AD/CF34/15 - Fuel Metering Unit Wiring

The Directive rests on several discrete, source‑stated components: applicability, the mandated actions, approved compliance material, time limits, and linkage to FAA action. Applicability is narrowly drawn. It lists two groups of engines:

• CF34-8C1/-8C5/-8C5B1/-8E5/-8E5A1 engines with GE FMU P/N 4120T01P02 and S/Ns WYG89156 through WYGB4222, and Woodward Governor FMU VIN 8061-926 with S/Ns 11954378 through 15140071; and
• CF34-10E series engines with GE FMU P/N 2043M10P05 and S/Ns WYGA3251 through WYGB4085, and Woodward Governor FMU VIN 8063-884 with S/Ns 13335695 through 15028283.

These applicability lists include a Note identifying aeroplane types on which the engines are known to be installed (Bombardier CRJ-700/-701/-900; Embraer ERJ 170 and ERJ 190 families), but the Note also explicitly states the lists are not exhaustive.

The mandated actions are twofold. Requirement 1: unless already done, perform a onetime test of the FMU for a miswired (reversed polarity) condition of the input wires to the overspeed solenoid, using paragraph 3A of the Accomplishment Instructions of the relevant GE Service Bulletin (SB) identified for each engine group (SB CF34-8C-AL S/B 73-0030 Rev 3; SB CF34-8E-AL S/B 73-0015 Rev 3; or SB CF34-10E S/B 72-0067 Rev 2). Requirement 2: if the FMU fails that test, remove the FMU (the AD states simply “remove the FMU”).

The AD accepts prior compliance if the SB work was completed before the effective date using certain earlier SB revisions (specific original and revision issue dates are listed). It also permits compliance via later SB revisions only if those revisions are approved by the FAA as an Alternate Method of Compliance to FAA AD 2008-05-01. Note 2 in the AD explicitly refers to FAA AD 2008-05-01 Amdt 39-15395.

Timing: For Requirement 1 the compliance window is within 2,200 hours time in service after the Directive’s effective date but not to exceed 24 months after that date. For Requirement 2 the timing is uncompromising: remove the FMU before further operation of the engine (that is, if the test is failed the engine must not be operated until the removal occurs).

The AD is signed by a CASA delegate and becomes effective 10 April 2008. The Background explicitly ties the AD to FAA‑reported field discoveries that a miswired overspeed solenoid could prevent shut down in an overspeed event and thereby may lead to uncontained engine failure. The AD therefore operates as a safety‑critical, mandatory maintenance action directed at a defined set of engine/part serial numbers and implemented via manufacturer SB procedures or FAA‑approved alternatives.

The Directive affects the parties who operate, maintain, or supply the affected CF34 engines and the FMUs specified. Primary affected parties are:

• Aircraft operators who have any of the listed CF34 engine models installed on their aeroplanes with FMUs falling within the stated P/N and S/N ranges. The AD’s Note 1 lists common platforms (Bombardier CL-600-2C10 CRJ-700/-701 and CL-600-2D24/-2D15 CRJ-900; Embraer ERJ 170-100/-200 for -8E5 engines; Embraer ERJ 190-100/-200 for -10E engines), but the AD explicitly states these lists are not exhaustive, so any operator with engines meeting the FMU P/N and S/N criteria is affected.
• Maintenance organisations and licenced maintenance personnel who perform maintenance and inspections on the affected engines, since the AD prescribes a specific test (paragraph 3A of the Accomplishment Instructions of the indicated GE SBs) that they must perform unless it has already been accomplished to the acceptable SB revisions.
• Parts suppliers, overhaul shops and FMU manufacturers (GE and Woodward Governor), because a failed test requires removal of the FMU; subsequent repair, rework, or replacement will involve these suppliers. The Directive specifies FMU P/Ns and VINs and precise S/N ranges, so parts traceability and inventory management functions are implicated.
• Civil aviation regulators and their delegates, principally the Civil Aviation Safety Authority (CASA), which issued the AD (signature by a CASA delegate appears on the AD), and the FAA whose AD and AMOC decisions are referenced. The AD ties compliance acceptance to FAA approvals of SB revisions as AMOCs to FAA AD 2008-05-01, creating an operational interface between CASA’s directive and FAA determinations.

Financially and operationally the immediate burden falls on operators and maintenance providers. Operators must schedule the one‑time test within the stated hours or months window, and they must ground or remove engines that fail the test before further operation. The AD does not provide funding, compensation, or cost estimates; it only prescribes the actions. Consequently, aircraft operators bear the direct costs of labour for testing, potential FMU removal and any subsequent actions necessary to return aircraft or engines to service, including sourcing replacement FMUs or carrying out repairs, if that is what they choose following the required removal.

Who decides: the AD prescribes who must act (operators/maintainers), the method (use SB paragraph 3A), the timing (2,200 hours or 24 months; or before further operation on failure), and who accepts alternate methods (FAA via AMOC to FAA AD 2008-05-01 for later SB revisions). The AD itself was issued by CASA (delegate) and becomes effective 10 April 2008.

Key duties flow directly from the AD’s labelled Requirements and the Compliance section. The duties are:

• Duty to determine applicability: Operators or maintainers must determine whether any engines in their fleet match the model, FMU P/N/VIN and S/N ranges set out in the AD’s Applicability table. The AD’s specific listings of engine models, FMU P/Ns, FMU VINs, and serial-number ranges define who owes action.
• Duty to perform the test (Requirement 1): Unless the test has already been performed in accordance with specified SB revisions, perform a one‑time test of the FMU for a miswired (reversed polarity) condition of the input wires to the overspeed solenoid, using paragraph 3A of the Accomplishment Instructions of the relevant GE Service Bulletin (SB CF34-8C-AL S/B 73-0030 Rev 3; SB CF34-8E-AL S/B 73-0015 Rev 3; or SB CF34-10E S/B 72-0067 Rev 2).
• Duty on failure (Requirement 2): If the FMU fails the test, remove the FMU. The AD specifies “remove the FMU” without detailing subsequent mandatory repair, replacement, or re‑installation procedures; however, it unequivocally requires removal prior to further engine operation (“For Requirement 2 - Before further operation of the engine.”).
• Duty to comply within the prescribed timeframe: For Requirement 1, the AD establishes a hard compliance window,within 2,200 hours time in service after the effective date of the AD, and no later than 24 months after that date. For Requirement 2, the duty is immediate in operational effect: removal before further engine operation if the test is failed.

Key rights or flexibilities set out in the AD are limited but concrete:

• Right to rely on acceptable prior compliance: Actions done prior to the Directive’s effective date in accordance with specified earlier SB revisions are acceptable for compliance with this Directive. The AD lists the exact earlier SB revision issue dates that are accepted.
• Right to use FAA‑approved later SB revisions: Later revisions of the listed SBs are considered acceptable for compliance with the equivalent requirements of this Directive only if they are approved by the FAA as an Alternate Method of Compliance (AMOC) to FAA AD 2008-05-01. This creates a right to rely on FAA AMOC approvals where they apply to the relevant SB revisions.
• Implicit right to seek alternative methods via FAA AMOC process: The AD’s acceptance of FAA‑approved AMOCs for later SB revisions implies that alternate methods of compliance approved through the FAA AD/AMOC process are recognised for the purposes of this Directive; the AD itself does not outline a separate CASA AMOC pathway in its text.

What the AD does not stipulate is also material to duties and rights: the Directive does not instruct what must be done after removal of a failed FMU, such as mandatory replacement with a particular part number, mandatory repair procedures, or re‑installation steps. It also does not specify record‑keeping requirements, nor does it provide penalties or enforcement provisions within the text. Rights to alternate compliance are defined narrowly by reference to FAA approvals, not a generic CASA process stated in the AD.

The AD sets mandatory maintenance requirements with explicit timing and procedural references, but the text does not specify statutory penalties or the enforcement mechanism within the document itself. The AD does, however, indicate the issuing authority and effective date: it is signed by David Punshon, Delegate of the Civil Aviation Safety Authority, dated 29 February 2008, and the Directive “becomes effective on 10 April 2008.” That signature and effective date establish administrative provenance.

Enforcement implications follow from the nature of an AD: once an AD is effective, affected engines must be in compliance with its requirements to be operated lawfully under airworthiness rules. The AD contains two enforcement‑critical stipulations: the compliance window for performing the one‑time test (2,200 hours time in service, or 24 months) and the requirement that if an FMU fails the test it must be removed before further operation. Those operational constraints mean that, in practice, non‑compliant engines cannot be lawfully operated without contravening the AD’s operational conditions. The document itself does not list consequences such as fines, suspension, or grounding actions; those enforcement mechanisms generally reside in the broader regulatory framework administered by CASA rather than in the AD text. The AD therefore creates mandatory technical requirements, leaving the implementation of any regulatory sanctions to the enforcing authority’s broader powers and procedures, which are not spelled out in the Directive.

The AD also references FAA AD 2008-05-01 and explicitly accepts FAA‑approved AMOCs to that FAA AD for later SB revisions as acceptable compliance methods. This creates an interjurisdictional compliance pathway: an FAA AMOC approval relevant to FAA AD 2008-05-01 can be relied upon to satisfy the equivalent requirements of this CASA AD, subject to the conditions stated.

Operational enforcement risk for operators comes in two concrete forms stated by the AD: timing non‑compliance (failing to perform the one‑time test within the stated hours or months) and operating an engine after it has failed the test without having removed the FMU (the AD requires removal “Before further operation of the engine”). The AD does not itself articulate how CASA will detect non‑compliance or what procedures CASA will use to enforce the AD; those processes fall outside the AD’s text.

The Directive explicitly creates an operational link between CASA’s requirements and FAA actions. Note 2 in the AD states “FAA AD 2008-05-01 Amdt 39-15395 refers.” Additionally, the AD affirms that later revisions of the specified GE Service Bulletins are acceptable for compliance with the AD only if those later revisions are “approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2008-05-01.” That text establishes a cross-reference and conditional acceptance: FAA approval of a later SB revision as an AMOC to the FAA AD is treated as acceptable compliance for the equivalent requirements of this CASA AD.

Practically, this means operators seeking to rely on a later SB revision must be aware of any FAA AMOC decisions concerning that SB revision and FAA AD 2008-05-01. The AD thereby integrates Australian mandatory maintenance requirements with the FAA’s AMOC determinations for the related FAA AD. The AD does not mention other domestic Australian instruments by number, nor does it set out how CASA will treat non‑FAA AMOC alternatives; the only conditional pathway to accept later SB revisions expressly mentioned is FAA AMOC approval to that specific FAA AD.

The AD also interacts with manufacturer documentation insofar as it mandates compliance with paragraph 3A of the Accomplishment Instructions of named GE Service Bulletins. The AD accepts certain earlier SB revisions performed prior to the effective date as compliant, and it permits FAA‑approved later revisions for compliance as noted above. Therefore, the AD functions as a legal requirement that operationalises certain manufacturer SB procedures into mandatory regulatory obligations.

The AD does not itself modify certification certificates, type certificates, or other statutory licences; it declares mandatory corrective or preventive maintenance steps for affected engines. It likewise does not articulate how compliance is to be recorded or certified; those procedures are left to the broader regulatory and maintenance oversight systems. Finally, the AD’s linkage to FAA AD 2008-05-01 implies that operators who already complied with the FAA AD and associated SBs under FAA terms may have fulfilled CASA’s requirements, provided the SB revisions fall within the accepted versions listed or are covered by the FAA AMOC approach set out in the AD.

The Directive itself contains an internal history of acceptable earlier Service Bulletin revisions and establishes a conditional acceptance mechanism for later SB revisions based on FAA AMOC approval. It lists the following SB revisions as acceptable if accomplished prior to the effective date of the Directive:

• For CF34-8C: SB CF34-8C-AL S/B 73-0030, original issue dated 25 May 2007; Revision 1 dated 19 July 2007; Revision 2 dated 28 August 2007.
• For CF34-8E: SB CF34-8E-AL S/B 73-0015, original issue dated 1 June 2007; Revision 1 dated 19 July 2007; Revision 2 dated 28 August 2007.
• For CF34-10E: SB CF34-10E S/B 72-0067, original issue dated 7 June 2007; Revision 1 dated 26 July 2007.

These earlier SB revisions are explicitly listed as “acceptable for compliance with this Directive” where the SB work was accomplished prior to the effective date.

For later SB revisions, the AD states: “Later revisions of the SBs listed in Requirement 1, approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2008-05-01, are considered acceptable for compliance with the equivalent requirements of this Directive.” Thus the Directive establishes an amendment pathway where subsequent manufacturer SB revisions can be used to meet the AD, but only if the FAA has approved those later revisions as AMOCs to the FAA AD. This creates a de facto amendment mechanism that relies on FAA determinations rather than further CASA amendments to the AD text.

The AD becomes effective on 10 April 2008; it is signed on 29 February 2008 by a CASA delegate. The AD does not list later amendments to itself or provide an internal history of revisions to the AD text. It therefore operates as a single AD issued on the stated dates, with the only amendment flexibility provided via acceptance of later SB revisions as FAA AMOCs. There is no text in the Directive indicating subsequent superseding ADs, cancellations, or corrections; the document does not record any amendment to itself.

Because the AD explicitly references FAA AD 2008-05-01 Amdt 39-15395, any amendments to that FAA AD or later FAA AMOC decisions could affect which SB revisions are accepted for compliance under this Directive, per the conditional language contained in the AD. The Directive does not itself track or adopt FAA amendments automatically; it accepts FAA‑approved AMOCs for later SB revisions as meeting the equivalent requirements, which creates an external dependence on FAA administrative actions for the acceptance of revised SB materials.

The text of the AD contains no litigation history. There are no court decisions, appeals, or judicial reviews recorded in the instrument. The document includes a Background section explaining the safety rationale (FAA advised of miswired FMU overspeed solenoids discovered in the field, which could prevent engine shutdown and may lead to uncontained engine failure), but it does not reference any disputes, enforcement proceedings, or legal challenges.

Given the absence of litigation material in the instrument, there is no source‑stated case law, precedent, or judicial interpretation recorded within the AD itself. The only inter‑jurisdictional administrative reference is to FAA AD 2008-05-01 Amdt 39-15395, and the AD recognises FAA AMOC approvals to that FAA AD as acceptable for later SB revisions. The AD does not include any record of appeals, petitions for reconsideration, or legal challenges to the AD text or its requirements.

Accordingly, an analyst relying solely on this source must conclude the AD contains no litigation history and provides no details of any legal actions taken in relation to it. Any enquiries into subsequent litigation or enforcement actions would require consultation of CASA records, court repositories, or industry incident reports beyond the AD text, which are not contained in the provided document.

The Directive is short, precise, and technical, but several practical pitfalls and points of potential operational confusion are visible within the AD’s text:

• Narrow serial‑numbered applicability: The AD applies only to FMUs within specific P/Ns, VINs and S/N ranges. Operators must verify FMU P/N, VIN and serial numbers exactly against the AD’s lists. Engines on the same aircraft type but with FMUs outside the stated P/N/VIN/S/N ranges are not covered by the AD. Misidentification of parts or incorrect reading of serial numbers could lead to non‑compliance or unnecessary maintenance action.
• “Unless previously accomplished” caveat: Requirement 1 is subject to prior completion in accordance with specific SB revisions. Operators must confirm that prior work was done to the exact SB revision dates listed as acceptable; some earlier revisions are explicitly accepted if done before the effective date. Work done to different SB revisions or under different procedures may not be accepted unless the later SB has FAA AMOC approval, so verify the SB revision actually used.
• FMU removal without follow‑up instructions: Requirement 2 simply states “If the FMU fails the test, remove the FMU.” The AD provides no direction within its text on the subsequent mandatory steps (repair, replacement, testing of a replacement FMU, or re‑installation). That lack of specificity creates an operational gap: removal is mandatory, but the AD does not mandate or describe what must be done next to restore airworthiness. Operators must therefore refer to manufacturer procedures, parts approvals and their own continuing airworthiness obligations to determine next steps.
• Timing calculation: Compliance for Requirement 1 is defined as “Within 2,200 hours time in service after the effective date of this Directive, but not to exceed 24 months after the effective date.” Operators must calculate hours-in-service for affected engines and schedule work accordingly. Failure to account correctly for aggregate hours or to recognise the 24‑month hard cap could produce inadvertent non‑compliance.
• Operational impact on availability: The AD requires removal before further operation if the FMU fails the test. That requirement could ground aircraft or remove engines from service with short notice, depending on when testing occurs and where spares and repair facilities are available. The AD does not provide grace periods or temporary authorisations.
• Reliance on FAA AMOC approvals: The AD allows later SB revisions to be used if approved by the FAA as AMOCs to FAA AD 2008-05-01. Operators who intend to rely on later SB revisions must confirm that the FAA has indeed approved those revisions as AMOCs to that specific FAA AD. An SB revision approved by the FAA in a different context, or an FAA AMOC to a different FAA AD, would not automatically be acceptable under the terms of this AD.
• Service Bulletin paragraph reference: The AD prescribes the test to be performed using “paragraph 3A of the Accomplishment Instructions” of the relevant SB. Operators must be sure to follow paragraph 3A precisely; performing a different paragraph or part of the SB may not meet the AD’s requirement unless the SB revision in use has FAA AMOC approval.
• Acceptance of prior work is time‑limited: The AD accepts certain earlier SB revisions only if the work was already done prior to the effective date. That means retroactive reliance is not available; any work done after the effective date needs to be performed under the SB revision specified in Requirement 1 or a later SB revision accepted via FAA AMOC.
• No penalties or record instructions in the AD: The AD does not specify penalties nor does it set out what records must be kept to demonstrate compliance. Operators should not assume that absence of explicit record requirements means record keeping is unnecessary; typical regulatory practice requires maintenance records, but the AD itself is silent about record retention or audit procedures.

These gotchas arise from the AD’s narrow technical criteria, the operational immediacy of the removal requirement on failure, the AD’s conditional reliance on FAA AMOCs for later SB revisions, and the lack of prescriptive post‑removal requirements inside the AD text.

Compliance under this AD requires a short, test‑driven sequence of determinations and actions drawn directly from the AD text. The steps below are the actions the AD requires; they are stated in the AD and must be followed as prescribed.

1. Confirm applicability:

   • Identify engines in your fleet that are CF34 models listed in the AD (CF34-8C1/-8C5/-8C5B1/-8E5/-8E5A1; CF34-10E series).
   • For each engine, confirm the FMU part number and serial number fall within the ranges listed in the AD:
     • GE FMU P/N 4120T01P02, S/Ns WYG89156 through WYGB4222, and Woodward Governor FMU VIN 8061-926, S/Ns 11954378 through 15140071 for the -8C/-8E group as listed; or
     • GE FMU P/N 2043M10P05, S/Ns WYGA3251 through WYGB4085, and Woodward Governor FMU VIN 8063-884, S/Ns 13335695 through 15028283 for the -10E group.
   • Don’t rely solely on aircraft model type. The AD’s applicability depends on the FMU P/N/VIN and the serial number ranges.

2. Check whether the one‑time test has already been performed:

   • If the FMU was tested before the effective date of this AD in accordance with one of the earlier SB revisions explicitly accepted by the AD (the dates and revision numbers are listed in the AD), that prior action satisfies the requirement.
   • If the work was done under a later SB revision, confirm that the later revision has been approved by the FAA as an AMOC to FAA AD 2008-05-01; only then will that work be acceptable for compliance with this AD.

3. Perform the onetime test (Requirement 1) if not previously accomplished:

   • Use paragraph 3A of the Accomplishment Instructions of the GE Service Bulletin applicable to your engine:
     • CF34-8C engines: SB CF34-8C-AL S/B 73-0030 Revision 3 dated 1 November 2007;
     • CF34-8E engines: SB CF34-8E-AL S/B 73-0015 Revision 3 dated 1 November 2007;
     • CF34-10E engines: SB CF34-10E S/B 72-0067 Revision 2 dated 28 August 2007.
   • The AD prescribes the method of testing,use paragraph 3A exactly as the AD requires.

4. Observe the AD’s timing deadline:

   • Complete the test within 2,200 hours time in service after the AD’s effective date, but in any event not later than 24 months after the AD’s effective date (the AD becomes effective on 10 April 2008).

5. If the FMU fails the test (Requirement 2):

   • Remove the FMU. The AD states explicitly that removal must occur and specifies timing: removal must be done before further operation of the engine.
   • The AD does not specify mandatory next steps after removal. Operators must determine, under applicable maintenance and airworthiness rules and manufacturer guidance, the correct follow‑up (repair, replacement, reinstallation procedures and approvals). Any replacement or rework undertaken should be done in accordance with approved part data and within the relevant airworthiness and parts‑approval framework.

6. Acceptable prior actions and later SBs:

   • If the work was already done prior to the AD’s effective date using one of the earlier SB revisions listed in the AD, that satisfies the AD’s test requirement.
   • If you intend to use a later revision of any of the listed SBs, confirm the FAA has approved that later SB revision as an AMOC to FAA AD 2008-05-01; only then is the later SB revision acceptable to meet this AD.

7. Operational safety considerations:

   • Do not operate an engine after it has failed the test without first removing the FMU as required. The AD states removal is required “Before further operation of the engine.”
   • Schedule testing to minimise operational disruption and avoid sudden grounding when a unit fails, recognising that removal may necessitate replacement or repair before the aircraft returns to service.

8. Documentation and audit readiness:

   • Although the AD does not spell out record‑keeping requirements, maintain contemporaneous records that clearly show: applicability determination, SB revision(s) used, date and results of the paragraph 3A test, and the removal action where applicable. These records will be necessary to demonstrate compliance to regulators or auditors, and to support any warranty or supplier interactions.

9. Coordinate with parts suppliers and maintenance providers:

   • Anticipate potential need for FMU replacement or repair logistics where a unit fails, and verify availability of parts, authorised repair centers, and any required approvals for replacement parts.

10. Liaise with regulatory and manufacturer channels where necessary:

• If you believe an alternate method of compliance is warranted, note the AD’s reference to FAA AMOC acceptance: later SB revisions are acceptable only when the FAA has approved them as AMOCs to FAA AD 2008-05-01. Coordinate any AMOC status checks with the FAA and with CASA if clarification is required.

By following the steps above,confirming applicability, checking prior work, performing the paragraph 3A test within the AD’s time window, removing any FMU that fails prior to further operation, and retaining clear records,operators will meet the Directive’s explicit requirements. Where the AD is silent (for example, on post‑removal procedures or record retention specifics), operators must follow applicable manufacturer guidance and the broader airworthiness regulatory framework to return the engine and aircraft to service lawfully.