AD/CFM56/28 - Low Pressure Turbine Rear Frame

The AD deploys a small set of technical and regulatory instruments to achieve its objective: lifecycle limits, mandatory inspections, incorporation of Engine Shop Manual Temporary Revisions into approved maintenance programmes, and repair/replacement where life history is uncertain. Each concept is anchored in the AD text.

1. LCF life limits. The AD requires the operator's approved maintenance programme to "incorporate the new LCF life limits" for a defined set of LPT rear frame part numbers, "in accordance with the CFM56-7B ESM chapter 05 Temporary Revision (TR) 05-0097, 05-0098, and 05-0099, as applicable." The concept is that the ESM Temporary Revisions prescribe low cycle fatigue life limits that components must not exceed; the AD makes those limits mandatory in the operator's maintenance documentation.

2. Approved operator maintenance programme. The regulatory instrument targeted is the "approved operator maintenance programme." The AD commands an amendment to that programme, not a recommendation. By directing a change to a programme that is itself subject to prior approval, the AD operates through the operator’s documented and sanctioned maintenance regime.

3. Engine Shop Manual Temporary Revisions and subsequent incorporation. The AD identifies specific ESM TRs and ties their incorporation into later formal ESM revisions ("following Revision 38 that incorporate these Temporary Revisions") as an acceptable means to implement the life limits. The mechanism is therefore: ESM TRs specify the technical limit; either the TRs themselves or their later incorporation into an ESM revision are the acceptable technical baselines.

4. Traceability of cycles, and the remedy when traceability fails. The AD hinges on whether "the number of total cycles accumulated by a LPT rear frame ... can be positively established." Note 2 defines the "number of total cycles" as "the sum of the number of cycles accumulated before and after compliance with CFM56-7B S/B 72-0527." Where positive establishment is not possible, the operator must either remove and replace the LPT rear frame or perform inspections per one of two specified Service Bulletins (S/B 72-0558 rev2 or S/B 72-0579 rev4). The mechanism is therefore a binary compliance path driven by record availability.

5. Acceptable later revisions. The AD explicitly states that "The use of later approved revisions of the Service Bulletins is acceptable for compliance with the requirements of this AD." That creates operational flexibility as long as the later revisions are "approved" in the sense used in the AD (the AD does not itself define the approval process).

6. Time-bound compliance. The AD imposes clear timing: Requirement 1 within 30 days of effectiveness; Requirement 2 within 300 cycles of effectiveness. The dual timing logic recognises that programme amendments are a short-term administrative act, whereas the physical inspection or replacement regime may be phased in as cycles accrue.

7. Relationship to prior modification activity. The listed LPT rear frames were "introduced by the CFM56-7B Service Bulletin S/B 72-0527 revision 02 issued 21 January 2008" and were "obtained by modifying (reworking) older P/N LPT frames." The AD recognises that modification history matters, and Note 2 treats cycles accumulated both before and after that rework as relevant to total cycles for the life-limit calculation.

8. Reference to external regulatory action. The AD notes that "EASA AD 2009-0009 dated 15 January 2009 refers." This signals that the AD is not an isolated technical instruction but sits alongside or follows comparable regulatory action from the European Aviation Safety Agency. The AD does not incorporate the EASA AD text, it merely references it.

These main concepts specify how technical lifecycle risk (LCF) is converted into regulatory obligations: amend the operator’s approved maintenance documentation to include ESM-derived life limits, and where historical traceability of cycles fails, apply inspection or replacement requirements per specified Service Bulletins, with explicit timing and acceptance of later approved revisions.

The AD explicitly names "CFM International CFM56-7B turbofan engines equipped with a low pressure turbine (LPT) rear frame part number" followed by twelve part numbers (340-166-254-0, 340-166-255-0, 340-166-256-0, 340-166-257-0, 340-166-258-0, 340-166-259-0, 340-177-551-0, 340-177-552-0, 340-177-553-0, 340-177-554-0, 340-177-555-0, 340-177-556-0). The Applicability clause therefore identifies affected engines by model and by component part number. The AD further notes these engines are "known to be installed on, but not limited to, Boeing 737-series aeroplanes." The AD therefore affects any operator in Australia holding or operating an affected engine configuration, regardless of airframe, provided the listed LPT rear frames are present.

Primary parties affected, as derived from the AD text, are:

• Operators holding "approved operator maintenance programmes" for aircraft with CFM56-7B engines that contain any of the listed LPT rear frame P/Ns. The core obligation is to "Amend the approved operator maintenance programme" to incorporate the life limits in the specified ESM Temporary Revisions.

• Maintenance organisations and engineers who implement maintenance programme changes and carry out inspections or removals, because the AD requires specific inspections "in accordance with CFM56-7B Service Bulletin S/B 72-0558 revision 2, or ... S/B 72-0579 revision 4" when cycle history cannot be positively established. Those workscopes fall to whoever performs the maintenance under the operator’s programme.

• Asset holders or record-keepers responsible for engine/component life tracking. The AD draws a compliance distinction based on whether "the number of total cycles accumulated by a LPT rear frame ... can be positively established." That places a compliance burden on whoever maintains life-limited parts records (operators, maintenance control, possibly lessors or continuing airworthiness managers).

• CFM International as the author of the Engine Shop Manual Temporary Revisions and Service Bulletins named in the AD, insofar as compliance will proceed to the technical material they supply. The AD makes specific reference to ESM TRs and S/B numbers; later approved revisions of the Service Bulletins are accepted for compliance, indicating CFM's ongoing S/B revision path will be operationally relevant.

• Regulatory authority personnel responsible for oversight of operator maintenance programme approvals. The AD requires amendment of "approved operator maintenance programme[s]," implying the approved programmeholder must submit changes to the approving authority for acceptance under whatever approval process governs those programmes. The AD text itself does not detail the approval mechanism, but the document targets approved programmes as the locus of action.

Indirectly affected parties include parts suppliers and logistics providers: the AD permits "remove and replace" as an option where cycles cannot be positively established, which will generate demand for replacement LPT rear frames and associated procurement activity. The AD does not state supply arrangements, lead times, or parts availability.

Finally, the AD references EASA AD 2009-0009 and Engine Shop Manual documents and Service Bulletins. Organisations who track ADs for continued airworthiness (airworthiness engineers, technical records teams, compliance units) will need to integrate this AD into their monitoring and compliance frameworks.

The AD does not explicitly identify any other groups (for example, passengers, insurers or leasing companies); any cost or insurance implications are not stated in the text. The AD also does not identify exemptions or carve-outs; the obligations attach to the operator maintenance programme for affected engines as specified.

The AD sets out precise duties and a small number of procedural flexibilities that can be read as rights. Every operative clause in the AD is enforceable as a duty to the extent the AD is an enforceable instrument; the AD text itself identifies the operative duties and explicit acceptances.

Duties

1. Amend the approved operator maintenance programme (Requirement 1). Operators must amend their approved maintenance programmes to "incorporate the new LCF life limits for LPT rear frame" for the enumerated part numbers "in accordance with the CFM56-7B ESM chapter 05 Temporary Revision (TR) 05-0097, 05-0098, and 05-0099, as applicable or subsequent revisions of the Engine Shop Manual following Revision 38 that incorporate these Temporary Revisions." This is an affirmative duty with a 30-day compliance window measured from the AD's effective date.

2. Where cycles cannot be positively established (Requirement 2). If the "number of total cycles accumulated by a LPT rear frame" of any listed P/N "cannot be positively established," the operator must either: a. Remove and replace the LPT rear frame; or b. Perform inspections "in accordance with CFM56-7B Service Bulletin S/B 72-0558 revision 2, or CFM56-7B Service Bulletin S/B 72-0579 revision 4, as applicable."

   Requirement 2 has a 300-cycle compliance window measured from the AD's effective date.

3. Recordkeeping and life calculation (implicit). While the AD does not lay out a specific recordkeeping form, Note 2 and the structure of the obligations make it clear that operators must be able to "positively establish" the "number of total cycles" for each listed LPT rear frame; Note 2 defines "number of total cycles" as "the sum of the number of cycles accumulated before and after compliance with CFM56-7B S/B 72-0527." That creates a duty to determine and document cycles across modification events.

4. Use of specified technical material. Where inspections are used as the compliance path, they must be performed "in accordance with" the specified Service Bulletins (S/B 72-0558 rev2 or S/B 72-0579 rev4) unless later approved revisions are used. This is a duty to follow the named technical guidance unless and until a later approved revision is adopted.

Rights or operative flexibilities

1. Use of later approved revisions. The AD expressly states "The use of later approved revisions of the Service Bulletins is acceptable for compliance with the requirements of this AD." That is a procedural right to adopt later approved S/B revisions instead of the specific revision numbers named in the AD.

2. Incorporation via later ESM revision. Requirement 1 allows the new LCF life limits to be incorporated "in accordance with the ... Temporary Revision ... or subsequent revisions of the Engine Shop Manual following Revision 38 that incorporate these Temporary Revisions." This provides an option to implement the life limits either by direct reliance on the Temporary Revisions or by waiting for their formal incorporation into an ESM revision after Revision 38, so long as the later ESM revision incorporates those TRs.

3. Two alternative compliance paths for unestablished cycles. Where history is uncertain, the operator has a choice: remove and replace the LPT rear frame, or perform the specified inspections. That choice permits consideration of operational, cost and logistical factors in selecting the most appropriate path.

Other procedural points

• The AD does not define the process by which later revisions of Service Bulletins or Engine Shop Manual updates become "approved" for the purpose of compliance; the AD simply states acceptance of later approved revisions. Therefore, operators will need to rely on the approval paths available in their regulatory/maintenance framework to confirm whether a later revision is acceptable.

• Timing obligations are unambiguous: Requirement 1 must be met within 30 days, Requirement 2 within 300 cycles. The AD does not include staged extensions or conditional waivers in the text.

• The AD does not include any express exemptions, transitional licences, grandfathering beyond the specific provisions, or alternate method of compliance (AMOC) language within the text. The AD does not itself establish an AMOC process; it only accepts later approved revisions of the named Service Bulletins.

Grounding all these duties and flexibilities in the AD text ensures that the operator’s immediate actions are to update the approved maintenance programme within 30 days, verify cycle history for each listed P/N, and, where cycles cannot be positively established, either replace the component or carry out inspections per the named Service Bulletins within 300 cycles of the AD becoming effective.

The text of the AD does not set out specific penalties, sanctions, or the enforcement processes that will be applied for non-compliance. The document states the effective date ("This Airworthiness Directive becomes effective on 28 January 2009") and is signed by a Delegate of the Civil Aviation Safety Authority, but there are no express penalty clauses or enforcement procedures included in the AD as published.

Consequently, the AD itself operates as a mandatory instrument that imposes operational duties (amendment of the approved operator maintenance programme and inspection/replacement requirements for certain LPT rear frames), but it leaves unspecified within its text the administrative or legal consequences for failing to comply. The AD includes an explicit reference to relevant technical material and prescribes compliance windows. That structure implies that compliance is required, but the AD does not enumerate how non-compliance will be detected, reported, or sanctioned within the text itself.

Operators and maintenance organisations should therefore treat the AD’s obligations as mandatory technical requirements. The AD’s signature by a CASA delegate and the stated effective date indicate the directive’s formal regulatory status; nonetheless, the AD text provides no procedural detail about enforcement actions, penalties, or civil aviation sanctioning. It similarly does not identify any administrative review mechanism, appeal process, or formal provision for alternative compliance methods within the AD document itself.

Because the AD references external technical documents (Engine Shop Manual Temporary Revisions and specific Service Bulletins), compliance with the AD necessarily involves following those technical prescriptions within the timeframes given. The AD does state that "The use of later approved revisions of the Service Bulletins is acceptable for compliance with the requirements of this AD," which suggests a degree of formal approval for alternative technical versions when such approval exists. That acceptance is procedural, not punitive: it is a permitted pathway rather than a penalty regime.

In short, the AD contains mandatory technical requirements and explicit compliance windows, but does not itself specify enforcement mechanisms or penalties in the text provided. Any question about penalties, enforcement processes, or administrative remedies is therefore outside the AD’s explicit content and would require reference to other regulatory instruments or the administering authority’s enforcement policies, none of which are included in the AD text supplied here.

The AD explicitly cross‑references and depends upon particular technical documents and another regulator’s AD; those are the only interactions identified in the AD text.

1. Engine Shop Manual (ESM) Temporary Revisions. The AD requires incorporation of LCF life limits "in accordance with the CFM56-7B ESM chapter 05 Temporary Revision (TR) 05-0097, 05-0098, and 05-0099, as applicable or subsequent revisions of the Engine Shop Manual following Revision 38 that incorporate these Temporary Revisions." The AD therefore interacts directly with the ESM TRs as authoritative technical material. The mechanism is prescriptive: the operator’s maintenance programme must adopt the ESM-specified life limits.

2. Service Bulletins. Where cycle history cannot be positively established, the mandated inspections must be performed "in accordance with CFM56-7B Service Bulletin S/B 72-0558 revision 2, or CFM56-7B Service Bulletin S/B 72-0579 revision 4, as applicable." The AD also permits the use of "later approved revisions of the Service Bulletins" for compliance. Thus, the AD interacts with the Service Bulletin regime by elevating certain revisions of S/Bs to mandatory compliance documents where traceability is absent.

3. Prior Service Bulletin that created the P/Ns. The AD recounts that the listed LPT rear frames were "introduced by the CFM56-7B Service Bulletin S/B 72-0527 revision 02 issued 21 January 2008" and that they are "obtained by modifying (reworking) older P/N LPT frames." Note 2 clarifies that the "number of total cycles accumulated of the LPT rear frame is the sum of the number of cycles accumulated before and after compliance with CFM56-7B S/B 72-0527." Hence the AD interacts with that earlier Service Bulletin by treating the modification event as a point in the life history that must be aggregated for life-limit calculation.

4. EASA AD reference. The AD text states "EASA AD 2009-0009 dated 15 January 2009 refers." This signals alignment or correspondence with a European Aviation Safety Agency AD issued earlier in January 2009. The AD does not reproduce EASA’s text but recognises that EASA has issued related requirements. The AD therefore interacts conceptually with international regulatory action on the same technical issue.

5. Approved revisions and approval processes. The AD accepts "later approved revisions" of Service Bulletins and allows life limits to be incorporated in subsequent ESM revisions "following Revision 38 that incorporate these Temporary Revisions." The AD therefore presupposes the existence of an approval process for S/B and ESM revisions, but it does not define that approval process within the AD text. The practical interaction will be with the internal processes of the aircraft/engine manufacturer and whatever oversight process confirms those revisions for use in the jurisdiction.

6. Operator maintenance programme approval. The AD requires amendment of "the approved operator maintenance programme." That implicitly interacts with the administrative regimes that approve such programmes, because the operator’s programme must be amended and, by implication, approved or accepted as amended. The AD does not specify the approval mechanics, but the mandated change interacts with the approval status of the maintenance programme.

The AD does not reference or interact, within its text, with other statutes, civil aviation acts, penalty provisions, aviation insurance statutes, or contractual frameworks (such as leases). It confines its cross-references to manufacturer technical material (ESM TRs and Service Bulletins) and to the EASA AD. Any interaction with broader legal instruments or with contractual obligations will arise in implementation contexts but is not described in the AD text itself.

In sum, the AD’s interactions are primarily technical and procedural: it converts specified manufacturer technical documents into mandated elements of the operator’s approved maintenance programme, accepts later approved technical revisions, and references the related EASA AD.

The AD itself documents the immediate technical amendment history relevant to the LPT rear frames and the AD’s genesis. The AD identifies the following sequence of technical changes and dates, as stated in the AD text:

• 21 January 2008: CFM56-7B Service Bulletin S/B 72-0527 revision 02 was issued. The AD explains that the LPT rear frame part numbers listed in the AD "were introduced by the CFM56-7B Service Bulletin S/B 72-0527 revision 02 ... They are obtained by modifying (reworking) older P/N LPT frames." This Service Bulletin therefore created the new part numbers by rework of existing frames.

• 19 September 2008: CFM56-7B Engine Shop Manual Temporary Revisions TR 05-0097, 05-0098, and 05-0099 were issued. The AD states these Temporary Revisions were issued on that date and that, "Before the issue of the CFM56-7B Engine Shop Manual (ESM) Temporary Revisions ... the concerned LPT rear frames were neither subject to a life limit nor to a mandatory inspection." The Temporary Revisions therefore introduced the LCF life limits or inspection mandates for the newly reworked P/Ns.

• 15 January 2009: EASA AD 2009-0009 dated 15 January 2009 is referenced in the AD as a related regulator action. The AD does not reproduce EASA’s AD but includes the reference as part of its background materials.

• 23 January 2009: The AD document is signed by James Coyne, Delegate of the Civil Aviation Safety Authority. That date is provided at the end of the AD text.

• 28 January 2009: The AD "becomes effective on 28 January 2009." That is the effective date specified by the AD.

The AD itself contains provisions that accept post-publication technical amendments in defined ways: it allows the use of later approved revisions of the named Service Bulletins for compliance and it allows the "subsequent revisions of the Engine Shop Manual following Revision 38 that incorporate these Temporary Revisions" as the basis for incorporating LCF life limits into the operator’s maintenance programme. That is the only amendment-flexibility expressly provided in the AD text.

No other legislative or amendment history is recorded in the AD. The AD does not itself list any prior ADs from CASA superseded by this AD. It does not note subsequent amendments to the AD. The AD’s text is self-contained regarding the immediately relevant technical documents and the sequence that led to the issuance of the AD: S/B 72-0527 rev02 introduces the modified P/Ns; ESM TRs establish life limits; EASA issues a corresponding AD; CASA issues this AD, effective 28 January 2009.

Operators should note that the AD permits, for compliance purposes, the adoption of later approved revisions of the Service Bulletins and later ESM revisions that have incorporated the Temporary Revisions; thus, the AD accommodates a limited amendment pathway for the referenced technical materials.

The AD text as supplied contains no litigation history. There are no references in the AD to any past, pending or concluded legal proceedings, challenges, appeals, or court decisions relating to the AD, the named Engine Shop Manual Temporary Revisions, the Service Bulletins, or the underlying technical issues. The AD provides only the technical background, the operative requirements, the compliance windows, and references to manufacturer documents and an EASA AD.

Because the AD does not include litigation history or references to judicial or administrative challenges within the text, there is no information in the AD about any legal disputes concerning the underlying technical findings, the issuance of the AD, or enforcement actions. Similarly, the AD does not set out any administrative appeal mechanism or alternate method of compliance (AMOC) in the document itself; therefore, no procedural litigation history is recited.

If a reader requires information about any litigation or legal challenges arising from this AD, or any enforcement actions taken for non-compliance, that information is not present in this AD text and would need to be obtained from other sources outside the AD document. The AD’s only legal procedural indicator within the supplied text is the signature line: "James Coyne, Delegate of the Civil Aviation Safety Authority," dated 23 January 2009, which speaks to the issuing authority but not to litigation.

In short, there is no litigation history recorded in this AD.

This AD contains a number of operational and compliance details that may produce unintended outcomes or create implementation risk if overlooked. Each "gotcha" below is grounded in the AD text.

1. Positive establishment of cycles is the compliance hinge. Requirement 2 is triggered when "the number of total cycles accumulated by a LPT rear frame ... cannot be positively established." Note 2 clarifies that "the number of total cycles accumulated of the LPT rear frame is the sum of the number of cycles accumulated before and after compliance with CFM56-7B S/B 72-0527." If records are incomplete or fragmented around the time of the S/B 72-0527 rework, operators must either replace the frame or carry out inspections within 300 cycles. The practical implication is that imperfect historical records , even by omission around a rework event , will force the operator into a potentially costly inspection or replacement path.

2. Dual timing requirements can mismatch operational rhythms. Requirement 1 must be implemented within 30 days of the AD’s effective date; Requirement 2 within 300 cycles. Operators who operate parts near-life limits or that cannot establish life history must be careful to observe the 300-cycle window. Airlines with high utilization rates may hit 300 cycles quickly, while low-utilisation operators may have more breathing room; the AD does not provide alternative windows based on operational tempo.

3. "Remove and replace" is an absolute option with material consequences. Where cycles are not positively established, the operator may "remove and replace the LPT rear frame" as an alternative to inspections. This is an operationally heavy action: component removal and replacement requires parts availability, shop labour, and aircraft downtime. The AD does not provide guidance on lead times or parts sourcing; operators who elect replacement must manage these logistical and financial burdens.

4. Specified Service Bulletin revisions are named, but later approved revisions are acceptable. The AD mandates inspections "in accordance with CFM56-7B Service Bulletin S/B 72-0558 revision 2, or ... S/B 72-0579 revision 4," but adds that "The use of later approved revisions of the Service Bulletins is acceptable for compliance." There is potential ambiguity over what constitutes a "later approved revision" and which authority must "approve" it for the purposes of the AD. Operators must ensure that any later revision relied upon is indeed formally accepted under the relevant approval process.

5. ESM TRs vs full ESM revision. Requirement 1 allows incorporation of the life limits either by directly applying TRs 05-0097/05-0098/05-0099, or by relying on a subsequent ESM revision "following Revision 38 that incorporate these Temporary Revisions." Some organisations may delay amending their approved maintenance programme until those TRs are incorporated into a new ESM revision. That delay is acceptable under the AD text only if the subsequent ESM revision actually incorporates the TRs; otherwise operators risk non-compliance if they rely on an assumed future incorporation that does not occur.

6. Applicability to engines "known to be installed on, but not limited to, Boeing 737-series aeroplanes." The AD lists applicability to CFM56-7B turbofan engines with particular P/Ns and notes they are "known to be installed on, but not limited to, Boeing 737-series aeroplanes." Operators and maintenance managers must check fleet configurations carefully: the AD applies to the listed engine/component P/Ns wherever they are installed, not just on Boeing 737-series airframes.

7. No penalties or enforcement procedures in the AD text. The AD does not state enforcement mechanisms or sanctions for non-compliance. Parties may misinterpret the absence of penalty language as an indication of permissive enforcement. The AD nevertheless creates mandatory compliance obligations; the absence of in-text enforcement provisions does not necessarily alter external enforcement regimes that may apply under other instruments.

8. Definition of "total cycles" includes cycles both before and after the S/B 72-0527 modification. For components obtained by reworking older frames, cycles must be aggregated across the rework event. If records were not kept at the time of modification, this will complicate attempts to "positively establish" total cycles.

9. Risk of operational disruption from inspections. Where inspections are mandated, the AD does not specify whether inspections must be performed in-line, in-shop, or at overhaul. The referenced Service Bulletins will contain operational detail, but operators must be prepared for scheduling changes to accommodate inspections required within 300 cycles.

10. No explicit mention of alternative methods of compliance in the AD text. The AD does not provide an AMOC pathway within the document itself, other than acceptance of later approved S/B revisions. If an operator seeks an alternate technical approach not described in the AD, the AD text does not set out the process to obtain formal acceptance of that alternate approach.

Each of these operational pitfalls derives from the AD’s text and the interplay between recordkeeping, technical documentation, and timing. They create concrete implementation challenges for operators, maintenance organisations and technical records staff.

This section sets out concrete steps, grounded in the AD text, that an operator or maintenance organisation should follow to meet the AD’s requirements. Each step cites the relevant AD provision.

1. Identify affected engines and components (Applicability). Review the operator’s fleet and maintenance records to identify any CFM56-7B turbofan engines equipped with LPT rear frame part numbers: 340-166-254-0, 340-166-255-0, 340-166-256-0, 340-166-257-0, 340-166-258-0, 340-166-259-0, 340-177-551-0, 340-177-552-0, 340-177-553-0, 340-177-554-0, 340-177-555-0, 340-177-556-0. The AD’s Applicability clause lists these P/Ns directly.

2. Amend the approved operator maintenance programme within 30 days (Requirement 1). Incorporate the "new LCF life limits" for the applicable LPT rear frame P/Ns "in accordance with the CFM56-7B ESM chapter 05 Temporary Revision (TR) 05-0097, 05-0098, and 05-0099, as applicable or subsequent revisions of the Engine Shop Manual following Revision 38 that incorporate these Temporary Revisions." The AD requires this amendment "within 30 days after the effective date of this AD." Ensure the maintenance programme documentation explicitly records the life limits and any associated inspection intervals or removal thresholds included in the ESM TRs.

3. Determine total cycles for each listed LPT rear frame (Note 2 and Requirement 2 trigger). For each affected LPT rear frame, determine whether "the number of total cycles accumulated" can be "positively established." Note 2 defines total cycles as "the sum of the number of cycles accumulated before and after compliance with CFM56-7B S/B 72-0527." Ensure record searches include the pre‑ and post‑S/B 72-0527 periods and that the aggregation method is documented.

4. Where cycles are positively established, record and manage life consumption against the newly mandated LCF life limits. If life limits are documented in the operator’s amended maintenance programme per Requirement 1, manage each component against those limits and schedule overhaul/removal when the life limit approaches.

5. If cycles cannot be positively established, elect and execute an approved compliance path within 300 cycles (Requirement 2). The AD gives two alternatives: a. Remove and replace the LPT rear frame; or b. Perform inspections "in accordance with CFM56-7B Service Bulletin S/B 72-0558 revision 2, or CFM56-7B Service Bulletin S/B 72-0579 revision 4, as applicable."

   The AD states that these actions must be completed "within 300 cycles after the effective date of the AD." If choosing inspections, obtain and follow the correct Service Bulletin revision. The AD permits "later approved revisions of the Service Bulletins" for compliance; ensure any later revision used is formally approved under the operator’s or regulatory approval processes.

6. Obtain the referenced technical documents and confirm revision status. Acquire copies of:

   • CFM56-7B Engine Shop Manual chapter 05 Temporary Revisions TR 05-0097, 05-0098, 05-0099; and/or the subsequent ESM revision that incorporates them (post-Revision 38).
   • CFM56-7B Service Bulletin S/B 72-0527 revision 02 (for understanding the modification history and cycle aggregation).
   • CFM56-7B Service Bulletin S/B 72-0558 revision 2.
   • CFM56-7B Service Bulletin S/B 72-0579 revision 4.

   The AD text identifies these documents by number and revision; compliance requires reliance on the specified technical content in the applicable revisions (unless later approved revisions are used).

7. Document amendments and actions taken. Record the amendment to the approved maintenance programme, the determination of total cycles for each component, and the remedial action taken where cycles were not positively established (replacement or inspections). The AD requires changes to the "approved operator maintenance programme," so amendments and any inspections/replacements should be auditable against the AD’s compliance dates.

8. Coordinate approval where necessary. Because the AD directs an amendment to "the approved operator maintenance programme," ensure that any formal approval processes that apply to the operator’s maintenance programme are followed when submitting and implementing the amendment reflecting the ESM life limits. The AD does not describe the approval process, but it targets the approved programme as the instrument to be amended.

9. Monitor for later approved revisions. The AD allows the use of "later approved revisions of the Service Bulletins" and for life limits to be incorporated via later ESM revisions that include the TRs. If relying on later revisions for compliance, confirm and document the approval status of those later revisions before relying on them to meet the AD obligations.

10. Track compliance windows and fleet utilisation. Because Requirement 2 uses a 300-cycle window, track cycles for affected engines to ensure inspections or replacements occur before the 300-cycle deadline from the effective date (the AD becomes effective 28 January 2009). Ensure that operational tempo does not cause inadvertent non-compliance through miscalculation of cycles.

11. Consider logistics for replacement. If electing to "remove and replace" an LPT rear frame where cycles cannot be positively established, plan for parts acquisition, shop capacity and aircraft downtime. The AD does not supply guidance on parts sourcing or lead times; practical planning will be necessary.

12. Preserve records of compliance. Keep auditable records showing timely amendment of the approved maintenance programme in accordance with Requirement 1, records that demonstrate the positive establishment of total cycles where applicable, and records of inspections or replacements performed under Requirement 2 within the 300-cycle window.

Each of these steps is derived from the AD text and its explicit requirements. The AD’s compliance model is prescriptive: incorporate ESM TR-specified LCF life limits into the approved maintenance programme within 30 days, and remedy any unestablished cycle histories by removal/replacement or inspection within 300 cycles, following the named Service Bulletins or later approved revisions.