AD/F100/90 - Electrical Power - AC Contactors

Applicability and scope: The AD is limited to F28 Mark 0100 aircraft "all serial numbers" except those already modified per SBF100‑24‑037 (Applicability). It therefore addresses a fleet-defined population rather than specific serial-numbered aircraft only.

Prescriptive maintenance action: The AD prescribes specific hardware work,removal of conventional nuts and lock washers and installation of self-locking nuts,and functional testing of the AC Bus Transfer System pursuant to the Accomplishment Instructions of Fokker Services SBF100‑24‑041 (Requirement 1). That testing is an integral part of the mandated rectification, not optional verification.

Parts control: The AD imposes a parts-installation restriction. Contactors P/N SG02206 "may not be installed on any aircraft as a replacement part, unless it has been modified in accordance with Goodrich Power Systems SB SG02206‑24‑01 dated 4 March 2008 or later revision approved by the EASA" (Requirement 2). This converts a maintenance action into an ongoing parts-control rule after the specified date.

Alternative compliance route: The AD explicitly allows an alternative compliance method: replacement of SG02206 with "improved versions in accordance with SBF100‑24‑037" is acceptable as an alternate method for Requirement 1, provided the replacement occurs within 36 months of the AD effective date (Note 1). Both the mandated action and the alternate route are tied to specific service bulletins and to EASA approval of later revisions.

Temporal structure: The AD sets two different time boundaries. For mitigations mandated by Requirement 1, the deadline is 36 months after the AD’s effective date. For the parts prohibition in Requirement 2, the operative date is "After 31 May 2011" (Compliance). The AD itself became effective on 31 July 2008.

Safety rationale and uncertain causal mechanism: The Background describes multiple incidents: electrical burning smell in the cockpit traced to "partly molten terminal" and heat damage to contactor studs, attributed to poor torque of the terminal/stud connection and possible subsequent loosening under vibration. Investigations also found some burned contactors where a "flat spring lock washer" suggested the connection had been fully torqued when overheating occurred. The AD states the "exact cause for the increase in temperature ... could not be determined" but observes that "an increase of the temperature inside the contactor could lead to reduction of the reliability of the contactor stud/terminal connection due to loss of lock washer tension" (Background). The AD therefore addresses mechanical retention (self-locking nuts), replacement/modification of the contactor, and post-work functional tests.

Regulatory cross-references: The AD anchors compliance and acceptability of revisions to the approval of the European Aviation Safety Agency. It also refers to EASA AD 2008‑0091 (Note 2), making EASA approvals and related service bulletins the reference instruments for methods of compliance.

Delegation and issuance: The AD was issued under the authority of the Civil Aviation Safety Authority, signed by a delegate (James Coyne) and dated 13 June 2008, with an effective date of 31 July 2008. The AD therefore functions as a CASA airworthiness requirement using service bulletin instructions as the technical execution standard.

Aircraft operators: Operators of F28 Mark 0100 (Fokker F100) aircraft are directly affected. The Applicability clause specifies "F28 Mark 0100 aircraft, all serial numbers" unless already modified per SBF100‑24‑037. Operators of those aircraft must ensure that the items and tests prescribed by the AD are performed within the compliance windows.

Maintenance organisations and maintenance personnel: Organisations that carry out aircraft maintenance, including licensed engineers responsible for structural/electrical work, must perform the hardware replacement (nuts and lock washers to self-locking nuts) and the AC Bus Transfer System tests "in accordance with the Accomplishment Instructions of Fokker Services SBF100‑24‑041" (Requirement 1). They must also ensure correct installation practices and retention of records sufficient to demonstrate compliance with the AD's requirements and timing.

Parts suppliers and component manufacturers: Suppliers of contactors P/N SG02206 and suppliers/distributors of improved versions defined in SBF100‑24‑037 are affected. The AD bars installation of unmodified SG02206 as a replacement after 31 May 2011 unless modified per Goodrich SB SG02206‑24‑01 (Requirement 2), which places a constraint on parts supply chains and inventory management for those supplying SG02206 or improved alternatives.

Continuing airworthiness managers and certifying staff: Personnel responsible for airworthiness compliance, continuing airworthiness management organisations (CAMOs) and authorised release certificate signatories must lodge, track and apply the AD’s compliance schedule: Requirement 1 within 36 months of the effective date, and the post‑31 May 2011 prohibition on unmodified parts. They also must determine whether particular aircraft are excluded because they were already modified per SBF100‑24‑037 on or after 2 October 2003 (Applicability).

Regulatory authorities and delegated agents: CASA, via its delegate who signed the AD, is the issuing authority. The AD explicitly references EASA-approved revisions to the named service bulletins as the instrument that defines the detailed technical work, so national regulators and maintenance organisations must rely on EASA approvals of later revisions to determine allowable methods (Requirement 1 and Note 1; Requirement 2).

Aircraft engineers and safety investigators: Engineers charged with root-cause analysis and recurrent inspections will take the AD as an instruction to eliminate a known source of cockpit smoke/fire risk linked to contactor terminal/stud overheating. The Background documents incidents of "partly molten terminal" and heat-damaged studs, and notes both under-torquing and possible temperature-induced loss of lock washer tension as potential mechanisms. That factual record will influence inspection and monitoring regimes.

Operators’ compliance planners and procurement: Those who schedule maintenance checks and manage spare parts inventories must plan to: (a) accomplish the mandated hardware change/test within 36 months of 31 July 2008; (b) ensure no unmodified contactors are installed as replacements after 31 May 2011 unless modified per Goodrich SB; and (c) accept replacement of contactors with improved versions per SBF100‑24‑037 as an alternate method, provided action is completed within the 36‑month window (Note 1 and Compliance).

Primary duties

• Execute the specified hardware modification: For aircraft that fall within the Applicability clause and are not already modified per SBF100‑24‑037, perform the work described in Requirement 1, namely remove standard nuts and lock washers from contactors P/N SG02206, install self-locking nuts, and "perform the applicable tests on the AC Bus Transfer System in accordance with the Accomplishment Instructions of Fokker Services SBF100‑24‑041 dated 29 January 2008 or later revision approved by the EASA" (Requirement 1).

• Implement parts-control restrictions: Do not install P/N SG02206 as a replacement part after 31 May 2011 unless it has been modified per Goodrich Power Systems SB SG02206‑24‑01 "or later revision approved by the EASA" (Requirement 2).

• Observe deadlines: Complete Requirement 1 "Within 36 calendar months after the effective date of this Directive." Ensure parts-prohibition compliance for Requirement 2 "After 31 May 2011" (Compliance).

Conditional rights and accepted alternatives

• Alternate method of compliance for Requirement 1: Operators may replace contactors P/N SG02206 with improved versions "in accordance with SBF100‑24‑037 or later revision approved by the EASA" as an acceptable alternative to the self-locking-nut modification, provided the replacement occurs within 36 months after the AD’s effective date (Note 1). That creates an operator right to choose replacement rather than retrofit when performed within the stated period and to EASA-approved service bulletin revisions.

• Use of later-revision service bulletins: The AD allows the use of "later revision[s] approved by the EASA" for both Fokker SBF100‑24‑041 and SBF100‑24‑037 and the Goodrich SB SG02206‑24‑01. That gives operators and maintainers a right to use updated technical instructions, but only to the extent those revisions have EASA approval.

Documentation and inspection obligations implicit in the duty: While the AD does not list specific recordkeeping steps within its text, performing the Accomplishment Instructions of a Fokker Service Bulletin and executing the prohibition on installation presupposes recordable maintenance actions, parts traceability and date-stamped compliance entries. Operators therefore have the de facto duty to document the modifications/replacements and the functional tests, consistent with their broader airworthiness obligations.

No statutory penalties specified in the AD text: The AD sets out required actions and compliance dates but does not, in its text, specify penalties or enforcement sanctions. The AD must therefore be read alongside the issuing authority’s enforcement framework, but the AD itself contains the operational duties (Requirements 1 and 2) and their timing (Compliance).

Rights to rely on EASA approvals: The AD repeatedly conditions acceptability on EASA approval of later revisions of the cited service bulletins and Goodrich SB. Operators have the right to rely on a revision only after it has the stated approval status.

Scope exclusions: If an aircraft "has been modified in service in accordance with Fokker Service Bulletin SBF100‑24‑037 dated 2 October 2003 or later revision approved by the EASA" it falls outside the AD’s Applicability. That is a specific right or exemption for aircraft already modified per that bulletin.

Operational discretion limited to technical choices within AD framework: Operators can select between the retrofit (self-locking nuts + testing) and the approved replacement route within the allocated time window for Requirement 1; beyond that window the AD imposes the parts-prohibition which constrains future installation options.

The AD text sets mandatory maintenance actions and dates but does not specify civil or criminal penalties, fines, or a particular enforcement procedure in its body. The document contains the procedural requirements (Requirements 1 and 2) and specific compliance windows (Compliance), but it does not itself include penalty provisions or an enforcement schedule.

Implication of mandatory compliance: The AD uses mandatory language,"Remove ... install ... perform ... in accordance with" and "may not be installed",which indicates non-discretionary obligations for applicable operators and maintainers. The AD’s issuance by the Civil Aviation Safety Authority (signed by James Coyne, Delegate, 13 June 2008) communicates it is an authoritative airworthiness instrument. In practice, such directives are instruments by which a regulator imposes continuing airworthiness obligations; however, the AD itself does not set out the regulatory sanctions for non-compliance within the text provided.

Enforcement mechanics not stated: The AD references service bulletins and EASA approvals for methods and revisions, but it does not describe how CASA will verify compliance, inspect records, or prosecute breaches. The document does not prescribe inspection frequencies, show-cause processes, notice periods for non-compliance, or administrative sanction mechanisms in its text.

Record-keeping and audit risk: Although the AD does not state record-keeping obligations, the requirement to perform the Accomplishment Instructions of a service bulletin and to avoid unmodified part installation logically gives rise to an audit trail requirement , maintenance entries, certification by authorised personnel, and parts-traceability documents will be necessary to demonstrate compliance if queried by the regulator. The AD itself does not state those documentary standards.

References to EASA approvals and service bulletin revisions: The AD conditions acceptance of later-service-bulletin revisions on EASA approval. Non-conformance with the specific, EASA‑approved documentation cited could therefore be used as a basis for regulatory action, but the AD text does not list the specific enforcement responses for such non-conformance.

No infringement notice language within the AD: The document does not contain an infringement-notice mechanism or specify monetary penalties, de‑registration, or grounding procedures in its text. Any enforcement action would therefore proceed under CASA’s broader regulatory powers and enforcement policies, which are not set out in this AD.

Reliance on EASA approvals: The AD repeatedly ties permissible methods of compliance and acceptable service bulletin revisions to "later revision approved by the European Aviation Safety Agency (EASA)." Specifically, both SBF100‑24‑041 and SBF100‑24‑037 are allowed only in their original forms or "later revision approved by the EASA" (Requirement 1 and Applicability; Note 1). The Goodrich SB SG02206‑24‑01 is likewise acceptable "or later revision approved by the EASA" (Requirement 2). This constructs an interface between CASA’s airworthiness directive and EASA’s approval process: operators must not only follow the service bulletin but ensure the revision used has EASA approval as required by the AD.

Integration with manufacturer Service Bulletins: The AD does not itself contain the technical steps beyond the high-level requirement; instead, it delegates detailed execution to Fokker Service Bulletin SBF100‑24‑041 for the nuts and testing, to SBF100‑24‑037 for replacement with improved contactors (as an alternate method), and to Goodrich Power Systems SB SG02206‑24‑01 for modification of replacement parts. The AD therefore interoperates with manufacturer and supplier technical documentation, making those service bulletins the operational instruments for compliance when used in the approved form.

Parts eligibility and continuing airworthiness rules: By prohibiting installation of unmodified P/N SG02206 after 31 May 2011 unless modified per an approved Goodrich SB, the AD creates a parts-eligibility rule that will interact with spare parts management, maintenance release processes, and continuing airworthiness obligations. Operators will need to ensure their parts procurement and installation policies reflect that restriction.

Airworthiness certification and release processes: The AD’s mandated tests (AC Bus Transfer System tests per SBF100‑24‑041) must be performed and, under standard continuing airworthiness practice, signed off by authorised personnel. Although the AD does not spell out certification mechanics, it interacts with the broader legal framework that requires authorised release certificates and records for maintenance actions.

Cross-references to other airworthiness directives: The AD expressly "refers" to EASA AD 2008‑0091 (Note 2). That creates a direct link between this AD and another AD that may contain complementary or parallel requirements. Operators must consider both documents together where relevant.

Exemptions and prior modifications: The Applicability clause excludes aircraft already modified in service in accordance with SBF100‑24‑037 dated 2 October 2003 or later EASA-approved revision. That establishes a carve-out that interacts with prior-modification records and may affect fleet-level compliance planning.

No textual reference to criminal statutes or civil penalty clauses: Within the AD text there is no citation to particular sections of Australian aviation law, criminal statutes, or administrative penalty provisions. Therefore, any enforcement action, sanctions or criminal liability would derive from broader aviation regulatory instruments or laws administered by CASA, which are not reproduced in the AD.

Operational safety overlay: The Background describes incidents of overheating, partial melting of terminals and possible arcing that "could lead to ... loss of electrical power systems, electrical arcing and fire/smoke in the cockpit." That technical safety framing interacts with mandatory safety-of-flight obligations and with any emergency directives that might be promulgated under other regulatory powers; however, the AD itself limits its instructions to the named mechanical and parts‑control measures.

Dates in the AD: The AD was signed on 13 June 2008 and states that it "becomes effective on 31 July 2008" (Compliance). The Compliance section sets specific windows: Requirement 1 "Within 36 calendar months after the effective date of this Directive" and Requirement 2 "After 31 May 2011."

References indicating amendment pathways: The AD repeatedly allows "later revision[s] approved by the EASA" for the Fokker Service Bulletins SBF100‑24‑041 and SBF100‑24‑037 and for the Goodrich SB SG02206‑24‑01. That language provides a mechanism for the AD to be implemented using updated technical documents without reissuing the AD itself, so long as those revisions receive EASA approval. Thus the AD is structured to accept technical updates via an external approval process rather than internal amendment.

Alternate method of compliance timing: Note 1 creates an alternative compliance pathway tied to SBF100‑24‑037, but it conditions that alternative on being "accomplished within 36 months after the effective date of this Directive." That creates a temporally limited amendment-like provision: the AD recognises a particular replacement action as equivalent to the retrofit only if done in that period.

No internal revision series shown in the text: The supplied AD text does not include a historical log of amendments to the AD itself (for example, no "AD/F100/90 Amendment 1" entries). Therefore, based on this document alone, the AD stands as issued with the stated effective date and compliance windows; any later changes would be reflected either in a separate AD or by EASA-approved revisions to the referenced service bulletins.

Dependence on external updates: Because the AD delegates detailed technical steps to service bulletins and recognizes their later EASA-approved revisions, the practical effect of any amendment to the work instructions will flow through service bulletin revisions that are subject to EASA review and approval. The AD thus embeds a conditional amendment pathway external to CASA: service bulletin updates that receive EASA approval become acceptable for compliance without the AD being reworded.

No recorded amendments or rescission in the supplied text: The document does not record prior ADs for this subject or subsequent amendments, nor does it show a rescission date. It does reference EASA AD 2008‑0091, but it does not indicate whether that EASA AD amends this AD or vice versa. Any subsequent changes after the effective date are not contained in this text.

The AD as provided does not contain or cite any judicial decisions, enforcement notices, appeals, or litigation arising from its issuance or from its subject matter. No cases, tribunals, or judicial reviews are referenced in the text. The AD refers to EASA AD 2008‑0091 and to particular service bulletins as technical instruments, but it does not record any litigation challenging the AD, the service bulletins, or the Goodrich modification.

Absence of judicial references: Because the AD contains no litigation references, there is no record within this document of administrative appeals, stays, injunctions, or contested enforcement actions relating to these requirements. The AD is a technical and regulatory instrument rather than a case report.

Implication for practitioners: For lawyers, compliance officers, or risk managers reviewing this AD, the absence of litigation history in the text means that one cannot infer from this AD whether disputes occurred in practice, or whether enforcement actions were taken under other regulatory instruments. The AD itself provides the operative requirements and compliance windows; any record of disputes, penalties, or judicial review would need to be sought outside this document.

Reference to EASA AD only as regulatory cross-link: The AD lists EASA AD 2008‑0091 (Note 2) but does not describe any legal outcomes connected to that EASA AD. In short, the supplied AD provides no litigation or adjudicative history.

Applicability carve-out and proof burden: The Applicability excludes aircraft "modified in service in accordance with Fokker Service Bulletin SBF100‑24‑037 dated 2 October 2003 or later revision approved by the EASA." Operators relying on that exclusion must be able to prove prior compliance with SBF100‑24‑037. Absent clear records demonstrating a compliant modification per the specified bulletin and EASA-approved revision, the aircraft remains within the AD’s scope and the operator must perform Requirement 1 or the alternate replacement within the 36‑month window.

Timing asymmetry between retrofit and parts prohibition: Requirement 1 must be met "Within 36 calendar months after the effective date of this Directive," while Requirement 2's prohibition operates "After 31 May 2011." The effective date of the AD is 31 July 2008, so operators must track these two separate dates. A common operational pitfall is treating all dates as identical; the AD imposes different operational constraints at different times.

Alternate compliance is time-limited: Note 1 permits replacing SG02206 with improved versions per SBF100‑24‑037 as an alternate method for Requirement 1, but only if the replacement is "accomplished within 36 months after the effective date." Replacement after that period may not be accepted as satisfying Requirement 1 and could leave the aircraft non‑compliant.

Dependence on EASA approvals: Multiple provisions permit only "later revision[s] approved by the EASA." Practitioners must confirm the approval status of any service bulletin revision before relying on it. Using a later revision that lacks EASA approval would not meet the textual conditions of the AD.

Parts control after the prohibition date: Requirement 2 bars installation of P/N SG02206 as a replacement "unless it has been modified in accordance with Goodrich Power Systems SB SG02206‑24‑01 dated 4 March 2008 or later revision approved by the EASA." If an operator sources SG02206 parts from stock, the parts’ modification status must be traceable; installing an unmodified part after 31 May 2011 would contravene the AD. Inventory management and parts tagging therefore become critical.

Uncertain cause but mandated mechanical fix: The Background states the "exact cause for the increase in temperature ... could not be determined" and documents instances in which terminals were improperly torqued as well as instances where evidence suggested a fully torqued connection at failure. The AD prescribes self-locking nuts or replacement/modification of the contactor as remedies despite the causal uncertainty. Practitioners should note that the AD addresses a failure mode symptomatically (retention and part redesign) rather than by eliminating a single identified cause.

Functional testing requirement: The AD requires "the applicable tests on the AC Bus Transfer System" per the Fokker SB SBF100‑24‑041. Operators must ensure that their maintenance procedures include the correct tests and that test results are recorded. Failure to perform the mandated tests or to follow the Accomplishment Instructions precisely could be a compliance gap.

Documentation and certification expectations implied: Although the AD does not specify recordkeeping requirements, demonstrating compliance to a regulator will require dated maintenance entries, certified release documents and parts-traceability records. The AD’s silence on documentary form is a practical risk; practitioners must ensure records meet regulatory standards outside this document.

Interactions with other ADs and service bulletins: The AD "refers" to EASA AD 2008‑0091 and ties acceptable methods to service bulletin revisions. Operators must be cautious not to assume that following a service bulletin printed after the AD is sufficient; the AD conditions acceptability on EASA approval.

Potential supply-chain friction: The prohibition on installing unmodified SG02206 after a fixed date imposes an obligation on parts suppliers and purchasers to verify modification status. Stockpiled unmodified parts may become unusable for F28 Mark 0100 installations post‑31 May 2011 unless modified per Goodrich SB, which creates a logistics and valuation issue for parts managers.

Identify applicability and records: First, determine whether each aircraft is within the AD’s Applicability: "F28 Mark 0100 aircraft, all serial numbers, unless modified in service in accordance with SBF100‑24‑037 dated 2 October 2003 or later revision approved by the EASA." Confirm with maintenance records whether SBF100‑24‑037 was previously applied. If so, document the service bulletin revision and any EASA approvals relied upon to support the exclusion.

Select method of compliance for Requirement 1 within the 36‑month window: The AD sets two pathways for Requirement 1. The primary pathway is to: (a) "Remove the standard nuts and lock washers from electrical power contactors part number ... SG02206"; (b) "install new self‑locking nuts"; and (c) "perform the applicable tests on the AC Bus Transfer System in accordance with the Accomplishment Instructions of Fokker Services SBF100‑24‑041 dated 29 January 2008 or later revision approved by the EASA" (Requirement 1). Follow the Accomplishment Instructions precisely, using the version of SBF100‑24‑041 that is either the dated bulletin or a later EASA‑approved revision. Record the work, with dates, part numbers, and signatory details for authorised personnel.

Alternate pathway for Requirement 1: Alternatively, replace contactors P/N SG02206 with "improved versions in accordance with SBF100‑24‑037 or later revision approved by the EASA" as an alternate method of compliance, but only if the replacement is "accomplished within 36 months after the effective date of this Directive" (Note 1). If choosing this route, ensure SBF100‑24‑037’s EASA approval status and use the instructions in the approved revision. Record the replacement details, including serial numbers of replacement parts and conformity to the service bulletin.

Comply with parts-installation restriction after 31 May 2011: For forward maintenance planning, do not install SG02206 as a replacement on any aircraft "unless it has been modified in accordance with Goodrich Power Systems SB SG02206‑24‑01 dated 4 March 2008 or later revision approved by the EASA" (Requirement 2). That means before installing any SG02206 part after 31 May 2011, obtain evidence that the part has been modified per the Goodrich SB and that the revision used is EASA‑approved where required. Update parts records and procurement procedures to reject unmodified P/N SG02206 stock for F28 Mark 0100 installation after that date.

Confirm service bulletin revision approvals: For any SBF100‑24‑041, SBF100‑24‑037 or Goodrich SB SG02206‑24‑01 revision intended to be used, confirm EASA approval status. The AD explicitly conditions acceptability on EASA approval of later revisions. Keep a copy of the revision and the approval reference to attach to maintenance records.

Perform AC Bus Transfer System tests and retention of results: The AD requires "the applicable tests on the AC Bus Transfer System." Ensure the testing procedures and pass/fail criteria match those in the Accomplishment Instructions of SBF100‑24‑041. Capture test data and sign-offs in the aircraft maintenance records. If tests indicate anomalies, follow the fault-resolution steps in the service bulletin and do not return the aircraft to service until the specified corrective actions are completed and documented.

Manage parts inventory and procurement: Immediately review spare parts inventory for SG02206 contactors. For parts due to be installed after 31 May 2011, verify modification per Goodrich SB or plan for replacement with improved versions per SBF100‑24‑037. Establish parts‑traceability tags or electronic records identifying modification status, modification dates, and the Goodrich SB revision applied.

Coordinate with suppliers and maintenance providers: Ensure Goodrich, Fokker Service Bulletin holders or parts suppliers can provide certified evidence of modifications or manufacture to the improved specification. For outsourced maintenance, include the AD compliance steps and documentation requirements in contracts or work orders.

Plan scheduling and resource allocation: Because Requirement 1 has a 36‑month window from the effective date (effective date 31 July 2008), schedule the retrofit or replacement work into maintenance plans so that the work completes within that timeframe. Implement compliance tracking mechanisms (e.g., compliance registers) to avoid missing the deadline.

Document compliance evidence: Even though the AD text does not prescribe exact recordkeeping formats, expected documentary evidence includes maintenance release entries, parts installation records (part numbers and serial numbers), signed statements that the Accomplishment Instructions were followed, and test results for the AC Bus Transfer System. Retain copies of the specific, EASA‑approved service bulletin revisions used and any supplier modification certificates for Goodrich SB modifications.

Consider fleet-level and operational impacts: If multiple aircraft require the modification or replacement, consider bulk procurement of improved contactors per SBF100‑24‑037 or batching maintenance events to minimise aircraft downtime. Ensure that planned maintenance supports the required testing and that ground maintenance slots provide sufficient time.

Verify compliance for excluded aircraft: For any aircraft claimed to be excluded because they were previously modified per SBF100‑24‑037, assemble and retain documentation proving the date and revision used, and verify that the revision relied upon was EASA‑approved if the exclusion language requires it.

Prepare for audits or regulatory queries: Given the AD’s mandatory nature and its reliance on EASA approvals, be prepared to produce traceable records of the work performed, the service bulletin versions and approvals used, and the proof that any SG02206 installed after 31 May 2011 was modified per the Goodrich SB.

Escalation path for ambiguity: If any ambiguity arises in the Accomplishment Instructions or the EASA approval status of a service bulletin revision, consult the issuing authority or the service bulletin originator (Fokker or Goodrich) for clarification and retain written confirmation of any technical direction relied upon.

By following the specified physical modifications, tests and the parts‑control prohibitions and by retaining the EASA‑approval evidence for any later-revision service bulletins, operators and maintainers will have implemented the requirements stated in AD/F100/90.