AD/F50/99 - Electrical Power - AC Contactors

Applicability and exclusions, mandated modification or testing, an accepted alternative compliance route, and a parts‑installation prohibition are the AD’s core concepts. Applicability is stated narrowly: F27 Mark 050 and Mark 0502 aircraft, all serial numbers, unless they were modified during production to incorporate Fokker ECR 51780 or were modified in service in accordance with Fokker Service Bulletin SBF50-24-030 dated 6 November 2003 or a later EASA‑approved revision. That language places two explicit carve-outs from the AD’s mandatory actions for aircraft already modified either in production or by an earlier service bulletin revision approved by EASA.

Requirement 1, the operational core, obliges removal of the standard nuts and lock washers from SG02206 contactors, installation of new self‑locking nuts, and performance of the applicable AC Bus Transfer System tests, following the Accomplishment Instructions of Fokker Services SBF50-24-031 dated 29 January 2008 or a later EASA‑approved revision. The AD explicitly accepts an alternate method: full replacement of SG02206 contactors with improved contactors per SBF50-24-030 or later EASA‑approved revision, but only if accomplished within the same 36‑month compliance window.

Requirement 2 creates a forward-looking restriction on spare parts: SG02206 contactors may not be installed as replacement parts on any aircraft after 31 May 2011 unless they have been modified per Goodrich Power Systems SB SG02206-24-01 dated 4 March 2008 or a later EASA‑approved revision. The AD therefore regulates both in‑service modification of fitted components and the permissibility of future installations of the same part number.

Background material in the AD explains the operational safety rationale: incidents of overheating, molten terminals, heat damage to studs, and electrical arcing tied to poor torque or lock washer tension on the terminal/stud connection within SG02206 contactors. The AD identifies the contactor locations in the aircraft electrical system, namely Generator Line Contactor, Bus Tie Contactor, Auxiliary Power Contactor and External Power Contactor, and links the condition to risk of loss of electrical power, arcing, and cockpit fire or smoke.

The AD repeatedly ties acceptability of technical documents to EASA approval, so the operative technical instructions are those Accomplishment Instructions or service bulletins that have EASA endorsement. The effective date of the AD is 31 July 2008 and the compliance period for Requirement 1 is 36 calendar months from that date.

The Directive directly affects operators and maintenance organisations responsible for F27 Mark 050 and Mark 0502 aircraft that have, or may install, Electrical Power Contactors P/N SG02206. The AD’s Applicability clause specifies those aircraft “all serial numbers,” excluding only aircraft modified in production to incorporate Fokker ECR 51780 or modified in service per Fokker Service Bulletin SBF50-24-030 dated 6 November 2003 or later EASA‑approved revision. Therefore the primary duty-bearers are aircraft operators, aircraft owners, and the maintenance organisations that perform scheduled and unscheduled work on these aircraft.

Maintenance supply chains and parts suppliers are also affected by Requirement 2, which prohibits installation of SG02206 contactors as replacement parts after 31 May 2011 unless the contactor has been modified in accordance with Goodrich Power Systems SB SG02206-24-01 dated 4 March 2008 or later EASA‑approved revision. That provision changes the market for replacement contactors by conditioning acceptability on an approved modification, thereby imposing a compliance requirement on the vendors and on maintenance shops that purchase and fit those parts.

Certifying authorities and delegated representatives are implicated by the AD’s cross‑reference to EASA approvals. The AD makes specific work instructions mandatory only when performed in accordance with the referenced Fokker and Goodrich service bulletins or later EASA‑approved revisions. Consequently, the regulatory compliance status of any particular revision of a service bulletin is material to applicability and to whether an alternate method is acceptable.

Aircraft lessors and financiers should take note because the Directive introduces a mandated modification and part‑installation prohibition that may affect maintenance planning and asset availability. The AD imposes a timeline, requiring the primary modification or test within 36 calendar months of the AD’s effective date, which has operational consequences for scheduling maintenance windows.

Finally, the AD’s background links the condition to safety risks in multiple electrical system locations: Generator Line Contactor, Bus Tie Contactor, Auxiliary Power Contactor and External Power Contactor. That linkage suggests multiple system components on affected aircraft could require inspection or action, potentially broadening who must act beyond a narrow subpopulation of aircraft.

The Directive imposes discrete duties and prescribes acceptable methods of compliance. Key duties are:

• Identify applicability. Operators and maintainers must determine whether an aircraft falls within the AD’s applicability, taking into account the stated exclusions for production or in‑service modifications (Applicability clause).
• Carry out Requirement 1 within the stated compliance window. For aircraft to which the AD applies, remove standard nuts and lock washers from Electrical Power Contactors P/N SG02206, install new self‑locking nuts, and perform the applicable AC Bus Transfer System tests per the Accomplishment Instructions of Fokker Services SBF50-24-031 dated 29 January 2008 or a later EASA‑approved revision (Requirement 1 and Compliance clauses).
• Alternatively, replace the contactors with improved versions. The AD expressly permits replacement of SG02206 with improved contactors in accordance with SBF50-24-030 or later EASA‑approved revision as an alternate method of compliance for Requirement 1, provided the replacement is accomplished within 36 months after the AD’s effective date (Note 1).
• Observe the parts‑installation prohibition. Do not install SG02206 contactors as replacement parts on any aircraft after 31 May 2011 unless the part has been modified in accordance with Goodrich Power Systems SB SG02206-24-01 dated 4 March 2008 or a later EASA‑approved revision (Requirement 2 and Compliance clauses).

Rights and discretion embedded in the Directive are limited and procedural. The AD conditions technical compliance on following the Accomplishment Instructions of the referenced Fokker and Goodrich service bulletins or later revisions approved by EASA. That effectively delegates technical detail and approved procedures to those documents rather than to the AD text. It also provides an alternate accepted method of compliance, giving operators a choice to perform either the nut/washer modification plus testing or to replace contactors with an improved version within the compliance window.

The AD does not in its text specify exemptions, tolerances for delayed compliance, or an application process for alternative methods outside the described alternate compliance route. The only formal discretion expressly recorded is the acceptance of later revisions of the referenced service bulletins, but only if those revisions are approved by EASA. The AD therefore centralises technical certification decisions with EASA approvals and the referenced service bulletin authors within the Australian regulatory requirement.

The AD itself does not set out specific civil or criminal penalties or enforcement mechanisms in its text. It is an instrument issued by the Civil Aviation Safety Authority, signed by a CASA delegate, and prescribes mandatory modifications and prohibitions for applicable aircraft. In practice, compliance with airworthiness directives is enforceable under the broader statutory framework under which CASA operates, but the Directive text reproduced here contains no explicit penalty schedule, infringement fines, or criminal sanctions.

The Directive does anchor mandatory compliance to exact technical documents and deadlines, for example the 36 calendar month compliance window for Requirement 1 and the effective prohibition on installing unmodified SG02206 contactors after 31 May 2011. Those temporal limits create clear compliance expectations which, if unmet, result in aircraft being non‑compliant with an AD. Non‑compliance with an AD commonly has regulatory consequences under the aviation safety regime; however those enforcement steps, penalty amounts, or administrative processes are not set out in this Directive.

Enforcement will likely follow the usual airworthiness oversight channels because the AD is issued by CASA and references EASA‑approved revisions as the operative technical standards. The AD’s dependence on EASA approvals for the acceptability of certain procedures and parts could be relevant in any enforcement review, because only those service bulletin revisions that are EASA‑approved are prescribed by the AD. The absence of an enforcement clause in the AD text does not remove the Directive’s mandatory nature; rather it requires competent authorities and operators to rely on CASA’s enforcement mechanisms external to the AD document to ensure compliance.

The Directive’s background material describes safety risks , overheating, electrical arcing, partial melting, and possible cockpit fire or smoke , which typically inform the priority CASA will place on enforcing the AD. The AD indicates an expected timeline and a prohibition on certain part installations, giving compliance auditors concrete items to check. The AD does not specify appeal or review procedures within its text.

The AD explicitly cross‑references and depends upon technical material that is subject to EASA approval, thereby creating a regulatory interaction between Australian airworthiness requirements and EASA‑approved service bulletin revisions. The applicability clause and the various requirements state that the work must be accomplished in accordance with Fokker Services SBF50‑24‑031 dated 29 January 2008 or later revision approved by EASA, and that the alternate method uses Fokker SBF50‑24‑030 or later EASA‑approved revision. Requirement 2 conditions installation of SG02206 parts on modification per Goodrich Power Systems SB SG02206‑24‑01 dated 4 March 2008 or later EASA‑approved revision. The AD further notes that EASA AD 2008‑0091 refers, which situates the CASA AD within parallel regulatory actions by EASA.

By requiring compliance with EASA‑approved revisions of the referenced service bulletins, the AD makes the operative technical standard dependent on external approvals and therefore interacts with EASA processes. Any subsequent revision of the Fokker or Goodrich service bulletins will be operative only if it carries EASA approval, according to the AD’s text. That creates a dependency on the EASA process for determination of what is an acceptable method of compliance under the AD.

The Directive converts technical workmanship instructions, normally contained in non‑regulatory service bulletins, into a mandatory regulatory requirement. In doing so the AD explicitly folds those service bulletins into the Australian airworthiness compliance regime for the affected aircraft. The AD does not itself repeal or amend other statutes, but it should be read as an enforceable instrument within the broader civil aviation statutory framework under which CASA operates.

The AD contains carve-outs for aircraft modified per Fokker ECR 51780 or SBF50‑24‑030 dated 6 November 2003 or later EASA‑approved revision. Those carve‑outs affect how the AD overlaps with previous service bulletin compliance histories. If an aircraft was already modified in production to incorporate ECR 51780 or modified in service in accordance with SBF50‑24‑030, the AD’s specified actions do not apply to that aircraft under the stated applicability. The AD therefore recognises and interacts with the prior maintenance and modification record of the aircraft.

The Directive itself records a limited internal timeline and references several dated service bulletins and an EASA AD. The AD became effective on 31 July 2008 and is dated 13 June 2008, signed by James Coyne as Delegate of the Civil Aviation Safety Authority. The AD refers to Fokker Service Bulletin SBF50‑24‑031 dated 29 January 2008 as the procedural document for Requirement 1. The alternate compliance route references Fokker SBF50‑24‑030 dated 6 November 2003. The parts‑installation prohibition is conditioned on modification per Goodrich Power Systems SB SG02206‑24‑01 dated 4 March 2008.

The Compliance provisions impose two deadlines tied to the AD’s issuance and operation: Requirement 1 must be accomplished within 36 calendar months after the AD’s effective date, which was 31 July 2008. Requirement 2, the prohibition on installing unmodified SG02206 contactors, applies after 31 May 2011. Note 1 explicitly permits replacement of SG02206 contactors with improved versions per SBF50‑24‑030 as an alternate method of compliance, provided such replacement is done within the 36‑month window from the effective date. Note 2 states that EASA AD 2008‑0091 is relevant.

Aside from these dates and references, the AD does not record amendments to itself, nor does it include a history of supersessions or prior versions of the AD within the reproduced text. The only amendment mechanism visible in the AD is its tolerance for later revisions of the referenced service bulletins, but only if those revisions receive EASA approval. In other words, the AD locks in its technical requirements to particular service bulletins, but permits those to be updated only through the EASA approval process.

The AD’s text therefore records a short list of dated technical documents that determine compliance and a two‑stage compliance timetable: an initial 36‑month modification or replacement window tied to the effective date, and a later parts‑installation prohibition that commences on 31 May 2011. The AD does not list any prior amendments to the AD itself in the provided text.

The Directive text provided contains no record of litigation, appeals, judicial review, or case law arising from this AD. There are no references to court proceedings, administrative reviews, or contested enforcement outcomes in the reproduced document. The AD is an administrative airworthiness instrument issued by the Civil Aviation Safety Authority and signed by a CASA delegate, with no litigation items appended.

Because the Directive itself does not record litigation or precedent, the document does not provide a statutory or judicial history that would clarify contested points such as the scope of the Applicability clause, the interpretation of the deadlines, or disputes about what constitutes an EASA‑approved revision. The AD does, however, incorporate external approvals and service bulletin revisions as the operative technical standards, and those external instruments could be the subject of separate administrative or legal proceedings; no such proceedings are recorded here.

Given the absence of litigation history in the AD, readers needing to understand judicial treatment, enforceability disputes, or interpretive controversies will not find those materials in this text. Any questions about how the AD’s requirements have been applied, enforced, or contested in tribunal or court will require sourcing from external records and case law, which are not part of the Directive text provided.

The AD does reference EASA AD 2008‑0091; that reference may point to parallel regulatory action that could have its own administrative record. The Directive itself does not report outcomes of any regulatory coordination, nor does it summarise disputes or appeals concerning EASA approvals or the referenced service bulletins.

Several practical pitfalls and potential sources of confusion are embedded in the AD’s language and structure.

First, applicability exclusions rely on earlier modifications and on EASA approval status. The AD excludes aircraft modified during production to incorporate Fokker ECR 51780 and aircraft modified in service in accordance with Fokker Service Bulletin SBF50‑24‑030 dated 6 November 2003 or later EASA‑approved revision. Operators must be able to demonstrate the aircraft’s modification history to rely on these exclusions. Absent clear records showing incorporation of ECR 51780 or SBF50‑24‑030 compliance, an operator cannot assume exclusion. The AD ties the acceptability of revisions to EASA approval, so mere possession of a later‑dated service bulletin may not be sufficient unless that revision is EASA‑approved.

Second, the AD accepts replacement of SG02206 with improved contactors per SBF50‑24‑030 as an alternate means of compliance, but only if that replacement is accomplished within 36 calendar months after the AD’s effective date. That gives operators a defined window to pursue the replacement alternative. Failure to replace within that window does not nullify the AD’s primary requirement; operators who miss the window must still comply with the prescriptive nut/washer removal and self‑locking nut installation and testing path.

Third, the parts‑installation prohibition on SG02206 contactors after 31 May 2011 should be read carefully. The AD does not ban use of the part number outright; it conditions the installation of SG02206 as a replacement part on modification in accordance with Goodrich SB SG02206‑24‑01 dated 4 March 2008 or a later EASA‑approved revision. Maintenance shops sourcing spare SG02206 contactors must ensure the spare has undergone the specified modification and, crucially, that the modification is evidenced and acceptable under EASA‑approved documentation. Uncertainty or inconsistency in vendor documentation could pose compliance risk at reinstallation time.

Fourth, the AD repeatedly requires that the technical methods be performed in accordance with service bulletins "or later revision approved by the EASA." That phrase makes the EASA approval status of any service bulletin revision a material fact for compliance. Operators must track EASA approvals for those service bulletins. The AD itself does not list the process or the list of approved revisions; it simply conditions acceptability on EASA approval.

Fifth, the AD’s background identifies multiple system locations where the affected contactors are used. That increases the scope of inspection and potential work beyond a single access point. Operators must ensure that all locations using SG02206 are identified and addressed; overlooking another installation location (Generator Line Contactor, Bus Tie Contactor, Auxiliary Power Contactor, External Power Contactor) would risk partial compliance.

Sixth, the AD contains several dates: the issue date 13 June 2008, the effective date 31 July 2008, a 36‑month compliance window from that effective date, and a later date of 31 May 2011 for the parts‑installation prohibition. Confusion between the issue date and effective date could lead to scheduling errors. Operators should calculate the compliance deadline from the stated effective date.

Finally, the AD does not include enforcement mechanisms, penalty levels, or appeals processes within its text. That absence does not mean there is no enforcement; however, it does mean operators must consult applicable CASA enforcement procedures and potentially seek confirmation if there is uncertainty about compliance options or any needed deviations.

Compliance requires three practical steps, plus attention to documentary prerequisites.

1. Confirm applicability. Review the aircraft maintenance and modification record to determine whether the aircraft is an F27 Mark 050 or Mark 0502 and whether it was modified in production to incorporate Fokker ECR 51780 or modified in service in accordance with Fokker Service Bulletin SBF50‑24‑030 dated 6 November 2003 or a later EASA‑approved revision. If either exclusion applies, the AD’s mandatory actions do not apply to that aircraft under the AD’s Applicability clause.

2. Choose and perform the accepted method. If the AD applies, elect either:

   • Requirement 1 path: Remove the standard nuts and lock washers from electrical power contactors P/N SG02206, install new self‑locking nuts, and perform the applicable tests on the AC Bus Transfer System, following the Accomplishment Instructions of Fokker Services SBF50‑24‑031 dated 29 January 2008 or a later EASA‑approved revision. This work must be accomplished within 36 calendar months after the AD’s effective date of 31 July 2008.
   • Alternate method: Replace SG02206 contactors with improved versions in accordance with Fokker SBF50‑24‑030 dated 6 November 2003 or later EASA‑approved revision, provided the replacement is performed within the same 36‑month window. Note 1 in the AD identifies this replacement as an acceptable alternate means of compliance for Requirement 1.

Follow the Accomplishment Instructions in the referenced Fokker service bulletin exactly as they are written, but only to the extent that the bulletin revision in use is EASA‑approved, because the AD conditions compliance on EASA approval of later revisions.

3. Comply with the parts‑installation restriction. After 31 May 2011 do not install SG02206 contactors as replacement parts unless the contactor has been modified in accordance with Goodrich Power Systems SB SG02206‑24‑01 dated 4 March 2008 or a later EASA‑approved revision. If sourcing replacement contactors, obtain documented evidence that the Goodrich modification has been carried out and that the modification follows an EASA‑approved revision of the Goodrich service bulletin.

Operational and administrative practicalities to observe:

• Recordkeeping: retain maintenance records evidencing which method was used, the service bulletin revision followed, the dates of accomplishment relative to the AD’s effective date, and any vendor modification certificates for replaced parts. The AD’s compliance hinges on timing and on following EASA‑approved revisions.
• Scope identification: inspect all locations in the electrical power system where SG02206 contactors are used, including Generator Line Contactor, Bus Tie Contactor, Auxiliary Power Contactor and External Power Contactor as noted in the AD’s background, to ensure comprehensive compliance across the aircraft.
• Verify EASA approvals: before relying on a later revision of a referenced service bulletin as an acceptable method of compliance, verify that the revision has been approved by EASA, because the AD permits only EASA‑approved later revisions.
• Scheduling: plan the work to fit within the 36‑month window for Requirement 1 or the replacement window for the alternate method, and ensure parts procurement and vendor modification lead times will not jeopardise timely compliance.
• Parts procurement: if intending to reuse or fit spare SG02206 contactors after 31 May 2011, ensure those parts have been modified per Goodrich SB SG02206‑24‑01 and have the necessary documentation to prove the modification followed an EASA‑approved revision.

Who pays and who performs:

• The AD assigns the substantive work obligation to aircraft operators and maintenance organisations; they will bear the direct costs of parts, labour, testing and aircraft downtime. Parts suppliers will need to supply only properly modified parts after the date specified.
• The AD conditions acceptability on following specified service instruction documents, so maintenance organisations should follow those instructions and secure any certification or sign‑off required by the usual maintenance release processes.

If there is doubt about applicability, the precise EASA approval status of a service bulletin revision, or whether a particular modification or replacement satisfies the AD, seek clarification from the Civil Aviation Safety Authority and consult the referenced service bulletins and EASA AD 2008‑0091 as noted in the Directive.