AD/CL-600/70 - AC Contactors

This directive operationalises three core concepts: targeted applicability, a material/part‑based failure mechanism, and a phased compliance regime tied to a manufacturer service bulletin.

• Targeted applicability: the AD identifies affected aeroplanes narrowly by model and serial number range (Model CL‑600‑2B19, serial numbers 7003-7990 and 8000-8070). Only those serial numbers are subject to the inspection and replacement requirement (Applicability). The text does not expand applicability beyond these serial numbers.

• Material/part‑based failure mechanism: the AD attributes the risk to contactors that have a terminal base plate made from a non‑G9 melamine material (specified as Ultem 2200 or black in colour). The background describes eight incidents of short‑circuit failures involving the named Tyco Hartman contactors 1K4XD and K4XA located in the avionics bay; in several cases arcing, initiated by contaminants between power studs, resulted in a fire that continued until power to the contactor was interrupted either by wire burn‑through or generator falling offline (Background). The AD therefore treats the terminal base plate material as the characteristic that produces the safety risk.

• Phased compliance tied to a Service Bulletin and regulator approval: the inspection and replacement steps must be accomplished in accordance with Bombardier Service Bulletin 601R‑24‑123 Revision B (16 February 2007) or a later revision that has been approved by the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada. The directive explicitly references that SB and requires compliance with it (Requirement 1 and 2). The AD establishes a 12‑month compliance window for performing the inspections and replacements (Compliance), but imposes an immediate ban, effective as of the AD’s effective date, on installing the problematic contactors as replacement spares (Requirement 3).

The directive also records regulatory coordination: it references Transport Canada AD CF‑2006‑17R1 and notes that an earlier Transport Canada requirement to seal non‑G9 terminal base plates with RTV was an interim action now superseded for Australian purposes by the inspection and replacement requirement (Background; Note). The AD therefore links material specification, a manufacturer SB, and an international regulator’s prior action into a single domestic requirement. The AD does not, in the text provided, set out inspection detail beyond prescribing the Service Bulletin as the procedure to follow, nor does it specify record‑keeping, certification of work, or penalties.

The AD directly affects operators and maintainers of Bombardier (Canadair) CL‑600‑2B19 aeroplanes within the specific serial number ranges listed in the applicability clause: 7003 through 7990 inclusive and 8000 through 8070 inclusive (Applicability). That group, as identified in the AD, must carry out the inspection (Requirement 1) and, where applicable, the replacement (Requirement 2) within the 12‑month compliance window after the AD’s effective date. The AD also immediately affects maintenance organisations, parts suppliers and maintenance personnel because it prohibits, as of the effective date, installation of contactors with a non‑G9 terminal base plate as replacement parts (Requirement 3). That prohibition operates on spare parts procurement and installation decisions and therefore affects entities that hold inventories of the specified P/Ns D‑18ZZA and D‑7GRZ or that supply those parts.

Specific parts and part numbers are identified and therefore those responsible for parts identification and inventory control are within scope: AC contactors 1K4XD and 2K4XD, P/N D‑18ZZA; utility bus contactor K4XA, P/N D‑7GRZ (Requirement 1); and the approved replacement P/Ns D‑18ZZC and D‑7GSZ (Requirement 2). The AD binds recipients to accomplish the inspection and replacement in accordance with Bombardier Service Bulletin 601R‑24‑123 Revision B or a later Transport Canada‑approved revision. The note that the Service Bulletin or later revision must be "approved by Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada" assigns an approval role to that Canadian authority for any later SB revision used in compliance (Requirements 1 and 2).

The AD does not state any obligation on other aircraft types, nor does it extend requirements to serial numbers outside those ranges. The AD also references prior Transport Canada action (AD CF‑2006‑17R1) and states that the sealing remedy previously mandated by Transport Canada is now considered interim; the Australian AD replaces the interim sealing approach with inspection and replacement requirements for the specified fleet (Background). The directive does not identify any obligations for Australian regulators beyond publication of the AD, nor does it specify obligations for airworthiness authorities in other jurisdictions.

The AD imposes a sequence of duties on affected operators and maintenance organisations and states limited decision rights in relation to acceptable compliance methods.

Duties imposed by the directive, stated in the AD text:

• Duty to inspect: Operators must, unless already accomplished, visually inspect contactors 1K4XD, 2K4XD (AC service bus) and K4XA (utility bus) to determine whether the contactors have a non‑G9 terminal base plate. The inspection is to be accomplished in accordance with Bombardier Service Bulletin 601R‑24‑123 Revision B, dated 16 February 2007, or later revision approved by the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada (Requirement 1). This is the primary affirmative duty.

• Duty to replace: If inspection reveals a non‑G9 terminal base plate on any of the identified contactors, the operator must replace the AC service bus contactors 1K4XD and 2K4XD with P/N D‑18ZZC, and the utility bus contactor K4XA with P/N D‑7GSZ, in accordance with the same Bombardier Service Bulletin or later revision approved by the Transport Canada Chief (Requirement 2). This is a conditional duty triggered by inspection findings.

• Duty to avoid installing prohibited parts: As of the effective date, contactors with a non‑G9 terminal base plate (the implicated parts) may not be installed on any aircraft as replacement parts (Requirement 3). This is an absolute prohibition, effective immediately.

Timing duties:

• The inspection and replacement duties (Requirements 1 and 2) must be completed within twelve months after the effective date of the Directive (Compliance). The immediate prohibition on installing non‑G9 contactors as replacements (Requirement 3) is effective on the AD’s effective date.

Decision rights and approvals:

• The AD prescribes the procedure to be followed (Bombardier SB 601R‑24‑123 Revision B, or later revision approved by the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada). This assigns decision authority over any later SB revision to a named Transport Canada official , the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada , for the purposes of accepting a later procedural revision as compliant with the AD (Requirements 1 and 2).

Rights, limitations and unspecified matters:

• The AD does not, in the text provided, specify exemptions, alternatives to the SB procedure, waivers, or a process for demonstrating equivalent corrective action. It does not specify rights of appeal, record‑keeping requirements, or the administrative process for declaring compliance in the text provided. The AD does note that "unless already accomplished" the inspection must be done, which recognises completed work performed before the AD’s effective date.

In short, the AD creates affirmative inspection and conditional replacement duties with a defined compliance window and an immediate prohibition on installing the implicated parts as replacements. It assigns approval authority for any later SB revision to the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada.

The text of the AD as provided sets out requirements, timing and the approved means of compliance but does not itself specify civil, administrative or criminal penalties, nor does it attach an enforcement regime in the words printed. The AD records the effective date (2 August 2007) and prescribes compliance obligations with explicit timing: Requirements 1 and 2 must be completed within 12 months after the effective date, and Requirement 3 is effective immediately (Compliance). The AD is published and signed by a delegate of the Civil Aviation Safety Authority (David Punshon, Delegate of the Civil Aviation Safety Authority, 14 June 2007), which indicates it is issued under the relevant regulatory powers of that authority; however the directive text provided does not spell out enforcement mechanisms, sanctions, or administrative steps to record compliance.

Because the AD does not contain express penalty clauses in the provided text, a reader should not assume specific penalties from this document alone. The AD does, however, operate as a regulatory instrument that prescribes mandatory technical work and an immediate prohibition on installing specified parts; non‑compliance with a mandatory AD is typically actionable under the broader aviation safety regulatory framework, but any specific enforcement actions, sanctions or administrative penalties are not enumerated in the AD text provided. The AD does reference a Transport Canada AD (CF‑2006‑17R1) and a Bombardier Service Bulletin as the approved procedural documents; compliance is defined by adherence to those documents. The AD does not describe audit, inspection, reporting, or certification procedures required to demonstrate compliance in the record provided.

Therefore, from the source text: the directive creates mandatory technical obligations with specific timing and part prohibitions, but it does not itself set out penalty provisions or enforcement steps in the text supplied.

The AD explicitly references prior Transport Canada action and a manufacturer Service Bulletin, creating cross‑jurisdictional and manufacturer‑driven interaction.

• Interaction with Transport Canada AD CF‑2006‑17R1: The AD includes the note "Transport Canada AD CF‑2006‑17R1 refers" and a background statement that the original Transport Canada AD CF‑2006‑17 (which was not mandated in Australia) required sealing of non‑G9 terminal base plates with RTV sealant as an interim measure. The Australian directive states that application of RTV sealant is now considered an interim action and replaces that with the inspection and replacement requirements it prescribes. Thus, the AD interacts with the prior Transport Canada instrument by acknowledging it and adopting a different, mandatory corrective path for the Australian applicability set (Background; Note). The AD also delegates approval of any later Service Bulletin revision to the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada, thereby incorporating a role for a foreign authority in approving an accepted means of compliance (Requirements 1 and 2).

• Interaction with Bombardier Service Bulletin 601R‑24‑123: The AD makes the Bombardier SB the required procedure for inspection and replacement by reference; it directs compliance "in accordance with Bombardier Service Bulletin (SB) 601R‑24‑123, Revision B, dated 16 February 2007, or later revision approved by Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada" (Requirement 1 and 2). This means that the procedural or technical content of the SB becomes the de facto method of compliance with the AD; any later SB revision will require approval by the named Transport Canada official before it can be treated as compliant.

• Interaction with parts‑supply and maintenance regulatory frameworks: by prohibiting the installation of contactors with non‑G9 terminal base plates "on any aircraft as a replacement part" as of the AD effective date (Requirement 3), the directive intersects with rules governing parts procurement, maintenance organisation practices, and parts conformity. The AD identifies specific P/Ns for the affected items and specific replacement P/Ns, making the parts regime an operational focus.

• Interaction with the domestic regulatory framework: the AD is signed by a CASA delegate (David Punshon) and is presented as an Australian airworthiness directive. The text does not recite the enabling statute or enforcement provisions; accordingly, the AD should be read in the context of the broader Australian aviation safety law which governs mandatory ADs and enforcement, although the AD text itself does not cite those enabling provisions.

Limitations of the text provided: the AD does not specify how compliance is to be recorded with CASA, whether approvals for equivalent fixes will be accepted, or how the immediate prohibition interacts with existing parts inventories. Those interaction points are not set out in this text and therefore would require consultation of CASA procedural guidance, the enabling legislation, or direct contact with CASA staff.

The AD text references a specific manufacturer Service Bulletin and a prior Transport Canada AD; it does not itself record any superseding amendments to the AD within the text provided. The amendment‑related items in the document are:

• Bombardier Service Bulletin 601R‑24‑123, Revision B, dated 16 February 2007, is the SB revision expressly cited as the required procedural document for inspections and replacements (Requirement 1 and 2). The AD allows for a later revision of that SB to be used only if it is approved by the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada.

• Reference to Transport Canada AD CF‑2006‑17R1: the AD notes that the original Transport Canada AD CF‑2006‑17 mandated sealing with RTV sealant, and that this application of RTV is now considered interim action (Background). The AD implicitly replaces that interim measure with the inspection and replacement regime described. The AD does not indicate any amendment to the Transport Canada AD itself.

• Dates and issuance: the AD is dated "8/2007" and is stated to become effective on 2 August 2007. It is signed by David Punshon, Delegate of the Civil Aviation Safety Authority, dated 14 June 2007. The AD number appearing in the text is AD/CL‑600/70.

• No subsequent amendments recorded in the provided text: the document as provided gives no information on any amendment, revocation or supersession of this AD after its 2 August 2007 effective date. If any amendment occurred after the version provided, it is not contained in this text.

Operationally, the AD leaves open the possibility that a later revision of the Bombardier SB could be approved by the named Transport Canada official and thereby be used as an updated means of compliance. The AD itself contains no mechanism for CASA to approve alternative procedures in the text given, nor does it list any later AD numbers or amendments.

The text of the directive does not include or mention any litigation, legal challenges, administrative appeals, or case references. It contains factual background about eight incidents involving short‑circuit failures and resulting fires, and it refers to a prior Transport Canada AD, but it does not report any legal disputes or court proceedings connected to the subject matter. The AD was issued by a CASA delegate and states technical requirements and compliance timing; any judicial or administrative review, disputes over interpretation, or enforcement actions are not described in the AD text provided.

Therefore, from the source document alone, there is no litigation history to report. Users seeking material on any legal challenges, enforcement actions, or precedent concerning this AD would need to consult external records, court databases, regulatory enforcement logs, or follow‑on ADs and amendments that are not part of the text supplied here.

The directive contains several concrete features that may produce practical traps for operators, maintainers and parts suppliers. These are facts present in the AD text; they are not speculative.

• Narrow applicability can be overlooked: the AD applies only to CL‑600‑2B19 aeroplanes with serial numbers 7003-7990 inclusive and 8000-8070 inclusive (Applicability). Operators who maintain mixed fleets or who rely on shorthand model descriptions may fail to check serial numbers precisely and therefore may misidentify which aircraft are subject to the AD. The AD does not compel action on aircraft outside these serial numbers.

• "Unless already accomplished" caveat: the inspection requirement is prefaced by "Unless already accomplished" (Requirement 1). If an operator has previously performed an inspection or replacement consistent with the SB, they may not need to repeat it. The AD does not define the level of evidence required to establish that prior work is acceptable, nor does it set out a record‑keeping standard in the text for proving prior accomplishment.

• Immediate prohibition vs 12‑month compliance window: the AD prohibits installation of contactors with a non‑G9 terminal base plate as replacement parts "as of the effective date of this Directive" (Requirement 3), while allowing 12 months to inspect and, if necessary, replace existing installed units (Compliance). This creates a situation where acquiring or installing the implicated parts as spares is immediately forbidden, but removing existing installed parts may be deferred for up to 12 months. Maintenance and supply chains that depend on replacement parts should note that inventories of the specified P/Ns D‑18ZZA and D‑7GRZ become unusable as replacements from the AD effective date, even if installed units remain serviceable for the compliance window.

• Parts and part numbers are exact: the AD identifies P/N D‑18ZZA and D‑7GRZ as the implicated parts and P/N D‑18ZZC and D‑7GSZ as mandated replacements (Requirement 2). Procurement, depot maintenance and parts catalogues must map part numbers accurately. The AD does not provide equivalence criteria beyond the specified replacement P/Ns and the Service Bulletin.

• Material identification via appearance: the AD describes the non‑G9 terminal base plate as "Ultem 2200 material or black in colour" (Background). Visual inspection is the mandated means to determine whether the terminal base plate is non‑G9. Visual identification of material types by colour and appearance can be error‑prone; the AD requires the inspection to follow the Bombardier SB, which may include specific inspection cues, but the AD text itself relies on visual inspection.

• Service Bulletin revision and foreign approval: the AD requires compliance with Bombardier SB 601R‑24‑123 Revision B dated 16 February 2007, or a later revision approved by the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada (Requirement 1 and 2). That delegations approval power to a Transport Canada official for any later SB revision. Operators should not assume that a later SB revision is automatically acceptable without that approval.

• Inventory and disposal consequences not spelled out: the AD forbids installation of non‑G9 contactors as replacements (Requirement 3) but does not state what to do with existing spare inventories, whether disposal or return to manufacturer is required, or how to account for stored prohibited parts. The AD text itself is silent on these practical matters.

• Gaps in serial number coverage: the serial number ranges exclude numbers 7991-7999 (assuming continuity). The AD does not explain this exclusion. Users should not infer reasons or a broader application beyond the explicit serial numbers.

• No enforcement or compliance reporting language in the AD text: as noted elsewhere, the document sets requirements and timing but does not include express enforcement, reporting, or certification language. Practical compliance will likely require operators to consult CASA process guidance, but that guidance is not contained in the AD itself.

These "gotchas" are points that arise directly from the way the AD is drafted, the precise identification of parts and serial numbers, the interplay of timing rules, and the referencing of external approval authority for SB revisions.

The AD prescribes a narrow, procedural route to compliance. The following steps reflect the requirements as stated in the AD text; they do not add obligations beyond the AD, but organise the work to fit the AD’s mandatory elements.

1. Confirm applicability

   • Verify the aircraft model and serial number. The AD applies only to Bombardier CL‑600‑2B19 aeroplanes with serial numbers 7003 through 7990 inclusive and 8000 through 8070 inclusive (Applicability). Do not assume applicability based on model alone; confirm the serial number.

2. Review prior work

   • Determine whether the inspection or replacement has already been accomplished. The inspection obligation is qualified by "Unless already accomplished" (Requirement 1). Maintain documentation of any prior compliance to support the claim that the work was performed before the AD’s compliance window.

3. Obtain the approved procedural document

   • Acquire Bombardier Service Bulletin 601R‑24‑123, Revision B dated 16 February 2007, and follow it. The AD requires inspections and replacements to be done "in accordance with" that SB or "later revision approved by Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada" (Requirement 1 and 2). If you intend to use a later SB revision, secure formal approval from the named Transport Canada official before treating it as an acceptable means of compliance.

4. Inspect the specified contactors

   • Visually inspect AC service bus contactors 1K4XD and 2K4XD, P/N D‑18ZZA, and the utility bus contactor K4XA, P/N D‑7GRZ, to determine whether any have a non‑G9 terminal base plate as per the SB procedure (Requirement 1). The AD identifies the non‑G9 base plate as Ultem 2200 material or black in colour (Background). Ensure the inspection follows the SB’s steps for access, de‑energising, and identification cues.

5. Replace if non‑G9 is found

   • If inspection reveals a non‑G9 terminal base plate on any of the identified contactors, replace the AC service bus contactors 1K4XD and 2K4XD with new P/N D‑18ZZC, and replace utility bus contactor K4XA with new P/N D‑7GSZ, following the SB (Requirement 2).

6. Respect the immediate prohibition on replacements

   • Do not install contactors with a non‑G9 terminal base plate as replacement parts on any aircraft as of the AD effective date (Requirement 3). Ensure parts procurement and stores management prevent installation of the prohibited P/Ns for replacement use from the effective date forward.

7. Meet timing requirements

   • Complete Requirements 1 and 2 within twelve months after the Directive’s effective date (Compliance). Requirement 3 is effective as of the AD’s effective date (Compliance; Requirement 3).

8. Internal control steps (practical)

   • Segregate inventory: isolate any stocked P/N D‑18ZZA and D‑7GRZ items to prevent inadvertent installation as replacements.
   • Communicate: inform maintenance personnel and supply chain managers of the immediate replacement prohibition and the 12‑month inspection/replacement window.
   • Document: while the AD text does not specify recordkeeping, maintain records demonstrating inspection dates, findings, parts replaced (including serial numbers and P/Ns), and the SB revision used. This documentation will support assertions that compliance has been accomplished and can be necessary if CASA audits or inquiries follow.
   • Coordinate approvals: if intending to use a later SB revision, contact the Chief, Continuing Airworthiness, Aircraft Certification, Transport Canada to obtain the approval specified in the AD before relying on that revision.

9. Cross‑reference related documents

   • Note the AD’s reference to Transport Canada AD CF‑2006‑17R1 and the background that RTV sealing was previously considered an interim action. If prior sealing has been applied, record whether it was done and whether replacement is still required under this AD (the AD treats sealing as interim and now requires inspection and replacement where non‑G9 parts are present).

10. Seek regulatory clarification if necessary

• The AD does not state reporting procedures or the documentation that CASA will accept as proof of compliance. If there is uncertainty about acceptable evidence of prior accomplishment, substitution of parts, or disposal of prohibited spares, seek clarification directly from CASA or consult any CASA procedural guidance accompanying the AD.

These steps follow directly from the AD’s numbered Requirements 1-3, its Compliance timing, the Applicability clause and the Service Bulletin reference. The AD prescribes the SB as the method of compliance and assigns approval for any later SB revision to a named Transport Canada official; ensure those conditions are met when performing the work.