AD/CFM56/27 - Low Pressure Turbine Rear Frame Life - 5 Series Engines

The AD is built around a handful of interlocking concepts, stated in the source text and reproduced here with the wording and references used in that text.

1. Applicability by engine model and by part number. The AD applies only to a defined subset of CFM56-5B engines and only when they are equipped with an LPT rear frame having one of four specified part numbers: 338-171-703-0, 338-171-704-0, 338-171-705-0, 338-171-706-0. The AD expressly notes these engines are known to be installed on, but not limited to, Airbus A318, A319, A320 and A321 series aircraft (Applicability).

2. Low cycle fatigue (LCF) life limits. The central technical measure is the imposition of LCF life limits on the identified LPT rear frames, as set out in chapters 05-12-04, 05-12-24 and 05-21-03 of the CFM56-5B ESM, revision 47, or later approved revision (Requirement 1). The AD makes the ESM chapters the controlling reference for life-limit values and associated procedures.

3. Conditional remedial pathway for unknown life. If the "number of cycles accumulated since new" by an affected LPT rear frame cannot be established, the AD requires either removal and replacement of the part or performance of inspections in accordance with Service Bulletin S/B 72-0620, initial issue, or a later approved revision (Requirement 2).

4. Time-limited compliance windows. The AD prescribes two implementation timings: one action within seven days after the effective date (unless already done), and a second action within 300 cycles after effectiveness. The AD became effective on 3 September 2007 (Compliance; Effective date).

5. Document integration and approval pathway. The AD relies on CFM technical documents (ESM revision 47 and Service Bulletin S/B 72-0620) but allows for "or later approved revision", which permits reliance on future revisions that receive approval. The AD also references EASA AD 2007-0221 and attributes the technical change to CFM’s Temporary Revision TR 05-0145 which introduced the life limits and was later integrated into ESM revision 47 (Background; Note 2).

6. Safety rationale as stated by the issuer. The AD’s background explains the technical rationale: a "refined damage tolerant approach accounting for crack initiation and propagation" led CFM to establish LCF life limits to ensure any cracking present will not grow to unsafe levels. The source states that prior to TR 05-0145, the affected LPT rear frames were not subject to life limits in commercial applications and that corporate application engines had a 22 500-cycle limit (Background).

These concepts combine a prescriptive regulatory switch , a life-limit control anchored to manufacturer documentation , with an operationally demanding remediation route where provenance of part usage (cycles since new) cannot be established. The AD couples a technical defect-detection paradigm (damage tolerance and LCF) with time-limited operator obligations and reliance on manufacturer-approved supporting material.

The AD explicitly identifies the affected population by engine model, application type, and part number. The primary direct parties are aircraft operators who operate the stated CFM56-5B variants with the listed LPT rear frame part numbers (Applicability). That group breaks down as follows according to the source:

• Commercial operators of CFM56-5B engines: Models listed include CFM56-5B1/P, -5B2/P, -5B3/P, -5B3/P1, -5B4/P, -5B4/P1, -5B5/P, -5B6/P, -5B7/P, -5B8/P and -5B9/P, when the engine is equipped with LPT rear frame P/N 338-171-703-0, 338-171-704-0, 338-171-705-0 or 338-171-706-0.

• Corporate operators: CFM56-5B6/P and -5B7/P turbofan engines operating in corporate application are included where converted per SB 72-0308, if fitted with the specified LPT rear frame P/Ns. The AD states "(conversion per SB 72-0308)" in the applicability block.

• Maintenance organisations and engineers who are responsible for maintaining those engines and who must update maintenance programmes and conduct or supervise inspections in accordance with the ESM and the Service Bulletin referenced.

• Aircraft owners and lessors: while not named expressly, they bear economic consequences because operators must either replace parts or undertake inspections, and maintenance programme revisions affect continuing airworthiness obligations.

• Supply and overhaul providers: shops that manufacture, supply or install LPT rear frames identified by the listed P/Ns will be affected by replacement demand and by any documented inspection procedures in the Service Bulletin.

The AD also notes installation context: those engines are "known to be installed on, but not limited to, Airbus A318, A319, A320 and A321 series aircraft", which signals that operators of those airframes should check for affected engines, but the AD itself is not limited to those aircraft types (Applicability).

Who pays: The source itself assigns the operational obligations to the operator by mandating compliance actions. The AD requires either adoption of ESM life limits into maintenance programmes, or removal/replacement or inspection under the Service Bulletin where cycles cannot be established. Therefore the direct economic burden of inspections, replacement parts, labour, and aircraft downtime falls on the responsible operator or maintenance/lessor arrangements. The AD does not specify mechanisms for cost recovery or compensation.

Who decides: The AD is issued by the Civil Aviation Safety Authority (CASA) and is signed by the CASA delegate (Charles Lenarcic), making CASA the issuing regulator. However, the AD expressly defers to the manufacturer's ESM and Service Bulletin content "or later approved revision", which means the technical content and life limits are determined by CFM (as codified in the ESM), subject to regulator approval of any later revisions.

Secondary effects: operators who cannot immediately establish cycles for an affected part must choose between replacement and inspection. That decision shifts maintenance scheduling, possible part procurement, and downtime planning; it also may prompt record-keeping reviews to prevent recurrence of unknown provenance.

The AD places several affirmative duties on operators and provides one form of procedural flexibility in the form of "or later approved revision". The duties and the formal rights (document choices) are set out directly in the AD text.

Key duties

• Establish applicability: Operators must identify whether their installed engines and fitted LPT rear frames fall within the listed models and part numbers. The AD lists the affected models and P/Ns in the Applicability table. This identification is a prerequisite to the remaining duties.

• Adopt ESM LCF life limits: For affected parts, operators must "comply with the LCF life limits in accordance with the chapters 05-12-04, 05-12-24 and 05-21-03 in the CFM56-5B ESM, revision 47, dated 15 January 2007, or later approved revision" (Requirement 1). Practically that means updating the aircraft/engine maintenance program to reflect those life limits and to apply any associated mandatory inspections, retirement for cause, or scheduling constraints contained in the cited ESM chapters.

• Remedial action when cycles unknown: If the "number of cycles accumulated since new" by a qualifying LPT rear frame cannot be established, the operator must either remove and replace the affected LPT rear frame, or perform inspections in accordance with CFM56-5B Service Bulletin S/B 72-0620 initial issue or a later approved revision (Requirement 2).

• Time-bound execution: The duties must be carried out within the specified compliance windows: certain actions are required "within 7 days after the effective date of this AD, unless previously accomplished", and others "within 300 cycles after the effective date of this AD" (Compliance). The AD effective date is 3 September 2007.

Rights and procedural flexibility

• Use of later approved revisions: The AD allows operators to comply by reference to revision 47 of the ESM "or later approved revision", and the Service Bulletin initial issue "or later approved revision". That wording gives operators the right to rely on updated versions of the manufacturer's documents, provided those revisions have been approved. The AD does not itself specify the approval authority or process; it uses that phrase to permit non-retrogressive compliance to accepted later revisions.

• Choice between removal/replacement and inspection: Where cycles since new are unknown for an LPT rear frame, the operator has a choice: remove and replace the part, or follow the inspection procedure in the referenced Service Bulletin. The AD does not require replacement in all such cases but makes replacement one of two mandatory options.

Operational compliance obligations that follow from these duties

• Documentation and record-keeping: The AD implicitly requires operators to determine life since new. If an operator cannot establish cycles since new, the AD triggers the contingent duty described above. This makes accurate record-keeping of cycles an operational prerequisite to avoid immediate replacement or inspections.

• Maintenance programme revision: The AD explicitly states that operators must "revise their aircraft maintenance programs in accordance with these LCF life limits" (Background). That is an explicit obligation to change standing maintenance documentation and scheduling.

What the AD does not specify

• The AD does not specify detailed enforcement mechanisms, administrative penalties or civil remedies in the event of non-compliance. The source text contains no penalty provisions and does not identify a point of appeal or dispute resolution mechanism. The AD also does not set out specific LCF threshold numbers in the body of the AD; it instead directs users to the ESM chapters for the life-limit values and associated procedures.

The text of this AD sets mandatory technical and procedural obligations and an effective date but does not include express penalty provisions or describe enforcement actions or sanctions within the AD text itself. What the source does state about enforcement in concrete terms is limited to the following factual items:

• The AD sets firm compliance windows. The compliance block requires certain actions "within 7 days after the effective date of this AD, unless previously accomplished" and "within 300 cycles after the effective date of this AD." The AD "becomes effective on 3 September 2007." Those deadlines are the AD’s enforcement schedule.

• The AD is issued by the Civil Aviation Safety Authority, signed by a CASA delegate (Charles Lenarcic). The issuer and signature identify the regulatory origin of the obligation.

The source does not specify:

• any monetary penalties, licence sanctions, or civil penalties that will be imposed for non-compliance;
• a process for administrative enforcement or follow-up inspections by CASA; or
• a timeline for potential removal from service on non-compliant aircraft.

Practical enforcement implications drawn from what the AD requires

• The AD makes compliance with specified life limits and remedial action, in particular removal/replacement or inspection where cycles since new cannot be established, mandatory for operators of affected engines. Failure to implement those mandatory measures could leave an aircraft in a non-compliant airworthiness state under the administering regulator’s regime. The AD does not itself state the downstream consequences, but the presence of the AD imposes an affirmative continuing airworthiness obligation on operators in respect of the affected parts.

• The AD’s reliance on manufacturer documents "or later approved revision" creates an administrative approval link: operators must ensure they are using approved revisions of the ESM and Service Bulletin. The AD does not explain the approval process or identify the approver beyond the phrase "later approved revision".

What to record or expect given the silence on penalties

• Because the AD does not set out penalties, operators should treat the AD’s duties as mandatory technical requirements with compliance dates. The AD gives specific technical work items and deadlines. If an operator is unable to meet the AD’s deadlines or disputes the technical basis, nothing in the AD provides an internal appeal mechanism; any such dispute would need to be handled through the regulator’s general procedures, which are not described in the AD text.

In sum, the AD creates mandatory technical obligations and deadlines but leaves unspecified in the text any enforcement process or sanctions. The AD does, however, establish by its effective date a legal obligation on affected operators to adopt the prescribed life limits or carry out the specified remedial steps.

The AD explicitly cross-references manufacturer documentation and a European regulator’s directive, creating a web of inter-document dependency that determines how the AD is applied in practice. The source identifies these interactions as follows:

• Manufacturer technical documents as normative references. The AD makes the CFM56-5B Engine Shop Manual (ESM), revision 47 (15 January 2007), the controlling document for LCF life limits by requiring compliance "in accordance with the chapters 05-12-04, 05-12-24 and 05-21-03" in that manual. It also makes CFM56-5B Service Bulletin S/B 72-0620 the prescriptive inspection procedure where cycles since new cannot be established (Requirement 1 and 2). These references mean that the AD’s substantive obligations are implemented through manufacturer material. The AD further allows "or later approved revision" of those manufacturer documents, so later versions of the ESM or Service Bulletin that receive approval will also be acceptable for compliance.

• Reference to an EASA AD. The AD contains "Note 2: EASA AD 2007-0221 dated 13 August 2007 refers." That indicates an alignment with EASA regulatory action; the AD draws on the EASA AD as a referential authority or point of equivalence. The AD text also explains that the life-limit content was first introduced by CFM’s ESM Temporary Revision TR 05-0145 and subsequently incorporated into ESM revision 47, which is "approved by EASA and its content has been integrated in revision 47 of the CFM56-5B ESM, dated January 15, 2007" (Background). The AD therefore cross-links CASA’s action to the EASA approval of the manufacturer revision.

• Maintenance programme regulatory obligations. The AD explicitly requires operators to "revise their aircraft maintenance programs in accordance with these LCF life limits" (Background). Although the AD does not recite the domestic maintenance programme regulation by section number, it creates an obligation to modify maintenance programmes to reflect the ESM life limits and associated procedures. That means the AD operates as an instruction to alter documents and processes subject to the broader civil aviation continuing airworthiness regime.

• Service Bulletins and revision approvals. The AD’s acceptance of "later approved revision" for ESM and Service Bulletin materials creates an interaction with the regulatory approval framework for those documents. The AD does not identify the approving authority for later revisions, but the phrase implies that compliance can rely on subsequent revisions that are formally approved, which embeds the AD within a dynamic process of approved manufacturer revisions.

What the AD does not do

• The AD does not repeal, amend or replace other statutory provisions in the Civil Aviation Regulations within its text. It does not list cross-referrals to domestic statutory sections or penalties. The AD functions as a directive that requires operators to take certain actions; its legal force derives from its issuance by CASA and its effective date.

Net effect of interactions

• Operators must manage their domestic maintenance programmes to trace to manufacturer-approved technical material, which the AD adopts as normative. Ensuring compliance thus typically requires aligning local maintenance practices with the ESM chapters and the Service Bulletin and tracking any later approved revisions. The reference to the EASA AD signals international regulatory alignment rather than a unilateral change in domestic law.

The AD’s own text records a concise amendment background and a short chain of related document changes. The provided text identifies the following steps and dates:

• Temporary Revision TR 05-0145. CFM introduced the requirement to life-limit the concerned LPT rear frames via a CFM56-5B Engine Shop Manual Temporary Revision numbered TR 05-0145. The AD states that "Before the issue of the CFM56-5B Engine Shop Manual (ESM) Temporary Revision (TR) 05-0145, the concerned LPT rear frames were not subject to a life limit in commercial applications, and in corporate applications the CFM56-5B6/P and -5B7/P engines were life limited to 22 500 cycles."

• ESM revision 47. The technical content of TR 05-0145 was subsequently "approved by EASA and its content has been integrated in revision 47 of the CFM56-5B ESM, dated January 15, 2007." The AD directs operators to the life limits in chapters 05-12-04, 05-12-24 and 05-21-03 of that ESM revision 47, or a later approved revision (Requirement 1; Background).

• EASA AD reference. The AD expressly refers to EASA AD 2007-0221 dated 13 August 2007 (Note 2). That EASA AD appears to be the European regulator’s corollary action; the AD’s Note 2 simply records the reference.

• Service Bulletin initial issue. The AD refers to CFM56-5B Service Bulletin S/B 72-0620, initial issue, as the inspection method to be used where cycles since new cannot be established (Requirement 2). The AD allows the use of that Service Bulletin "or later approved revision".

• AD issuance and effective date. The AD itself is dated 11/2007 DM, signed by the CASA delegate (Charles Lenarcic) on 28 August 2007, and the AD "becomes effective on 3 September 2007."

No further amendments or revision history are contained in the source text. The AD, by referencing "or later approved revision" for the ESM and Service Bulletin, opens a path for future amendments to the technical material to become the operative standard once they have been approved, but the AD text does not list subsequent amendment numbers or dates beyond those above.

The source text contains no litigation history. There is no record in the provided AD of any legal proceedings, appeals, judicial review, or litigation related to AD/CFM56/27. The instrument itself is an administrative directive setting mandatory technical obligations; the text documents its issuance, the technical references, and the compliance timing, but does not mention any challenge to or court decisions about the AD.

What the AD does record that is relevant to potential disputes

• The AD cites manufacturer and regulator documents as the normative technical basis: CFM56-5B ESM revision 47 (or later approved revision), CFM56-5B Service Bulletin S/B 72-0620 (or later approved revision), and EASA AD 2007-0221. Where disputes over technical content or compliance arise, those documents will be central to any administrative or judicial review. The AD itself does not include dispute-resolution procedures.

• The AD leaves open the question of approval of later revisions. The AD allows "or later approved revision" for both the ESM and the Service Bulletin, but does not specify the approval mechanism. Any contest about whether a later revision is "approved" will therefore look to the broader regulatory framework and approval records, which the AD does not reproduce.

Consequences of the absence of litigation history in the source

• Because the AD does not include litigation history, one cannot cite any judicial interpretation of the AD or any precedent about how its clauses have been applied in court from the provided text. Any legal uncertainty about the AD’s technical or procedural requirements would have to be resolved through regulator guidance or external legal processes not recorded in this AD.

The AD contains a number of practical and legal features that may produce operational surprises if not carefully observed. These items are grounded in the specific language of the AD.

1. Narrow applicability tied to part numbers. Applicability is not by engine type alone. The AD applies only when an affected CFM56-5B engine is equipped with LPT rear frame P/N 338-171-703-0, 338-171-704-0, 338-171-705-0 or 338-171-706-0. Operators may mistakenly assume all CFM56-5B engines are covered; the AD text requires verification of P/Ns. The AD also notes the engines are "known to be installed on, but not limited to," Airbus A318-A321 aircraft, which signals the need to check actual equipment fit.

2. Short compliance windows. The AD sets two short, different time limits: an action within 7 days after the effective date "unless previously accomplished" and another action within 300 cycles after the effective date. Because the AD became effective on 3 September 2007, these are immediate and operationally demanding deadlines. Operators that have not already reconciled cycle counts may find themselves facing forced removal or immediate inspection scheduling.

3. Unknown cycles triggers replacement or inspection. If the "number of cycles accumulated since new" cannot be established for an affected LPT rear frame, the AD obliges removal and replacement or inspections in accordance with S/B 72-0620 (Requirement 2). That creates a direct demand for traceability. Poor or incomplete records are a direct compliance risk and can impose immediate replacement cost or inspection burden.

4. Technical content is externalised. The AD does not print the life-limit numbers or inspection steps. Instead it directs operators to chapters in the ESM and to a Service Bulletin for details. That means compliance requires access to the ESM revision 47 (or later approved revision) and to S/B 72-0620. Operators must ensure they obtain and verify the correct revision and any approval status if relying on later revisions.

5. "Or later approved revision" introduces change risk. The AD permits "or later approved revision" for the ESM and S/B materials. While that provides flexibility, it also means technical obligations can change if later revisions are approved. Operators must track approvals to ensure they are complying with the then-current approved revision.

6. Corporate conversions included by reference. The AD includes corporate application engines CFM56-5B6/P and -5B7/P "conversion per SB 72-0308". Operators with converted engines must check whether their conversion falls within the SB 72-0308 scope. Misunderstanding the conversion reference may lead to under- or over-inclusion.

7. No explicit penalties or enforcement language in the AD text. The AD mandates actions but does not specify penalties or enforcement steps within the document. Operators therefore must interpret the AD as a binding technical requirement issued by CASA which must be reflected in maintenance programmes, but the AD itself provides no enforcement protocol or sanctions details.

8. Record-keeping is effectively decisive. The AD places decisive weight on the ability to establish "number of cycles accumulated since new". That single piece of information determines whether an operator can rely on the new life limits or must resort to replacement/inspection. Poor historical records therefore materially increase compliance costs and operational disruption.

9. Integration with maintenance programmes is mandatory. The Background explicitly says the AD "requires operators to revise their aircraft maintenance programs in accordance with these LCF life limits" (Background). That is an operational duty that reaches beyond simple one-off inspections; it requires formal maintenance programme revision and scheduling changes.

10. International regulatory corollary. The AD references EASA AD 2007-0221 and ESM approval by EASA. Operators operating across jurisdictions should note that the AD is not isolated; it sits in the context of manufacturer and European regulator action. However, the AD does not explain the implications of discrepancies between different jurisdictions' directions beyond the reference.

These "gotchas" emphasise practical steps: identify affected P/Ns, reconcile cycles since new promptly, secure appropriate ESM and Service Bulletin revisions and approvals, and revise maintenance programmes quickly to meet the 7-day and 300-cycle deadlines.

The AD itself prescribes the required actions; a compliance checklist derived directly from the AD text and the AD’s documentary references is set out below. Each step is grounded in the AD’s stated requirements and timing.

1. Identify affected engines and parts

   • For each aircraft in the operator’s fleet check the engine model and confirm whether it is one of the listed CFM56-5B variants: CFM56-5B1/P, -5B2/P, -5B3/P, -5B3/P1, -5B4/P, -5B4/P1, -5B5/P, -5B6/P, -5B7/P, -5B8/P and -5B9/P in commercial application; plus CFM56-5B6/P and -5B7/P in corporate application where conversion per SB 72-0308 applies (Applicability).
   • Confirm the LPT rear frame part number installed is one of: 338-171-703-0, 338-171-704-0, 338-171-705-0, or 338-171-706-0 (Applicability).

2. Establish cycles since new for each affected LPT rear frame

   • Immediately attempt to reconcile maintenance and service records to establish the "number of cycles accumulated since new" for each relevant LPT rear frame. The AD makes clarity on cycles decisive: if the cycles can be established, the operator proceeds under Requirement 1; if cycles cannot be established, Requirement 2 applies.

3. Adopt the LCF life limits into the maintenance programme

   • If cycles since new can be established, revise the operator’s aircraft/engine maintenance programme to "comply with the LCF life limits in accordance with chapters 05-12-04, 05-12-24 and 05-21-03 in the CFM56-5B ESM, revision 47, dated 15 January 2007, or later approved revision" (Requirement 1; Background). Obtain and apply the specific life-limit values and any associated inspection/retirement procedures stated in those chapters.

4. If cycles since new cannot be established

   • Choose one of the AD’s two mandatory routes: remove and replace the LPT rear frame, or perform inspections "in accordance with CFM56-5B Service Bulletin S/B 72-0620 initial issue, or later approved revision" (Requirement 2). The AD does not allow continued service without taking one of these two actions.

5. Follow the AD’s timing requirements

   • Comply with the AD’s specific timing requirements: implement the required actions "within 7 days after the effective date of this AD, unless previously accomplished" and "within 300 cycles after the effective date of this AD" as applicable (Compliance). The effective date in the AD is 3 September 2007. Operators must map their actions against both time and operational cycles.

6. Use approved revisions

   • The AD permits reliance on "or later approved revision" of the CFM56-5B ESM and S/B 72-0620. Where an operator intends to rely on a later revision, ensure that the revision is formally approved and that the version used for compliance is documented in maintenance records.

7. Document the compliance steps

   • Maintain clear records showing identification of affected parts, reconciliation of cycles since new, maintenance programme revisions adopting the ESM life limits, inspection records if S/B 72-0620 procedures were used, or records of removal and replacement. The AD’s structure makes these records the primary evidence of compliance.

8. Coordinate maintenance scheduling and part acquisition

   • Plan for potential removal and replacement where cycles since new cannot be established. Replacement will require sourcing the specified LPT rear frame and associated labour and downtime. If inspections under S/B 72-0620 are chosen, allocate appropriate shop time and inspection capability.

9. Track approvals and changes

   • Monitor for any "later approved revisions" of the ESM or S/B 72-0620 that the AD accepts as compliant alternatives. Obtain documented evidence of the approval status before relying on any later revision.

10. Consider the corporate conversion clause

• For corporate application engines (CFM56-5B6/P and -5B7/P), check whether the engine has been converted per SB 72-0308, because the AD’s applicability includes those engines only in that conversion context. Ensure conversion documentation is available and reconciled.

11. Integrate changes into continuing airworthiness management

• Update fleet-level continuing airworthiness documentation and scheduling software to reflect the new LCF life limits and the inspection/removal contingencies. The AD explicitly requires a revision of the aircraft maintenance programme in accordance with the life limits (Background).

Who bears the cost and performs the work

• The AD assigns duties to the operator and therefore the operator bears the operational and financial burden of inspections, parts replacement, maintenance programme revisions, staff time, and any resulting aircraft downtime. The AD does not specify external funding or compensation mechanisms.

A succinct compliance checklist (directly traceable to AD text)

• Step 1: identify engines and LPT rear frame P/Ns (Applicability).
• Step 2: reconcile cycles since new for each affected P/N (Requirement 2 contingency).
• Step 3: where cycles are known, adopt ESM chapter life limits into maintenance programme (Requirement 1; Background).
• Step 4: where cycles are unknown, either remove/replace the LPT rear frame or perform S/B 72-0620 inspections (Requirement 2).
• Step 5: meet the 7-day and 300-cycle compliance windows (Compliance).
• Step 6: retain records of approvals, inspections, removal/replacement, and maintenance programme revisions.

These steps reflect the AD’s technical and procedural pathways as set out in the source text and are the actions necessary to meet the AD’s mandated obligations.