AD/CL-600/77 - Engine Exhaust Nozzle

This AD is organised around a small number of concrete regulatory concepts that control legal and operational effect.

Applicability: The scope is aircraft-specific. The AD lists exact serial numbers to which it applies (serial numbers 7003-7067 and 7069-7947) (Applicability). Operators must determine whether their airframes fall within those ranges before applying the AD’s obligations.

Method of compliance by reference: The AD makes mandatory specific portions of Bombardier SB 601R-78-021. It distinguishes between Part A (inspection) and Part B (replacement), and allows later NAA approved revisions of those parts to be used. The AD therefore delegates the procedural detail to the SB but retains statutory force over compliance with the SB’s specified parts (Requirement 1; Requirement 3).

Tiered obligations and terminating action: The AD sets a two-tier regime. Tier one is inspection and recurring inspection (Requirements 1 and 2). Tier two is replacement of hardware (Requirement 3). Completing replacement for a given engine exhaust nozzle cancels the inspection requirement for that nozzle (Requirement 3). The AD therefore contemplates partial compliance status at the aircraft level , one nozzle may be upgraded and no longer require inspection, while the other nozzle remains on the inspection cycle until replaced.

Temporal compliance windows: The AD sets explicit flight-hour deadlines from the AD’s effective date (30 August 2007): initial inspection within 1,500 flight hours, recurring at intervals not exceeding 1,500 flight hours, and hardware replacement within 4,000 flight hours (Compliance). Those windows convert the AD’s safety objective into discrete scheduling and production-planning constraints for operators.

Immediate safety stop for certain findings: If inspection finds a bolt missing or fractured, the AD requires replacement of the attachment hardware before further flight for that nozzle (Requirement 1.a). This creates an immediate pre-flight prohibition to operate with an identified defect until it is rectified.

Reference to another regulator and antecedent safety analysis: The AD cites Transport Canada AD CF-2006-19 and states Bombardier’s SB was issued to introduce inspection and replacement because investigations found bolt stress margins were inadequate following three reported in-flight exhaust nozzle/fairing departures (Background). That background statement supplies the safety rationale embedded in the AD but is presented as factual narrative rather than normative provision.

Authority and issuance: The signature block shows the AD was issued by a delegate of the Civil Aviation Safety Authority and includes a date, and the AD carries a stated effective date (signature and effective date). The AD text itself contains no penalty provisions or enforcement process beyond the compliance requirements.

Taken together, these concepts create a compliance regime that is limited in scope to listed serial numbers, relies on a manufacturer service bulletin as the procedural standard, imposes recurring inspections until replacement is performed, and forces immediate grounding where a bolt is found missing or fractured.

Primary affected parties:

• Aircraft operators and owners of Bombardier CL-600-2B19 aircraft whose serial numbers fall within the ranges 7003-7067 and 7069-7947 (Applicability). The AD applies only to these serial numbers; operators must check their aircraft identity against that list before applying the AD’s obligations.
• Maintenance organisations and licensed maintenance personnel who perform inspections and hardware replacement tasks pursuant to the Bombardier Service Bulletin referenced by the AD (Requirement 1; Requirement 3). They will need to use the Accomplishment Instructions in Part A and Part B of SB 601R-78-021 or later NAA approved revisions.

Secondary affected parties and consequential impacts:

• Airlines and other operators that deploy these airframes in commercial service. The inspection and replacement regime imposes scheduling constraints (inspection within 1,500 flight hours; replacement within 4,000 flight hours) and may require removal from service if a bolt is found missing or fractured (Compliance; Requirement 1).
• Supply-chain participants who supply replacement hardware. Requirement 3 mandates replacement with new attachment hardware according to Part B of the SB, which will create demand for compliant hardware inventories.
• Regulatory administrators and their delegates charged with oversight and acceptance of repairs and technical records. The AD references NAA approvals of later SB revisions, which implies an interaction point with national aviation authorities for acceptable revision versions (Requirement 1; Requirement 3).

Who is not affected, per the text:

• Aircraft outside the listed serial-number ranges are not subject to this AD as written (Applicability).
• The AD’s terminating action is explicitly per engine exhaust nozzle; completion of Requirement 3 terminates Requirements 1 and 2 only for the applicable engine exhaust nozzle, not for the entire aircraft unless both nozzles are replaced (Requirement 3). Therefore, an operator that replaces only one nozzle’s hardware must continue to inspect the other nozzle.

Immediate operational consequences for operators:

• If an inspection finds a bolt missing or fractured, the operator must replace the hardware before further flight for that nozzle (Requirement 1.a). Practically, that imposes a no-fly condition for the affected engine nozzle until corrected.
• Operators who have not previously completed the inspection must do so within the initial window of 1,500 flight hours after the AD’s effective date; recurring inspections follow thereafter until replacement for each nozzle is completed (Compliance).

The AD directs behaviour for a relatively narrow set of actors but imposes operational and maintenance obligations that affect scheduling, parts procurement, and line maintenance procedures for each affected aircraft.

The AD sets specific duties and defines the technical method by which those duties must be performed; it does not explicitly state rights such as appeals or exemptions within the text provided.

Duties imposed:

• Duty to inspect: Operators must inspect both left and right engine exhaust nozzles per Accomplishment Instructions, Part A of Bombardier SB 601R-78-021 dated 2 June 2006, or later NAA approved revisions (Requirement 1). The duty is to follow the SB’s Part A instructions precisely, or an NAA approved later revision.
• Duty to take immediate corrective action if defect found: If an inspection reveals a bolt missing or fractured, the operator must replace the existing engine exhaust nozzle attachment hardware with new hardware before further flight, in accordance with Requirement 3 (Requirement 1.a).
• Duty to repeat inspections: Operators must repeat Requirement 1 at intervals not exceeding 1,500 flight hours until the terminating action is completed for the relevant nozzle (Requirement 2; Compliance 2).
• Duty to replace hardware within a defined window: Operators must replace the exhaust nozzle attachment hardware in accordance with Accomplishment Instructions, Part B of the SB within 4,000 flight hours after the AD’s effective date (Requirement 3; Compliance 3). Completion of that replacement for a nozzle removes the inspection duty for that nozzle (Requirement 3).

Method-of-compliance duty:

• Use of the specified SB parts and allowance for later NAA approved revisions means the AD requires operators to adopt the manufacturer’s procedure unless a later NAA-approved revision is used (Requirement 1; Requirement 3). The duty is not a generic “inspect and fix” obligation; it is an obligation to use the SB methodology or its NAA-approved updates.

Record-keeping and evidentiary duty implicit in practice:

• Although the AD text does not explicitly require particular logbook entries, the nature of AD compliance means operators will need to show when they performed the inspections and replacements to demonstrate compliance with the flight-hour windows. The AD therefore creates an implied duty to maintain evidence of compliance.

Rights and procedural matters (explicit and implicit):

• The AD permits compliance using later NAA approved revisions of the Bombardier SB (Requirement 1; Requirement 3). That creates a procedural route for operators to use updated technical guidance once it has received NAA approval.
• The document does not include an express right of appeal, exemption, or relief in the text provided. Any such rights or avenues for relief would exist under the broader regulatory framework external to this AD, but the AD itself simply specifies the technical duties and timing.

Scope of termination:

• Completion of Requirement 3 for a nozzle constitutes terminating action for Requirements 1 and 2 for that particular engine exhaust nozzle only (Requirement 3). This creates a right of relief from the inspection duty, but only when the replacement has been completed for the relevant nozzle.

Immediate operational constraint:

• The requirement to replace an attachment if a bolt is missing or fractured before further flight creates an immediate constraint on aircraft operation where that defect is found (Requirement 1.a).

In short, the AD prescribes affirmative duties to inspect and replace hardware using specified manufacturer procedures, specifies timing for those duties, allows later NAA-approved SB revisions to be used, and provides termination of the inspection obligation for each nozzle once replacement is completed.

The text provided is an Airworthiness Directive that sets mandatory technical and timing obligations but does not itself include penalty provisions, fine schedules, or explicit enforcement procedures within its text. The AD does, however, state its effective date and bear the signature of a Civil Aviation Safety Authority delegate (signature block; effective date 30 August 2007), indicating formal issuance by the regulator.

What the document does state about enforcement indirectly:

• It creates mandatory compliance obligations (the inspection and replacement requirements and their compliance windows) that, by virtue of being an AD, are issued under the authority of the regulator. The AD’s enforceability flows from that status, but the AD text does not specify sanctioning mechanisms, remedial notices, or procedural steps for enforcement action.

What the document does not provide:

• No penalties, infringement notice amounts, or criminal/regulatory sanction descriptions appear in the AD’s text. No administrative procedures for applying for alternative methods of compliance (AMOC) or exemptions are specified in the text provided. No enforcement timeline, inspection regime by the regulator, or audit process is set out.

Implications for operators and maintainers:

• Operators should treat the AD as a mandatory directive to be complied with within the stated flight-hour windows and perform replacement when required. The absence of penalties in the AD text does not mean there are none under the broader aviation safety statute or regulatory framework; such penalties, and the processes for enforcement, would be set out in the applicable aviation safety legislation and CASA enforcement policies rather than in the AD itself. The AD does not provide those legislative enforcement provisions.

Practical enforcement risk:

• Non-compliance with an AD typically has operational consequences (airworthiness certificates, maintenance release validity, insurance, and commercial implications) even where the AD does not itself spell out penalties. The AD text, however, presents only the technical and timing obligations and a signature/effective date; it does not itself state the range of enforcement remedies or procedures available to the regulator.

Users of this document must therefore be aware that enforcement and penalty regimes are determined outside the AD text and should consult the relevant aviation safety legislation and regulator policies for the specific enforcement framework applicable to failure to comply.

The AD text itself is narrowly focused on the technical requirement and refers to a related foreign regulator AD and a manufacturer service bulletin. The AD’s interactions with other laws and instruments, as reflected in the text, are limited and specific.

Direct cross-instruments referenced in the AD:

• Bombardier Service Bulletin 601R-78-021 dated 2 June 2006 is the technical method of compliance; Part A covers inspection and Part B covers replacement. The AD requires use of those Parts as the procedural standard and allows the use of later NAA approved revisions of those Parts (Requirement 1; Requirement 3).
• Transport Canada Airworthiness Directive CF-2006-19 dated 28 July 2006 is explicitly referred to in a Note in the AD (Note). The AD therefore acknowledges an antecedent regulatory action by another national aviation authority; the text does not specify further legal consequences of that reference beyond acknowledging it as a related instrument.

Delegation and approval interactions:

• The AD permits later NAA approved revisions of the Bombardier SB to be used to comply (Requirement 1; Requirement 3). That creates an interaction point between the operator and the relevant National Aviation Authority for acceptance of later revisions. The AD does not itself set the process for NAA approval; it simply conditions compliance on NAA approval where a later revision is used.

What the AD does not mention (and therefore should be checked against relevant law):

• The AD does not state how it interacts with airworthiness certificate requirements, continuing airworthiness responsibilities, maintenance release processes, or broader statutory obligations under aviation safety law. Those relationships are governed by the underlying aviation statutes and regulatory instruments outside the AD text.
• The AD contains no provisions about the interface with commercial contracts, warranties, product liability, insurance, or supplier obligations with Bombardier or parts suppliers. Any contractual remedies or claims arising from the defect or from the need to replace hardware would be governed by contract law and warranty regimes outside this AD.

Practical interoperability points for operators:

• Operators must use the Bombardier SB or later NAA-approved revisions to comply. This requires liaison with the manufacturer for the SB and with the NAA for approval status of any SB revision used.
• Because the AD references a Transport Canada AD, operators should be alert that other jurisdictions may have parallel ADs with overlapping or differing compliance provisions; the AD text does not harmonise those regimes for operators.

In short, the AD interacts directly with a Bombardier Service Bulletin and indirectly references a Transport Canada AD. It relies on existing NAA approval mechanisms for later revisions of the SB. The AD does not set out its relationships to other statutory enforcement mechanisms or administrative processes; those remain in the broader regulatory framework beyond the text.

The document provided does not contain an amendment history section. The contents that bear on temporal provenance are these items in the text:

• Bombardier Service Bulletin 601R-78-021 is dated 2 June 2006 and is the operative technical document referenced for Parts A and B (Requirement 1; Requirement 3).
• The AD is signed by a delegate of the Civil Aviation Safety Authority on 25 June 2007 (signature block) and states that the AD becomes effective on 30 August 2007 (Compliance; effective date).
• The AD includes a note referring to Transport Canada AD CF-2006-19 dated 28 July 2006 (Note).

No later amendments, revisions, supersessions, or variations to this particular AD are contained in the text provided. The AD does allow later NAA-approved revisions of the Bombardier SB to be used as the method of compliance, but that is not an amendment to the AD itself; it is a process-direction permitting later approved technical revisions to satisfy the AD’s instructions (Requirement 1; Requirement 3).

If an amendment history is required beyond what is present in this document, operators or advisers must consult the issuing regulator’s database or official AD register for any subsequent ADs, corrective Federal Aviation Administration or other NAA directives, or for official amendment bulletins. The AD text itself contains no record of having been amended prior to the stated effective date, and no post-effective amendments are reflected in the supplied material.

The AD text contains no litigation history and does not mention any court proceedings, appeals, or disputes related to the AD, the Bombardier Service Bulletin, the underlying technical failure, or Transport Canada AD CF-2006-19. The Background section discusses three reported in-flight departures of engine exhaust nozzle and fairing and an investigative finding that the retaining bolts provided less than desirable stress margins, but it does not describe any litigation arising from those incidents (Background).

Because the document provided contains no litigation record, there is no case law, interlocutory decision, statutory judicial interpretation, or enforcement litigation included in the text that could be referenced here. Any litigation arising from these facts or this AD would be recorded outside this document in court or administrative records. The AD itself is a regulatory instrument and not a record of litigation.

If litigation history is material for a compliance or risk assessment, the appropriate course is to review court records, regulator enforcement records, and any public statements from the regulator, Bombardier, or affected operators for subsequent disputes. The AD text does not supply that material.

This AD contains a number of potential practical pitfalls and points of ambiguity that operators and maintenance organisations should note carefully and manage, based strictly on the AD text.

Serial-number scope gap: The Applicability lists serial numbers 7003 through 7067, and 7069 through 7947 (Applicability). That listing omits serial number 7068. The AD does not explain whether omission of 7068 is deliberate (e.g., a different configuration) or clerical; operators must confirm the applicability of the AD to any airframe near that boundary rather than assume inclusion.

Per-nozzle termination: Completion of Requirement 3 is explicitly a terminating action only for the applicable engine exhaust nozzle (Requirement 3). That creates a scenario where one nozzle on an aircraft can be upgraded and removed from the inspection cycle while the other nozzle remains subject to recurring inspections until its replacement. Operators must track compliance status at the nozzle level, not only at the aircraft level, to avoid missing continuing inspection obligations.

Immediate grounding trigger: Requirement 1.a requires replacement before further flight if a bolt is missing or fractured. The AD therefore creates an immediate no-fly condition for affected nozzles until the replacement is completed. Failure to understand this could lead to inadvertent flight with an identified defect. The AD does not provide any interim ferry or special flight permission within its text.

Dependency on SB version and NAA approval: The AD mandates the use of Part A and Part B of SB 601R-78-021 dated 2 June 2006, or later NAA approved revisions (Requirement 1; Requirement 3). Using a later SB revision requires NAA approval. Operators who adopt a later SB revision without confirming NAA approval risk non-compliance. The AD does not specify how NAA approval is to be evidenced in maintenance records.

Flight-hour counting and compliance windows: The compliance obligations are expressed in flight hours after the AD’s effective date (initial inspection within 1,500 flight hours; replacement within 4,000 flight hours; recurring inspections at intervals not to exceed 1,500 flight hours) (Compliance). Operators must be careful in counting flight hours from the AD’s effective date (30 August 2007) and in accounting for any flight hours already accrued since that date to calculate remaining time to compliance. The AD text does not address alternative time metrics (calendar days, cycles), only flight hours.

Parts availability and lead time: The AD requires replacement with new attachment hardware in accordance with Part B of the SB (Requirement 3). The AD contains no provision for parts supply, nor does it include any allowance for extended lead times. If the replacement hardware is not immediately available, the operator faces potential unscheduled removal from service if inspection reveals a missing or fractured bolt. The AD provides no exception for supply-chain issues.

Record-keeping expectations not specified: The AD does not specify the form of records required to demonstrate compliance. While operators will typically record AD compliance in maintenance logs, the AD text does not set out a required form or retention period. That omission means operators must apply usual maintenance record practices under the broader regulatory framework to prove compliance.

No explicit penalty or relief mechanism in the AD text: The AD does not state penalty amounts or the process for seeking exemptions or alternative methods of compliance (the AD does allow later NAA-approved SB revisions). Operators should not assume the AD provides procedural avenues for relief; any such mechanisms will be in the regulator’s broader administrative framework and are not described here.

Reference to foreign regulator AD: The AD notes Transport Canada AD CF-2006-19 (Note). Differences between jurisdictions’ ADs might exist; the AD does not reconcile any differences or address how to prioritise multiple authorities if an operator is subject to several regimes.

Ambiguity about partial compliance: If an operator has already performed actions under the Bombardier SB before the AD date, the AD states initial inspection is required “within 1,500 flight hours … unless previously accomplished” (Compliance 1). The AD does not specify how to document or validate prior accomplishment for the purposes of counting down to replacement or verifying terminating action. Operators must maintain and be able to produce records proving prior accomplishment to avoid duplicate work or disputed compliance.

In practice, these “gotchas” mean operators must be meticulous about serial-number applicability, per-nozzle record-keeping, flight-hour calculations, use of NAA-approved SB revisions, parts procurement lead times, and documentation of any work performed before the AD’s effective date.

This section translates the AD’s textual requirements into an operational compliance checklist and practical steps, strictly as required and permitted by the AD text.

Preliminary steps

1. Verify applicability: Confirm the affected aircraft serial number falls within 7003-7067 or 7069-7947 (Applicability). Do not assume aircraft outside this list are covered.
2. Establish effective date baseline: The AD is effective 30 August 2007 (effective date). Flight-hour compliance windows are measured from that date. Calculate flight hours accumulated since that date to establish remaining time for initial inspection and mandatory replacement.
3. Obtain the correct SB documentation: Acquire Bombardier Service Bulletin 601R-78-021 dated 2 June 2006 and identify Part A (inspection) and Part B (replacement). If planning to use a later SB revision, obtain evidence that the revision is NAA approved before using it to comply with the AD (Requirement 1; Requirement 3).

Inspection programme (Requirement 1 and 2) 4. Initial inspection: If not already completed prior to the AD, perform an inspection of both left and right engine exhaust nozzles in accordance with the Accomplishment Instructions, Part A, of SB 601R-78-021 within 1,500 flight hours after the AD’s effective date (Compliance 1; Requirement 1). 5. Immediate action if defect found: If inspection finds any bolt missing or fractured, do not dispatch the aircraft until replacement of the engine exhaust nozzle attachment hardware is completed for the affected nozzle, in accordance with Requirement 3 (Requirement 1.a). 6. Recurring inspections: If no bolt is missing or fractured, schedule and perform repeat inspections at intervals not to exceed 1,500 flight hours until the replacement of that nozzle’s attachment hardware is performed (Requirement 2; Compliance 2).

Replacement (Requirement 3) 7. Replacement window: Plan and execute replacement of the existing engine exhaust nozzle attachment hardware with the new hardware specified in Accomplishment Instructions, Part B of SB 601R-78-021 no later than 4,000 flight hours after the AD effective date (Compliance 3; Requirement 3). 8. Termination documentation: When replacement for a specific nozzle is completed, document that replacement in the aircraft maintenance records and indicate that Requirements 1 and 2 are terminated for that nozzle per the AD’s wording (Requirement 3). Maintain records showing the replacement conforms to Part B of the SB or to a later NAA approved revision.

Maintenance and record-keeping details 9. Use authorised maintenance personnel: Ensure inspections and replacements are performed by appropriately licensed maintenance personnel and organisations under applicable regulatory maintenance standards. The AD requires compliance with SB instructions; it does not specify personnel, so normal regulatory maintenance qualifications apply. 10. Record flight hours: Maintain an auditable record of flight hours consumed by the aircraft to demonstrate compliance with the AD’s flight-hour windows. Use the aircraft’s official flight-time logs to compute deadlines for inspection and replacement. 11. Evidence of NAA-approved revisions: If using a later revision of the SB, retain documentation from the NAA demonstrating approval of that revision to support compliance. 12. Document remedial actions: If a bolt is found missing or fractured and replacement is performed pre-flight, record the finding, the immediate action taken, and parts installed, including part numbers and SB references used.

Parts and logistics 13. Procure compliant hardware: Source the replacement attachment hardware specified in Part B of the SB. Verify that the parts supplied match the part numbers and installation instructions in the SB or in a later NAA-approved revision. 14. Plan lead time into schedules: Because replacement can be required before further flight if a defect is found, plan inventory or supplier lead times accordingly to reduce risk of AOG (aircraft on ground) situations.

Coordination and approvals 15. Liaise with the NAA where necessary: If an operator wishes to use a later SB revision, confirm NAA approval before implementing that revision as the method of compliance. Retain records of approval. 16. Confirm compliance status per nozzle: Track compliance on a per-nozzle basis. Replacement of one nozzle is terminating action only for that nozzle. Ensure that the remaining nozzle(s) continue on the 1,500 flight‑hour inspection cycle until replaced.

Practical contingency planning 17. Pre-prepare maintenance slotting: Schedule inspections and replacements to fit within the required flight-hour windows, to avoid unscheduled removals from service. 18. Establish emergency repair procedures: Where an inspection reveals a missing or fractured bolt and replacement hardware is not immediately available, operators must consult the regulator’s procedures outside this AD for any possible relief or special flight authorisation; the AD itself requires replacement before further flight (Requirement 1.a).

Final verification 19. Sign-off and log entries: After performing inspection and/or replacement, enter the maintenance action into the aircraft logbooks with cross-reference to the AD and the SB Part used, including serial numbers of parts installed and the maintenance release signature as required under applicable maintenance regulations. 20. Retain evidence for audits: Keep copies of SB instructions used, NAA approvals (if any), parts invoices and traceability, inspection findings, and logbook entries to demonstrate compliance in regulatory audits or reviews.

This compliance plan follows the AD’s requirements: inspection per Part A within 1,500 flight hours unless already done (Compliance 1), repeating inspections not to exceed 1,500 flight hours (Compliance 2), replacement per Part B within 4,000 flight hours (Compliance 3), and immediate replacement prior to further flight if a bolt is missing or fractured (Requirement 1.a). Documentation of work and any NAA approvals must be retained to evidence conformity with the AD.