AD/CL-600/110 - Flap Actuator Pinion Gear

The AD is built on a small set of concrete regulatory mechanics. First, it is limited by aircraft model, serial range, and installed component P/Ns. The applicability clause restricts coverage to Bombardier CL-600-2B19 aircraft, S/N 7003 and subsequent, that have the inboard flap actuators with either P/N 601R93101-21 or P/N 601R93101-25 installed. That means both airframe identity and installed-component identity are gating conditions for the AD's obligations.

Second, the AD operates by serial-number control. Rather than mandating blanket replacement of all actuators, the directive requires operators to inspect the serial number (S/N) of each relevant actuator (Requirements 1.a and 2.a) and to replace only those actuators whose S/Ns are explicitly listed in the AD (Requirements 1.b and 2.b). The AD provides two separate S/N lists: a longer list under Requirement 1 for P/N 601R93101-21 and some P/N 601R93101-25 items, and a separate list under Requirement 2 for additional P/N 601R93101-25 S/Ns. The reliance on discrete S/N lists channels compliance costs toward those specific serial-numbered items rather than all stock of the part numbers.

Third, the AD sets staged timing. For Requirement 1.a (inspect S/N of each P/N 601R93101-21 and P/N 601R93101-25 installed), the compliance window is "Within 100 flight cycles from the effective date" (Compliance). If a listed S/N is found then replacement must be done "Before further flight." For Requirement 2.a (inspect S/N of each P/N 601R93101-25 installed), the inspection window is longer: "Within 500 flight cycles from the effective date." Again, replacement for listed S/Ns must be done "Before further flight." The staged windows create an urgency hierarchy for the two groups of affected actuators.

Fourth, the AD recognises verification by records. Notes 2 and 3 explicitly allow serial-number verification to be performed by review of the aircraft maintenance records rather than requiring destructive or physical inspection. This reduces immediate physical labour and aircraft access needs when records are reliable.

Fifth, the directive controls reinstallation and marking. Requirement 3 prohibits replacement (that is, installation) of flap actuators with the listed S/Ns on any aircraft unless those listed S/Ns are identified with suffix "A" (for Requirement 1 S/Ns) or suffix "B" (for Requirement 2 S/Ns). Notes 4 and 5 clarify that the suffix indicates a conforming gear set has been installed and that Transport Canada AD CF-2009-13 is relevant. Mechanically, this creates an identification regime: a listed S/N may remain in inventory and may be installed only after the conforming gear set is fitted and the S/N is re-identified with the appropriate suffix.

Finally, the AD includes the regulatory provenance and effective date. It becomes effective on 2 July 2009 and bears the signature block "James Coyne, Delegate of the Civil Aviation Safety Authority" dated 22 May 2009. The background statement situates the AD in supplier conformance issues, specifically missing acceptable certificates of conformance for the pinion gears, with the safety risk characterised as possible flap failure.

These concepts together mean the AD functions through component-level serial-number controls, targeted replacement obligations, timing windows, an allowance for records-based verification, and a marking requirement to permit reinstallation only after remedial work. The AD cross-references a Transport Canada AD, suggesting shared concern across regulators about the same component lot or supplier documentation.

Primary affected parties are operators of Bombardier Inc Model CL-600-2B19 aircraft, serial number 7003 and subsequent, that have inboard flap actuators P/N 601R93101-21 or P/N 601R93101-25 installed. The directive's applicability clause narrows the universe to that airframe and serial-number cohort. Operators in that cohort must inspect,and where relevant replace,actuators as prescribed.

Secondary affected parties include maintenance organisations and engineers who will be tasked with conducting the inspections, replacing actuators, and documenting compliance. The AD explicitly allows serial-number verification through maintenance records (Notes 2 and 3), thereby engaging maintenance record-keepers and continuing airworthiness staff in the compliance process. Where physical inspection is required for serial-number identification, line maintenance and hangar teams will incur labour and access costs.

Parts suppliers, component pools, and spares managers are also affected. The AD’s serial-number lists require parts managers to screen inventories for the listed S/Ns. Where a listed S/N actuator is discovered in stock, staff must either refrain from installing it until it is made conforming and appropriately suffixed, or arrange for replacement work. Note 1 creates a substitution pathway: replacing a P/N 601R93101-21 with a P/N 601R93101-25 that does not have a listed S/N satisfies Part A/Requirement 1. That creates demand for non-listed P/N 601R93101-25 units.

Owners, lessors and lessees are implicated through operational control and asset value effects. If an affected actuator must be replaced "Before further flight" (Requirement 1.b, 2.b), then aircraft downtime is immediate and availability is reduced until a compliant actuator is procured and installed. Lessors who rely on contract clauses and lessee maintenance practices will be affected through asset availability and potential cost allocation disputes.

Regulatory and certification staff at the operator will be engaged to ensure entries into the maintenance logbook and to confirm that any serial-number verifications by records meet the AD requirements. The AD references Transport Canada AD CF-2009-13, so international operations, maintenance organisations servicing aircraft with Canadian provenance, and supply chains that cross jurisdictions will have to reconcile multiple ADs addressing the same parts.

Finally, the manufacturer and the actuator supplier are affected in reputational and remedial terms, since the background ties the AD to a lack of acceptable certificates of conformance for the pinion gears from the supplier. While the AD does not set out contractual remedies, the identification of supplier non-conformance will trigger procurement and warranty processes for operators and parts managers.

Who pays. The directive places the physical inspection, replacement, and record verification burdens on operators and their maintenance providers. It does not quantify costs in the text. The timing requirements mean some replacements are urgent and must occur before further flight when a listed S/N is found, imposing immediate replacement costs and aircraft downtime.

Duties

• Inspect the serial number of each installed flap actuator of P/N 601R93101-21 and P/N 601R93101-25 within 100 flight cycles from the effective date (Requirement 1.a). For those actuators within the listed S/Ns under Requirement 1, replace the actuator before further flight (Requirement 1.b).
• Inspect the serial number of each installed flap actuator of P/N 601R93101-25 within 500 flight cycles from the effective date (Requirement 2.a). For those actuators with S/Ns listed under Requirement 2, replace the actuator before further flight (Requirement 2.b).
• Do not install flap actuators with serial numbers listed in Requirement 1 or 2 onto any aircraft after the effective date unless those S/Ns are identified with suffix "A" (Requirement 1 list) or suffix "B" (Requirement 2 list). This is Requirement 3.
• Follow the effective date: the AD becomes effective on 2 July 2009.

Rights, permitted methods and clarifications in the AD

• Record-based verification: Notes 2 and 3 permit S/N verification to be carried out through review of aircraft maintenance records rather than requiring physical inspection. This is an affirmative permission to use records where they exist and are reliable.
• Substitution option: Note 1 provides a compliance pathway by allowing replacement of an existing P/N 601R93101-21 with a P/N 601R93101-25 that does not have a listed serial number in paragraph (B) of the AD, and such substitution satisfies Requirement 1/Part A. Practically, this enables operators to replace a suspect P/N 601R93101-21 by installing a P/N 601R93101-25 that is not on the AD's S/N lists.
• Identification suffix: Notes 4 and 5 explain the meaning of suffix "A" and "B", specifically that the suffix indicates a conforming gear set has been installed, and that Transport Canada AD CF-2009-13 is referenced. The AD therefore supplies the criterion for allowing reinstallation of previously listed S/Ns.

Operational constraints and implications embedded in the duties

• Temporal constraints: For listed serial-number actuators found under Requirement 1 or 2, the replacement duty is immediate before further flight. The inspection windows differ: 100 flight cycles for the first group and 500 flight cycles for the second. These time limits create scheduling priorities and operational downtime risk.
• Inventory control: Requirement 3 effectively requires inventory managers to segregate and prevent installation of listed S/N actuators until they are made conforming and re-identified with the suffix. Operators must therefore maintain effective parts control processes to avoid inadvertent installation.
• Documentation: Even where physical inspection is not required, operators must be able to demonstrate that maintenance records were reviewed and that the S/Ns were verified. The AD’s allowance for record verification implicitly creates a documentation duty.

What the AD does not expressly grant or set out

• The AD does not provide an explicit administrative appeal process or express remedies for inability to source replacement actuators. It does not set financial compensation mechanisms. It also does not specify how the suffix marking is to be applied, whether physically on the actuator or in documentation, beyond stating that the suffix indicates a conforming gear set has been installed (Note 4). The AD also does not specify enforcement measures or penalties within its text.

These duties and limited rights create a compliance regime centred on serial-number identification, replacement for listed items, substitution options under specified conditions, and identification marking for any reinstallation of previously listed items. Operators and maintenance organisations must plan for inspections, replacements, record reconciliation, and inventory segregation accordingly.

The AD text itself does not set out penalties, fines, or a detailed enforcement process. Its operative content is framed as requirements, compliance timeframes, and prohibitions tied to specified part numbers and serial numbers. The signature block shows issuance by the Delegate of the Civil Aviation Safety Authority and includes an effective date of 2 July 2009, which demonstrates the regulatory source and date from which the requirements apply.

Because the AD contains specific prescriptive actions (inspect S/Ns within stated flight cycles, replace listed S/Ns before further flight, and prohibit installation of listed S/Ns without suffix identification), in practice compliance will need to be documented and verifiable. Notes 2 and 3 permit S/N verification through maintenance records, which creates an evidentiary pathway for demonstrating compliance. The AD does not stipulate the form of records or entries required.

The AD also cross-references Transport Canada AD CF-2009-13 dated 26 March 2009. That cross-reference indicates that other jurisdictional airworthiness directives address the same underlying component issue and may have parallel compliance expectations. The AD does not describe whether adherence to the Transport Canada AD satisfies CASA’s requirements; instead it references that AD for information.

Absent an express penalty clause in the AD text, the document limits itself to prescriptive safety actions and timing. The AD does not include a sanctions schedule, nor does it describe inspection or audit mechanisms to be executed by the issuing authority. The document does not describe how non-compliance will be remedied administratively, whether by grounding notices or other measures. It also does not describe the process for seeking an exemption, a deferral, or an alternative means of compliance.

Practical implications for regulated parties follow from the mandatory-seeming nature of ADs and the requirement for "before further flight" replacement in certain cases. Operators will need to produce demonstrable records showing inspections and replacements were completed within the stated timeframes, or demonstrate via maintenance records that the serial-number verification was performed. The AD’s absence of in-text penalties means that any enforcement or penalty action would rely on the issuing authority’s broader regulatory powers and processes, which are not set out in this AD document.

In short, the AD prescribes required actions and timeframes but does not itself enumerate enforcement mechanisms or sanctions within the text. It provides record-based compliance options but leaves enforcement procedures and penalties outside the explicit content of the directive.

The AD explicitly references Transport Canada AD CF-2009-13 dated 26 March 2009 (Note 5). That cross-reference signals regulatory coordination or parallel action by another national regulator addressing the same safety concern about flap actuator pinion gears and supplier certificates of conformance. The AD does not state that compliance with the Transport Canada AD substitutes for compliance with this AD. It simply refers to the foreign AD, meaning operators who operate across jurisdictions or who source parts internationally must reconcile this AD’s requirements with any concurrent directives issued by foreign civil aviation authorities.

The AD imposes serial-number-specific obligations on operators, which interact with maintenance record-keeping regimes. Notes 2 and 3 explicitly permit serial-number verification via review of aircraft maintenance records. Therefore, the AD requires that maintenance records,which are governed by other statutory and regulatory record-keeping obligations held by operators and maintenance organisations,be sufficiently detailed and reliable to permit S/N verification. The AD does not itself create a new record-keeping format or standard; it relies on existing records as evidence of compliance.

The AD’s requirements also interact with part-identification and parts-tracking practices within the maintenance and supply chain. Requirement 3 conditions reinstallation on the presence of suffix "A" or "B" to indicate that a conforming gear set has been installed. The AD does not prescribe whether this suffixing must be a physical marking on the actuator, an entry in the maintenance release, or a supplier certification entry in internal records. That regulatory silence means that operators will apply the suffixing approach consistent with other legislative or regulatory practices governing parts marking and traceability in their jurisdiction.

The AD identifies the delegate of the Civil Aviation Safety Authority as the issuer. It therefore sits within the CASA regulatory landscape. While the AD does not itself cite enabling legislation or penalties, it was issued by CASA via a delegate. Interactions with broader aviation safety law, civil aviation safety regulations and airworthiness regulatory frameworks are therefore implied, but not spelled out in this AD text. The AD’s operational constraints,inspect, replace, and mark,must be implemented within the operator’s broader statutory obligations under airworthiness, maintenance and record-keeping regimes that exist outside the AD document itself.

Procurement, warranty and supplier-conformance law will be engaged in practice because the background of the AD identifies a lack of acceptable certificates of conformance from the supplier. The AD does not address contractual remedies, warranties, or supplier liabilities; such legal claims would be handled under commercial and contract law outside of the AD. But operators and maintenance organisations will likely need to rely on supplier documentation and possibly supplier remedial actions to meet the AD’s Requirement 3 marking condition.

Finally, the AD does not explicitly address interactions with air operator certificates, operations specifications, or other operational approvals. However, because the AD sets "before further flight" replacement duties for listed S/Ns and defines compliance windows for inspection, operators must integrate these AD duties within their operational safety management, maintenance schedules and regulatory approvals to preserve flight status. The AD’s silence on penalty mechanisms and enforcement processes leaves the practical integration with other laws and regulatory instruments to the issuing authority and existing regulatory frameworks.

The AD text includes an effective date and a date of issuance but does not present a history of amendments or revisions within the document. The AD becomes effective on 2 July 2009 and is dated 22 May 2009 in the signature block. There is no text in the instrument that records prior versions, later amendments, revocations, or corrigenda. The only external reference is to Transport Canada AD CF-2009-13 dated 26 March 2009, which the AD "refers" to in Note 5, but no sequence of domestic amendments is recorded in the AD text.

Because no amendment log appears in the document itself, practitioners seeking to determine whether this AD has been subsequently amended, superseded, or revoked would need to look beyond the instrument’s text to the issuing authority’s administrative records, consolidated AD listings or regulatory database. The AD text does not provide retrospective modification clauses, transitional arrangements beyond the stated compliance periods, or a mechanism for future amendments within the document. It simply states requirements, notes, and compliance times tied to the stated effective date.

The absence of an internal amendment history in the text means the AD as provided should be treated as a snapshot effective on the stated date. Any enquiries about later changes, extensions, or alternative means of compliance would have to be pursued with the issuing delegate or via CASA’s official AD listing, neither of which is contained in the AD text itself. The AD also does not specify any sunset or review date. It regulates by serial-number identification and marking until action is taken to make listed S/Ns conforming and suffix them appropriately.

In short, the AD contains an effective date and issuance signature but no in-text amendment history. The document as provided does not record subsequent legislative or administrative changes.

The AD document contains no litigation history. It does not reference any judicial or administrative proceedings concerning its adoption, enforcement or legal challenges. There are no cited cases, no pending appeals, and no procedural disputes recorded in the text.

Because the AD is a directive focused on technical compliance,inspection and replacement of actuators by serial number,it is presented as a safety measure rather than a contested legal instrument within the document. The absence of litigation references means the text itself does not inform readers about any legal disputes over the AD’s content or application.

Practitioners requiring knowledge of any litigation that may have arisen from this AD,such as disputes over whether a particular S/N was required to be replaced, claims arising from grounding or maintenance costs, or supplier liability disputes,must consult court records, tribunal decisions, or administrative enforcement logs outside the AD text. The AD provides no data on disputes, challenges, or adjudicated controversies.

Where litigation might be relevant to operational decisions,such as whether to spend on replacement parts, or whether to contest an installation prohibition,operators and their counsel must look beyond the AD to external legal databases or regulatory enforcement records for any case law or decisions addressing this directive. The AD itself neither records nor summarises any such proceedings.

Ambiguities in marking and the suffix requirement. Requirement 3 prohibits replacement of listed S/N actuators on any aircraft unless the listed S/Ns are identified with suffix "A" (Requirement 1 list) or suffix "B" (Requirement 2 list). The AD clarifies that suffix "A" or "B" indicates a conforming gear set has been installed (Note 4). The AD does not specify the form of the suffixing. It does not mandate how or where the suffix must be recorded, whether it must be physically stamped on the actuator, entered into the maintenance release, or recorded in some other traceable way. That creates a risk of inconsistent practices across operators and maintenance organisations about what constitutes sufficient identification for reinstallation.

Physical inspection versus record-based verification. Notes 2 and 3 allow serial-number verification by review of the aircraft maintenance records. That is helpful where records are complete, but the AD does not define what level of documentary evidence is adequate. Operators relying on record review will need to ensure their records unambiguously link the actuator S/N to the physical component on the aircraft at the relevant time. If records are incomplete or ambiguous, an operator may have to perform a physical inspection or risk non-conformance with the inspector’s expectations.

Substitution path nuances. Note 1 says "Replacing the existing Flap Actuator P/N 601R93101-21 with the P/N 601R93101-25 that does not have a serial number listed in paragraph (B) of this AD also satisfies the requirement of Part A of this directive." The caveat is that the substitute P/N 601R93101-25 must not have a listed serial number. Operators must therefore verify both the part number and the absence of the S/N on the AD’s lists before relying on substitution. Supply-chain pressure for non-listed P/N 601R93101-25 parts may be significant, and operators must be careful to ensure that the replacement is genuinely not listed.

Inventory control and inadvertent installation. Requirement 3 effectively prohibits installation of listed S/Ns without the appropriate suffix. If spares pools or component exchanges are not well controlled, there is a risk of inadvertent installation of a listed S/N. The AD does not prescribe locking or quarantine procedures, so the work of preventing accidental installation falls to operators’ internal parts-control practices.

Timing and operational disruption. The AD imposes "Before further flight" replacement duties when a listed S/N is identified. That can create immediate aircraft grounding until replacement parts are available. The AD does not provide a deferral or alternative means of compliance within the text, so operators may be forced to source parts at short notice or otherwise manage flight cancellations and maintenance man-hours. Where the listed S/N is discovered during flight-line checks or prior to a revenue sector, the effect on operations is material.

Relationship to supplier documentation. The AD’s background attributes the problem to a lack of acceptable certificates of conformance from the supplier. Practically, operators may need supplier confirmations, overhaul shop documentation or proof of conformity to obtain the "A" or "B" suffix. The AD does not prescribe the content or issuer of the proof required to affix the suffix, creating potential dispute about what evidence suffices for reinstallation.

Cross-jurisdictional coordination. The AD refers to Transport Canada AD CF-2009-13. Where aircraft operate in multiple jurisdictions, operators may face multiple overlapping ADs with different compliance mechanics. The directive does not say whether compliance with the Transport Canada AD will be treated as compliance with this AD, so international operators must plan to satisfy both regimes.

No expressed enforcement or penalty mechanism. The AD does not state penalties for non-compliance in its text. While ADs generally function within a broader enforcement regime, the absence of in-text penalties means operators must rely on external regulatory guidance to understand enforcement consequences.

In short, the principal "gotchas" are the AD’s reliance on suffix marking without an explicit method, the permitted use of maintenance records without specifying documentary standards, the substitution pathway’s constraints, inventory control risks, immediate operational effects of "before further flight" replacements, and cross-jurisdictional coordination needs.

Follow these concrete steps tied to the AD’s text. The AD becomes effective on 2 July 2009, so count compliance windows from that date.

1. Identify applicability

   • Confirm whether the aircraft is a Bombardier Inc Model CL-600-2B19, S/N 7003 or subsequent, and whether either inboard flap actuator P/N 601R93101-21 or P/N 601R93101-25 is installed. The AD’s applicability clause is the gate for all subsequent steps.

2. Plan inspection timing

   • For P/N 601R93101-21 and P/N 601R93101-25 actuators covered by Requirement 1, schedule S/N inspection within 100 flight cycles from 2 July 2009 (Requirement 1.a and Compliance).
   • For P/N 601R93101-25 actuators covered by Requirement 2, schedule S/N inspection within 500 flight cycles from 2 July 2009 (Requirement 2.a and Compliance).

3. Inspect or verify serial numbers

   • Perform physical inspection of the actuators to read the serial numbers. Alternatively, where reliable, perform a review of aircraft maintenance records to verify the S/Ns, as Notes 2 and 3 explicitly permit record-based verification.
   • Compare each S/N against the AD’s lists. For Requirement 1 the AD lists specific S/Ns for P/N 601R93101-21 and specific S/Ns for P/N 601R93101-25. For Requirement 2 the AD lists P/N 601R93101-25 S/Ns. Ensure the comparison is exact.

4. If a listed serial number is found

   • Replace the listed actuator before further flight (Requirement 1.b and 2.b), as the AD requires immediate replacement for listed S/N findings.
   • If the actuator is P/N 601R93101-21 and you can obtain a P/N 601R93101-25 that does not bear a listed serial number, substitution satisfies Part A/Requirement 1 per Note 1. Validate the substitute’s S/N against the AD lists before installation.

5. Manage reinstallation and suffixing

   • Do not install any actuator whose S/N is listed in Requirement 1 or 2 on any aircraft unless the S/N is identified with suffix "A" (Requirement 1 list) or suffix "B" (Requirement 2 list) indicating a conforming gear set has been installed (Requirement 3 and Note 4).
   • Document the installation of any conforming gear set and the assignment of suffix "A" or "B". The AD does not define the precise form of the suffix notation, so include both physical and record-based identification where feasible: mark the component if practicable, and record the suffix in the maintenance log and parts ledger.

6. Record-keeping and audit trail

   • Even if S/N verification is accomplished via maintenance records, ensure the records explicitly show the S/N associated with the component on the aircraft at the time of inspection and any subsequent replacement. The AD permits record verification (Notes 2 and 3), therefore records must be auditable and unambiguous.
   • For replacements done because a listed S/N was found, create a maintenance entry that details the S/N removed, the S/N installed, the part number of the replacement, and any supplier documentation or conforming gear set documentation relied upon.

7. Supply-chain and parts procurement

   • Screen spare parts inventory against the AD’s S/N lists before installing components.
   • Segregate any listed S/N actuators in inventory and mark them to prevent inadvertent installation until a conforming gear set is installed and the suffix applied.
   • For sourcing replacements, ensure the replacement actuators do not have S/Ns listed in the AD lists, unless they have been made conforming and suffixed as indicated.

8. Liaison with suppliers and Transport Canada reference

   • Because the AD’s background cites unacceptable supplier certificates of conformance and it references Transport Canada AD CF-2009-13, coordinate with component suppliers and consult that Transport Canada AD for any complementary procedures or submission of conformity evidence.
   • Obtain and retain supplier certificates of conformance for replaced or modified actuators to demonstrate the existence of conforming gear sets that justify suffixing.

9. Operational integration

   • Schedule inspections and potential replacements to minimise aircraft downtime within the AD’s flight-cycle windows, accounting for the "before further flight" replacement obligation for listed S/Ns.
   • Notify relevant operational stakeholders, including flight operations and lessors, that activations of the AD may require immediate maintenance and may affect aircraft availability.

10. If in doubt

• Where the form of suffixing, the sufficiency of supplier documentation, or the adequacy of maintenance records is unclear, record conservatively by physically marking the component if feasible and retaining supplier attestations. The AD does not prescribe a suffixing method but requires suffix identification to permit reinstallation.

By following these steps,identify applicability, schedule inspections within the stated timeframes, verify S/Ns by physical check or records review, replace listed S/N actuators before further flight, ensure appropriate suffix identification after remedial work, and document every action,operators will implement the AD’s requirements as stated in the directive.