AD/JT8D/42 Amdt 1 - 8th Stage High Pressure Compressor Discs

The AD is a prescriptive, part‑specific safety measure focused on the 8th stage high pressure compressor (HPC) front hubs and HPC disks for named Pratt & Whitney JT8D engine variants. The main concepts are:

• Scope by model and part: The Applicability line names the JT8D engine variants covered , "JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17,-17A, -17R and -17AR" , and limits the parts to "8th stage high pressure compressor (HPC) front hubs as listed in Table 1 of FAA AD 2006-17-07R1." The instrument therefore ties domestic applicability to the FAA AD's Table 1 for precise part identification.

• Reference adoption with modification: The Requirement is to act "in accordance with FAA AD 2006-17-07R1 with a revised effective date of 26 October 2006." That means the AD does not itself recite all procedural detail but imports the FAA AD's mandatory actions, subject to the revised effective date and the listed corrections and relaxations.

• Remedial options: The Background summarises the remedial pathway in plain terms: parts that "have operated at any time with PWA 110-21 coating and that operated in certain engine models" must either be replaced, or undergo "visually inspecting and FMPI for cracking ... and re-plating them if they pass inspection." The inspection method named is fluorescent magnetic particle inspection (FMPI), a non‑destructive technique.

• Interaction with prior ADs: The Compliance paragraph explicitly treats prior inspections as counting toward compliance: "Any engine with a HPC front hub that has been inspected in accordance with AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07) counts as an inspection towards compliance with this AD." The instrument therefore recognises legacy inspection records under an earlier AD.

• Corrections and timing adjustments: The Background says the AD "makes necessary corrections to inadvertent reference errors and omissions found in FAA AD 2006-17-07, and relaxes some of the compliance times in Table 5." Thus the CASA amendment is not a verbatim adoption but changes cross‑references and some compliance intervals, while otherwise aligning with the FAA directive's structure.

• Effective date and legal force: The AD states an effective date and is dated and signed by a CASA delegate ("James Coyne, Delegate of the Civil Aviation Safety Authority, 23 October 2006"). The document therefore operates as an administrative amendment to the previous AD framework, with compliance obligations tied to the FAA AD text.

These concepts define a regime where specific parts are singled out for inspection or removal based on a coating history (PWA 110‑21), linked to a set of engine models, with compliance routed through an FAA AD that must be consulted for the detailed actions, tables and compliance times.

The instrument affects aircraft operators, maintenance organisations, parts suppliers and asset owners with the specified Pratt & Whitney JT8D engines and parts history. The Applicability expressly lists the engine models covered: "Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17,-17A, -17R and -17AR turbofan engines, with 8th stage high pressure compressor (HPC) front hubs as listed in Table 1 of FAA AD 2006-17-07R1." That wording identifies the class of engines and defers the precise part numbers and part‑markings to Table 1 of the FAA AD.

Who pays: operators owning affected engines will bear direct costs. The Background explains the prescribed remedial options: replacing HPC front hubs and HPC disks that have operated with PWA 110-21 coating, or performing visual inspections plus FMPI and re‑plating passing parts. Each action has operational and financial impact: replacement requires procurement of serviceable parts and downtime; FMPI inspections and re‑plating require maintenance shop time and specialist processes; record searches and traceability to determine whether a part "has operated at any time with PWA 110-21 coating" creates administrative work for operators and maintenance record-keepers.

Who decides and acts: Operators and maintenance organisations decide whether a part is to be replaced or inspected, but only within the constraints of the AD and the FAA AD it imports. The instrument also signals a regulatory decision by CASA to adopt the FAA AD with corrections and some relaxation to compliance times. The Compliance clause allows legacy inspections performed under "AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07)" to count toward compliance, which affects operators who already have those inspection records: such operators can apply those records rather than repeating inspections.

Supply chain and parts suppliers are affected because replacing HPC front hubs and disks will create demand for serviceable parts and potentially for re‑plating services. Maintenance facilities capable of FMPI and re‑plating will be required to carry out the specified inspections and corrective work. The text does not expand on availability of parts, lead times or cost allocation between lessors and operators; those practical allocations will be handled under existing commercial arrangements between asset owners and operators.

Finally, the instrument affects regulatory planners and safety managers within operators because it refers to additional documents (FAA AD 2006‑17‑07R1, Table 1, Table 5) which must be consulted to determine exact serialised part numbers, compliance intervals and the specific compliance reliefs that CASA provided.

The AD creates duties for operators and maintenance organisations by reference to the FAA AD and specifies one explicit counting rule for prior inspections. The central duty is to "Action in accordance with FAA AD 2006-17-07R1 with a revised effective date of 26 October 2006." That language makes the FAA AD's required inspections, replacements and re‑plating procedures mandatory for the applicable engines and parts, as of the revised effective date.

Duties expressed in the Background include either:

• replacing HPC front hubs and HPC disks that "have operated at any time with PWA 110-21 coating and that operated in certain engine models"; or
• "visually inspecting and FMPI for cracking of those parts and re-plating them if they pass inspection."

The AD also provides a specific administrative duty regarding compliance credit: "Any engine with a HPC front hub that has been inspected in accordance with AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07) counts as an inspection towards compliance with this AD." That creates a right for operators with such prior inspections to treat them as satisfying the AD's inspection requirement rather than repeating the work.

The instrument does not list appeals, exemptions or alternative methods of compliance (AMOCs) in the text provided; it likewise does not set out rights to defer compliance or specify approval processes within this document. The only explicit modification to the FAA AD is stated in the Background: the AD "makes necessary corrections to inadvertent reference errors and omissions found in FAA AD 2006-17-07, and relaxes some of the compliance times in Table 5." That is a limited right‑shaping mechanism in CASA's favour; operators must consult the amended timing in the final CASA text (or the referenced FAA AD as amended) to know whether they have longer or shorter compliance windows.

The AD establishes duties in a technical sense (inspection/replacement/re‑plating) and an evidentiary duty to demonstrate that prior inspections under AD/JT8D/29 Amdt 2 count toward compliance. The text does not specify documentation form, but the counting rule implies that maintenance records must be available to demonstrate prior compliance.

Rights in the text are limited and procedural: the right to rely on prior inspections covered by the stated AD. No other procedural remedies or discretionary reliefs are provided in the supplied instrument.

The supplied AD text does not specify penalties, sanctions or enforcement procedures. The document frames the actions as required "in accordance with FAA AD 2006-17-07R1 with a revised effective date of 26 October 2006" and sets an effective date of "26 October 2006," but it does not recite any enforcement clause, civil or criminal penalty, or administrative sanction in the content provided.

Because the instrument does not itself set out enforcement mechanisms, the text is silent on whether failure to comply will attract a specific fine, certificate suspension, grounding order, or other administrative penalty. The AD does explicitly create mandatory technical obligations by reference to the FAA AD, which in practice establishes a compliance expectation for airworthiness; however, any regulatory enforcement action, penalty regime, or process for seeking an alternative method of compliance is not addressed in the supplied material.

The absence of enforcement detail in this text creates practical implications for operators and maintainers: they must treat the AD as imposing immediate technical duties while recognising that the text here does not articulate how non‑compliance will be processed. The document does include an administrative attribution , "James Coyne, Delegate of the Civil Aviation Safety Authority, 23 October 2006" , indicating the instrument's origin in CASA, but no enforcement provisions are included.

Operators should therefore consult the broader regulatory framework and CASA guidance (not included in the supplied text) to determine the enforcement consequences, acceptable evidence of compliance, and any procedural routes for relief. The AD does provide at least one specific compliance concession , prior inspections under AD/JT8D/29 Amdt 2 will "count as an inspection towards compliance" , which functions as an administrative recognition of prior work; though the mechanism by which evidence is accepted or validated is not set out here.

In short, the AD makes technical requirements explicit but is silent in the supplied text about penalties and the formal enforcement process; those matters are either handled elsewhere in CASA's regulatory instruments or in the broader statutory enforcement powers of the regulator not reproduced in this document.

This AD expressly imports and modifies another administrative instrument: it requires action "in accordance with FAA AD 2006-17-07R1 with a revised effective date of 26 October 2006" and refers to Table 1 and Table 5 of that FAA AD. The Compliance paragraph also links to an earlier AD: "Any engine with a HPC front hub that has been inspected in accordance with AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07) counts as an inspection towards compliance with this AD." Therefore, this instrument is explicitly networked to at least two FAA airworthiness directives and treats those instruments as the substantive source of inspection content, part lists and compliance intervals.

Because the CASA AD imports the FAA AD's content, operators must read the FAA AD 2006-17-07R1 (and its tables, including Table 1 and Table 5) to obtain the detailed actions and specific part identifiers. The CASA text states that it corrects "inadvertent reference errors and omissions found in FAA AD 2006-17-07," and "relaxes some of the compliance times in Table 5," which means that CASA has not only adopted but also modified the FAA AD's references and timing. The CASA AD therefore co‑operates with, and overrides where stated, certain elements of the FAA text for operations under CASA's jurisdiction.

No other statutes, regulations, or international agreements are cited in the provided text. The instrument does not state how it interacts with Australian civil aviation legislation or with repair station approvals, maintenance release obligations, or export/import controls; those interactions are not addressed in the supplied material. The AD is an administrative amendment that relies on FAA technical content for details. Consequently, operational compliance requires cross-referencing: the CASA AD determines the domestic legal incidence, while the FAA AD supplies the technical methodology and part lists.

The text therefore creates a layered compliance architecture: (1) CASA's AD imposes the duty in Australia, (2) USA FAA AD 2006-17-07R1 supplies the technical requirements and the detailed tables, and (3) prior AD/JT8D/29 Amdt 2 inspections are eligible as compliance credit. Any practical or legal questions about precise part numbers, compliance intervals or the intended corrections to reference errors will be resolved by consulting the FAA AD, the referenced tables, and any errata or corrigenda to those FAA materials. The supplied text does not provide direct cross‑references to Australian maintenance standards beyond importing the FAA AD.

The supplied instrument itself is an amendment to AD/JT8D/42, styled "AD/JT8D/42 Amdt 1." The text records that "This Amendment becomes effective on 26 October 2006." It also notes that "The original issue of this AD became effective 26 October 2006." The signature block indicates the administrative act was dated "23 October 2006" and signed by "James Coyne, Delegate of the Civil Aviation Safety Authority."

The Background explains the purpose of the amendment: to require the same actions as FAA AD 2006-17-07 but to "make necessary corrections to inadvertent reference errors and omissions found in FAA AD 2006-17-07, and relaxes some of the compliance times in Table 5." That describes the nature of the amendment , corrective referencing and timing relaxation , rather than a change in substantive remedial technique.

There is also an explicit cross‑reference to an earlier AD: "Any engine with a HPC front hub that has been inspected in accordance with AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07) counts as an inspection towards compliance with this AD." That indicates a lineage of related ADs: AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07) is the antecedent whose inspections can be credited; AD/JT8D/42 (the original AD) has been amended by Amdt 1, and this Amdt 1 adopts FAA AD 2006‑17‑07R1 subject to corrections.

The instrument therefore establishes a short amendment chain recorded within the text: original AD/JT8D/42 issued and effective 26 October 2006; AD/JT8D/42 Amdt 1 (this instrument) effective 26 October 2006; the amendment’s date in the signature block is 23 October 2006, consistent with an administrative signing prior to the effective date. The supplied material does not list any other previous or subsequent amendments, nor does it include a schedule of revisions beyond the textual statements about corrections and Table 5 relaxations.

Readers should note that the detailed corrections to FAA AD 2006-17-07 and the specific changes to Table 5 compliance times are not reproduced in full in the supplied text; the amendment history references those corrections and relaxations but leaves the particulars to the FAA AD and its tables as modified by CASA.

The supplied AD text contains no litigation history. It does not name any court proceedings, administrative appeals, judicial reviews, or cases either challenging or upholding the AD or the FAA AD it references. No judicial decisions or enforcement actions are cited in the material provided.

Because the document is silent on litigation, there is no record in this source of legal contests over the AD's content, procedural adequacy, or enforcement. The absence of litigation history in the text supplied means readers cannot rely on any precedent history, judicial interpretation, or contested enforcement outcomes to interpret ambiguous terms in the AD; any such interpretive or procedural guidance would need to be sought elsewhere.

Practically, the lack of litigation history in the AD makes two points relevant for practitioners reviewing this source: first, the instrument should be read on its face and against the FAA AD without expecting court‑crafted interpretive gloss in this document; second, if ambiguity exists (for example between the Applicability list and the Background’s list of engine models), the absence of judicial clarification in the supplied text means operators will need to resolve ambiguities by consulting the FAA AD tables, seeking regulatory clarification from CASA, or relying on maintenance‑industry practice and internal legal advice.

The text also does not include any description of administrative challenge mechanisms, review periods, or processes for seeking an alternative method of compliance (AMOC). Those pathways, if available, are not referenced here. Therefore, for any party contemplating a legal challenge, seeking an exemption or testing the AD’s interpretation, the supplied text provides no procedural history or guidance on prior caselaw or administrative determinations.

This instrument has several practical traps for the unwary, as shown in the text supplied:

• Dependence on FAA AD tables not included here: The Applicability defers to "8th stage high pressure compressor (HPC) front hubs as listed in Table 1 of FAA AD 2006-17-07R1." The CASA AD therefore does not itself list the precise part numbers, serials or part‑markings; users must consult the FAA AD Table 1 to identify which physical parts are in scope. Failure to consult the FAA table may lead to under‑ or over‑identification of affected parts.

• Inconsistent lists between Applicability and Background: The Applicability names a set of JT8D variants (up to -17AR). The Background, however, states the PW investigation found that parts "that ever operated on JT8D-15, -15A, -17, -17A, -17R, -17AR, -209, -217, -217A, -217C, and -219 turbofan engines, could crack before reaching their published life limit." That Background list includes additional model designations (-209, -217 series, -219) not mirrored in the Applicability paragraph. This creates an ambiguity: the operative Applicability controls, but the Background suggests a broader technical concern. Operators must resolve the scope by reference to the FAA AD’s Table 1 and, if necessary, seek regulatory clarification.

• Credit for prior inspections is narrow and specific: The Compliance clause gives credit only for inspections "in accordance with AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07)." If an operator has conducted an inspection under a different procedure or under internal maintenance practice, that work may not qualify as compliance credit. The text requires the specific prior AD inspection to count.

• Technical requirement for FMPI and re‑plating: The Background specifies FMPI for cracking and re‑plating if parts pass inspection. FMPI and re‑plating are specialised services; not all maintenance facilities can perform them to aerospace standards. Operators must verify that their providers have the requisite capability and that records are producible.

• Timing adjustments are not reproduced: The Background notes that CASA "relaxes some of the compliance times in Table 5." However, the relaxed timings are not printed here. Assuming FAA timings without checking for CASA's relaxations could result in unnecessary accelerated work or missed relief. Operators must obtain the CASA‑amended Table 5 or an explicit statement of the revised times.

• Effective date and retroactivity: The AD becomes effective 26 October 2006. Any actions performed prior to that date may or may not be creditable, depending on whether they match the specified earlier AD (AD/JT8D/29 Amdt 2). The supplied text does not provide a full transition rule beyond the single counting clause, so careful record review is needed.

• Relying on the Background for obligations: The Background summarises required actions but the operative requirement is the cross‑reference to the FAA AD. Practitioners must not treat the Background narrative as the complete compliance text. The formal obligation is to "Action in accordance with FAA AD 2006-17-07R1" as modified.

• No enforcement language or AMOC described: The AD does not set out enforcement procedures or alternative compliance pathways in the supplied text. If an operator needs deviation or an alternative method of compliance, this document provides no procedural route; the operator will need to consult CASA or other regulatory guidance not included here.

These "gotchas" derive directly from the way the AD imports and modifies another instrument, and from the limited content reproduced in the supplied text. The safe course is to consult the FAA AD's tables and the full CASA amendment text to resolve these practical ambiguities.

Compliance in practice requires several concrete steps, since the CASA AD imports the FAA AD for procedural detail. Based on the supplied text, a compliance checklist would include the following actions:

1. Identify affected engines and parts:

   • Match fleet records against the Applicability list: "Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17,-17A, -17R and -17AR turbofan engines."
   • Consult Table 1 of FAA AD 2006-17-07R1 to determine the precise part numbers and part markings for "8th stage high pressure compressor (HPC) front hubs" included in scope.

2. Determine coating history:

   • For each HPC front hub and HPC disk, establish whether the part "has operated at any time with PWA 110-21 coating." This requires historical maintenance records, overhaul reports, and plating/re‑plating records.

3. Review prior inspections for credit:

   • If an engine's HPC front hub was inspected "in accordance with AD/JT8D/29 Amdt 2 (FAA AD 2003-12-07)," document that inspection precisely, as the Compliance paragraph entitles such inspections to count toward compliance. Ensure records show the inspection met the AD/JT8D/29 Amdt 2 procedure requirements.

4. Consult FAA AD 2006-17-07R1 and applicable CASA corrections:

   • Read FAA AD 2006-17-07R1 for the detailed inspection procedures, FMPI parameters, acceptance criteria, replacement thresholds, and Table 5 compliance intervals.
   • Obtain CASA's amended version or guidance to identify the "revised effective date of 26 October 2006," the corrections to "inadvertent reference errors and omissions" and the "relaxed" compliance times in Table 5. Do not rely solely on the FAA AD's unamended text.

5. Execute the specified technical work:

   • For parts that "have operated ... with PWA 110-21 coating" and are in the listed engine models, either replace the HPC front hub/HPC disk as required, or perform the visual inspection plus FMPI for cracking.
   • If FMPI is passed, arrange for re‑plating consistent with the requirements in FAA AD 2006-17-07R1 (re‑plating process and specifications must be referenced in the FAA AD).

6. Maintain and produce records:

   • Keep definitive records showing part identification, coating history, inspection procedures used (including FMPI reports), findings, re‑plating certificates, and part replacements. The Compliance clause that credits AD/JT8D/29 Amdt 2 inspections implies records will be needed to claim credit.

7. Programme fleet maintenance:

   • Adjust maintenance schedules to accommodate any required inspections or replacements within the required compliance windows. Because CASA relaxed some compliance times in Table 5 (per the Background), verify whether your fleet enjoys any additional time before the required action or whether the FAA AD timing still applies.

8. Seek clarification if scope is unclear:

   • Where the Background suggests a broader set of engine models (for example, the mention of JT8D-209, -217, -217A, -217C, -219) than the Applicability paragraph, obtain CASA clarification or confirm with the FAA AD Table 1 which specific engines and parts fall within scope. Do not assume the Background list creates additional obligations beyond the Applicability paragraph.

9. Coordinate with parts suppliers and maintenance providers:

   • Secure replacement HPC front hubs and HPC disks if replacements are required, or confirm availability of FMPI and re‑plating services and their compliance with the technical standards called up by the FAA AD.

10. Monitor regulatory updates:

• The AD amends an earlier instrument and refers to FAA material. Monitor CASA and FAA for any further amendments, corrections, or guidance, particularly any published errata to Table 1, Table 5, or the referenced AD numbers.

These steps follow directly from the operative clauses of the supplied text: the Requirement to act in accordance with FAA AD 2006-17-07R1 as of 26 October 2006, the explicit mention of FMPI and re‑plating in the Background, and the Compliance credit for prior inspections under AD/JT8D/29 Amdt 2. The critical compliance action is therefore not contained entirely within the CASA text provided, and full compliance requires consulting the referenced FAA AD and any CASA amendments or explanatory material that specify the corrections and relaxed timings described in the Background.