AD/B747/298 Amdt 2 - Thrust Reverser System Locks

The instrument is structured around a small set of technical countermeasures aimed at preventing inadvertent in‑flight deployment of thrust reversers. The main technical concepts are:

• CDU cone brake functional test: a recurring operational test to detect discrepancies in the cone brake of the centre drive unit on each reverser. The test procedure to be used depends on whether the reverser has been modified per Boeing SB 747-78-2151 or is in original configuration. The AD prescribes which Boeing service or alert service bulletins contain the required procedures (Requirement 1; Requirement 1.a and 1.b).

• TRAS lock (electromechanical lock or brake): a retrofit or production-installed lock intended to prevent reverser deployment unless commanded on the ground and under approved conditions. The AD requires installation and activation of TRAS locks per Boeing SB 747-78-2151 (Requirement 3.a; Requirement 3.a referencing SB 747-78-2151 Revision 1 or 2).

• Third locking system bracket and fasteners: structural hardware that may be required as part of the installation package on aircraft that did not have third locking installed in production. The AD references Lockheed Martin or MRAS service bulletins for this work (Requirement 3.b(i)).

• Wiring provisions and software/CMC upgrades: the TRAS lock installation requires installation of wiring provisions (SB 747-78-2132), IDS software updates for certain integrated display units and EICAS interface units (SB 747-31-2242), and replacement/upgraded central maintenance computers and CMC software versions (SB 747-45-2016) (Requirement 3.b(ii)-(v)).

• Dispatch limitations and MMEL interaction: where a TRAS-equipped reverser is deactivated for dispatch, the operator must use the MMEL and Boeing Dispatch Deviations Guide (D6U10151) to limit operations and to meet reactivation timelines (Requirements 6 and 7; Compliance statements).

The AD also establishes a hierarchy and alternatives for compliance. It lists multiple SB and ASB revisions by date and provides alternative acceptable software versions for IDS and CMC installations, which creates explicit tolerances for different implementations of the same technical outcome (Requirement 3.b(iv)-(v)). It recognises FAA-approved AMOCs to certain FAA ADs as acceptable for equivalent AD requirements in Australia (Note 5). The AD therefore blends prescriptive technical steps with targeted delegations to operator MMELs and recognised FAA approvals.

Mechanically the AD converts service‑bulletin actions and periodic functional testing into a mandatory regulatory obligation for the specified fleet subset. It ties together component functional tests, retrofit installations and software/hardware upgrades into a single compliance framework, with time-limited windows (650 TIS, 1,000 TIS, 36 months, 90 flight hours) and immediate corrective action requirements where tests fail.

This Directive applies narrowly to Boeing Model 747-400 series aeroplanes equipped with General Electric CF6-80C2 series engines, as stated in the Applicability clause. The AD further distinguishes affected aircraft by production line number and retrofit status. Model 747-400 aircraft line numbers 1061 and subsequent, equipped with CF6-80C2 engines, had a third locking system installed during production in accordance with PRR 80452-102, and those aircraft were not modified in accordance with Boeing SB 747-78-2151 (Note 1). In contrast, line numbers 700 through 1060 inclusive were the intended population for the SB 747-78-2151 retrofit (Note 1 and Note 2). This creates a cohorting effect where operators must first determine whether an aeroplane is in the factory‑fitted group or the retrofit group to identify the applicable test intervals and retrofit obligations (Requirement 1; Note 1).

Who pays: the immediate cost bearers are the operators and owners of the affected aeroplanes. They must perform recurring CDU cone brake functional tests at the specified intervals (650 or 1,000 hours TIS), carry out mandated repairs per the listed ASBs and SBs where tests fail, and where applicable install TRAS locks and associated hardware, wiring, software and CMC replacements. The AD requires certain retrofit installations within defined timeframes (for example, Requirement 3.a required installation within 36 months after the effective date of the original issue of the Directive). The AD does not allocate funding or subsidies. The only explicitly referenced other decision-makers are the aircraft manufacturer (Boeing), component vendors (Lockheed Martin, MRAS), and the FAA in its role approving AMOCs. CASA, through its delegate (Mike Higgins) issues the AD and determines its mandatory nature.

Who decides operational choices: operators decide whether to repair a failed functional test immediately or dispatch the aircraft under MMEL limitations, provided that no more than one thrust reverser is inoperative (Requirement 2.b). The AD requires adherence to the operator’s approved MMEL and to the Boeing Dispatch Deviations Guide D6U10151 for temporary deactivations (Requirements 6 and 7). Those operational choices will be subject to the operator’s safety management system, their maintenance organisation’s capabilities, and any oversight or acceptance by CASA.

Suppliers and maintenance organisations are affected if they are required to execute the SB/ASB work. The AD specifies acceptable SB and ASB revisions and software/CMC part numbers, which constrains which vendors and parts are deployable for compliance (Requirement 3.b, Requirement 3.b(iv-v)). The AD also recognises FAA AMOCs for certain FAA ADs as acceptable alternatives, which means operators interacting with the FAA compliance process may rely on those FAA approvals where applicable (Note 5).

The scope is deliberately narrow in aircraft type and engine model. Airlines or operators who do not operate Boeing 747-400s with CF6-80C2 engines are not affected. The AD also does not list penalties, criminal or civil sanctions, within the text; enforcement mechanisms are not described in the document itself.

Duties imposed by the AD are specific and immediate. The primary duties are:

• Perform CDU cone brake functional tests: Operators must perform the functional test on each thrust reverser’s CDU cone brake per the service bulletin procedures referenced in Requirement 1. The exact procedure depends on whether the thrust reversers were modified per Boeing SB 747-78-2151. For unmodified reversers, compliance may be through Boeing SB 747-78A2166 Revision 1, ASB 747-78A2166 Revision 2 paragraph 3.C, or the applicable section of Boeing SB 747-78A2113 Revision 2 or 3 (Requirement 1.a). For reversers modified per SB 747-78-2151, the test must be done per paragraph 3.C of ASB 747-78A2166 Revision 2 (Requirement 1.b).

• Repair or accept restricted dispatch: If a functional test cannot be successfully performed, or a discrepancy is detected, operators must either repair the CDU cone brake per Boeing ASB 747-78A2166 Revision 2 or Boeing SB 747-78A2113 Revision 2 or 3, or they may operate the aeroplane under the limitations of the operator’s approved MMEL provided no more than one thrust reverser is inoperative (Requirement 2; Compliance: For Requirement 2 - Before further flight after the Requirement 1 functional test).

• Install TRAS locks and associated modifications where applicable: For aircraft listed in SB 747-78-2151 Revision 2, operators must install and activate a TRAS lock on each thrust reverser per SB 747-78-2151 (Requirement 3.a). If the aircraft has not previously had the third locking system fitted, operators must also install a bracket and hardware per Lockheed Martin SB 78-1007 or MRAS SB 78-1007, install wiring provisions per Boeing SB 747-78-2132, install the TRAS lock and flexible drive cable per the Lockheed Martin or MRAS SB 78-1020 revisions, and upgrade IDS software and CMC hardware/software as specified (Requirement 3.b(i-v)).

• Functional test of TRAS locks: Where TRAS locks are installed, operators must carry out a functional test per ASB 747-78A2166 Revision 2 within 1,000 hours TIS after installation or within 90 flight hours after the effective date of the Directive, whichever is later, and repeat at intervals not exceeding 1,000 hours TIS (Requirement 4; Compliance: For Requirement 4).

• Repair unsuccessful TRAS lock tests before further flight: If the Requirement 4 functional test cannot be successfully performed, repair per ASB 747-78A2166 Revision 2 and repeat until successful (Requirement 5; Compliance: For Requirement 5 - Before further flight).

• Follow MMEL and Dispatch Deviations Guide for temporary installations: Where a TRAS-equipped or non-TRAS reverser must be installed temporarily, operators are permitted to dispatch under the 747-400 MMEL and follow the dispatch deviations guide for deactivation and reactivation timing (Requirements 6 and 7; Compliance: For Requirements 6 and 7).

Rights and procedural flexibilities embedded in the AD:

• Use of FAA-approved AMOCs: The AD accepts later revisions of the service bulletins contained within the AD that are approved by the FAA as an Alternate Method of Compliance to FAA AD 2003-16-16 as acceptable for compliance with the equivalent requirements of this AD. That gives operators a channel to use FAA AMOCs rather than seeking a separate CASA AMOC for those specific SB revisions (Note 5).

• Alternative software/part versions accepted: The AD explicitly lists multiple acceptable IDS software versions and CMC software versions and allows certain software alternatives where specified in the service bulletins (Requirement 3.b(iv-v)). This provides operators with constrained choice over particular software versions, reducing the risk of requiring a single OPERATOR-specific software revision.

• Terminating action: The AD states that accomplishing the functional test of the CDU cone brake per Requirement 1 constitutes terminating action for the repetitive tests required by AD/B747/277 Amdt 2 Requirement 2 (Note 3). This is a narrow right to relieve operators from a previously existing repetitive obligation, subject to meeting the new AD’s test.

What the AD does not specify as a right or process: the AD text does not detail an explicit process for CASA variances, penalties, or appeals. It also does not list any grant of funding or reimbursement for retrofit costs. Operators retain the established rights under their MMEL to dispatch with certain inoperative equipment, but must stick to the AD’s limitations.

The AD text itself does not set out monetary penalties, criminal sanctions, inspection regimes, or administrative fine schedules. The Directive is issued by CASA and signed by a CASA delegate (Mike Higgins), and it states the effective date of the Amendment (14 May 2014). The document imposes mandatory compliance duties by specifying actions, deadlines and conditions for dispatch. It does not, however, detail enforcement mechanisms, civil penalty provisions, or the process for CASA audits or enforcement actions within the text of the AD.

Operationally, the AD sets immediate technical obligations with "before further flight" requirements for failed functional tests (Requirement 2 and Requirement 5; Compliance: For Requirement 2 - Before further flight after the Requirement 1 functional test; Compliance: For Requirement 5 - Before further flight). This creates practical enforcement pressure because safety-critical components that fail tests must be repaired prior to further flight absent MMEL-authorised dispatch limitations. The AD also defines specific compliance intervals (650 TIS, 1,000 TIS, 36 months, 90 flight hours) which are administrative triggers that maintenance programmes and continuing airworthiness records must reflect.

Because the AD does not include procedural enforcement language, readers should note that CASA’s broader regulatory powers under aviation safety legislation govern enforcement and penalties for failing to comply with Airworthiness Directives. Such powers are not laid out in the text of this AD and therefore are not described here. The AD does reference FAA ADs for cross-acceptance purposes and indicates that FAA-approved AMOCs are acceptable for certain service bulletin revisions (Note 5), which may affect the practical compliance pathway and therefore the enforcement posture if operators rely on an FAA AMOC.

If a functional test fails, the AD instructs repair per the specified Boeing ASB/SB or temporary dispatch under MMEL limitations. That sequencing , test, repair or MMEL dispatch limitation , is an operational enforcement mechanism built into the AD’s requirements, because an operator may not lawfully continue normal operations with an unrectified failed test outside of MMEL allowances.

The AD explicitly interacts with other airworthiness directives, service bulletins and operator-approved documents. The AD superseded AD/B747/231 Amdt 1 (Background), and it states that the original issue of this Directive continued the repetitive inspection requirements of AD/B747/231 Amdt 1 but added TRAS lock installations and additional tests. It also states that accomplishing the functional test required by Requirement 1 constitutes terminating action for the repetitive tests of the CDU cone brake required by AD/B747/277 Amdt 2 Requirement 2 (which corresponds to paragraph (b)(1) of FAA AD 94-15-05) (Note 3). This creates an explicit regulatory linkage ensuring the Australian AD and prior Australian/FAA ADs are coordinated with respect to repetitive test obligations.

The AD references FAA AD 2003-16-16 and accepts FAA-approved AMOCs for later revisions of service bulletins contained within this AD as acceptable for compliance with the equivalent requirements of this AD (Note 5). That cross-acceptance creates an interaction with FAA regulatory practice and allows operators to rely on FAA AMOCs rather than seeking a new CASA AMOC for the specified SB revisions. The AD does not, however, state that all FAA approvals are automatically accepted; the acceptance is limited to later service bulletin revisions that are approved by the FAA as AMOCs to FAA AD 2003-16-16.

At an operational level the AD interacts with the operator’s MMEL and the Boeing 747-400 Dispatch Deviations Guide (D6U10151). Requirements 2, 6 and 7 explicitly allow temporary dispatch under a limited MMEL basis when repairs are not yet completed or when installing a component with or without a TRAS lock; in each case operators must follow the MMEL conditions and the Dispatch Deviations Guide for deactivation and reactivation time constraints (Requirement 2.b; Requirements 6 and 7; Compliance statements). That embeds the AD within the existing operational regulatory framework governing dispatch with defective equipment.

The AD also interacts with manufacturer-issued service and alert service bulletins. It makes compliance contingent upon performing work per specified Boeing SBs, Lockheed Martin SBs, Middle River Aircraft Systems SBs, and their particular revisions and dates (Requirement 1; Requirement 3.b(i-v)). It expressly lists acceptable software and CMC software revisions where the service bulletins allow alternatives (Requirement 3.b(iv-v)). This makes the AD an instrument for mandating certain SB-based corrective and retrofit actions, which in turn creates contractual and procurement interactions among operators, maintenance providers and OEMs or OEM-approved suppliers.

The AD does not reference or modify other civil laws or criminal statutes in Australia, nor does it contain language about judicial review, appeal or administrative challenge. It also does not specify how CASA will coordinate enforcement with other agencies. All such broader legal interactions are not covered within the text of this AD.

The AD contains its own amendment history within the text and background. Key dates and changes set out in the document are:

• Original issue of the Directive became effective on 22 January 2004. The original AD superseded AD/B747/231 Amdt 1, which was cancelled. The background states the original issue continued the repetitive inspection requirements of AD/B747/231 Amdt 1 and added TRAS lock installations and related modifications, plus additional repetitive functional testing and dispatch limitations (Background).

• Amendment 1 corrected editorial errors and an omission in the compliance statement of the original Directive (Background). The text does not provide the date Amendment 1 became effective within the excerpt provided, but it notes Amendment 1 was limited to editorial corrections and a compliance omission correction.

• Amendment 2 (this document), which becomes effective on 14 May 2014, notates the acceptability of an FAA-approved AMOC to FAA AD 2003-16-16 for the later revisions of service bulletins contained within this AD (Background; Note 5). This Amendment 2 is signed by Mike Higgins, CASA delegate, with the date 13 May 2014 on the signature block and the effective date noted as 14 May 2014 in the Compliance section.

The AD also references numerous service bulletin revision dates which are part of its substantive technical amendment history. Examples include Boeing SB 747-78-2151 original issue, Revision 1 and Revision 2 (Note 2), Boeing ASB 747-78A2166 Revision 2 dated 15 March 2001 (Requirement 1.a; Requirement 4), Boeing SB 747-78-2132 Revision 2 dated 11 December 1997 (Requirement 3.b(ii)), Boeing SB 747-31-2242 dated 18 April 1996 and acceptable IDS software versions (Requirement 3.b(iv)), and Boeing SB 747-45-2016 Revision 1 dated 2 May 1996 with acceptable CMC software versions (Requirement 3.b(v)). Lockheed Martin SBs and MRAS SBs and their revision dates are also listed for bracket and TRAS lock installations (Requirement 3.b(i) and (iii)).

One compliance timing clause references the "effective date of the original issue of this Directive" for Requirement 3.a, with the original issue effective date specified as 22 January 2004. The AD therefore contains provisions whose compliance windows are anchored to the original 2004 effective date, even though Amendment 2 of the AD is effective in 2014.

The Amendment 2 text also includes Editorial notes and cross-references to FAA ADs (Note 4) and specifically allows FAA AMOCs for certain SB revisions to be used. The AD’s amendment history therefore shows a progression from repetitive inspection requirements to mandated retrofits, software and hardware upgrades, and finally to limited cross-acceptance of FAA AMOCs in the 2014 amendment.

The AD text does not include any litigation history, judicial decisions, or references to court proceedings. It names only administrative acts: the original Directive, Amendment 1, and Amendment 2, and cross-references to FAA ADs. There are no cases, orders, or appeals mentioned in the document.

Because the source provided is the AD itself and its background notes, and it contains no mention of judicial review, enforcement proceedings, or contested decisions, this deep dive cannot cite any litigation history. If users require a record of legal challenges or judicial determinations concerning this AD, that information would need to be obtained from case law databases, CASA enforcement records, or court registries outside the text of the AD. The AD itself provides no adjudicative or litigation narrative.

There are several detailed technical and administrative traps that arise from the precise wording and cross-references within the AD. These are factual, text-based pitfalls to watch for:

• Narrow applicability: The AD applies only to Boeing 747-400 series aircraft powered by GE CF6-80C2 engines. Operators of other engine types or 747 variants are not in scope. A misidentification of engine model or production line number could lead an operator to either unnecessary compliance costs or inadvertent non‑compliance (Applicability clause).

• Line-number nuance: Note 1 states that Model 747-400 series aeroplanes line numbers 1061 and subsequent had a third locking system installed during production and were not modified per Boeing SB 747-78-2151. By contrast, SB 747-78-2151 targets line numbers 700 through 1060 inclusive. Operators must verify aircraft serial/line numbers and production configuration before selecting test procedures, retrofit requirements, and compliance intervals (Requirement 1; Note 1). Misclassification could result in applying the wrong test interval (650 TIS versus 1,000 TIS).

• Multiple service bulletin references and acceptable alternatives: The AD lists several SBs and ASBs and allowed alternate revisions or software/part versions for compliance (Requirement 1; Requirement 3.b(iv-v)). Careful reading is required to use the correct document revision for the specific action. For instance, Requirement 1.a allows compliance via Boeing SB 747-78A2166 Revision 1 dated 9 October 1997, ASB 747-78A2166 Revision 2 dated 15 March 2001, or Boeing SB 747-78A2113 Revision 2 or Revision 3. Operators must track which revision was used for each accomplishment action.

• Anchor to original effective date: Requirement 3.a requires installation of TRAS locks "within 36 months after the effective date of the original issue of this Directive." The AD states the original issue became effective on 22 January 2004. That makes the 36-month window nominally to 22 January 2007. Amendment 2 is effective 14 May 2014. Operators must carefully reconcile which compliance windows remain open and whether the action was already required to be complete many years earlier (Requirement 3.a; Background; Compliance statements).

• Termination and cross-references: The AD declares that accomplishing the functional CDU cone brake test per Requirement 1 "constitutes terminating action" for the repetitive tests required by AD/B747/277 Amdt 2 Requirement 2 (Note 3). Operators must maintain records demonstrating that the new Requirement 1 test was completed and compliant with the specified SB, because it relieves them of other repetitive obligations only if correctly performed.

• Dispatch and MMEL interplay: The AD allows dispatch under MMEL limitations where a test fails or when a TRAS‑equipped or non‑TRAS reverser is installed temporarily (Requirement 2.b; Requirements 6 and 7). However the AD also constrains the condition: no more than one thrust reverser may be inoperative. Operators need to ensure their MMEL authorisations and the Boeing Dispatch Deviations Guide D6U10151 are consulted and that reactivation timeframes are met, otherwise an operator could inadvertently dispatch outside the AD’s allowances.

• Ambiguity about enforcement: The AD does not state penalties or enforcement procedures. That absence may create uncertainty for operational decision-makers about prioritisation and overdue compliance remedy. It does, however, include "before further flight" requirements for certain repairs which create immediate operational constraints (Requirement 2; Requirement 5).

• AMOC and FAA reliance: Note 5 states that later revisions of Service Bulletins contained within this AD that are approved by the FAA as an AMOC to FAA AD 2003-16-16 are acceptable for compliance with the equivalent requirements of this AD. This produces a reliance pathway on FAA approvals but only for specific SB revisions and only insofar as the FAA approves them as AMOCs. Operators relying on FAA AMOCs should ensure documentation of FAA approval is available and that the approved AMOC specifically references the SB revision in question.

• Software/CMC version substitution: The AD allows multiple IDS software and CMC software versions as acceptable alternatives (Requirement 3.b(iv-v)). Operators should document exactly which software version was installed to ensure traceability. Using a non‑listed version without FAA/CASA acceptance could create compliance issues.

• Recordkeeping and evidence: The AD places mandatory technical duties without describing the administrative evidence required. Operators should maintain records showing which SB revision was used, the date of functional tests, TIS since last test, and any MMEL dispatch approvals relied upon. The AD itself does not list the records required, but the presence of terminating actions and cross-references to other ADs makes record evidence essential.

The AD sets out a concrete sequence of compliance tasks. The following steps are a direct reading of the AD’s requirements and compliance times:

1. Determine applicability:

   • Confirm whether each aeroplane is a Boeing Model 747-400 series equipped with GE CF6-80C2 engines (Applicability).
   • Confirm the aircraft production line number and whether a third locking system was installed in production (Note 1). Identify whether the aircraft has been modified per Boeing SB 747-78-2151 or is still in the unmodified configuration (Requirement 1; Note 1 and Note 2).

2. Plan and perform CDU cone brake functional tests:

   • For unmodified thrust reversers (not modified per SB 747-78-2151), perform the CDU cone brake functional test per Boeing SB 747-78A2166 Revision 1 dated 9 October 1997; or paragraph 3.C of ASB 747-78A2166 Revision 2 dated 15 March 2001; or the applicable section of Boeing SB 747-78A2113 Revision 2 dated 8 June 1995 or Revision 3 dated 11 September 1997 (Requirement 1.a).
   • For reversers modified per SB 747-78-2151, perform the test per paragraph 3.C of ASB 747-78A2166 Revision 2 (Requirement 1.b).
   • Schedule and document the initial and recurring intervals: 650 hours TIS intervals for Requirement 1.a aircraft; 1,000 hours TIS intervals for Requirement 1.b aircraft (Compliance: For Requirement 1.a and 1.b).

3. Address unsuccessful tests or discrepancies:

   • If a functional test cannot be successfully performed or discrepancy detected, repair the CDU cone brake per Boeing ASB 747-78A2166 Revision 2 or Boeing SB 747-78A2113 Revision 2 or 3 (Requirement 2.a).
   • Alternatively, if repair will not be completed before the next flight, operate under the operator’s approved MMEL subject to the limitation that no more than one thrust reverser is inoperative (Requirement 2.b). Ensure MMEL and dispatch deviations guide conditions are strictly followed (Compliance: For Requirement 2).

4. For aircraft listed in SB 747-78-2151 Revision 2, carry out TRAS lock installations and associated work:

   • Install and activate a TRAS lock on each thrust reverser per Boeing SB 747-78-2151 Revision 1 or Revision 2 as specified (Requirement 3.a).
   • If not previously accomplished, install bracket/fasteners for the third locking system per Lockheed Martin SB 78-1007 Revision 1 or MRAS SB 78-1007 Revision 2 (Requirement 3.b(i)).
   • Install wiring provisions per Boeing SB 747-78-2132 Revision 2 (Requirement 3.b(ii)).
   • Install TRAS lock and flexible drive cable per Lockheed Martin SB 78-1020 Revision 2 or MRAS SB 78-1020 Revision 3 or MRAS CF6-80C2B SB 78-1020 Revision 4 as applicable (Requirement 3.b(iii)).
   • Upgrade IDS software in the specified integrated display units and EICAS interface units per Boeing SB 747-31-2242 or acceptable listed IDS software versions (Requirement 3.b(iv)). Record which acceptable version was used.
   • Replace CMCs part number 622-8592-103 with part number 622-8592-105 and install new CMC software per Boeing SB 747-45-2016 Revision 1 or the acceptable software versions listed (Requirement 3.b(v)). Record part numbers and software versions.

5. Functional test of TRAS locks and repairs:

   • After TRAS lock installation, carry out the TRAS lock functional test per the Accomplishment Instructions of ASB 747-78A2166 Revision 2 within 1,000 hours TIS after installation or within 90 flight hours after the effective date of the Directive, whichever is later (Requirement 4; Compliance: For Requirement 4).
   • If the test cannot be successfully performed, repair per ASB 747-78A2166 Revision 2 and repeat the test until successful before further flight (Requirement 5; Compliance: For Requirement 5).

6. Manage temporary installations and dispatch limitations:

   • If it becomes necessary to install a thrust reverser with the TRAS lock installed prior to accomplishing SB 747-78-2151 on the airframe, dispatch is permitted per the 747-400 MMEL provided that the TRAS-equipped reverser is deactivated per Boeing D6U10151 and reactivation occurs within MMEL time constraints (Requirement 6).
   • If it becomes necessary after SB 747-78-2151 has been accomplished to install a thrust reverser without the TRAS lock, dispatch is permitted under MMEL conditions provided the non-TRAS reverser is deactivated per D6U10151 and reactivation occurs within MMEL time constraints (Requirement 7).
   • Ensure MMEL entries and any operational deviations are documented.

7. Recordkeeping and evidence:

   • Maintain records of all functional tests, repairs, SB/ASB accomplishment work, software/CMC part numbers and versions, and MMEL dispatch approvals. Keep documentation of any FAA AMOC approvals used to justify alternate SB revisions (Note 5).

8. Use FAA AMOCs where appropriate:

   • Where a later revision of a service bulletin listed in this AD has been approved by the FAA as an AMOC to FAA AD 2003-16-16, that FAA AMOC is considered acceptable for compliance with the equivalent requirements of this AD (Note 5). Retain evidence of the FAA approval in the maintenance records.

9. Confirm terminating action where relevant:

   • If relying on the terminating action that Requirement 1 satisfies repetitive tests from AD/B747/277 Amdt 2 Requirement 2, keep demonstrable records that the test was performed per the specified SB to establish termination of the prior requirement (Note 3).

10. Verify timelines and historical compliance:

• Check whether Requirement 3.a compliance window anchored to the original effective date of 22 January 2004 was met previously on each aeroplane. The AD text explicitly links certain compliance times to historical effective dates and may therefore represent obligations that were required years prior to this Amendment 2 coming into effect. Operators should reconcile historical maintenance records against these timelines (Requirement 3.a; Background; Compliance).

Following these steps will satisfy the letter of the AD. Operators should ensure their maintenance organisations have access to the exact SB/ASB revisions cited, retain proof of compliance and liaise with the FAA where AMOCs are to be used. The AD provides alternative acceptable software versions and AMOC pathways; document choices to demonstrate compliance with the specific clauses cited in the Directive.