AD/DART/31 - Intermediate Pressure Turbine Disc

The AD is framed around a small set of technical and regulatory concepts, each carrying operational implications that follow from the instrument’s text.

• Applicability conditional on service bulletin revision status. The AD applies only to specified Rolls‑Royce Dart engine models "that have the Initial Issue or Revision 1, but not Revision 2 or later Revisions of Rolls Royce Service Bulletin (SB) Da72‑533 incorporated" and which "have not been subject to a dimensional inspection of the IPT disc in accordance with the Engine Overhaul Manual, Chapter 72‑61‑1" (Applicability). That places model identity and historic maintenance actions (which SB revision has been incorporated and whether a prior dimensional inspection has been carried out) at the centre of the applicability test.

• Dual inspection routes. The operator has two alternative inspection routes: (a) dimensional inspection in accordance with SB Da72‑538 dated 10 June 2005 or later approved revisions; or (b) ultrasonic inspection of the HPT/IPT disc seal arm in accordance with SB Da72‑536. The AD explicitly conditions the ultrasonic option by requiring a dimensional inspection if the ultrasonic inspection shows wear outside allowable limits (Requirement 1 and 2). This creates an inspection hierarchy where non‑destructive testing can be used, but may trigger the more definitive dimensional check.

• Corrective action tied to dimensional measurement. The AD requires rework or replacement of the IPT disc "if wear outside allowable limits has been established as a result of inspection per Requirement 1 of this AD" (Requirement 3). The AD therefore treats the dimensional inspection as the determinative measurement for repair/replacement obligations.

• Temporal limits and installation prohibition. Requirements 1 and 2 must be completed "after effective date of the AD, but not later than 31 January 2006" and Requirement 3 must be complied with "before installation of the IPT disc in the engine, after effective date of the AD" (Compliance). The instrument therefore imposes a hard calendar deadline for initial inspections and a continuing obligation tied to installation activity after the effective date.

• Cross‑reference to foreign AD and approval. The text notes "German LBA Airworthiness Directive (AD) D‑2005‑197, as approved by EASA under approval number 2005‑5848 dated 10 June 2005 refers" (Note). That locates this instrument within international certification activity and indicates the original technical prompt came from an LBA AD that has an EASA approval record.

• Safety rationale tied to historical failure mode. The Background identifies a recurring failure mode since 1972, with frettage between the HPT disc and IPT disc seal arms leading to high cycle fatigue initiating in the seal arm radius and, in extreme cases, HPT disc release. The AD's actions are "intended to prevent HPT disc failure, which can result in an uncontained engine failure and damage to the aircraft" (Background).

These concepts map to concrete procedural choices for operators: determine applicability by checking SB Da72‑533 incorporation and prior EOM‑Chapter 72‑61‑1 dimensional inspection history; choose an inspection method within the permitted options; perform dimensional inspection if ultrasonic shows unacceptable wear; and rework or replace IPT discs that fail the dimensional check. The AD’s binding dates and the "before installation" rule create operational windows and restrict permissible installation activity for engines within scope.

The AD identifies the affected population narrowly but with operational consequences for several parties. The source text names the directly affected engines and the condition under which they are subject to the AD. It also implicitly identifies the actors who will carry out the prescribed actions.

• Engine types and configuration. The Applicability clause lists a comprehensive set of Rolls‑Royce Dart turboprop engine models by model number (for example, 528‑7E, 529‑8Z, 532‑7L, 535‑2, 542‑10, 552‑7R and others) and then qualifies this list by SB‑revision status and inspection history. Only engines "that have the Initial Issue or Revision 1, but not Revision 2 or later Revisions of Rolls Royce Service Bulletin (SB) Da72‑533 incorporated and which have not been subject to a dimensional inspection of the Intermediate Pressure Turbine (IPT) disc in accordance with the Engine Overhaul Manual, Chapter 72‑61‑1" fall within the AD's scope (Applicability). That means the set of affected assets is the intersection of model numbers and maintenance history/engineering-configuration status.

• Aircraft operators and engine owners. The AD requires physical inspections and any necessary rework or replacement of IPT discs. Those actions will be carried out by the party responsible for engine airworthiness, typically the aircraft operator or the engine owner and their contracted maintenance organisation. The source does not explicitly name maintenance organisations or approval categories, but the nature of the mandated tasks (SB‑based inspections and rework/replacement) makes operators, maintenance providers and component suppliers the parties who will incur the labour and parts costs, and who will make operational choices (e.g. schedule maintenance, choose ultrasonic vs dimensional inspection).

• Maintenance engineers and shops. The inspections are specified to be performed "in accordance with" particular Rolls‑Royce service bulletins (SB Da72‑538 and SB Da72‑536) or with the Engine Overhaul Manual Chapter 72‑61‑1 for prior dimensional inspections. Those documents set technical procedures. Therefore, engineers and maintenance stations performing SB work and overhaul tasks will have to follow the relevant SB procedures to comply.

• Regulators and certifying authorities. CASA is the issuing authority, as indicated by the signature block and effective date statement. The AD also references a German LBA AD and an EASA approval number, linking the instrument to actions taken by other civil aviation authorities. The presence of these references means national regulators and possibly certification authorities will be involved in accepting SB revisions and cross‑approving inspection methods as "later approved revisions" of SB Da72‑538.

• Supply side (spare parts suppliers). Requirement 3 mandates rework or replacement of IPT discs if dimensional inspection reveals wear beyond allowable limits. When replacement is necessary, supply of appropriately conformed IPT discs and any approved rework capability will directly affect operators' ability to comply before installing IPT discs in engines after the effective date.

In short, the AD is targeted at a defined set of Rolls‑Royce Dart engines conditioned by SB revision status and prior inspection history. The actors that pay the costs and carry out the work are the engine owners/operators and their maintenance providers. Regulators are the decision makers for the AD itself and for approval of any later SB revisions referred to in the AD. The AD’s text establishes the allocation of responsibilities in terms of who must perform inspections, who must carry out corrective action, and when that work must be done.

The AD spells out a short list of duties that bind the persons responsible for the affected engines, and it also leaves some procedural discretion in the choice of inspection method. The source document does not frame duties as civil or criminal penalties; it simply prescribes inspection and corrective-action obligations.

Duties imposed by the AD

• Determine applicability. The operator must first determine whether an engine falls within the AD’s scope by checking the engine model against the list and verifying whether SB Da72‑533 at Initial Issue or Revision 1 has been incorporated and whether a prior dimensional inspection per Engine Overhaul Manual Chapter 72‑61‑1 has been performed (Applicability). This is a threshold duty implicit in any compliance effort.

• Carry out an inspection, by one of two methods, within the prescribed time. The AD requires that within the compliance window (after the effective date but not later than 31 January 2006) the operator must either:

  1. "Carry out dimensional inspection of the IPT disc in accordance with SB Da72‑538 dated 10 June 2005 or later approved revisions" (Requirement 1); or
  2. "Carry out ultrasonic inspection of High Pressure Turbine (HPT) / IPT disc seal arm in accordance with Rolls Royce SB Da72‑536" (Requirement 2).

• Condition on ultrasonic outcome. If the ultrasonic inspection "shows wear outside allowable limits," the operator must then perform the dimensional inspection per Requirement 1. This converts the ultrasonic option into a staged approach where further action is mandatory if non‑destructive testing indicates problems.

• Rework or replace IPT disc where dimensional inspection shows excessive wear. Requirement 3 states: "Rework or replace the IPT disc, if wear outside allowable limits has been established as a result of inspection per Requirement 1 of this AD." The AD also imposes a timing constraint on this duty: the rework or replacement must be effected "before installation of the IPT disc in the engine, after effective date of the AD" (Compliance).

Discretion and rights preserved in the AD

• Choice of initial inspection method. Operators have the right to select either the dimensional inspection or the ultrasonic inspection initially, subject to the consequences for the ultrasonic path described above (Requirement 1 and 2). The AD therefore preserves discretion to use a less invasive NDT method first.

• Use of later approved revisions of SB Da72‑538. Requirement 1 permits the dimensional inspection to be done "in accordance with SB Da72‑538 dated 10 June 2005 or later approved revisions." The operator may therefore rely on later approved revisions of the SB rather than the exact dated issue. The AD does not specify the approving authority for those later revisions in its text; it simply allows "later approved revisions."

• No prescribed schedule for rework methodology. The AD mandates rework or replacement when wear is outside allowable limits but does not prescribe the exact rework techniques or which organisation must perform the rework, beyond the requirement that the action be taken. Rework would be expected to follow manufacturer procedures, but the AD text itself simply declares the duty to rework or replace.

Silences in the instrument

• The AD does not set out recordkeeping, reporting or certification steps that operators must take to demonstrate compliance. It also does not specify who is authorised to perform the inspections (for example, licensed maintenance organisations or authorised service centres). Those are matters left to the operator and to other regulatory regimes outside this AD’s text.

• The AD does not specify approvals for "later approved revisions" of SB Da72‑538 in the AD text; it simply allows their use. The AD also does not specify criteria for acceptable ultrasonic inspection results other than that they be compared against "allowable limits" referenced in the SBs.

In sum, the AD imposes concrete maintenance duties: check applicability, perform one of two inspections within a set timeframe, perform a dimensional inspection if ultrasonic shows excessive wear, and rework or replace IPT discs where dimensional inspection indicates excessive wear, with the installation prohibition pending rework. It retains limited discretion over inspection route and use of later approved SB revisions, and leaves operational details such as recordkeeping and approval authorities unstated in the document.

The AD text itself does not include any explicit penalty provisions or a detailed enforcement regime. The instrument is issued by CASA and carries an effective date, but neither fines nor enforcement procedures are specified in the source document.

What the source does state

• Issuing authority and effective date. The document bears the signature block "James Coyne, Delegate of the Civil Aviation Safety Authority" and states "This Airworthiness Directive becomes effective on 4 August 2005." Those elements identify CASA as the issuing regulator and give the AD an effective date (signature block; effective date statement). The AD thus creates mandatory technical duties from that date forward for engines within its applicability.

• No penalties or enforcement steps in the AD text. The source does not contain language about sanctions, suspension or revocation of certificates, civil penalties, or criminal penalties. It also does not prescribe a verification or reporting process to CASA for confirming compliance. The AD specifies time limits for compliance and the technical requirements themselves, but leaves enforcement detail unarticulated in the document.

Operational implications of that silence (grounded in the source)

• Compliance deadlines apply. The AD sets deadlines: Requirements 1 and 2 must be completed "after effective date of the AD, but not later than 31 January 2006" and Requirement 3 must be satisfied "before installation of the IPT disc in the engine, after effective date of the AD" (Compliance). Those are mandatory obligations established by the AD text.

• Enforcement mechanism not described. Because the AD text does not state penalties, any sanctions, oversight or enforcement mechanisms will be applied only to the extent established elsewhere in law or by CASA policy and practice. The AD itself does not specify how CASA will verify compliance or what administrative or legal consequences will follow non‑compliance. The document’s silence on enforcement particulars means operators must rely on their own interpretation of how CASA will treat a failure to comply and on other relevant regulatory instruments outside the AD text for formal enforcement procedures.

• Practical enforcement risk remains. The absence of explicit penalty clauses in an AD does not alter the immediate technical obligation created by the instrument; an operator would still face operational and safety risks if they do not comply with the AD’s inspection and corrective action requirements. The AD’s stated safety rationale , prevention of HPT disc failure that "can result in an uncontained engine failure and damage to the aircraft" , underscores the safety consequence that motivates regulatory action (Background). The source, however, does not tie non‑compliance to any specified administrative or legal penalty within the AD text itself.

In summary, the AD imposes mandatory maintenance duties from an effective date, but the AD document supplied is silent on penalty schedules or the procedural steps CASA will follow to enforce those duties. The existence of compliance deadlines and a regulator’s signature indicates enforceability in regulatory practice, but details of enforcement and penalties are not set out in the AD text provided.

The AD explicitly references other regulatory and manufacturer material and thereby sits in a network of technical documents and foreign airworthiness directives. The source shows direct cross‑references but does not purport to amend other laws or set out its relationship to broader regulatory instruments beyond those references.

Cross‑references inside the AD

• Service bulletins and the Engine Overhaul Manual. The AD ties its inspection and corrective duties to Rolls‑Royce service documents and the engine overhaul manual: Requirement 1 refers to SB Da72‑538 dated 10 June 2005 or "later approved revisions"; Requirement 2 refers to SB Da72‑536; the applicability exemption depends on whether the engine "have been subject to a dimensional inspection of the IPT disc in accordance with the Engine Overhaul Manual, Chapter 72‑61‑1" (Applicability; Requirements). The AD is therefore implemented through manufacturer technical documents and the operator’s maintenance records that reference the Engine Overhaul Manual (EOM).

• Foreign AD and European approval. The AD includes a note: "German LBA Airworthiness Directive (AD) D‑2005‑197, as approved by EASA under approval number 2005‑5848 dated 10 June 2005 refers." That shows coordination with a foreign authority’s AD and an EASA approval record, situating CASA’s AD in an international regulatory context. The AD therefore interacts with decisions and technical findings made by other aviation authorities, but the AD itself does not reproduce or restate the foreign AD’s legal mechanisms.

What the AD does not state about interactions

• No claim to override other instruments. The AD does not explicitly state whether it supersedes or supplements other national directives or how conflict between SB versions and regulatory instruments should be resolved. It simply permits use of "later approved revisions" of SB Da72‑538, without naming who approves them in the AD text.

• No cross‑reference to airworthiness certification statutes or the Civil Aviation Regulations. The AD text supplied does not include an express statement linking compliance with the AD to the continuance of an aircraft’s airworthiness certificate, nor does it cite specific Civil Aviation Regulation provisions or enforcement statutes. Those legal relationships, if relevant, are not stated in the AD document provided.

Practical interface implications based on the AD’s wording

• Maintenance conformity. Operators and maintainers will need to reconcile SB procedures and the Engine Overhaul Manual with any national maintenance regulations and approval processes for organisations and individuals performing the inspections and rework. The AD prescribes the technical standards to be followed but leaves procedural approvals and enforcement to the broader regulatory framework that is not set out in the AD text.

• International coordination matters. Because the AD refers to a German LBA AD and an EASA approval number, operators who conduct maintenance across jurisdictions or who rely on foreign parts and overhaul approvals will see this AD as part of a coordinated international response to a recurring failure mode. The AD’s allowance for "later approved revisions" may mean that updated SB revisions approved by a foreign or domestic authority could be used to comply, but the AD text does not specify the approver.

In short, the AD interacts directly with manufacturer SBs and the Engine Overhaul Manual and references related foreign AD activity and EASA approval, but it does not, within its text, map how it interacts with or alters broader legislative instruments or enforcement regulations. The AD thereby delegates technical content to SBs and situates itself among international airworthiness directives without defining the complete legal interface in the document supplied.

The AD text supplied contains only limited explicit amendment history. It identifies the AD by number and date and references specific SB revisions; it does not include a legislative amendment log or subsequent changes within the document itself.

Items present in the instrument

• AD identification and date. The document carries the identifier AD/DART/31 and the date code "8/2005" visible in the heading elements. It also states "This Airworthiness Directive becomes effective on 4 August 2005" (effective date statement). The signature line is dated "24 June 2005," showing the document’s origin and approval timing.

• Service bulletin revision references. The AD’s applicability depends on the revision status of Rolls‑Royce SB Da72‑533: engines are in scope where they "have the Initial Issue or Revision 1, but not Revision 2 or later Revisions of Rolls Royce Service Bulletin (SB) Da72‑533 incorporated" (Applicability). Requirement 1 permits dimensional inspection "in accordance with SB Da72‑538 dated 10 June 2005 or later approved revisions." The text thus recognises that SB Da72‑538 may have later approved revisions available in future and explicitly authorises their use.

• Reference to prior ADs. The AD notes the relevant German LBA AD D‑2005‑197 and its EASA approval number 2005‑5848 dated 10 June 2005 (Note). That functions as a cross‑reference to another authority’s directive rather than as an amendment history.

Silences and implications

• No later amendments recorded in the text. The document supplied contains no subsequent amendment record (for example, no "amended on" entries or revised AD numbers). There is no indication within the supplied AD that it has been superseded or varied after the effective date.

• No explicit mechanism for future amendment laid out. The AD allows the use of "later approved revisions" of SB Da72‑538, but it does not set out a mechanistic pathway by which the AD itself would be amended in future. Any change to the AD would presumably be made by CASA through standard amendment procedures, but the AD text provided does not describe such processes.

• Temporal window and expiry. The AD sets deadlines for inspection and a continuing requirement tied to installation after the effective date, but the document does not state that the AD itself will expire, be repealed, or be superseded at a future date. The compliance deadlines for the initial inspections (by 31 January 2006) make the AD temporally focused, but the instrument remains on the record as an active directive from the effective date unless and until CASA issues an amendment or cancellation notice, which is not present in the supplied text.

In short, the AD as supplied contains the initial issuance metadata (AD number, code, signature date, effective date) and references to specific SB revision statuses. It permits future use of "later approved revisions" of a specified SB, but it does not document any subsequent amendments or provide a formal amendment history beyond the initial issuance and cross‑referenced foreign AD.

The source document contains no litigation history. It is an administrative airworthiness directive that records the safety rationale, specified inspections and corrective actions, cross‑references to Rolls‑Royce SBs and to a German LBA AD and an EASA approval number, and the issuing signature. It does not mention any court decisions, appeals, notices of dispute, or judicial review related to its issuance or enforcement.

What is in the text

• No cases or tribunal references. The AD makes no reference to legal proceedings, appeals mechanisms, or past litigation about these service bulletins or the AD itself.

• No administrative review details. The AD does not set out an internal review or appeal process for operators who might dispute applicability or compliance requirements; it simply prescribes the actions and effective dates.

Implication for researchers or litigators

• Absence of litigation record within the AD. Because the supplied document lacks any litigation record, any inquiry into disputes, appeals, or enforcement proceedings arising from this AD would require external research beyond the AD text , for example, searching CASA enforcement records, court or tribunal files, or industry press. The AD itself provides neither litigation references nor pointers to appeal mechanisms.

• Factual record of safety incidents. The AD’s Background records in‑service failures since 1972 and three instances of HPT disc release. That historical safety data is part of the AD’s factual predicate for regulatory action, but the AD text does not link those incidents to any specific legal claims or cases (Background).

Therefore, the AD as presented has no litigation history recorded inside it. Any litigation history would have to be found outside the document text.

The AD has several technical and administrative features that create practical pitfalls for operators and maintainers. These "gotchas" arise from the AD’s conditional applicability, the inspection‑route structure, timing constraints, document references and silences on procedural points.

• Applicability depends on specific SB revision status. Engines are in scope only if they "have the Initial Issue or Revision 1, but not Revision 2 or later Revisions of Rolls Royce Service Bulletin (SB) Da72‑533 incorporated" (Applicability). Operators who assume the AD applies by model number alone may be wrong. They must verify whether SB Da72‑533 Revision 2 or later has been incorporated; units with those later revisions are excluded from this AD’s scope. Misreading or failing to check incorporation records can result in unnecessary inspections or, conversely, failure to inspect engines that are in scope.

• Exemption by prior dimensional inspection. The applicability condition also excludes engines that "have been subject to a dimensional inspection of the IPT disc in accordance with the Engine Overhaul Manual, Chapter 72‑61‑1." If a dimensional inspection was done previously under the EOM procedure, the AD does not apply. Operators must verify historical maintenance records precisely: an earlier dimensional inspection must have been performed "in accordance with" that specific EOM chapter to trigger the exclusion. Ambiguity in records or differences in procedure could create uncertainty over applicability.

• Two inspection routes with a mandatory follow‑up on certain ultrasonic results. The AD allows ultrasonic inspection as an initial option (SB Da72‑536) but requires a dimensional inspection if the ultrasonic inspection "shows wear outside allowable limits" (Requirements 1 and 2). Operators using ultrasonic methods to avoid downtime may still be required to carry out dimensional inspection on parts that show marginal or excessive wear, potentially leading to unexpected shop time or replacement costs.

• "Later approved revisions" ambiguity. Requirement 1 permits dimensional inspection "in accordance with SB Da72‑538 dated 10 June 2005 or later approved revisions." The AD does not define who can approve later revisions or how to confirm that a revision is "approved" for AD compliance. This leaves a procedural risk: using a later SB revision without the proper approval channel could lead to non‑conformity with the AD. Operators should ensure that the SB revision used is indeed an "approved" revision as contemplated by the AD.

• Timing mismatch and operational scheduling. The AD becomes effective on 4 August 2005, but the signature block is dated 24 June 2005 and the compliance deadlines require completion no later than 31 January 2006 for Requirements 1 and 2. Operators scheduling maintenance across fleets must ensure inspections fall within the window, and parts or maintenance capacity shortages could make compliance within the deadline challenging.

• Installation prohibition effect. Requirement 3 requires rework or replacement "before installation of the IPT disc in the engine, after effective date of the AD." That creates a strict pre‑installation obligation. If a remanufacturer, shop or operator installs an IPT disc after the effective date without having satisfied the dimensional inspection or required rework, that installation would be contrary to the AD. Careful inventory tracking and maintenance control procedures are therefore necessary to prevent inadvertent non‑compliant installations.

• No procedural or recordkeeping steps specified. The AD does not require specific reporting to CASA or specify recordkeeping steps to evidence compliance. That silence means operators must rely on general maintenance record standards and any separate regulatory guidance for evidence of compliance. Failure to retain clear inspection records could complicate later regulatory enquiries.

• Reference to foreign ADs and approvals. The AD refers to a German LBA AD and an EASA approval number. Operators conducting cross‑border maintenance should ensure that any approvals relied on for SB revisions or inspection acceptance are recognised by CASA for compliance with this AD.

• Safety history concentrated on specific failure mode. The Background records that since 1972 there have been a number of HPT disc diaphragm failures and three resulting in HPT disc release; the AD fixes on frettage between HPT and IPT disc seal arms as the attributed cause and prescribes inspections addressing wear in the IPT disc and seal arm. Operators should be alert that the AD targets that specific failure mechanism; inspection plans should therefore follow the SB instructions closely to ensure the intended defect mode is addressed.

Each of these points is grounded in the AD text. The operational consequence is that accurate maintenance records, careful SB revision verification, cautious use of ultrasonic inspection as an initial pathway, and tight control of parts installation post‑effective date are necessary to avoid non‑compliance and the operational risks the AD addresses.

The AD prescribes a clear but limited set of steps. Compliance requires verifying applicability, selecting and carrying out the appropriate inspection route within the AD’s timeframes, and performing required corrective action before installation.

Step 1 , Verify applicability before acting

• Check engine model against the AD’s list of Rolls‑Royce Dart models in the Applicability clause.
• Confirm maintenance history: determine whether SB Da72‑533 Initial Issue or Revision 1 has been incorporated. If Revision 2 or later has been incorporated, the engine is excluded from this AD.
• Confirm whether a dimensional inspection of the IPT disc has previously been carried out "in accordance with the Engine Overhaul Manual, Chapter 72‑61‑1." If such a dimensional inspection has already been performed under that EOM chapter, the engine is excluded from this AD.

Step 2 , Choose initial inspection method and schedule it within the compliance window

• The AD permits two initial inspection options, both of which must be completed "after effective date of the AD, but not later than 31 January 2006" (Compliance):

  • Option A (dimensional inspection): "Carry out dimensional inspection of the IPT disc in accordance with SB Da72‑538 dated 10 June 2005 or later approved revisions" (Requirement 1). Confirm that the SB revision you will use is the specified dated issue or a later approved revision.
  • Option B (ultrasonic inspection): "Carry out ultrasonic inspection of High Pressure Turbine (HPT) / IPT disc seal arm in accordance with Rolls Royce SB Da72‑536" (Requirement 2).

• Plan for shop access and parts availability so the inspection can be completed before 31 January 2006. Coordinate with maintenance providers to ensure the chosen SB procedures and tooling are available.

Step 3 , Follow up based on inspection outcomes

• If you chose Option B (ultrasonic) and the ultrasonic inspection "shows wear outside allowable limits," you must carry out the dimensional inspection per Requirement 1. That dimensional inspection will determine whether rework or replacement is required (Requirements 1 and 2).

• If the dimensional inspection (whether performed as the initial Option A or as a follow‑up to Option B) establishes "wear outside allowable limits," you must "Rework or replace the IPT disc" (Requirement 3). Arrange for approved rework procedures or replacement parts as required.

Step 4 , Prevent installation of non‑compliant IPT discs

• The AD requires that, after the effective date, any IPT disc that has wear outside allowable limits as established by the dimensional inspection must be reworked or replaced "before installation of the IPT disc in the engine" (Compliance; Requirement 3). Do not install an IPT disc after the effective date unless it has been inspected and, where necessary, reworked or replaced in accordance with this AD.

Step 5 , Ensure documentation and proof of compliance (practical steps, not mandated in the AD text)

• The AD itself does not prescribe reporting or documentation steps. However, maintain contemporaneous records of:
  • Applicability determination (SB incorporation and EOM dimensional inspection history).
  • Dates and results of SB Da72‑538 dimensional inspections and/or SB Da72‑536 ultrasonic inspections.
  • Any rework or replacement actions taken, including parts serial numbers and workshop certificates.
  • Dates of installation of any IPT discs after the AD effective date, with cross‑reference to the inspection/rework records.

Step 6 , Reconfirm use of "later approved revisions" where applicable

• If planning to rely on a "later approved revision" of SB Da72‑538, ensure that the revision is properly authorised as an "approved revision" for the purposes of the AD. The AD permits "later approved revisions" but does not identify the approver; confirm the status of the SB revision through Rolls‑Royce and CASA channels, or by reference to any applicable regulatory approvals tied to the SB.

Step 7 , Liaise with regulator or manufacturer on uncertainties

• Where records are unclear about prior EOM Chapter 72‑61‑1 dimensional inspections, or where SB revision approvals are ambiguous, engage CASA or Rolls‑Royce for clarifications. The AD text ties compliance to those facts, and reliable determinations are necessary to avoid unnecessary inspections or to prevent overlooking required inspections.

Summary of timing and mandatory actions (AD text distilled)

• Effective date: 4 August 2005.
• By 31 January 2006 at the latest: complete either dimensional inspection per SB Da72‑538 (dated 10 June 2005 or later approved revision) or ultrasonic inspection per SB Da72‑536 (Requirements 1 and 2).
• If ultrasonic shows wear outside allowable limits: perform dimensional inspection per Requirement 1.
• If dimensional inspection establishes wear outside allowable limits: rework or replace IPT disc, and do so before installing the IPT disc in the engine after the AD effective date (Requirement 3; Compliance).

Following these steps, and maintaining clear records of the applicability determination, inspection method chosen, inspection results, and any rework/replacement, will align an operator with the obligations set out in the AD text. The AD itself does not set reporting obligations; nevertheless, good maintenance practice requires retention of the documents that demonstrate compliance with the AD’s technical requirements.