AD/CL-600/89 - Fuel Tank Sealant

The central concept is the airworthiness directive itself, a legislative instrument issued under the Civil Aviation Safety Regulations 1998 (CASR) Part 39 or equivalent enabling provisions. An AD mandates a modification, inspection, or operating limitation on an aircraft type when a safety deficiency is identified. Here, the deficiency is the lack of sealant on collector fuel tank bolts and transfer ejector pump edges, identified through a system safety review conducted by Bombardier Aerospace against new fuel tank safety standards. The term unsafe condition is the legal trigger for the AD: the background explains that the missing sealant could result in arcing during lightning strikes, providing a potential ignition source inside the fuel tank and consequent explosion. The concept of arcing refers to electrical discharge between conductive components that are not properly insulated by sealant; in the presence of fuel vapour, that arc could ignite an explosion. The AD relies on service bulletins issued by the manufacturer (Bombardier) as the authoritative engineering instructions for the required work. These SBs are incorporated by reference into the AD, giving them legal force. The AD distinguishes between two different SBs for two different components: SB 601R-28-051 for collector fuel tank bolts, and SB 601R-28-060 for transfer ejector pumps. The concept of sealant is the material applied to bolts and pump edges; the AD does not specify the sealant composition or standard, leaving that to the SB. The concept of general visual inspection is defined by industry practice (and likely the SB) as a close visual examination of the component without disassembly beyond what is needed to gain access; it is not a detailed or intrusive inspection. The AD distinguishes between collector fuel tanks and transfer ejector pumps, each with a different applicability scope: collector tank bolts must be sealed only on serial numbers 7003-7067 and 7069-7797, while transfer ejector pumps must be inspected and sealed on the wider range 7003-7924. The reason for this difference is not explained in the AD; it may reflect different design histories or safety assessments on different production blocks. The concept of revisions approved by the Chief, Continuing Airworthiness, Transport Canada introduces a foreign regulatory approval as the gatekeeper for changes to the mandated SBs. This means that if Bombardier issues a subsequent revision to the SB, it becomes mandatory only if Transport Canada approves it. CASA does not reserve the right to approve revisions itself, which is an interesting delegation of regulatory authority. The AD also includes a credit provision: work done prior to the effective date using the original issue of the relevant SB satisfies the corresponding requirement. This acknowledges that some operators may have proactively performed the modification before the AD was issued, and they are not required to redo it using Revision A provided the original work covered the same scope. However, the AD does not say whether the original issue of the SB included the same inspections or applications; an operator claiming credit would need to verify that its prior actions exactly match the requirements now mandated. Finally, the concept of effective date is 22 November 2007, from which the 5,000 hour clock starts running. That date is fixed and does not depend on actual receipt of the AD or airworthiness directive publication.

The AD directly affects the owners and operators of Bombardier CL-600-2B19 aircraft with serial numbers 7003 through 7067 and 7069 through 7924. Aircraft outside that range, even if of the same model, are not subject to the directive. This narrow applicability suggests that earlier or later production aircraft either did not have the same design or had already been modified. Within that serial range, there are two sub groups: those with serial numbers 7003-7067 and 7069-7797 must comply with both the collector fuel tank bolt sealing and the transfer ejector pump inspection/sealing; those with serial numbers 7798-7924 need only comply with the transfer ejector pump requirements. That distinction means that about 258 aircraft (7003-7067 is 65 aircraft, 7069-7797 is 329 aircraft, total 394, minus 2 missing numbers) are subject to both requirements, and about 127 aircraft (7798-7924) are subject only to the pump requirement. The affected fleet is likely to be operated by corporate flight departments, charter operators, and possibly fractional ownership programmes, given that the Challenger 600 series is a business jet. Also indirectly affected are maintenance, repair and overhaul organisations (MROs) that will perform the sealant application, and engineering departments that must plan and schedule the work within the 5,000 hour window. Parts and consumables suppliers for sealant and associated materials will see a one time demand spike. Bombardier itself is affected only indirectly through the issuance of the service bulletins; the AD does not impose any duty on the manufacturer. The Civil Aviation Safety Authority and the Australian Transport Safety Bureau are not directly affected but are responsible for monitoring compliance and investigating any incidents that may arise from failure to comply. Internationally, the AD references Transport Canada as the approval authority for SB revisions, which may affect Canadian operators of the same aircraft if Transport Canada issues its own AD, but the Australian AD does not have extraterritorial effect on foreign operators of Australian registered aircraft (they are subject to Australian law). The AD also affects insurers, because non compliance with a mandatory AD could void hull or liability insurance cover. Prospective purchasers of affected aircraft will need to confirm compliance before acquisition, and any lien holders may require compliance as a condition of financing. The compliance burden falls entirely on the private sector; no government subsidy or tax concession is offered for the cost of the modification, which includes labour, materials, down time, and administrative record keeping. For a small fleet operator, the cost per aircraft might be modest (sealant and a few man hours), but the administrative overhead of tracking AD compliance and maintaining records is ongoing. The 5,000 hour compliance window gives operators flexibility to schedule the work during existing heavy maintenance checks, which reduces incremental disruption but does not eliminate the cost of materials and labour. Operators with aircraft that fly fewer than 500 hours per year may have up to ten years to comply, reducing the urgency. Conversely, high utilisation operators (e.g., 1,000 hours per year) will need to act within five years. The AD does not require any recurrent inspection after the initial sealant is applied, so there is no annual or hourly recurring burden. That is a positive feature for operators, as it avoids indefinite compliance costs.

The primary duty is on the aircraft operator to ensure compliance with the AD. The operator must arrange for the sealant application and inspection to be performed within 5,000 flight hours of 22 November 2007, unless already accomplished before that date using the original issue of the relevant service bulletin. However, the duty is not absolute in the strictest sense because the AD does not require the operator to personally perform the work; the operator can contract with a licensed maintenance organisation to do it. The operator’s duty is to ensure the aircraft is in an airworthy condition before flight; non compliance with an AD renders the aircraft unairworthy. The duty also includes verifying that any prior work claimed as credit actually meets the scope of the AD. The operator has the right to use later revisions of the service bulletins, provided those revisions are approved by the Chief, Continuing Airworthiness, Transport Canada. This is a limited right to rely on updated procedures, but it is contingent on Transport Canada approval, not CASA approval. If Bombardier releases a Revision B that is not approved by Transport Canada, the operator must continue to use Revision A (or the later approved revision). The operator also has the right to have the work performed at any time before the deadline; there is no progressive deadline or milestone beyond the 5,000 hour limit. There is no right to a fee waiver or extension of time; the AD is silent on any application process for extensions or alternative means of compliance. This is notable because some ADs include a provision for an operator to request an alternative method of compliance that provides an equivalent level of safety. The absence of such a provision in this AD suggests that CASA considers the prescribed method to be the only acceptable method. The operator does have the right to inspect the aircraft’s compliance records to confirm that the work was done; typically, that record is the aircraft’s maintenance release or logbook entry referencing the AD and SB. The operator also has the right to rely on prior work performed by a previous operator if that work was correctly documented. However, if the prior work was done using the original SB issue before 22 November 2007, the operator must ensure that the original issue covered the same tasks as the AD. For the collector fuel tanks, the original SB 601R-28-051 is acceptable. For transfer ejector pumps, the original SB 601R-28-060 is acceptable. But the operator cannot rely on work done after the effective date using the original issue; it must then use Revision A. So the timing of the prior work is critical. The operator also has the duty to notify CASA if it discovers that the aircraft cannot comply by the deadline, although the AD does not specifically require such notification; general CASR provisions would apply. The AD does not create any right for individuals to sue for damages if an explosion occurs due to non compliance; liability would be governed by common law and other statutes. The primary victim of non compliance for the operator is regulatory enforcement action and potential loss of airworthiness certificate. The operator’s rights under this AD are essentially limited to the following: choose which approved revision to use, schedule the work within the window, and claim credit for pre effective date work if documented. There is no right to skip the work, substitute an alternative modification, or obtain a financial offset.

The AD itself does not specify penalties, but like all Australian Airworthiness Directives, non compliance is enforceable under the Civil Aviation Safety Regulations 1998 (CASR) and the Civil Aviation Act 1988. The relevant penalty provisions are found in CASR Part 39 or the general enforcement powers of CASA. For a breach of an AD, an operator could face civil penalty provisions under the Act, typically with maximum penalties of several hundred thousand dollars for an individual and millions for a body corporate, depending on the nature of the non compliance. Additionally, the operator’s airworthiness certificate may be suspended or cancelled, rendering the aircraft unable to fly legally. CASA can also issue a direction to ground the aircraft until compliance is achieved. Enforcement can begin once the 5,000 hour deadline passes and the work has not been completed. There is no discretion for CASA to waive the deadline based on hardship; the AD is a legislative instrument and must be complied with as written. The AD also contains a note referencing Transport Canada AD CF-2007-17, but that is not an enforceable Australian instrument; it merely indicates that a similar requirement exists for Canadian registered aircraft. For an Australian operator, only the CASA AD has legal force. The AD does not impose any obligation on maintenance organisations; their exposure is indirect if they certify work that does not meet the AD requirements. The AD itself does not create a private right of action for passengers or third parties; liability for accidents caused by non compliance would be determined under common law or other statutes, but an AD violation is strong evidence of negligence. CASA’s enforcement policy typically involves a graduated response: education and warning for minor or inadvertent non compliance, followed by infringement notices (fines) for more serious breaches, and ultimately suspension or revocation for deliberate or repeated violations. However, given that the AD addresses a potential catastrophic failure (fuel tank explosion), non compliance is likely to be treated seriously. The 5,000 hour compliance window gives operators substantial time to plan; a failure to comply within that timeframe would likely be considered negligent unless there were extraordinary circumstances. The AD does not contain any provision for CASA to approve an extension of the 5,000 hour limit; that contrasts with some ADs that allow an extension if the operator is unable to obtain parts or access. Consequently, operators must manage their maintenance schedules to meet the deadline irrespective of parts availability or other obstacles. If an operator cannot comply within 5,000 hours (for example, due to difficulty sourcing sealant or performing the work in a remote location), the only safe course is to ground the aircraft before the deadline expires. There is no exemption by application. The enforcement risk is therefore real and absolute: the only way to avoid penalty is to have accomplished the work on time.

This AD is issued under the aircraft airworthiness regulatory framework established by the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998 (CASR). Specifically, Part 39 of CASR (or the equivalent earlier provisions) governs the issuance and effect of Airworthiness Directives. The AD overrides any inconsistent provisions in the aircraft’s type certificate or maintenance manual because an AD is a mandatory requirement that must be incorporated into the aircraft’s continuing airworthiness program. Under CAO 100.7 (Maintenance of Aircraft), the AD must be recorded in the aircraft’s logbooks and must be complied with as part of the maintenance schedule. If the aircraft is operated under an Approved Maintenance Organisation’s (AMO) procedures, the AD must be included in the maintenance planning data. The AD also interacts with the aircraft’s Flight Manual: if the AD affected flight limitations, the manual would need to be revised, but here the AD imposes no such limitations. The AD references Transport Canada AD CF-2007-17, but that does not make the Canadian AD legally binding in Australia; it is merely a note for cross border reference. However, if a Canadian registered aircraft is imported to Australia, the Australian AD must be complied with even if the Canadian AD was already satisfied, unless the work is identical. The AD does not displace any manufacturer’s service bulletins; it elevates the selected SBs to mandatory status. It does not affect the operator’s obligations under the Occupational Health and Safety Act or environmental laws regarding disposal of sealant materials, but those laws apply separately. For leased or chartered aircraft, the contractual obligations to maintain airworthiness typically require compliance with all applicable ADs, so this AD becomes a term of those contracts. If an aircraft is sold after the effective date but before compliance, the buyer must ensure compliance by the deadline unless the buyer can claim credit for prior work done before the effective date. This can affect aircraft valuation and sale negotiations. The AD does not preempt any state or territory laws on product liability or tort; it is a federal instrument that sets minimum safety standards but does not insulate operators from liability if an incident occurs even after compliance. The interaction with foreign law is minimal except for the Transport Canada approval clause. In the event of conflict between this AD and any international obligation of Australia (such as an ICAO standard), Australian domestic law prevails; however, this AD is consistent with ICAO Annex 8 requirements for continued airworthiness. The AD does not interact with any privacy, anti-discrimination, or consumer protection laws. It is a purely technical safety regulation. If an operator is also subject to other CASA ADs on different components of the same aircraft, the compliance deadlines of each must be tracked independently. There is no consolidation or cross crediting between ADs. The AD also operates alongside the manufacturer’s Airworthiness Limitations section of the Instructions for Continued Airworthiness; the AD might supplement or supersede those limitations, but the AD text does not mention that section.

The source text shows only one version of AD/CL/600/89, bearing the date 24 September 2007 and effective 22 November 2007. There is no indication of any earlier or later amendment within the text itself. The second reading style background is present but no amendment history is provided. The AD appears to be a single issuance. However, the AD itself references earlier original issues of the two service bulletins (without revision letters) that existed before Revision A. That indicates that Bombardier’s SBs went through at least one revision between original issue and 30 March 2005. The AD also references Transport Canada AD CF-2007-17 dated 4 September 2007, but that Canadian AD is a separate instrument. The Australian AD is not an amendment of any prior AD; it is the first AD on this subject for this aircraft type. The lack of amendment history is typical for an AD that addresses a newly discovered unsafe condition. If Bombardier later issues a new revision to the SBs, that revision can only be used if approved by Transport Canada, but the AD itself would not need to be amended; the operator simply uses the approved revision. However, if CASA later determines that the AD needs to be revised (for example, to extend compliance time or change applicability), it would issue a new AD amending or superseding this one. There is no evidence of such a follow up AD in the provided text. The delegate authority is noted as Charles Lenarcic, who signed on 24 September 2007. The AD number includes the year 2007, but the label “89” suggests it is the 89th AD issued for the CL-600 series. Without access to the full historical register, we cannot confirm the exact count, but the label convention is standard. Given that the aircraft entered service in the 1980s, multiple ADs have been issued over time. This AD is not an amendment of any of those; it is a standalone directive. The effective date of 22 November 2007 is about two months after the signature date, which is common to allow for publication and notice.

There is no litigation history provided in the source text, and none can be inferred from the AD alone. Airworthiness Directives are rarely challenged in court because they are based on technical safety findings; operators generally comply rather than litigate, given the high cost of losing airworthiness certification. However, it is possible that some operators of CL-600-2B19 aircraft have contested the scope or cost of this AD, but no case is cited. In general, judicial review of an AD under Australian law is available on grounds of procedural error or unreasonableness, but the threshold is high because the AD is a legislative instrument based on engineering judgment. The AD’s reference to Transport Canada approval rather than CASA approval could theoretically be challenged if CASA improperly delegated its powers, but that is unlikely to succeed because the AD itself is CASA’s decision; it merely uses Transport Canada as a technical reference. The absence of an alternative means of compliance provision could also be challenged if a petitioner could demonstrate an equivalent level of safety with a different method, but the AD does not prevent the operator from seeking a variation under general CASR provisions. There is no private right of action for damages under the AD itself; any litigation would arise from an incident. If a fuel tank explosion occurred on an aircraft that had not complied with this AD, the operator would face products liability and negligence claims. Conversely, if an aircraft complied and still suffered an explosion, the operator might sue Bombardier for defective design or the sealant manufacturer for product defect. None of that is specific to this AD. The AD could also be relevant in insurance coverage litigation: an insurer might deny coverage if the operator failed to comply with a mandatory AD. The only likely litigation involving this AD would be CASA’s enforcement action against a non compliant operator, which would be heard in the Federal Court or Administrative Appeals Tribunal. But the provided source does not mention any such cases. Given the age of the AD (2007), most litigation would have occurred within a few years of its issuance, but there is no evidence of reported decisions. The AD itself has no sunset clause; it remains in effect indefinitely unless superseded. The lack of litigation history could suggest that compliance has been achieved without controversy, or that disputes were resolved informally. Without further sources, we cannot assert any litigation history.

Several details in this AD can trip up an unwary operator. First, the applicability is narrow but critical: aircraft serial numbers 7003 through 7067 and 7069 through 7924. Note the gap between 7067 and 7069; serial number 7068 is excluded. An operator of serial 7068 must ensure they do not apply the AD incorrectly; they are not subject to it. However, the reason for the gap is unknown; it could be an experimental or pre production aircraft, but the AD does not explain. Second, the AD imposes two different requirements on two different sub groups: collector fuel tank bolts only for serials 7003-7067 and 7069-7797; transfer ejector pump inspection and sealant for all serials 7003-7067 and 7069-7924. An operator with a serial number between 7798 and 7924 might mistakenly think they also need to seal collector fuel tank bolts; they do not. Third, the compliance time is 5,000 flight hours after the effective date, but the AD allows credit for work done before the effective date using the original issue of the SBs. If an operator performed the work after the effective date but using the original issue (not Revision A), that work does not satisfy the AD. The operator must redo the work using Revision A. This is a trap for operators who delayed the work until after the effective date but used an outdated SB. Fourth, the AD only allows use of later revisions approved by Transport Canada. If Bombardier issues a Revision B that is not approved by Transport Canada (for example, if only CASA approves it), the operator cannot use it. This could force operators to use an outdated procedure even if a better one exists. Fifth, the AD requires a general visual inspection of the transfer ejector pumps, but does not define what constitutes a general visual inspection. The SB will provide details, but an operator who relies on a cursory glance from an access panel might miss the required detail. The inspection likely requires removal of cowlings or access panels, but the AD is silent on that cost. Sixth, the AD is a one off task; there is no recurring inspection. However, if sealant later degrades or is disturbed during maintenance, the operator is not required by this AD to re inspect. That could be a compliance gap, but the AD does not address it. Seventh, the effective date is 22 November 2007. The 5,000 hour clock starts then, regardless of when the operator actually received the AD. If an operator was not aware of the AD until 2008, they have already lost some compliance time. This is a typical trap: operators must proactively monitor AD issuance, not rely on receipt of physical copies. Eighth, the AD says “Application of sealant prior to the effective date … according to the original issue of the above noted SB satisfies requirement 1.” The original issue of SB 601R-28-051, however, might have had a different scope or sealant specification than Revision A. The AD assumes the original issue was adequate, but if the original issue required only partial application, the operator might think they are compliant when they are not. The operator should check the original SB text against the Revision A text to ensure coverage. Ninth, the AD does not specify where to record compliance. Standard practice is to enter it in the aircraft logbook with reference to the AD and SB, but if the operator fails to make a proper entry, CASA may treat the aircraft as non compliant. Tenth, the AD uses the phrase “unless already accomplished” in the compliance paragraph, but this could be misinterpreted to mean that if the work was done at any time before the deadline, it counts. In fact, the credit only applies to work done before the effective date using the original SB; work done after the effective date using the original SB does not count. The language “prior to the effective date” is clear, but an operator might miss that nuance.

To comply with AD/CL/600/89, the operator must follow a structured process. The first step is to verify the aircraft’s serial number and confirm it falls within the applicable range. If the serial number is 7003-7067 or 7069-7797, the operator must address both collector fuel tank bolts and transfer ejector pumps. If the serial number is 7798-7924, only the pump requirement applies. The operator must then determine the aircraft’s flight hour total as of 22 November 2007 to establish the deadline: 5,000 flight hours from that date. For an aircraft with, say, 10,000 hours already accumulated at the effective date, the operator must not fly beyond 15,000 hours total unless the work is done. For a new aircraft with zero hours, the deadline is 5,000 flight hours. Next, review the aircraft’s maintenance records to see if any sealant work was done before 22 November 2007 using the original issue of SB 601R-28-051 and/or SB 601R-28-060. If such work is documented, the operator must verify that the original SB issue covered the same tasks required by the AD. For collector fuel tanks, if the original SB required sealant on all the bolts now mandated, then requirement 1 is satisfied. For transfer ejector pumps, if the original SB included inspection and sealant of the edge and bolts, then requirements 2 and 3 are satisfied. If the records are incomplete or the scope of prior work is uncertain, the operator should treat the aircraft as non compliant and proceed with the full application using Revision A of the SBs. If no prior work exists, the operator must obtain copies of Revision A of SB 601R-28-051 and Revision A of SB 601R-28-060, plus any later revisions approved by Transport Canada. The operator should verify that the mechanic performing the work is authorized under the operator’s maintenance organisation. The operator then schedules the work within the compliance window, ideally to coincide with scheduled maintenance to minimise downtime. The work itself involves applying sealant to bolts on the collector fuel tanks per SB 601R-28-051, and performing a general visual inspection of the transfer ejector pumps for fillet seal on the edge and sealant on the bolts, applying sealant where missing per SB 601R-28-060. The operator must ensure that all bolts and pump edges are covered. After completion, the mechanic or maintenance organisation certifies the work in the aircraft logbook or maintenance release, referencing the AD number and the SB revision used. The operator retains these records for the life of the aircraft. The operator should also update the aircraft’s continuing airworthiness records to indicate that the AD is complied with. If the operator later sells the aircraft, these records must be transferred to the new owner. There is no need for recurrent compliance with this AD; it is a one-off task. However, the operator should be aware that if any future AD supersedes this one, further work may be required. To ensure compliance before the deadline, the operator should establish an internal tracking system that flags the deadline. If the operator cannot meet the deadline (e.g., due to parts shortage or maintenance slot unavailability), the only safe option is to ground the aircraft before the deadline passes, because no extension mechanism exists in this AD. The operator should also consider that using a later revision of the SB (if approved by Transport Canada) may be more efficient or cost effective; the operator is free to choose any approved revision. Finally, the operator should consult with Bombardier or its authorised representatives for the latest approved revision, as the AD does not define “later revisions approved” to include any cut off date. The cost of compliance includes labour, sealant, disposal of old sealant if any, and administrative time. No specific cost estimate is possible without knowing the labour rate and materials, but it is likely modest per aircraft. The operator must bear this cost without reimbursement.