AD/B747/326 - Flap Control Unit

This Directive deploys a fault-reduction and part-compatibility regime around flap control units on specific 747-400 family aeroplanes. The principal structural and operational concepts in the text are:

• Part-number targeted modification and replacement. The Directive is precise about part numbers. It mandates replacing at least one FCU P/N 285U0011-207 with P/N 285U0011-208 (Requirement 1), requires replacement of three FCUs P/N 285U0011-205/-206 with P/N 285U0011-207 for certain aeroplanes (Requirement 2), and forbids installation of P/N 285U0011-205/-206 as replacement parts as of the effective date (Requirement 3). These are hard part-identification controls; the work must follow Boeing service instructions cited in the Directive.

• Layered service-document reliance. The AD’s mandated work is to be accomplished “in accordance with the Accomplishment Instructions” of Boeing ASB 747-27A2386 (for 207→208) and SB 747-27-2319 (for 205/206→207). The ASB in turn references Boeing CSB 285U0011-27-06 as additional information for modifying 207→208; the SB references CSB 285U0011-27-04 for 205/206→207. The Directive thus creates a compliance chain: CASA’s AD mandates the action, Boeing ASB/SB specify how, and the CSBs provide component-level modification instructions.

• Staged compliance windows and interdependence. The compliance timetable for Requirement 1 is the earlier of three metrics (time, hours, cycles). Requirement 2 must be completed before or at the same time as Requirement 1, creating an ordering constraint for aeroplanes that still have 205/206. Requirement 3 is immediate. This staging addresses aircraft in differing configuration states and imposes sequencing on maintenance programmes.

• Safety objective expressed in operational terms. The Background ties the mechanical changes to operational failure modes: disengagement of all three FCUs could disable autoland/autopilot flap control and indications, exposing the aircraft to a potential non-normal high speed landing and runway departure risk. The Directive implements targeted changes designed to alter that failure probability or mode.

• Cross-reference to foreign regulatory action. The AD refers to FAA AD 2005-04-03 Amdt 39-13975, signalling alignment or harmonisation with the FAA requirement listed. The Directive is explicit that FAA AD is referred to, but the CASA instrument itself remains the operative mandate for the aircraft within the jurisdiction.

• Prohibition as an immediate supply-chain control. Requirement 3 operates as a prohibition on installing certain older FCUs as replacement parts from the effective date, constraining spare-parts inventories and replacement choices for operators and maintenance organisations.

These concepts govern what equipment may be fitted, how modifications are to be accomplished, the timing constraints, and the documentary sources that technicians must follow when performing the work.

The Directive names its applicability: Model 747-400, -400D and -400F series aeroplanes identified in Boeing ASB 747-27A2386, dated 13 March 2003. From that mechanical statement we can identify the classes of actors affected and the roles they must play.

• Operators and aircraft owners. Airlines or other operators who have in-service 747-400 series aeroplanes meeting the ASB’s identification are directly obliged to ensure the mandated replacements occur within the compliance windows. The Directive imposes discrete maintenance work and a prohibition on fitting certain FCU part numbers, so operators bear responsibility for planning, funding, and scheduling the work.

• Maintenance organisations and approved repair stations. The Directive requires compliance with Boeing Accomplishment Instructions and Component Service Bulletins. Maintenance and modification shops will need to obtain and follow ASB 747-27A2386 and SB 747-27-2319, plus referenced CSBs (285U0011-27-06 and 285U0011-27-04). This places the operational burden on entities that perform FCU replacement/modification work. They must also ensure their parts procurement and installation checks conform to the part numbers specified.

• Parts suppliers, distributors and stock-holders. Requirement 3 forbids installation of FCUs P/N 285U0011-205 or -206 as replacement parts as of the effective date. Suppliers and spares managers who hold inventories of those part numbers must alter disposal, rework, or segregation procedures. They will face decisions about inventory valuation, rework to a permissible P/N (if feasible under CSB instructions), or scrapping.

• Flight crew and operations departments. While the Directive does not change operating procedures, its Background identifies operational failure modes (loss of autoland/autopilot flap control and indications). Flight operations and crew training units will need to be aware of the mandated modifications because the Directive’s objective is to reduce those failure modes. Crews may need to understand any temporary operational restrictions imposed during modification scheduling, although the Directive itself does not impose operating limitations.

• Regulatory and oversight bodies. CASA (via the Delegate who signed the AD) is the issuing authority and will be the regulator that expects compliance. The Directive itself does not set out enforcement penalties; however, it puts operators within CASA’s AD compliance framework and its effective date determines enforceable obligations.

• Lessors, financiers and purchasers. Though not named in the text, aeroplane lessors and financiers will be affected operationally because the AD imposes mandated maintenance that can affect aircraft availability. Lessees must ensure modifications are done in line with the AD, and lessors will need documentary assurance of compliance when arranging transfers or redelivery. The Directive does not itself address contractual allocation of responsibility.

• Aircraft previously modified under older Boeing SBs. The Directive’s Requirement 2 specifically addresses aircraft identified in SB 747-27-2319 dated 24 January 1991. Those aircraft that still have FCUs P/N 205 or -206 are singled out for earlier or concurrent retrofits to P/N 207 prior to satisfying Requirement 1.

In short, the Directive primarily affects operators and their maintenance supply chain (MROs and parts suppliers), with secondary practical impacts for lessors and operational staff. The issuer is CASA (Delegate James Coyne), and compliance obligations attach to aircraft identified in the Boeing ASB specified in the Directive.

The Directive establishes duties on operators and maintenance organisations and prescribes which service documents must be followed. It does not set out rights in contractual or compensation terms; the duties are administrative and technical.

Key duties

• Perform specified FCU replacements. Operators must carry out the replacements described in Requirement 1 and Requirement 2, as applicable to each aeroplane, following Boeing ASB 747-27A2386 or SB 747-27-2319 Accomplishment Instructions respectively. The text is explicit: Requirement 1 requires replacing at least one P/N 285U0011-207 FCU with P/N 285U0011-208; Requirement 2 requires replacement of the three FCUs P/N 285U0011-205 or -206 with P/N 285U0011-207.

• Follow referenced service information. The Directive requires that modifications be accomplished “in accordance with the Accomplishment Instructions” of the cited Boeing service documents. The ASB and SB in turn refer to Component Service Bulletins (CSBs) for component-level modification instructions (CSB 285U0011-27-06 and CSB 285U0011-27-04).

• Respect the compliance timetable. For Requirement 1, operators must comply at the earlier of 60 months from the effective date, 25,000 hours time in service after the effective date, or 4,000 flight cycles after the effective date. Requirement 2 must be done before or concurrent with Requirement 1. Requirement 3 is effective from the Directive’s effective date.

• Prohibit installation of older part numbers. As of the effective date the Directive forbids installation of FCUs P/N 285U0011-205 or -206 as replacement parts (Requirement 3).

• Use Boeing documentation when modifying parts. The Directive’s Notes point operators to Boeing CSBs as additional sources of service information for the mechanics of modification; operators must incorporate that component-level guidance where relevant.

Rights and implied protections (as evident from the text)

• Right to follow specified instructions. The Directive does not give operators latitude to substitute alternate procedures. Compliance is directed to the Accomplishment Instructions in Boeing ASB/SB and the referenced CSBs. The AD therefore gives the operator a defined procedural route: follow those documents.

• No express compensation, variance or extension mechanism in the text. The Directive does not specify a right to compensation for costs, nor does it provide alternative compliance routes or extensions within its text. It does not spell out an administrative process for seeking relief from the AD’s requirements. Those matters, if available, would lie in CASA’s broader regulatory framework, but they are not in the Directive itself.

• No specified enforcement or penalty text. The AD does not itself list penalties for non-compliance or the enforcement mechanism in its wording. It establishes mandatory work and an effective date, which CASA will expect to be complied with.

Operational consequences of these duties

• Maintenance scheduling and documentation. Operators must schedule work to meet the earliest applicable compliance metric and document that work in accordance with the Boeing Accomplishment Instructions and usual maintenance-release processes.

• Parts management. The immediate prohibition on installing P/N 285U0011-205/-206 requires parts-management decisions: prevent their installation, and either modify or dispose of stock consistent with technical instructions.

• Sequencing constraints. Requirement 2 must be completed before or concurrent with Requirement 1; operators whose aeroplanes still have 205/206 must therefore plan a three-unit retrofit prior to performing the 207→208 change that addresses the autoland/autopilot disengagement risk.

In short, the Directive creates affirmative maintenance duties tightly coupled to Boeing’s ASB/SB/CSB documentation, prescribes a compliance schedule with sequencing, and immediately forbids certain parts from being fitted. The Directive does not articulate rights such as compensation or formal variance within its text.

The Directive text itself (AD/B747/326) identifies CASA as the issuer and provides an effective date (12 May 2005). It is signed by a CASA delegate (James Coyne). The AD sets mandatory technical and temporal obligations. However, the Directive as provided does not include specific penalty provisions, administrative sanction schedules, or procedural enforcement mechanisms within its text.

What the Directive states about enforcement and effect

• Effective date and mandatory nature. The Directive becomes effective on 12 May 2005. The use of the AD instrument and the imperative language (e.g. “This Directive requires replacing…”) indicates mandatory regulatory obligations as of that date. The signature by a CASA delegate identifies the issuing authority.

• Absence of explicit penalties in the text. The provided document does not specify civil penalties, criminal sanctions, or administrative fines for non-compliance. It likewise contains no articulated mechanisms for CASA to impose corrective action or enforcement steps within the AD wording itself.

Implications, constrained to the source

• Operators are placed under a clear, time-limited compliance duty by the AD text. Although the AD does not list penalties, the mandatory requirements and effective date create an enforceable regulatory obligation in practice; the Directive should be treated as binding technical regulation for the identified aeroplanes as of 12 May 2005.

• The AD cross-references FAA AD 2005-04-03 Amdt 39-13975, which serves informational or harmonisation purposes. The presence of that cross-reference shows alignment with an FAA regulatory action, but the Directive’s text does not import FAA enforcement mechanisms or penalties.

What the text does not supply

• No penalty schedule or enforcement process, no appeal or variance procedure, and no explicit guidance on how CASA will verify compliance are given in the AD text as provided. The Directive does not specify inspection regimes, reporting forms, mandatory service records to be supplied to CASA, or civil/criminal consequences for failing to comply.

Practical consequence for the reader

• Treat the Directive as a mandatory maintenance order with deadlines and sequencing constraints. Because the AD imposes explicit technical and timing obligations and is issued by CASA, operators should not ignore it on the basis that penalties are not specified in the text. The AD text does not provide the enforcement toolbox; operators and advisers who require certainty about potential sanctions or compliance verification will need to consult CASA’s broader regulatory framework or contact CASA directly for enforcement policies and administrative procedures. Those details do not appear in this Directive.

In summary, the Directive mandates specific actions with an effective date and schedules but does not include penal or enforcement detail within the text provided. The reader should note the absence of explicit penalty provisions in the AD itself while recognising the mandatory nature of the obligations.

Within the text of the Directive the primary legal and regulatory interactions are with Boeing service documentation and the referenced FAA AD. The AD establishes a technical obligation that sits in a broader regulatory and contractual environment; the Directive itself references other safety instruments and service documents but does not articulate statutory cross-references or interaction clauses with Australian aviation statutes in its text.

Documentary and regulatory cross-references in the AD

• Boeing service documents. The AD requires that the mandated replacements be accomplished in accordance with the Accomplishment Instructions of Boeing ASB 747-27A2386 (13 March 2003) for Requirement 1, and of SB 747-27-2319 (24 January 1991) for Requirement 2. The ASB explicitly refers to Boeing CSB 285U0011-27-06 (13 March 2003) as additional service information; the SB refers to CSB 285U0011-27-04 (24 January 1991) likewise. The Directive therefore integrates Boeing’s supply of technical instructions into CASA’s mandatory action: compliance with the AD is compliance with CASA, contingent on implementing the Boeing Accomplishment Instructions and CSBs.

• FAA AD reference. Note 3 in the Directive states “FAA AD 2005-04-03 Amdt 39-13975 refers.” The AD therefore aligns with or notes a parallel FAA action. The Directive itself remains a CASA instrument for domestic regulatory effect, but the FAA reference indicates that the subject matter is the same issue addressed by a foreign regulator.

Regulatory and practical interactions implied by the text

• Interface with maintenance and airworthiness regulation. Although the AD text does not recite specific Australian legislation (for example, the Civil Aviation Act or Aviation Safety Regulations) nor does it set out how this AD sits within CASA’s enforcement framework, the fact of an AD being issued implies that compliance is an airworthiness requirement for continuing to operate applicable aeroplanes in Australian territory. The Directive relies on Boeing service instructions as the technical content of those airworthiness actions.

• Parts and supply chain controls. The immediate prohibition on installing FCUs P/N 285U0011-205 or -206 as replacement parts interacts directly with spares management practices governed by airworthiness and maintenance regulations. The AD’s prohibition is a technical constraint that affects what parts can lawfully be installed post-effective date.

• Contractual and commercial interactions. The AD does not address contracts, but its requirements will interact with commercial contracts (leases, maintenance agreements, insurance, warranty arrangements). For example, the requirement to modify parts may trigger warranty claims, chargeable maintenance under lease terms, or obligations under maintenance contracts. None of those interactions are specified in the text of the AD; they are consequential.

What the AD does not state

• The Directive does not specify its relationship to Australian statute texts or provide a clause amending other statutory instruments. It contains no guidance on how to seek exemptions, nor does it set out reporting formats, penalties, or other administrative sanctions within the AD itself. It does not specify whether compliance with the FAA AD alone is sufficient for CASA compliance; instead it refers to the FAA AD for information.

Practical takeaways limited to the source

• To comply with CASA’s AD, operators must follow Boeing’s cited documents’ Accomplishment Instructions and observe the compliance timetable. The Directive’s cross-references to Boeing CSBs and the FAA AD are informational and prescriptive only to the extent they are cited as the required method of accomplishment; these documents are part of the compliance chain set by CASA in the AD text.

In short, the Directive’s interactions are documentary and procedural: it makes Boeing ASB/SB/CSB the operative technical method, notes the FAA AD for related reference, and thereby creates a compliance obligation that will sit alongside but is not explicitly cross-referenced to other Australian legislative provisions in the text provided.

The Directive’s provided text contains a limited and specific amendment history: issuance and effective dates, and no further amendments are recorded within this document.

• Issuance and effective dates. The AD is dated 31 March 2005 (signed by James Coyne, Delegate of the Civil Aviation Safety Authority) and states that it becomes effective on 12 May 2005. Those are the only temporal markers the Directive provides.

• No subsequent amendments listed in the document. The provided text does not contain any later amendment entries, revisions, superseding directives, or cancellation notices. It does not include an amendment log or history beyond the issuance and effective date.

• References to older Boeing service bulletins. The Directive incorporates prior Boeing documentation into its required actions, specifically SB 747-27-2319 dated 24 January 1991 and CSBs dated the same day in 1991 as additional information for earlier conversions. Those Boeing documents are not amendments to the AD but are referenced service literature that the AD relies on to define required actions.

• Reference to FAA AD. The Directive refers to FAA AD 2005-04-03 Amdt 39-13975. This is a cross-reference to a foreign authority’s action that is contemporaneous or relevant, but the text does not list any change history arising from reciprocal amendments.

What is absent in the AD text

• No revocation or supersession language. The AD does not state that it supersedes an earlier CASA AD, nor that it will be superseded at a later date. No expiry or review date is specified other than compliance windows for the mandated work.

• No transitional amendments or extensions recorded. The AD does not contain clauses for later extensions of compliance deadlines or administrative relief.

If one is seeking an authoritative amendment history beyond this single-document content, the Directive itself as provided only records the original issue and effective date. Any subsequent amendments, revocations, or supersessions are not present in the material given. Users requiring an up-to-date amendment history should consult CASA’s official AD registry or related communications; those materials are outside the scope of the Directive text presented here.

The provided AD text does not record any litigation, legal challenges, judicial review proceedings, or disputes connected to AD/B747/326. There are no cases cited in the document, no notices of appeals, and no reference to court activity.

What the AD explicitly contains

• No mention of legal proceedings. The Directive does not state that it is subject to litigation, nor does it identify any judicial decisions interpreting or challenging its content.

• No recorded legal outcomes. There are no administrative law challenges, stay orders, injunctions, or compliance orders referenced in the document.

Implications for the reader

• The absence of litigation references in the AD means this document, as provided, contains no recorded disputes or judicial interpretation to inform how its provisions have been applied, contested, or read by courts or tribunals. For practitioners seeking precedential developments or litigation outcomes, the Directive offers no such record.

• If legal history or case law is required for advisory purposes, that material will need to be identified outside the AD text itself, for example in court databases, CASA compliance records, or aviation-law reporting resources. Nothing in the AD text purports to summarise or reproduce any litigation.

In short, there is no litigation history in the document supplied.

The Directive’s succinct format hides a number of practical traps and sequencing pitfalls that an operator, maintenance organisation or parts manager must watch. These “gotchas” arise from part-number precision, sequencing rules, and cross-referenced service documentation.

• Misreading “replace at least one FCU” (Requirement 1) as meaning “replace any single unit anywhere.” The Directive requires replacing at least one FCU P/N 285U0011-207 with P/N 285U0011-208 in the main equipment centre, per ASB 747-27A2386. Do not assume this is optional or that a local patch suffices; the compliance timetable applies, and the action must be done in accordance with the Accomplishment Instructions. The AD’s background refers to disengagement of “all three FCUs,” so replacing just one is the specified minimum mitigation step under this AD; however Requirement 2 mandates replacement of all three in certain configuration cases.

• Sequencing requirement: Requirement 2 must be done before or concurrent with Requirement 1. If an aeroplane still has FCUs with P/N 285U0011-205 or -206, Requirement 2 requires replacing all three with P/N 285U0011-207 before or at the same time as performing the 207→208 upgrade mandated in Requirement 1. Failure to plan sequencing correctly can lead to rework or non-compliance.

• Parts prohibition effective immediately. Requirement 3 forbids installation of FCUs P/N 285U0011-205 or -206 as replacement parts on any aeroplane as of the effective date. That prohibition affects inventories and maintenance planning from 12 May 2005 onwards. Spares managers must ensure that those part numbers are quarantined, modified where appropriate per CSBs, or otherwise managed.

• Reliance on Boeing Accomplishment Instructions and CSBs. The AD mandates work “in accordance with the Accomplishment Instructions” of the specified ASB/SB; the ASB and SB direct technicians to CSBs for component-level modifications. Do not treat the AD as a recipe that can be performed absent the referenced Boeing service documents. The AD requires the Boeing documents be followed.

• Multiple compliance metrics for Requirement 1 , choose the earliest. Requirement 1’s compliance deadline is the earlier of 60 months after the effective date, 25,000 hours time in service after the effective date, or 4,000 flight cycles after the effective date. Operators must track all three metrics and act at the earliest one. Miscalculating or missing the earliest trigger is a common operational risk.

• Applicability is limited to aircraft identified in ASB 747-27A2386. Operators must check whether their aeroplane is identified in that ASB. Do not assume all 747-400 variants are affected: the AD’s applicability clause ties obligation to the ASB identification list.

• Confusion over part-number lineage. The Directive discusses three distinct part numbers: 285U0011-205, -206, -207 and 285U0011-208. The SB/CSB chains show an upgrade path (205/206 → 207 → 208). Ensure documentation for each aircraft clearly records which P/Ns are fitted, which modifications have been done, and whether any FCU has been modified under the CSB so that the P/N on the component may have changed.

• Potential downtime and scheduling effects. The AD does not state how long the required modification takes, but replacing and/or modifying FCUs can affect dispatch reliability and scheduled maintenance windows. Poor planning may cause aircraft to miss scheduled flights or require lease/lessor notification. Those operational implications are not quantified in the AD but flow from the technical work required.

• Parts availability and modification path. The ASB and SB reference CSBs as additional sources of service information for modifying FCUs. Operators must verify whether they can obtain new P/N 285U0011-208 units or must modify existing 207 units under CSB instructions. Treat assumptions about part availability with caution; the AD’s timing constraints still apply regardless of supply constraints.

• Documentation and evidence. While the AD does not itself lay out a reporting format, any maintenance action performed “in accordance with the Accomplishment Instructions” must be recorded in maintenance records. Lack of clear traceable evidence that the required action and timing were complied with is a practical compliance risk.

• International regulatory nuance. The AD refers to FAA AD 2005-04-03. Operators that fly under multiple jurisdictions should ensure they meet CASA’s AD in addition to any FAA requirements; do not assume that compliance with one regulator’s AD automatically satisfies another’s obligations unless explicitly stated in the relevant instruments.

These practical pitfalls are directly traceable to the Directive’s part-number specificity, sequencing language, compliance metrics, and cross-reference to Boeing service documents.

The Directive specifies the mandatory technical steps and compliance windows; compliance requires a clear sequence, parts verification, documentation of work per Boeing Accomplishment Instructions, and inventory controls. Below is a compliance checklist derived directly from the AD text.

1. Verify applicability

   • Confirm whether the aircraft is a Model 747-400, -400D or -400F series aeroplane and whether it is identified in Boeing Alert Service Bulletin (ASB) 747-27A2386 dated 13 March 2003. The AD applies to those aeroplanes identified in that ASB.

2. Inventory and part-number audit

   • Inspect and record the part numbers of the installed main-equipment-centre FCUs. Identify whether the aircraft has FCUs with P/N 285U0011-205, -206, -207 or already 285U0011-208.
   • Quarantine any stock of FCUs P/N 285U0011-205 or -206 so they are not installed as replacement parts after the effective date. Requirement 3 forbids installation of those parts as replacement parts as of the effective date.

3. Sequence retrofit work where applicable

   • If the aeroplane is identified in Boeing SB 747-27-2319 (24 January 1991) and currently has FCUs P/N 285U0011-205 or -206, you must replace the three FCUs with P/N 285U0011-207 in accordance with the Accomplishment Instructions of SB 747-27-2319. Requirement 2 requires this to be done before or concurrently with Requirement 1.
   • For aeroplanes not affected by SB 747-27-2319, Requirement 1 still applies if the aircraft is identified in ASB 747-27A2386.

4. Perform the 207 → 208 modification or replacement

   • Accomplish Requirement 1 by replacing at least one FCU having P/N 285U0011-207 with a new or modified FCU having P/N 285U0011-208 in accordance with the Accomplishment Instructions of ASB 747-27A2386 (13 March 2003).
   • Consult Boeing CSB 285U0011-27-06 dated 13 March 2003 as the additional referenced service information for modifying an FCU P/N 285U0011-207 to P/N 285U0011-208.

5. Schedule to the earliest compliance metric

   • For Requirement 1, schedule the replacement at the earliest of: a) Within 60 months after the effective date (effective date 12 May 2005), or b) Within 25,000 hours TIS after the effective date, or c) Within 4,000 flight cycles after the effective date.
   • If the aircraft is subject to Requirement 2, ensure the three-unit replacement required by Requirement 2 is accomplished before or at the same time as the 207→208 work.

6. Follow the Accomplishment Instructions precisely

   • Perform the work “in accordance with the Accomplishment Instructions” of the referenced ASB or SB. Those Accomplishment Instructions will include the detailed procedural steps, tests, and acceptance criteria. The ASB/SB in turn point to the CSBs for component-modification procedures; ensure the appropriate CSBs are used for component-level modification.

7. Maintain documentary evidence

   • Record completion of the mandated work in the aircraft’s maintenance records as per standard airworthiness documentation practices. The AD itself requires the Accomplishment Instructions to be followed; the resulting maintenance paperwork should provide traceable evidence that the AD’s requirements were met within the specified compliance window.

8. Manage parts inventory and procurement

   • Ensure that P/N 285U0011-205 and -206 are not installed as replacement parts from the effective date. For stock already on hand, determine whether they can be modified to an acceptable P/N under the CSB instructions or must be otherwise disposed of in line with internal policy and technical instructions.
   • Source new or modified FCUs P/N 285U0011-207 or 285U0011-208 as required, but only install parts consistent with the AD.

9. Coordinate with stakeholders

   • Coordinate scheduling with flight operations, leasing parties, and maintenance providers to manage downtime. For leased aeroplanes, coordinate with lessors to confirm which party bears the costs under contractual terms; the AD does not specify cost allocation.

10. Note related foreign ADs and harmonisation

• Be aware that FAA AD 2005-04-03 Amdt 39-13975 is referred to in the Directive. If the aeroplane operates internationally, confirm any additional foreign regulatory obligations, but treat CASA’s AD as the operative domestic requirement.

11. Verify completion and continuing compliance

• After work completion, ensure maintenance release and airworthiness certificate requirements are met. Keep records to demonstrate that the work was done according to the ASB/SB/CSB and within the compliance window specified by the AD.

Who should perform the work

• Use appropriately authorised maintenance organisations or authorised personnel competent in accordance with the Accomplishment Instructions in the Boeing documents. The AD requires adherence to those instructions, so competent execution consistent with those documents is essential.

Practical record-keeping and audit readiness

• Keep a clear audit trail linking the actual work performed to the AD’s Requirements (1-3), to the Boeing ASB/SB/CSB used, and to the date and flight-hour/cycle calculation that triggered the required action. The AD does not specify a reporting form, but operators should be prepared to show documentary proof of compliance if queried by CASA or other interested parties.

In sum, compliance consists of: confirming applicability, auditing installed FCU part numbers, sequencing and performing required replacements in accordance with Boeing’s Accomplishment Instructions and referenced CSBs, complying by the earliest applicable deadline, prohibiting installation of certain older part numbers immediately, and documenting the work in maintenance records.