AD/CL-600/88 - Fuel System Safety - Electrical Bonding

The AD organises a small set of aircraft-safety regulatory concepts into a prescriptive corrective action. The primary technical concept is electrical bonding between fuel-system components: the AD identifies a material/finish characteristic (anodised aluminium reducer coupling, visually identifiable by a blue colour) that is associated with potentially insufficient electrical bonding between the fuel boost pump canister and the pressure pick-up line. The safety consequence stated in the AD’s background is that insufficient bonding could permit arcing during lightning strikes, creating an ignition source inside a fuel tank and consequential fuel-tank explosion. The AD treats that finding as an unsafe condition requiring mandatory corrective action.

The regulatory concept is the Airworthiness Directive as a compliance instrument. The AD prescribes inspection (a “detailed visual inspection” as defined by the SB’s Accomplishment Instructions) and replacement where necessary, with deadlines: the inspection within 5 000 hours time in service after the effective date; replacement prior to further flight when anodised parts are found. The AD binds operators to follow the Bombardier SB 601R-28-057 dated 4 December 2003 or later revisions only if those later revisions are approved by the Chief, Continuing Airworthiness, Transport Canada. That creates a dependency: the actionable maintenance steps are those in the manufacturer’s SB as accepted by the relevant continuing-airworthiness authority. The AD also cross-references regulatory alignment: it notes the Transport Canada AD CF-2007-18 and cites the background process , a system safety review against new fuel tank safety standards (Chapter 525 of the Transport Canada Airworthiness Manual through NPA 2002‑043) and assessment using Policy Letter No. 525 001 , thereby anchoring the CASA AD to Transport Canada’s standard-setting and compliance review process.

The AD’s compliance architecture is binary and operational. Either no anodised coupling is present, in which case the AD requires no further action after completion of the inspection, or an anodised coupling is present, in which case replacement with an IVD-coated coupling is mandatory and must be completed before further flight. The practical effect is to require operators to change maintenance practices for the affected fleet segment to inspect for and remove the anodised coupling finish risk, using the manufacturer-prescribed procedures authorised by the continuing-airworthiness authority.

The AD explicitly affects a defined set of aircraft: Bombardier CL-600-2B19 aeroplanes with serial numbers 7003 through 7067 and 7069 through 7797. Owners and operators of those specific airframes are the primary parties obliged to act under the AD, because the directive requires actions (inspection, and, if necessary, replacement) to be carried out on the aircraft. Maintenance organisations and certifying staff who perform the Accomplishment Instructions in Bombardier Service Bulletin 601R-28-057 will be operationally engaged; the AD requires use of that SB or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Regulatory actors named in the directive include the Civil Aviation Safety Authority (the AD is issued under its authority and signed by its delegate, Charles Lenarcic) and Transport Canada (the AD refers to Transport Canada’s system safety review, Chapter 525 of its Airworthiness Manual, Policy Letter No. 525 001, and Transport Canada AD CF-2007-18). Bombardier Aerospace is an affected stakeholder in the sense that the AD relies on Bombardier’s Service Bulletin as the technical means to comply and cites Bombardier’s system safety review as the origin of the identified non‑compliances.

Third parties affected indirectly include airlines that lease or operate affected airframes, insurers who underwrite those operations, and any service suppliers that must source IVD-coated replacement couplings that conform to the SB instructions. The AD does not specify who supplies or pays for the replacement parts; the text requires the operator to carry out the inspection and to replace anodised couplings with IVD-coated items “according to the Accomplishment Instructions” of the Bombardier SB. The AD also makes no provision for aircraft outside the listed serial numbers, so owners/operators of other CL-600 variants or serials are not within the AD’s immediate scope as written.

Duties established by the AD are concrete and prescriptive. Two duties are central:

• Duty to inspect: Operators must carry out "a detailed visual inspection for the presence of an anodised (blue colour) fuel boost pump reducer coupling" in accordance with the Accomplishment Instructions of Bombardier SB 601R-28-057, dated 4 December 2003, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada. The compliance window for this inspection is within 5 000 hours time in service after the AD’s effective date.

• Duty to replace, if required: If the inspection reveals any anodised fuel boost pump reducer coupling, the operator must replace the anodised coupling with a coupling having an ion vapour deposition (IVD) coating, again following the SB’s Accomplishment Instructions or later TC‑approved revisions. The replacement must be completed prior to further flight after the inspection.

Rights and procedural boundaries in the AD are framed by references and approvals. The AD gives operators the right to rely on later revisions of the Bombardier SB only if those revisions are approved by the Chief, Continuing Airworthiness, Transport Canada. That condition channels permissible means of compliance through the continuing airworthiness authority’s approval process. The AD also contains an explicit short-circuit: "If the inspection reveals that none of the fuel boost pump reducer coupling is anodised, no further action is required by this Directive." That provides a clear compliance outcome where the risk characteristic is absent.

The AD does not allocate responsibility for sourcing replacement parts, funding the work, or lodging compliance records; it restricts itself to the inspection and replacement duties and their timing. It also does not specify maintenance-certification privileges, but the requirement to follow Bombardier’s Accomplishment Instructions implies work performed by personnel authorised to carry out SB-described maintenance. The AD further prescribes that replacements be made "according to the Accomplishment Instructions of SB 601R-28-057, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada," thereby limiting acceptable technical methods to the manufacturer’s procedures as accepted by the continuing-airworthiness authority.

The AD text supplied does not set out civil or criminal penalty provisions, nor does it describe an enforcement regime or sanctions. It prescribes mandatory technical actions (inspection within 5 000 hours TIS and replacement prior to further flight if anodised couplings are found) and declares the AD’s effective date, but it does not specify fines, suspension mechanisms, or administrative penalties within the document itself.

The AD documents the safety rationale and the corrective actions, thereby creating explicit compliance requirements for the affected serial-numbered aircraft. The enforcement mechanism implicit within an AD is that an operator who does not carry out the mandated inspection and replacement will have an aircraft for which the unsafe condition identified in the AD remains uncorrected; the AD does not enumerate enforcement steps beyond the directive text. The AD does link to pre-existing regulatory processes by reference to Transport Canada’s system safety review, NPA 2002‑043, and Policy Letter No. 525 001, but the Directive does not restate or expand any enforcement policy from those sources.

Practically, the AD creates a compliance obligation with two clear time constraints: inspect within 5 000 hours time in service after the effective date, and replace any identified anodised couplings prior to further flight after inspection. Those time constraints create operational limits: an operator that discovers anodised couplings must not continue flying that aircraft until replacement is completed as required by the AD. The AD does not provide guidance on how compliance evidence should be recorded or filed, nor does it identify which authority will verify compliance or the administrative process for that verification in this text. Readers of the AD should note those absences in the Directive when determining local enforcement and record‑keeping practices consistent with their national aviation regulatory framework and organisational processes.

The AD explicitly cross-references Transport Canada instruments and Bombardier documentation, creating a layered compliance relationship. The AD cites Bombardier Service Bulletin (SB) 601R-28-057 dated 4 December 2003 as the technical means to perform the required inspection and replacement, and conditions the use of any later SB revisions on approval by the Chief, Continuing Airworthiness, Transport Canada. This makes the manufacturer’s SB part of the AD’s normative compliance route, but only as approved by the stated continuing‑airworthiness authority.

The AD situates the safety requirement within Transport Canada’s regulatory development process. It states that Bombardier completed a system safety review against new fuel tank safety standards introduced in Chapter 525 of the Transport Canada Airworthiness Manual through Notice of Proposed Amendment (NPA) 2002‑043, and that identified non‑compliances were assessed using Transport Canada Policy Letter No. 525 001 to determine if mandatory corrective action was required. The AD notes that Transport Canada AD CF‑2007‑18 is a related reference. That linkage indicates that CASA’s AD for Australian-registered aircraft references and relies upon the outcome of Transport Canada’s normative process and remedial action.

The AD therefore interacts with other laws and regulatory instruments in two concrete ways. First, it embeds Bombardier’s SB as the procedural standard, but only to the extent that the SB is either the specified dated version (4 December 2003) or a later revision approved by the Chief, Continuing Airworthiness, Transport Canada. Second, it ties the safety obligation to the international regulatory dialogue arising from Transport Canada’s Chapter 525 introduction and the assessment procedure in Policy Letter No. 525 001 as the source of the identified unsafe condition.

What the AD does not do in the text provided is specify how compliance with this AD maps to local certification, maintenance release processes, or record‑keeping required by national law beyond the AD’s own instructions. It also does not specify interactions with airworthiness-directive enforcement regimes, export/import rules for replacement parts, or obligations under lease contracts or insurance policies; any such interactions would need to be determined from the applicable national regulatory frameworks, contract terms, or insurer requirements rather than from the AD text itself.

The directive text identifies several document dates and relationships that constitute its immediate amendment and reference history. The Bombardier Service Bulletin cited is SB 601R-28-057, dated 4 December 2003; the AD permits later revisions of that SB to be used only if such later revisions are "approved by the Chief, Continuing Airworthiness, Transport Canada." The AD itself is dated 12/2007 and was signed by Charles Lenarcic, Delegate of the Civil Aviation Safety Authority, on 24 September 2007; it states an effective date of 22 November 2007. The AD also refers to Transport Canada AD CF‑2007‑18 and to procedural antecedents in Transport Canada’s Chapter 525 Airworthiness Manual and NPA 2002‑043, and the assessment process under Policy Letter No. 525 001.

There is no text in the AD that records prior amendments to AD/CL‑600/88 itself, nor does the document list supersessions of earlier CASA ADs. The only temporal relationships recorded in the AD are (1) the dated SB (4 December 2003), (2) the AD’s signature date (24 September 2007), and (3) the AD’s effective date (22 November 2007). The AD authorises the use of later revisions of the SB subject to Transport Canada approval; that mechanism is the sole explicit pathway in the AD’s text for using amended technical instructions. No further amendment or revision history of the AD text is supplied in the document provided.

Operators should note two procedural implications from the AD text: first, that later SB revisions may become the operative compliance method only when approved by the named Transport Canada official, and second, that the AD cross-references Transport Canada’s regulatory changes (Chapter 525 and NPA 2002‑043) that were the context for the safety review. Any subsequent amendments to the AD, or to the Bombardier SB, would need to be checked against CASA’s and Transport Canada’s published AD records and the SB revision history as approved by the Chief, Continuing Airworthiness, Transport Canada.

The AD document supplied contains no litigation history. It does not reference legal proceedings, appeals, administrative litigation, or case law arising from this Directive. The text is limited to the regulatory finding (the unsafe condition and its technical basis), the prescriptive corrective actions, relevant documentary references (Bombardier SB 601R‑28‑057, Transport Canada AD CF‑2007‑18, Chapter 525 NPA 2002‑043, and Policy Letter No. 525 001), and signature/issue dates. There are no case citations, references to contested enforcement actions, or described judicial review outcomes in the provided material.

Given that absence, readers seeking litigation or appeal history will need to consult administrative or judicial records held by the Civil Aviation Safety Authority, relevant courts, or industry databases to see whether any appeals or legal challenges were brought in relation to AD/CL‑600/88. The AD itself neither anticipates nor records such proceedings in its text.

Several practical and textual details in the AD can create operational pitfalls if overlooked.

• Narrow serial-number scope and a serial-number gap. The AD applies only to CL-600-2B19 serial numbers 7003 through 7067 and 7069 through 7797. Serial number 7068 is not included in the listed range. Operators must not assume blanket applicability across all CL‑600 airframes; they must check the aircraft’s serial number precisely against the listed ranges before proceeding. The AD’s applicability language is the controlling text for whether an aircraft falls within scope.

• Inspection method and source of instructions. The AD requires a "detailed visual inspection" "according to the Accomplishment Instructions of Bombardier Service Bulletin (SB) 601R‑28‑057, dated 4 December 2003, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada." The AD therefore channels the inspection method to the SB’s Accomplishment Instructions and restricts the use of later SB revisions unless approved by the named Transport Canada authority. Operators who use other maintenance-data sources or informal inspection checklists are not following the AD as written.

• Binary replacement requirement and flight limitation. If anodised couplings are found, replacement with IVD-coated couplings is mandatory "prior to further flight after the Requirement 1 inspection." That phrasing creates a strict flight‑limitation until replacement is completed. Aircraft found to have anodised couplings cannot legally be flown further unless and until the mandated replacement is performed according to the SB instructions. That may have operational and scheduling consequences.

• Timing for inspection. Requirement 1 must be completed "within 5 000 hours time in service after the effective date of this Directive." The effective date is 22 November 2007. Operators needed to calculate the applicable deadline in hours TIS, not calendar days, and to account for flight time accumulation from the effective date. Failure to compute and track hours correctly could result in missed compliance windows.

• Dependence on Transport Canada approvals. The AD allows later SB revisions to be used only if approved by the Chief, Continuing Airworthiness, Transport Canada. That creates a dependency on a foreign continuing‑airworthiness authority’s approvals when implementing later SB changes. Operators relying on a later SB revision must confirm the specific revision is approved, and document that approval as part of compliance.

• No procedural detail on record-keeping or proof of compliance. The AD does not set out how to record or submit proof of compliance. Operators must therefore rely on standard maintenance-recording practices and any separate CASA or national requirements to document completion of the inspection and replacement.

• Implicit parts requirement. The AD specifies replacement with an IVD-coated coupling, but it does not set out a specific part number in the AD text supplied. Operators must ensure the replacement coupling conforms to the SB’s parts instructions and any applicable approval process; sourcing the correct IVD-coated part and establishing its conformity can be an operational detail that requires attention.

Follow a strict, documented process that tracks the AD’s explicit requirements and the Bombardier SB instructions referenced in the Directive.

1. Applicability check. Confirm the aircraft’s serial number. The AD applies only to CL‑600‑2B19 aircraft, serial numbers 7003 through 7067 and 7069 through 7797. Do not apply the AD procedures to aircraft outside those serial numbers unless otherwise instructed by a subsequent AD or bulletin.

2. Obtain the correct SB revision and approvals. Use Bombardier Service Bulletin 601R‑28‑057 dated 4 December 2003, or a later revision only if that later revision is explicitly approved by the Chief, Continuing Airworthiness, Transport Canada. Document which SB revision is used and, if a later revision is used, retain the approval notice or reference.

3. Schedule the inspection within the AD timeframe. Calculate the aircraft’s hours time in service from the AD’s effective date (22 November 2007) and ensure the detailed visual inspection required by Requirement 1 is completed within 5 000 hours time in service thereafter. Maintain clear time‑tracking records to demonstrate the inspection fell within the prescribed window.

4. Perform the detailed visual inspection per the SB. Carry out the inspection "according to the Accomplishment Instructions of Bombardier Service Bulletin 601R‑28‑057." Ensure personnel performing the inspection are authorised to undertake the SB work and that their certification status aligns with applicable maintenance regulations.

5. Determine outcome and act accordingly. If the inspection reveals no anodised (blue-colour) reducer couplings, the AD specifies "no further action is required by this Directive." Record the inspection result in the aircraft’s maintenance log and retain the SB work order/documentation. If any anodised couplings are found, do not return the aircraft to service until the replacement mandate is met.

6. Replace anodised couplings before further flight. If anodised parts are present, replace them with couplings having ion vapour deposition (IVD) coating "according to the Accomplishment Instructions of SB 601R‑28‑057, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada." Use the parts and processes specified in the SB, and perform functional checks as required by the SB instructions.

7. Document replacement and parts conformity. Record part numbers, supplier information, batch/serial identifiers where available, and the maintenance-release certification for the work performed. Ensure traceability showing the replacement parts conform to the SB’s requirements and, if relevant, that the SB revision in use was TC‑approved.

8. Retain records and prepare for verification. The AD text does not specify submission or filing processes; therefore, maintain complete maintenance records consistent with national regulatory requirements so that compliance can be evidenced to CASA or other competent authorities if requested.

9. Cross-reference Transport Canada notices. Note the AD’s reference to Transport Canada AD CF‑2007‑18 and the role of Chapter 525 NPA 2002‑043 and Policy Letter No. 525 001 in the identification of the unsafe condition. Where necessary for corporate compliance, align internal audit and continuing-airworthiness records with those external references.

10. Consider operational implications. If anodised couplings are found, schedule replacement to avoid unnecessary downtime; remember the AD requires replacement prior to further flight. Confirm availability of appropriate IVD-coated couplings and competent maintenance resources before commencing inspection if operational continuity is a priority.

By following the SB Accomplishment Instructions as referenced and keeping contemporaneous, auditable maintenance records, an operator will meet the prescriptive requirements of AD/CL‑600/88 as stated in the Directive text.