AD/RB211/37 - Engine - Low Pressure Turbine Shaft

The AD revolves around a small set of tightly specified technical and procedural concepts. Applicability identifies which engines are subject to the directive: RB211‑22B series (all models, all serial numbers) and a defined list of RB211‑524 variants (RB211‑524B4‑D‑02; RB211‑524D4‑19; RB211‑524D4‑39; RB211‑524D4‑B‑19; RB211‑524D4‑B39; RB211‑524D4X‑19; RB211‑524D4XB‑19), all serial numbers. The AD explicitly excludes some engines that are listed in the Rolls‑Royce NMSB but are "not affected by the same unsafe condition" (Applicability Note 2). That distinction is central: compliance obligations apply only to the engines listed as applicable in the AD text.

The core technical object is the low pressure turbine (LPT) shaft. The documented defect pathway is: corrosion pits at rear cooling air holes initiating cracks, cracks detected by Magnetic Particle Inspection (MPI) at overhaul, crack propagation leading to shaft failure, and potential uncontained LPT failure (Background). The AD therefore prescribes inspection by reference to a manufacturer service bulletin (Rolls‑Royce NMSB 72‑AF336), rather than drafting in new inspection techniques or numerical thresholds for crack size. The required inspection technique is the accomplishment instructions of that NMSB; the AD notes the cracks were found by the "standard Magnetic Particle Inspection (MPI) technique defined in the associated engine manual" (Background). Those references operate as normative technical prescriptions: the AD delegates procedural detail to the NMSB and to the engine manual's MPI definition.

Timing is specified as shop‑visit triggered, and in some cases by engine cycles: RB211‑22B series, maximum 3,500 engine cycles between inspections; RB211‑524B4‑D‑02, maximum 4,000 engine cycles; the listed RB211‑524D4 variants are to be inspected at the "Normal shop visit interval" (Compliance table). The AD sets an effective date (13 March 2008) and includes a transitional handling for engines already in shops on that date where the LPT shaft had been completely disassembled to piece‑part level and had not been reprotected with corrosion resistant coating: those engines must be inspected prior to installation on an aircraft (Compliance).

Remedy is removal and replacement. The AD prescribes replacement of any LPT shaft found to be cracked with a "serviceable LPT shaft" (Requirement 3). The AD also cross‑references an EASA AD (EASA AD 2007‑0310R1 dated 8 January 2008) as relevant (Note 3).

In sum, the main concepts are: a defined population of engine models; a specific component (LPT shaft) with a documented corrosion‑initiated cracking mode; inspection and repeat inspection requirements tied to a manufacturer NMSB; shop‑visit and engine‑cycle timing rules; and mandatory replacement of cracked components.

The AD directly affects operators and maintainers of the listed RB211 engine models. The "Applicability" clause identifies the engines in scope: "RB211‑22B series engines, all models, all serial numbers; and RB211‑524B4‑D‑02, RB211‑524D4‑19, RB211‑524D4‑39, RB211‑524D4‑B‑19, RB211‑524D4‑B39, RB211‑524D4X‑19 and RB211‑524D4XB‑19 engines, all serial numbers." The AD notes these engines are "known to be installed on, but not limited to, Boeing 747 series aircraft; and Lockheed L‑1011 series aircraft" (Applicability). That language signals that aircraft operators, maintenance organisations, and possibly owners of other aircraft types that carry these engines must apply the AD.

Maintenance organisations and licensed engineers who perform engine shop visits are affected operationally because the inspection is to be conducted "in accordance with the accomplishment instructions of Rolls‑Royce NMSB 72‑AF336" and the detection technique referenced in Background is the standard MPI defined in the engine manual. The AD imposes an inspection obligation that arises at specific maintenance events: when the LPT shaft is "completely disassembled to piece‑part level" during a shop visit (Compliance).

Supply chain actors are affected to the extent that cracked shafts must be replaced with "serviceable LPT shafts" (Requirement 3). That creates demand for replacement parts and may affect parts inventories and logistics for operators and maintenance shops. Where replacement requires a new or overhauled shaft, procurement, part traceability and certification of serviceability will be implicated.

Regulators and their delegates are implicated administratively by the AD itself. The document is issued by the Civil Aviation Safety Authority, signed by a delegate (Charles Lenarcic) and contains cross‑references to an EASA AD; those elements relate to regulatory coordination and recordkeeping (signature, effective date 13 March 2008). There is no separate reference in the AD to operator financial relief, exemptions, or transitional approvals within the text supplied.

Third parties such as lessors, aircraft managers, insurers and safety managers will be affected indirectly because the AD mandates inspection and possible replacement at shop visits and prior to installation in certain circumstances. Operators who lease these engines or aircraft must ensure maintenance records and compliance evidence are current before return to service or transfer. The AD does not mention lessee/lessor allocation but the practical effect is that whoever is responsible for maintenance at the relevant time must comply.

Finally, the AD excludes certain engines that appear in the associated Rolls‑Royce NMSB but "are not affected by the same unsafe condition and therefore this AD does not apply to those engines" (Applicability Note 2). That exclusion matters to operators who might otherwise apply the NMSB to a broader set of configurations; misreading applicability could create unnecessary inspections or overlooked obligations.

The AD imposes clear duties and leaves little room for alternative compliance methods within the text provided. Primary duties:

• Inspect the LPT shaft: "Inspect the LPT shaft in accordance with the accomplishment instructions of Rolls‑Royce NMSB 72‑AF336 unless previously accomplished" (Requirement 1). The AD makes the NMSB the operative inspection instruction set.

• Repeat the inspection: "Repeat the inspection detailed in Requirement 1 of this AD" (Requirement 2). The AD does not itself specify the full repeat interval for every model inside the Requirement text, but it supplies a Compliance table that sets maximum time between inspections in engine cycles for specified models and ties other models to "Normal shop visit interval".

• Replace cracked shafts: "All LPT shafts inspected according to Rolls Royce NMSB 72‑AF336 and found to be cracked must be replaced with serviceable LPT shafts" (Requirement 3).

Timing duties and conditional obligations:

• For engines in shop on the effective date where the LPT shaft has been completely disassembled to piece‑part level and the shaft has not been reprotected with corrosion resistant coating, the inspection must be performed prior to installing the engine on an aircraft (Compliance). This creates a duty linked to a state of disassembly on the effective date.

• For all other engines, the inspection is required at the next engine shop visit after the effective date when the LPT shaft is completely disassembled to piece‑part level (Compliance). The AD therefore uses the shop visit milestone as the trigger for the inspection obligation, not an immediate fleet‑wide calendar inspection unless a shop visit occurs.

• Repeat inspections must follow the schedule in the Compliance table: RB211‑22B series , maximum 3,500 engine cycles between inspections; RB211‑524B4‑D‑02 , maximum 4,000 engine cycles between inspections; RB211‑524D4 variants , "Normal shop visit interval" (Compliance table).

Rights and delegations in the text:

• The AD delegates procedural detail to Rolls‑Royce via NMSB 72‑AF336 and to the engine manual's MPI definition. The AD does not, in the supplied text, specify an alternative approved method of compliance; it states inspection "in accordance with" the NMSB. Parties seeking an alternative method of compliance would need to refer to broader regulatory frameworks not contained in the AD text.

• The AD itself does not provide any exemption, deferral, or cost‑sharing mechanism. The only temporal accommodation is the shop‑visit trigger and the special case for engines already disassembled on the effective date. There is a cross‑reference to EASA AD 2007‑0310R1 (Note 3), which may be relevant to coherent international compliance strategies, but the AD text does not elaborate rights arising from that reference.

Documentation and evidence duties are implied: because the AD ties inspections and replacement to safe‑for‑service determinations and NMSB instructions, reasonable inference from the text is that maintenance organisations must retain records showing the NMSB was followed and that any cracked shaft was replaced with a "serviceable" one. The AD does not state recordkeeping requirements explicitly in the supplied text, but the prescribed actions imply a need to document compliance for airworthiness and return‑to‑service.

The AD text supplied does not set out civil or criminal penalties, nor does it reproduce a sanctions schedule. It is an airworthiness directive issued by the Civil Aviation Safety Authority and signed by a delegate (Charles Lenarcic). The directive establishes mandatory technical compliance obligations (inspection, repeat inspection, replacement) and an effective date (13 March 2008). The AD itself functions as a regulatory instrument; enforcement and penalty mechanisms would be those available to the regulator under the broader statutory framework that governs airworthiness directives, but that statutory framework and specific penalty provisions are not included in the text supplied.

What the AD does provide that is relevant to enforcement is a clear set of directives and timing triggers which a regulator can observe for compliance verification: the requirement to perform inspections according to Rolls‑Royce NMSB 72‑AF336; the requirement to conduct repeat inspections according to the engine‑model‑specific maximum engine cycles or normal shop visit intervals; and the immediate replacement obligation for any shaft found cracked. The AD also sets an effective date and provides a point of contact in the sense of a signature and date (delegate Charles Lenarcic, 21 January 2008), which anchors the administrative chain of responsibility.

Because the AD imposes actions that must be taken "prior to installing the engine on an aircraft" in specified circumstances and at the "next engine shop visit" in others, regulators can determine non‑compliance by auditing maintenance records, shop visit reports, and parts replacement certifications. The directive's reliance on an external NMSB and the engine manual's MPI definition provides concrete technical standards for inspectors to reference when assessing whether the inspection was performed in accordance with the prescribed method.

The AD also explicitly references EASA AD 2007‑0310R1 dated 8 January 2008, which may be used by regulators when coordinating enforcement or cross‑checking compliance against related European requirements. The AD, however, does not set out how enforcement actions will be initiated, nor does it list fines, revocations, or suspension processes. Those enforcement instruments are outside the AD text and would be found in the CASA enabling legislation and enforcement policies, which are not reproduced here.

The AD references and interacts procedurally with materials external to the AD text, but it contains no express discussion of other statutes or regulations. The explicit interactions it does identify are with industry technical materials and a foreign regulator's AD:

• Manufacturer documentation: The AD mandates inspections "in accordance with the accomplishment instructions of Rolls‑Royce NMSB 72‑AF336" and references the engine manual's MPI technique as the detection method used when the cracks were found (Background). This means the AD operates by incorporating, by reference, manufacturer technical instructions as the standard of compliance. The AD thus functionally binds operators to the NMSB as the procedural normative document for the inspections required under the AD.

• Foreign regulator AD: The AD states "Note 3: EASA AD 2007‑0310R1 dated 8 January 2008 refers" (Requirement/Notes). That cross‑reference indicates the CASA AD aligns with or takes into account an EASA action on the same unsafe condition. The AD does not incorporate the EASA AD in full, but the reference signals regulatory coordination and that operators who are subject to both jurisdictions may need to reconcile requirements.

• Manufacturer non‑modification service bulletin scope and exclusions: The AD notes that "Some RB211‑524 series engines and all RB211‑535 series Engines, although listed in the referenced Rolls‑Royce Non Modification Service Bulletin (NMSB), are not affected by the same unsafe condition and therefore this AD does not apply to those engines" (Applicability Note 2). That statement draws a boundary between the AD's applicability and the broader NMSB distribution list. It therefore interacts with the NMSB not by blindly adopting all models referenced in the NMSB but by selectively applying the AD to a subset. This selective application can create a legal interplay between the NMSB as technical guidance and the AD as a binding legal instrument.

• Procedures and standards for inspection: By specifying the standard MPI technique defined in the engine manual as the method by which cracks were and should be detected, the AD implicitly interacts with the engine manual's technical definitions and inspection thresholds. The AD does not reproduce those technical thresholds or MPI parameters, but it establishes that compliance hinges on executing the techniques as defined in the engine manual and the NMSB.

The AD does not reference civil aviation statutes, penalty provisions, approved alternative methods of compliance, or recordkeeping statutes in the supplied text. Those legal interactions would typically exist in the broader regulatory framework and CASA's enforcement instruments, but they are not stated in the AD content provided. Operators who must integrate this AD into existing maintenance and continuing airworthiness systems will need to map it onto their obligations under the applicable certification and continuing airworthiness regulations and their contractual obligations under leases and maintenance agreements; that mapping is a compliance implementation task not detailed in the AD text itself.

The AD document contains limited internal amendment history information. The principal dated elements present in the text are:

• Effective date: "This Airworthiness Directive becomes effective on 13 March 2008" (Compliance). That is the operative commencement date for the obligations within the AD.

• Date of signature and issue: The AD is signed "21 January 2008" by "Charles Lenarcic, Delegate of the Civil Aviation Safety Authority" (signature block). That date is the administrative issuance date from the CASA delegate.

• Cross‑reference to EASA: The AD contains a note referring to "EASA AD 2007‑0310R1 dated 8 January 2008" (Note 3). That reference is the closest material in the AD to an external amendment or related regulatory instrument. It suggests that the CASA AD was issued after the EASA material and that the EASA directive had an earlier revision on 8 January 2008.

• Versioning and identifiers: The document header lists "AD/RB211/37" and repeats the label multiple times, and it includes the date "3/2008" in the header. Those identifiers provide an archival reference but do not themselves describe prior amendments within the supplied text.

No other amendment history (such as superseded ADs, rescission, or later revisions) appears in the supplied document. The AD does not include an explicit "Amendments" section or a record of past versions beyond the identifiers and the EASA cross‑reference. The absence of further amendment detail in the AD means that, within the supplied material, compliance obligations should be understood as originating with the effective date of 13 March 2008 and the issuance dated 21 January 2008, with the referenced EASA AD dated 8 January 2008 as contextual material.

Practically, operators and maintainers tracking changes to their obligations will need to consult CASA records and any later AD publications to discover subsequent amendments, revocations or reissues; those are not contained in the AD text supplied here.

The supplied AD text does not include any litigation history. There are no references to court decisions, administrative appeals, disputes, or adjudications relating to this AD within the document. The AD contains only regulatory obligations, technical instructions, applicability notes and a cross‑reference to an EASA AD; it does not describe challenges, stay orders, or legal interpretations arising from the directive.

Because the AD itself does not provide litigation details, one cannot, from this text alone, identify any court or tribunal proceedings that have interpreted, challenged or enforced the AD. The document does not mention any appeals processes or mention any instances where the AD was stayed, altered by a court, or otherwise subject to judicial review in the material supplied.

For operational and legal practitioners, the absence of litigation history in the AD text means that any inquiry into precedent, case law, or administrative appeals concerning this AD must be conducted outside the AD document. Parties seeking to determine whether the AD has been the subject of litigation, or whether there are adjudicative interpretations impacting how the AD should be read, would need to consult external sources: CASA publications, court records, tribunal decisions, or regulatory databases. None of that material is included in the AD text provided.

In short, the AD file presented contains no litigation history, and the AD itself does not indicate any ongoing or concluded legal proceedings related to it.

The AD includes several provisions and phrasing that create practical compliance pitfalls if read carelessly. These are explicit in the text and merit attention.

1. Applicability nuance. The AD states that some engines listed in the Rolls‑Royce NMSB are not affected: "Some RB211‑524 series engines and all RB211‑535 series Engines, although listed in the referenced Rolls‑Royce Non Modification Service Bulletin (NMSB), are not affected by the same unsafe condition and therefore this AD does not apply to those engines" (Applicability Note 2). Gotcha: maintenance staff might apply the NMSB to a broader set of engines without checking the AD’s narrower applicability. The AD is the binding instrument; following the NMSB alone without checking the AD’s applicability could either cause unnecessary inspections or, conversely, leave applicable engines unchecked if the NMSB's model list is relied upon rather than the AD’s model list.

2. Shop visit trigger versus calendar action. The inspection obligation is tied to the LPT shaft being "completely disassembled to piece‑part level" during a shop visit (Compliance). Gotcha: operators who interpret the AD as requiring immediate out‑of‑cycle inspections for every engine may overreact. Conversely, operators who assume compliance can wait indefinitely until the next scheduled shop visit need to note the special case for engines already in shop at the effective date.

3. Effective‑date special case. If, on the effective date (13 March 2008), the engine "is undergoing a shop visit where the LPT shaft has been completely disassembled to piece‑part level ... and the LPT shaft has not been reprotected with corrosion resistant coating; prior to installing the engine on an aircraft" the inspection is required before post‑shop installation (Compliance). Gotcha: a shop visit that had already occurred but where re‑protection was applied could change the timing. The AD’s conditional language requires careful operational record checks for discrete shop visits straddling the effective date.

4. Multiple scheduling metrics. The AD provides engine‑cycle limits for some models (3,500 cycles for RB211‑22B; 4,000 cycles for RB211‑524B4‑D‑02) and "Normal shop visit interval" for others (RB211‑524D4 family). Gotcha: operators must map engine cycles to their own maintenance intervals and ensure their recordkeeping allows them to determine when the maximum interval or the next "normal shop visit interval" arises.

5. Reliance on manufacturer documents. The AD requires inspections "in accordance with the accomplishment instructions of Rolls‑Royce NMSB 72‑AF336" and references the engine manual’s MPI definition. Gotcha: the NMSB and engine manual are separate documents. Failure to obtain the correct revision of the NMSB or to use the exact MPI procedure defined in the engine manual could result in non‑conforming inspections. The AD does not itself include the inspection steps.

6. Replacement part standard. The AD requires replacement "with serviceable LPT shafts" for any shaft found cracked. Gotcha: the AD does not define "serviceable" in the supplied text. Operators must ensure that the replacement shaft meets serviceability criteria per the engine manual, parts instructions, or approval processes. Procurement of parts, traceability and certification of conformity therefore are potential points of non‑compliance if not handled according to the engine manual or organizational procedures.

7. Cross‑reference to EASA AD. The AD notes "EASA AD 2007‑0310R1 dated 8 January 2008 refers" (Note 3). Gotcha: operators subject to multiple jurisdictions must ensure they satisfy any additional or differing obligations imposed by EASA or other regulators; the supplied AD is silent on reconciling differences beyond referencing the EASA document.

8. Detection technique expectations. The Background states cracks "were found at normal component overhaul, by the standard Magnetic Particle Inspection (MPI) technique defined in the associated engine manual" and that cracks initiate from corrosion pits. Gotcha: if an operator uses an alternative inspection technique or a different MPI threshold, they may miss relevant cracks or render the inspection non‑conforming to the AD requirement to follow the NMSB and engine manual technique.

9. Documentation: the AD implies but does not state explicit recordkeeping requirements. Gotcha: absence of explicit documentation instructions in the AD does not relieve operators of the need to maintain records required under broader airworthiness regulations. Operators must ensure their audit trail demonstrates that the NMSB instructions were followed and that replacements were made when cracks were detected.

10. Broad header repetition and formatting. The document repeats headings and identifiers (AD/RB211/37 repeated, "Engine - Low Pressure Turbine Shaft" repeated). Gotcha: paperwork and database entry should use the AD identifier consistently to avoid duplicate or missed entries due to header formatting oddities.

Follow the AD's prescriptive steps precisely, using the referenced technical materials and the timing rules provided.

1. Confirm applicability. Check that the engine serial number and model are one of the engines listed under "Applicability": RB211‑22B series (all) or the specified RB211‑524 variants (RB211‑524B4‑D‑02; RB211‑524D4‑19; RB211‑524D4‑39; RB211‑524D4‑B‑19; RB211‑524D4‑B39; RB211‑524D4X‑19; RB211‑524D4XB‑19). Note that some RB211‑524 series engines and all RB211‑535 series engines listed in the Rolls‑Royce NMSB are explicitly excluded from this AD (Applicability Note 2). Do not rely solely on the NMSB engine list.

2. Acquire governing technical documents. Obtain the exact Rolls‑Royce Non Modification Service Bulletin 72‑AF336 referenced in the AD and the relevant engine manual definition of the Magnetic Particle Inspection (MPI) technique, because the AD requires inspection "in accordance with the accomplishment instructions of Rolls‑Royce NMSB 72‑AF336" and notes the MPI technique used (Requirement 1; Background). Use the edition/revision of the NMSB and manual that the operator's procedures require for regulatory compliance, ensuring the instructions match what the AD calls for.

3. Schedule initial inspection according to the AD's timing rules. If, on the AD's effective date (13 March 2008), any applicable engine "is undergoing a shop visit where the LPT shaft has been completely disassembled to piece‑part level ... and the LPT shaft has not been reprotected with corrosion resistant coating," perform the inspection before installing the engine on an aircraft (Compliance). For all other engines, plan the inspection at the next engine shop visit after the effective date when the LPT shaft is completely disassembled to piece‑part level (Compliance). Do not assume calendar dates will substitute for the shop‑visit trigger unless the shop visit occurs.

4. Perform inspection per the NMSB. At the disassembly to piece‑part level, carry out the inspection exactly as set out in Rolls‑Royce NMSB 72‑AF336 and using the MPI technique as defined in the engine manual. Maintain procedural fidelity to the accomplishment instructions and retain evidence of the inspection steps performed.

5. Apply repeat inspection intervals. After the initial inspection, repeat the inspection per Requirement 2 and the Compliance schedule: RB211‑22B series , maximum 3,500 engine cycles between inspections; RB211‑524B4‑D‑02 , maximum 4,000 engine cycles between inspections; RB211‑524D4‑19, RB211‑524D4‑39, RB211‑524D4‑B‑19, RB211‑524D4‑B39, RB211‑524D4X‑19 and RB211‑524D4XB‑19 , at the "Normal shop visit interval" (Compliance table). Map engine cycles and normal shop visit intervals to your maintenance planning to ensure inspections are not missed.

6. Replace cracked shafts immediately. If the inspection finds a cracked LPT shaft, replace it with a "serviceable LPT shaft" prior to returning the engine to service (Requirement 3). Ensure replacement parts meet the serviceability standards and approval processes documented in the engine manual and organisational procedures. Record part numbers, serial numbers and certification documents for traceability.

7. Recordkeeping and evidence. Even though the AD does not specify records in the supplied text, maintain clear records that show the NMSB instructions were followed, the MPI technique used, findings of the inspection, any replacements made and the status of the engine before installation. These records support airworthiness certificates, regulatory audits and any later inquiries about compliance with the AD.

8. Liaise with stakeholders. Inform aircraft owners, lessors, and other affected parties of applicable inspections or replacements, particularly where shop visits or installations occur close to the AD effective date or when engines are moved between operators. Coordinate with parts suppliers to ensure availability of serviceable LPT shafts where replacement is necessary.

9. Coordinate with regulatory and international references. Take note of the AD’s reference to "EASA AD 2007‑0310R1 dated 8 January 2008" (Note 3). Operators with international operations should check whether additional or differing requirements apply under EASA or other jurisdictional ADs and reconcile action plans accordingly.

10. Quality assurance. Ensure that inspections and replacements are performed by personnel qualified to the organisation’s maintenance approvals and that the shop visit disassembly to "piece‑part level" is documented consistent with the engine manual and organisational maintenance release procedures. Because the AD ties its obligations to that disassembly state, ensure that shops and certifying staff explicitly document the disassembly level when performing the inspection.

Following these steps aligns maintenance actions with the AD text: inspect per Rolls‑Royce NMSB 72‑AF336 at the specified shop‑visit or cycle intervals, replace any cracked LPT shafts with serviceable parts, and document compliance before returning the engine to service.