: Several determinations in the AD require approval by the Manager, Seattle ACO, FAA. The AD permits either an identification method "approved by the Manager, Seattle ACO, FAA or in accordance with Appendix A of Boeing Special Attention Service Bulletin 747-25-3429" (Requirement: 1.b) and requires installation of new blankets "using a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA" (Requirement: 1.a). These references create an enforcement and approval relationship between CASA’s AD and FAA technical approvals.

• FAA AD 2008-23-09: The AD notes that "FAA AD 2008-23-09 refers" (Note 2). This indicates that an FAA AD addressing the same or similar hazard exists and is relevant to the technical context of the CASA AD.

Because the AD directs operators to meet a US regulatory standard and to obtain FAA Manager approvals and to rely on a Boeing service bulletin for serial-number definition and Accomplishment Instructions, it effectively coordinates Australian airworthiness action with FAA procedures and Boeing technical guidance. The AD does not, in its text, reconcile differences between Australian regulatory law and the referenced documents; it simply makes adherence to those external standards and approvals part of the CASA AD’s compliance obligations.

The AD does not cite any Australian statutory provisions within the text, nor does it set out how the AD interacts with Australian statutory enforcement mechanisms. The document is an authoritative CASA AD effective on 15 January 2009 and signed by a CASA delegate; its operational effect is to impose the stated technical obligations on the applicable aeroplanes and the responsible persons, using the referenced foreign standards and approvals as the technical benchmarks.

The AD text itself contains limited material on amendment history. Key dated items in the instrument are:

• Issuance and signature: The AD is signed "David Villiers, Delegate of the Civil Aviation Safety Authority" and dated "24 November 2008" (end of instrument). That records the date of the AD’s adoption or signature.

• Effective date: The AD "becomes effective on 15 January 2009" (Compliance; Effective date). That is the operative date for the prohibition on installations and the beginning of the 96‑month compliance window.

• Notes referencing other instruments: Note 2 states that "FAA AD 2008-23-09 refers." The AD therefore locates itself in relation to an FAA AD that pre-exists or parallels it; the AD text does not itself amend that FAA AD but cross-references it.

The instrument does not include any textual amendments to prior CASA instruments, nor does it list earlier versions or superseded CASA ADs. There is no in-text history of amendments, revisions, revocations, or consolidations of this AD. The AD does not include any schedules of future amendments or sunset provisions beyond the fixed compliance period. It does not, within the published content, show amendment dates or an amendment log.

Any further amendment history or later changes to this AD are not present in the supplied text. The AD does, however, explicitly rely on Boeing Special Attention Service Bulletin 747-25-3429 and on FAA AD 2008-23-09, which may themselves have amendment histories outside this instrument. The AD also embeds a continuing prohibition on installing AN-26 constructed blankets "after the effective date", which is a permanent restriction until and unless the AD itself is amended or rescinded; the AD text contains no amendment provision or specified review mechanism.

In short, the supplied instrument records its date of signature (24 November 2008) and effective date (15 January 2009) and cross-references existing external FAA materials, but it does not contain an internal amendment history or a record of prior AD versions in the text provided.

The supplied AD does not include any litigation history, citations to judicial decisions, or references to disputes or appeals. The instrument itself is a regulatory directive and contains no record of court challenges, administrative appeals, or litigation outcomes within the text provided. It does reference FAA AD 2008-23-09 and Boeing Special Attention Service Bulletin 747-25-3429, but those references are technical and procedural; no legal proceedings involving those instruments are recorded in the text.

Therefore, within the four corners of this AD text, there is no litigation history to report. Any judicial or administrative proceedings that may have arisen in respect of this AD, the referenced FAA AD, or Boeing’s service bulletin are not present in the supplied material. The AD records its issuance (24 November 2008) and effective date (15 January 2009) but contains no account of legal challenge or review.

If a practitioner requires litigation history, administrative challenge records, or case law interpreting this AD, that material is not contained in this document and would need to be sourced separately from court or tribunal records, or from CASA administrative records, none of which are part of the supplied text.

The AD contains a number of operational and evidentiary details that create common pitfalls for implementers.

• Approved identification method requirement: The AD allows exemption from replacement only if an identification method shows the blanket is not constructed of AN-26, and that identification method must be "approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA or in accordance with Appendix A of Boeing Special Attention Service Bulletin 747-25-3429" (Requirement: 1.b). Relying on an ad hoc in‑house test or an informal visual inspection that is not FAA‑approved or not following Boeing Appendix A will not satisfy the AD on its face.

• Manager, Seattle ACO approvals: Several determinations require approval by the Manager, Seattle ACO, FAA (Requirement: 1.a and 1.b). If an operator seeks to use an alternative method for replacement or a non-Boeing identification process, it must obtain that Manager approval. That creates a procedural dependency on a specific FAA office.

• Scope of affected areas: The AD lists multiple fuselage locations where AN-26 may be installed, including hard-to-access zones such as "areas attached to the underside of floor panels", "behind flight deck panels and circuit breaker panels" and "air ducting" (Requirement: 1.a(i)-(vii)). Those spaces often require significant disassembly for inspection and replacement. An operator that plans narrow inspections could miss affected blankets that the AD intends to capture.

• Part-marking exception is limited and specific: The AD states that "Insulation material that is part-marked with a date of manufacture indicating that it was manufactured before July 1981 or after December 1988 is not constructed of AN-26" (Note 1). Part-marking is a narrow evidentiary proof; older or unmarked materials or materials with ambiguous markings will not benefit from that exception.

• Replacement material performance standard: The AD requires replacement blankets to "comply with 14 CFR 25.856(a)" when using the FAA‑approved method path (Requirement: 1.a). That imports a specific US flammability standard; purchasers must ensure supplier documentation evidences compliance with that standard. Using materials that simply "feel" less flammable without documentation will not meet the AD’s stated requirement.

• Temporal window but immediate installation ban: While the removal and replacement can be completed "within 96 months", the installation prohibition applies "after the effective date" (Compliance: 1-2). That means that even if an operator defers full replacement until late in the 96‑month window, they must still not install any unmodified AN-26 constructed blankets during that period. That can complicate urgent repairs that might otherwise have used on-hand AN-26 material.

• Interface with Boeing SB and Appendix A: Relying on Boeing Special Attention Service Bulletin 747-25-3429 as the Accomplishment Instructions path requires access to that SB and compliance with its Appendices. Operators must confirm they have the correct revision of Boeing SB 747-25-3429 and any relevant Appendix A procedures; the AD itself does not reproduce Appendix A content.

• Cross-jurisdictional approvals: Because the AD explicitly references FAA Manager approvals and 14 CFR standards, operators must coordinate with FAA approvals even though this is a CASA AD. Practitioners should note that the AD does not itself define how those FAA approvals are to be obtained or documented for CASA oversight; that operational interface may raise coordination issues.

• Record evidence: The AD requires actions that will have to be demonstrably completed within a compliance window but does not set out a specific record-keeping regimen in the text. Operators should not assume that a verbal assurance suffices; the AD’s structure implies documentary proof will be needed, particularly for the identification exceptions and for demonstrating replacement material compliance with 14 CFR 25.856(a).

• Note on FAA AD reference: The AD states "FAA AD 2008-23-09 refers" (Note 2). The presence of the FAA AD may contain additional or differing technical detail; implementers must check that FAA AD to understand any parallel or supplementary requirements.

These "gotchas" are derived directly from phrasing in the AD and the compliance mechanics it sets up. They point to practical risks in implementation: relying on unapproved tests, overlooking difficult-to-access installation locations, misunderstanding the limited part-marking exemption, mishandling replacement materials’ documented compliance with 14 CFR 25.856(a), and assuming the compliance window relaxes the immediate installation prohibition.

The AD sets a limited menu of compliance routes and concrete steps, which form a practical checklist for operators and maintenance organisations.

1. Determine applicability to your aeroplane:

   • Confirm the model and serial number. The AD applies to "Boeing 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series aircraft, serial numbers as defined in Boeing Special Attention Service Bulletin 747-25-3429, and Boeing 747-400 series aircraft, serial numbers 23719, 23720, 23814, 23816, 23817, 23818, 23819, 23820, 23999, 24061, and 24062" (Applicability). Cross-check the SB for serials if your aircraft is in the 747-100/200/300/SR/SP bracket.

2. Identify whether installed insulation is AN-26:

   • Use an identification method "approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA or in accordance with Appendix A of Boeing Special Attention Service Bulletin 747-25-3429" (Requirement: 1.b). Reliance on part-marking is permitted where the material is part-marked with a manufacture date that indicates manufacture before July 1981 or after December 1988; such part-marked material is "not constructed of AN-26" (Note 1).
   • If identification shows the blanket is not AN-26 using an approved method, replacement is not required for that blanket per the AD.

3. Choose a compliance pathway for blankets identified as AN-26:

   • Path A (FAA‑approved method): Remove all affected insulation blankets from pressurised areas of the fuselage and install new insulation blankets using "a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA". Ensure the replacement blankets "comply with 14 CFR 25.856(a)" (Requirement: 1.a). The AD lists the specific areas in which affected insulation may be present; inspect and, if necessary, work in crown areas, behind flight deck and circuit breaker panels, behind sidewalls/lavatories/closets/galleys, cargo compartments, air ducting, waste and water tubing, and underfloor panels (Requirement: 1.a(i)-(vii)).
   • Path B (Boeing SB): Remove the existing fuselage insulation blankets and install new insulation blankets "in accordance with the Accomplishment Instructions of the Boeing Special Attention Service Bulletin 747-25-3429" (Requirement: 1.b). Use Appendix A of the Boeing SB for identification if relying on that method.

4. Observe the temporal limits:

   • Complete the required removal/replacement "within 96 months after the effective date of this Airworthiness Directive" (Compliance: 1). The AD becomes effective on 15 January 2009, so schedule work within the 96‑month window from that date (Compliance; Effective date).
   • Do not install any AN-26 constructed insulation blanket as a replacement "after the effective date" unless that blanket "has been modified to comply with 14 CFR 25.856(a)" (Requirement: 2). Ensure replacement parts are documented as modified to comply with 14 CFR 25.856(a) before installation.

5. Procurement and material evidence:

   • Where replacements are required, ensure suppliers provide documentation demonstrating compliance with 14 CFR 25.856(a) for the replacement material, or that the replacement installation method has FAA Manager approval as specified.
   • For any AN-26 material proposed for reuse or reinstallation, obtain evidence of modification to meet 14 CFR 25.856(a) and retain that evidence.

6. Coordination with FAA and Boeing:

   • If seeking to use an alternative identification or installation method not described in Boeing SB Appendix A or the Accomplishment Instructions, apply to the Manager, Seattle ACO, FAA for the requisite approval; document any FAA Manager approvals received.
   • Obtain and keep copies of the Boeing Special Attention Service Bulletin 747-25-3429 Accomplishment Instructions and Appendix A if relying on that compliance path.

7. Documentation and scheduling:

   • Keep contemporaneous records of identification, approvals, removal and installation work, and replacement-material certification demonstrating compliance with 14 CFR 25.856(a), because the AD’s obligations require demonstrable completion within the specified period.
   • Plan maintenance slots to access the listed fuselage areas; the AD’s specified locations include areas that often require disassembly, which will affect FYR and docking plans.

8. Exceptions and evidence:

   • Use part-marking evidence when present and within the specified date ranges to avoid unnecessary replacement (Note 1). Document any reliance on part-marking, including photographs and manufacturer stamping details.

9. Ongoing maintenance practice:

   • After the effective date, do not accept or install an AN-26 constructed blanket as a replacement unless modified to comply with 14 CFR 25.856(a). Update procurement and stores control processes to prevent inadvertent use.

10. Check parallel guidance:

• Consult FAA AD 2008-23-09 and Boeing Special Attention Service Bulletin 747-25-3429 for technical detail, and ensure the specific Accomplishment Instructions and Appendix A referenced by the AD are available and understood before beginning work.

By following these steps , confirm applicability, use approved identification methods, select one of the two compliance paths, ensure replacement materials meet 14 CFR 25.856(a), obtain any required FAA Manager approvals, and retain documentary proof , an operator will implement the AD’s requirements within the compliance window and meet the AD’s installation prohibition that applies after the effective date.

The AD’s operative language makes several practical implementation implications explicit or inevitable.

• Access and labour: The AD lists numerous fuselage locations (Requirement: 1.a(i)-(vii)), many of which require panel removal or cabin/cargo disassembly to reach. Planning for the work therefore requires allocation of labour hours, access panels, possible temporary cabin reconfiguration, and coordination with scheduled heavy maintenance visits.

• Inventory control: The prohibition on installing AN-26 constructed blankets after the effective date (Requirement: 2) requires parts and stores control to prevent installation of prohibited material. Maintenance units must quarantine or reclassify stock and verify supplier certificates for replacement blankets.

• Evidence trail: Because the AD makes FAA approvals and Boeing SB procedures central to acceptable methods, maintainers must retain the approvals, Accomplishment Instruction references, and material certification demonstrating compliance with 14 CFR 25.856(a). The AD’s exemption for certain part-markings (Note 1) also requires documentary capture of those markings.

• Coordination with FAA and Boeing: The AD directs operators toward FAA Manager approvals and Boeing Accomplishment Instructions. Operators who are not US-based will need to engage with the specified FAA office or rely on Boeing’s SB Appendix A where available; plan for cross‑agency coordination timelines.

• Timing: The 96-month compliance window provides time to schedule work, but the immediate installation ban on AN-26 constructed blankets after the effective date means that any in-service repairs after 15 January 2009 will need replacement materials that meet the AD’s standard; do not assume the compliance window allows temporary use of AN-26 materials.

• Technical conformity: Replacement blankets must "comply with 14 CFR 25.856(a)" (Requirement: 1.a). Ensure that suppliers can provide test reports and certificates demonstrating compliance with that standard. If seeking alternative methods, obtain the Manager, Seattle ACO, FAA approval in writing.

These practical considerations are implied by the AD’s explicit text and the locations and standards it cites; they should be incorporated into a compliance plan and maintenance programme.