This airworthiness directive (AD) requires identification, repeated inspection and ultimate removal from service of specific main landing gear (MLG) axle pistons installed on Fokker Services F100 (F28 Mark 0100) aeroplanes where those pistons were overhauled by Aerospace NDI (ANDI) Pty Ltd using specified plating processes and process serial numbers. The AD is limited in scope to Goodrich MLG part numbers listed in the Applicability block, namely part numbers 41050 series (41050 -7 through -16) and 41060 series (-3 through -6) fitted with pistons part number 41141-7 that were treated using either the AeroNikl or Atotech plating processes and the enumerated process serial numbers. The Applicability also captures any MLG overhauled at ANDI while ANDI held CASA Certificate 1-RT6UE between 25 October 2019 and 18 November 2021 where either the AeroNikl or Atotech plating processes were used.

Mechanically the AD imposes two distinct duties. First, until affected pistons are removed, operators must carry out a detailed visual inspection (DVI) of the pistons prior to each flight, in accordance with Fokker Services All Operators Message (AOM) AOF100.230#5, “as in force at the date of this AD” (Requirement). The AD notes that pistons are marked with a serial number engraving near the torque link connection point, which is the means of physical identification. Second, the AD mandates permanent removal from service, and rendering unsalvageable, of all affected pistons (Requirement, b). Timing differs by plating process: pistons overhauled using the AeroNikl process must be removed by the AD’s effective date, and those overhauled using the Atotech process must be removed before 1 February 2024 (Compliance). The AD commences on 24 November 2022, which the text describes as the effective date (This AD commences on 24 November 2022 (the effective date)).

The AD is presented as an instrument to support Fokker Services AOM requirements and to implement an EASA notification concerning non‑compliance with SAE/AMS2424 plating process requirements. The Background identifies the technical hazard as internal hydrogen embrittlement leading to cracking and potential MLG axle piston failure with resultant dual wheel separation. The AD explicitly requires removal to prevent affected units entering the worldwide supply chain, in line with the EASA request to CASA.

The AD operates through three principal concepts: applicability by parts and treatment history, interim mitigation by inspection, and final mitigation by permanent removal and destruction. Applicability is narrow and part‑specific. The AD lists the aircraft model (F28 Mark 0100) and specific Goodrich MLG part numbers and piston part number 41141-7. It then lists discrete process serial numbers for two plating process providers, AeroNikl and Atotech, and captures any MLG overhauled at ANDI under a specified CASA certificate during a precise date window. This creates a testable inclusion rule for each installed piston: match aircraft model, MLG part number, piston part number, and either recorded process serial number or overhaul by ANDI in the defined period with the listed processes.

The DVI is the interim risk control. The AD prescribes a DVI “prior to each flight” until the affected pistons are removed from service, using Fokker Services AOM AOF100.230#5 as the inspection procedure. The AD notes the physical marking method for pistons, an engraving near the torque link connection point, which is the operational identification step to decide whether a piston is subject to the AD.

The final control is removal and rendering unsalvageable of all affected pistons. The AD distinguishes between pistons treated by AeroNikl, which must be removed by the AD’s effective date, and pistons treated by Atotech, which have a later removal deadline of 1 February 2024. The Background anchors the AD to an identified non‑conformity with the SAE/AMS2424 process standard, missing detailed process sheets and insufficient evidence that test specimens represented actual piston treatments. The cited hazard is hydrogen embrittlement, a metallurgical failure mode caused by improper plating or post‑plating handling that can induce cracking and lead to axle piston failure and dual wheel separation.

The AD references two kinds of external authorities. First, it supports Fokker Services All Operators Messages (AOMs), specifically AOF100.230#3 (earlier) and AOF100.230#5 (current reference for DVI). Second, it follows a notification from the European Aviation Safety Agency, which requested removal of the affected Atotech units prior to 1 February 2024 to safeguard airworthiness and prevent entry into the worldwide supply chain. The AD also references the SAE/AMS2424 process standard as the benchmark that was not complied with. Finally, the AD identifies the relevant ANDI CASA certificate number and the time window when ANDI operated as holder of that certificate, which is a determinant for applicability.

The AD affects a defined set of stakeholders directly and several groups indirectly. Primary actors who bear duties are air operators and aircraft maintenance organisations responsible for Fokker F100 (F28 Mark 0100) aircraft that have Goodrich MLG part numbers listed in the Applicability and pistons part number 41141-7 that were plated under the listed process serial numbers or overhauled at ANDI during the specified date window. The Requirement instructs operators to carry out detailed visual inspections prior to each flight, and to remove and render unsalvageable all affected pistons. Therefore, operators pay for the time and labour of inspections, the operational cost of potential flight delays or cancellations if an inspection grounds an aircraft, and the capital cost of replacing the removed pistons and any consequential maintenance required.

Maintenance organisations and shops that maintain or overhaul Goodrich MLG assemblies must confirm overhaul histories, process serial numbers and engravings, and, where necessary, remove and dispose of affected pistons. The Applicability clause extends to “any other MLG that was overhauled at Aerospace NDI (ANDI) Pty Ltd as holder of CASA Certificate 1-RT6UE between 25 October 2019 to 18 November 2021 using either the AeroNikl or Atotech plating processes.” That language pulls in MLG units where process serial numbers may not be recorded on the piston but the overhaul records show ANDI as the overhaul organisation in the defined timeframe.

Parts suppliers, lessors and operators of spare parts inventories are affected because the Background explicitly notes an objective of preventing affected units being introduced into the worldwide supply chain. The AD therefore has practical effects on spares management: affected spare pistons or MLG assemblies must be identified, quarantined and removed. This is a compliance cost to entities that hold inventory, and an opportunity cost where affected spares would otherwise be used.

Civil Aviation Safety Authority (CASA) is the issuing authority. The AD bears the signature of the CASA delegate, and the text records the AD’s commencement date. The AD references EASA as the agency that reported the non‑conformance with SAE/AMS2424 and requested removal. Fokker Services is referenced as the source of the inspection procedure (AOM AOF100.230#5) and earlier AOM directives. The AD therefore affects the chain of regulatory and manufacturer documents that operators must consult.

Indirectly affected parties include passengers and insurers. The AD imposes inspection and removal duties that can affect aircraft availability, which may have commercial consequences. The AD does not specify compensation regimes, insurance handling or commercial remedies; those are matters for operators, lessors and insurers to handle consistent with their contracts and broader regulatory enforcement frameworks.

Duties in the AD are explicit and prescriptive. The central duties are:

• Identification: Use piston serial number engraving near the torque link connection point to determine whether a piston is subject to the AD (Requirement, Note).
• Repeated inspection: Carry out a Detailed Visual Inspection (DVI) of the pistons in accordance with Fokker Services AOM AOF100.230#5, “as in force at the date of this AD,” prior to each flight until the pistons are removed (Requirement; Compliance a).
• Removal and disposal: Permanently remove all affected pistons from service and render them unsalvageable (Requirement b). For AeroNikl‑treated pistons the removal is required by the AD’s effective date; for Atotech‑treated pistons removal is required before 1 February 2024 (Compliance b).

The AD establishes the manufacturer’s AOM as the procedural reference for inspections. The text requires operators to follow Fokker Services AOM AOF100.230#5 “as in force at the date of this AD,” which means operators must obtain and follow the current AOM text referenced by the AD at the time of the AD’s commencement. The AD also notes a prior AOM (AOF100.230#3) that had earlier removal deadlines for AeroNikl components.

Rights are not set out in the AD. The AD text does not include provisions for alternative methods of compliance, derogations, exemptions, or an appeal mechanism within the AD itself. The document does not prescribe administrative review procedures or conditions under which a different inspection method might be accepted. Consequently, operators who believe alternative measures are appropriate must seek relief, if available, through the usual CASA administrative channels or other processes that are external to the AD text. The AD does not create a right to compensation or any other statutory entitlement; it imposes obligations that must be complied with under the terms stated.

Operationally, the AD preserves the operator’s ability to use Fokker Services AOMs as the inspection methodology. The AD does not prescribe other repair or replacement parts to use, other than requiring removal and rendering unsalvageable of the affected pistons. The AD does not provide a defined disposal method; it only requires that the removed pistons be rendered unsalvageable, which operationally means destroyed or otherwise rendered unusable so they cannot be reintroduced into service or the supply chain.

The AD text does not specify civil or criminal penalties, nor does it define the enforcement mechanisms to be used if an operator fails to comply. The document communicates mandatory aviation safety actions and contains an effective date; it does not set out administrative sanctions, fine levels, suspension regimes, or specific enforcement procedures in the body of the AD. The AD therefore operates as a prescriptive safety mandate, with enforcement logically falling within the broader regulatory powers and compliance framework of the Civil Aviation Safety Authority. The text itself, however, provides no explicit enforcement provisions or penalty schedules.

Because the AD is an instrument issued by CASA, enforcement of its requirements would be conducted under CASA’s general regulatory powers and enforcement processes rather than by penalty provisions contained within the AD. The AD’s text includes the signature of a CASA delegate and an effective date, which establishes its operative status. The Background notes EASA involvement and the supporting function of the AD in relation to Fokker Services AOM requirements, but it does not alter the lack of specific penalty clauses in the AD text.

In practice, enforcement options available to CASA outside the AD may include administrative action, grounding notices, suspension of air operator certificates, or other regulatory instruments, but those options are not described in this document. The AD therefore leaves the specific enforcement response to CASA’s wider regulatory toolkit and any applicable aviation legislation and enforcement policies that are external to the AD itself.

Operators should treat the AD as mandatory for covered components and should document compliance actions carefully. The AD’s requirements for pre‑flight inspections and for permanent removal from service are objective and verifiable, and non‑compliance can be demonstrated by absence of inspection records or by continued operation with identified pistons past the specified deadlines. The AD does not include instructions about reporting non‑conformance findings, but operators would typically report findings and corrective actions through normal maintenance release and regulatory reporting channels.

Within the AD text the instrument interacts directly with manufacturer guidance, an international aviation agency notification and an industry process standard. The AD explicitly supports, and cross‑references, Fokker Services All Operators Messages. The Requirement instructs operators to carry out inspections “in accordance with Fokker Services All Operators Message (AOM) AOF100.230#5, as in force at the date of this AD.” The Background states that AeroNikl components were required to be removed from service in accordance with Fokker AOM AOF100.230#3 before 1 March 2022 and that the CASA AD supports the requirements stated within the Fokker AOM. That establishes a direct textual link between CASA’s AD and the manufacturer’s operational instructions.

The AD references the SAE/AMS2424 process standard as the technical benchmark for the plating/treatment process. The Background signals that ANDI‑overhauled pistons were not compliant with SAE/AMS2424, that detailed process sheets were missing, and that there was insufficient proof that test specimens were representative of the process applied to the pistons. This anchors the AD’s safety concern to an industry standard, which is a technical point of interaction rather than a statutory cross‑reference.

The AD also reports a notification from the European Aviation Safety Agency. EASA’s request that remaining Atotech‑affected components be removed before 1 February 2024 is recited in the Background as the rationale for the Atotech removal deadline. This indicates international regulatory co‑ordination: CASA is implementing an AD that aligns with an EASA risk‑mitigation measure aimed at preventing affected components entering the worldwide supply chain.

The AD names Aerospace NDI (ANDI) Pty Ltd as the overhaul organisation and identifies the specific CASA certificate number held by ANDI during a stated period. That operational detail links the AD to CASA’s certification processes for maintenance organisations, but the AD does not itself modify certificate conditions. The AD’s Applicability leverages the fact of ANDI’s certificate status and the date window to capture items that may not have explicit process serial numbers recorded on the piston.

What the AD does not do, within its text, is expressly amend or vary any statutory provision, create new legislative offences, or set out a penalty regime. It does not modify the terms of CASA certificates, nor does it include procedural provisions for appeals, alternative compliance, or compensation. The AD functions as a safety directive that interfaces with manufacturer documentation, an industry standard and an international regulator’s request, leaving broader legal consequences and enforcement mechanisms to be found in the larger regulatory framework under CASA.

The AD document contains several date references and cross‑references to prior manufacturer communications, but the AD text itself does not record any formal amendments to the directive subsequent to its issuance. The document records that the AD commences on 24 November 2022 and carries the signature of the CASA delegate dated 24 October 2022. The AD identifies itself as AD/F100/98 and as 22/2022; the header shows “AD/F100/98” and “22/2022,” indicating catalogue and year identifiers used by the issuing authority.

The Background references prior Fokker Services AOM AOF100.230#3 which required removal of the affected AeroNikl components before 1 March 2022. The current AD cites Fokker AOM AOF100.230#5 as the operative inspection procedure, “as in force at the date of this AD.” Those cross‑references indicate a sequence of manufacturer messages, where earlier AOM #3 had an earlier removal expectation for AeroNikl components, and AOM #5 contains the inspection methodology the AD formally mandates. The AD therefore references an antecedent instruction from the aircraft manufacturer as part of its factual and regulatory context.

No text within the AD sets out revision dates for the AD itself, and there is no in‑document schedule of amendments or version history beyond the header identifiers, the signature date and the effective date. The AD’s application of Fokker AOM “as in force at the date of this AD” signals that future changes to that AOM after the AD’s commencement would not be automatically incorporated by the AD unless the AD is amended or reissued; operating personnel must follow the AOM that was current as at the AD’s date for the DVI requirement. The AD does not contain an express mechanism for amendment, and no subsequent amendments are included in the supplied text.

Operators should therefore treat the AD as having a fixed effective date and content as published, and should watch CASA notices and Fokker Services communications for any separate amendments to the AD or to the referenced AOMs. The AD as supplied documents the current state of requirements at the time of signature and commencement, and any changes to the AD would be expected to be issued as a separate instrument.

The supplied AD contains no litigation history. The document makes no reference to legal challenges, court decisions, administrative appeals, or precedent related to the AD. It cites EASA and Fokker Services communications, and it documents the technical rationale and compliance obligations, but it does not include any description of prior or subsequent court proceedings, enforcement actions, or legal disputes concerning the subject matter.

Because the AD itself is a regulatory instrument and does not contain a litigation record, stakeholders seeking information about litigation would need to consult CASA enforcement records, court databases, or other public records external to this AD. The AD does not set out any dispute resolution mechanisms, nor does it indicate the existence of contested applications or decisions. Consequently, there is no litigation history to summarise in the text provided.

Several operational and compliance pitfalls arise directly from the AD’s structure and wording that operators and maintenance organisations should note. First, identification depends on piston serial number engraving. The AD notes that “The pistons are marked by serial number by an engraving near the torque link connection point.” That means an operator must physically access and visually inspect the torque link area to confirm serial numbers, which can be time consuming and, in some maintenance configurations, require jacking or partial disassembly. If serial numbers are worn, obscured or unrecorded in maintenance logs, the operator must rely on physical inspection rather than paperwork alone.

Second, the Applicability breadth is precise but requires detailed record searches. The AD lists discrete process serial numbers for AeroNikl and Atotech. It also captures “any other MLG that was overhauled at Aerospace NDI (ANDI) Pty Ltd as holder of CASA Certificate 1-RT6UE between 25 October 2019 to 18 November 2021 using either the AeroNikl or Atotech plating processes.” Operators who have MLG with pistons lacking a recorded process serial number but with overhaul records showing ANDI as the overhauler in that date window must treat those parts as affected until proven otherwise. Consequently, incomplete maintenance records, parts transfers between aircraft, and parts in storerooms may cause unexpected identification duties.

Third, the AD creates a dual operational regime. Until removal, operators must carry out DVIs “prior to each flight” per Fokker AOM AOF100.230#5. That imposes a recurring operational burden until the pistons are removed. The AD also sets different removal deadlines by plating process: AeroNikl‑treated pistons must be removed by the AD’s effective date, and Atotech‑treated pistons must be removed before 1 February 2024. Operators must therefore both inspect daily and plan parts replacement and logistics to meet the deadlines, balancing inspection costs and replacement timing.

Fourth, the AD requires pistons be “permanently removed from service and rendered unsalvageable.” That wording is operationally significant. It prevents simple reconditioning or reissue of removed pistons within the air transport supply chain. Operators must decide how to render parts unsalvageable in a manner that satisfies audit and regulatory scrutiny, and they must prove disposition in records to demonstrate compliance with the AD’s intent to prevent reintroduction to the supply chain.

Fifth, the AD references Fokker Services AOM AOF100.230#5 “as in force at the date of this AD.” That creates a dependency on manufacturer documentation; operators must obtain the correct AOM version and ensure the DVI procedure used corresponds precisely to the AOM current at the AD date. If a later AOM revision appears after the AD date, the AD’s wording suggests operators must follow the AOM as it stood when the AD took effect, not necessarily subsequent revisions, unless a later AD or CASA guidance says otherwise.

To comply with the AD using only the measures and references contained in the AD, an operator should take the following sequential steps and record them for auditability.

1. Identify affected aircraft and components:

   • Search maintenance and overhaul records for the fleet to find F28 Mark 0100 aircraft with Goodrich MLG part numbers in the Applicability list: 41050‑7 through 41050‑16 and 41060‑3 through 41060‑6, fitted with pistons part number 41141‑7 (Applicability).
   • Search overhaul records for Aerospace NDI (ANDI) Pty Ltd as the overhaul organisation during the period 25 October 2019 to 18 November 2021, while ANDI held CASA Certificate 1‑RT6UE, and identify MLG that were overhauled by ANDI using AeroNikl or Atotech plating processes (Applicability).

2. Physically inspect pistons for identification marks:

   • For suspect pistons, perform a physical inspection to locate the serial number engraving near the torque link connection point; the AD notes this engraving as the identification method (Requirement, Note).

3. Cross‑check process serial numbers:

   • Compare the engraved serial numbers to the lists of AeroNikl and Atotech process serial numbers included in the Applicability. If a piston’s serial number matches any listed AeroNikl or Atotech serial number, classify it as affected. If the piston lacks a recorded process serial number but overhaul records show ANDI as the overhauler within the specified date window, classify it as affected.

4. Implement interim inspections:

   • Until the affected pistons are removed from service, carry out a Detailed Visual Inspection (DVI) of each affected piston prior to every flight, using Fokker Services AOM AOF100.230#5 as the inspection procedure, “as in force at the date of this AD.” Obtain the referenced AOM version current at the date of the AD and follow its inspection steps for each pre‑flight check (Requirement; Compliance a).

5. Schedule and carry out removal:

   • For pistons overhauled using the AeroNikl process, ensure removal from service by the AD effective date, 24 November 2022 (Compliance b(i)). For pistons overhauled using the Atotech process, schedule removal before 1 February 2024 (Compliance b(ii)).
   • Removal must be permanent and the pistons must be rendered unsalvageable (Requirement b). Record the date, location and method of disposal or destruction used to render pistons unsalvageable.