AD/DHC-8/151 - Spoiler Upload Valves and Rudder Shutoff Valves

The AD directly affects operators and maintainers of Bombardier DHC-8-400, -401 and -402 aeroplanes falling in the serial number ranges specified. Specifically, operators of aircraft with S/N 4105 through 4172 must comply with Requirement 1 (spoiler unload valves) and operators of aircraft with S/N 4113 through 4179 must comply with Requirement 2 (rudder shutoff valves). Aircraft whose serial numbers fall in the overlap of those ranges will be subject to both requirements. The AD also affects maintenance organisations and line maintenance providers who perform inspections and parts replacement under the applicable Bombardier service bulletins because the inspections must be carried out “in accordance with” SB 84-27-37 or SB 84-27-39.

Parts suppliers and inventory managers are affected by Requirement 3, which prohibits installation of specified valves unless they have been inspected by the manufacturer and labelled with an “A” suffix after the serial number as per the service bulletins. Spare parts providers holding valves within the forbidden S/N ranges will therefore face constraints on supplying those parts for installation on affected airframes unless the manufacturer has performed the required inspection and labelling. The manufacturer (Bombardier) is implicated through the instruction to follow its service bulletins and the requirement that it inspect and label replacement valves. The AD also cross-references Transport Canada; the service bulletins can be superseded only with the approval of the Chief, Continuing Airworthiness, Transport Canada, meaning a national regulator’s approval controls acceptable procedural changes.

Regulatory and compliance staff within operators and maintenance organisations will be responsible for scheduling and documenting the required inspections, determining whether replacement is necessary, sourcing compliant replacement valves, and ensuring that no prohibited valves are installed. Flight operations personnel will be affected operationally where a leaking valve is found because the AD requires replacement “prior to further flight,” thereby creating an immediate operational constraint. The Civil Aviation Safety Authority is the issuing body, with the AD effective date specified and the delegate’s signature shown, which identifies CASA as the regulator enforcing this directive.

The AD imposes the following concrete duties on operators and maintenance organisations, as stated in the text.

• Applicability determination: Operators must determine whether their aircraft fall within the serial-number ranges specified. Requirement 1 is applicable to Models 400/401/402 S/N 4105-4172; Requirement 2 to Models 400/401/402 S/N 4113-4179.

• Inspections: For applicable aircraft, operators must inspect left and right spoiler unload valves P/N 396000-1005 in accordance with Bombardier SB 84-27-37; and inspect left and right rudder shutoff valves P/N 412700-1001 in accordance with Bombardier SB 84-27-39. The AD requires the inspections “in accordance with” those service bulletins or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

• Immediate action for leaks: If leaking or weeping is found during inspection, the AD requires replacement of the affected valve prior to further flight. This is an absolute temporal duty: aircraft with a leaking valve may not continue to be flown until replacement has been effected.

• Scheduled replacement where no leak found: If the inspected valve shows no leaking, the AD nonetheless requires replacement of the inspected valve(s) within 6,000 flight hours from the time of the initial inspection mandated by this AD.

• Installation limitation: From the effective date of the AD, no replacement of Spoiler Unload Valves P/N 396000-1005 with S/N 0289-0424, and Rudder Shutoff Valves P/N 412700-1001 with S/N 0239-0384, is allowed to be installed on DHC-8 Series 400 aeroplanes unless the valves have been inspected by the manufacturer and labelled with a suffix “A” after the S/N, as indicated in the service bulletins.

• Compliance windows: The AD sets specific timing for the mandatory actions. Initial inspections for Requirements 1 and 2 must be completed within 750 flight hours after the effective date of the AD. Where leaking is found, replacement is required prior to further flight. Where no leak is found, replacement must occur within 6,000 flight hours from the time of initial inspection.

Rights and procedural levers embedded in the text include:

• Reliance on service bulletins or later approved revisions: The AD explicitly permits compliance via later revisions of the identified Bombardier service bulletins, provided those later revisions are approved by the Chief, Continuing Airworthiness, Transport Canada. This creates a discrete regulatory approval point for procedural changes.

• Manufacturer inspection and labelling as condition precedent to installation: Requirement 3 assigns to the manufacturer the role of performing the inspection and affixing the “A” suffix; operators may install those items only if that manufacturer action has occurred. The AD thereby creates a right for operators to install valves that bear the approved label, subject to the manufacturer’s completion of the inspection.

The AD does not specify monetary penalties or an administrative enforcement regime in its text. The AD becomes effective on a stated date and is issued under the authority of the Civil Aviation Safety Authority delegate, which sets the regulatory obligation. The text does not set out appeal or exemption processes; for any procedural change the AD defers to later revisions of the Bombardier service bulletins as approved by the relevant Transport Canada official.

The AD itself sets compliance obligations and effective dates but does not state specific monetary penalties or civil sanction mechanisms in the text provided. The document identifies the issuing authority by signature and gives an effective date, indicating that the AD is a binding airworthiness instrument once effective. The AD requires inspections within defined windows and imposes a mandatory “prior to further flight” replacement requirement where leaking or weeping is found. That temporal phrasing creates an operational enforcement mechanism: an aircraft that has an identified leaking valve must not be flown until replacement is completed.

Enforcement will involve the responsible aviation regulator and the operator’s continuing airworthiness processes because the AD expressly references the Bombardier service bulletins and places approval authority for later revisions with the Chief, Continuing Airworthiness, Transport Canada. The AD also notes Transport Canada AD CF-2009-25R1 dated 23 July 2009, indicating that this CASA AD has a counterpart reference in Transport Canada documents; that cross-reference suggests regulatory coordination between national authorities.

The text shows that the AD’s compliance obligations are specific and time-limited. It requires documentation of inspections, replacements, and the installation status of valves with or without the manufacturer’s “A” suffix. While the AD does not list administrative or criminal penalties in the document, the requirement that replacement be effected prior to further flight where leaking is found creates an operational control point that can be observed by inspectors, auditors and regulators. The absence of explicit penalty text in the AD means any sanctions, if applied, would be drawn from the broader regulatory framework under which CASA operates rather than from this AD alone. The AD does not contain an explicit process for requesting exemptions or alternative means of compliance within the document itself; instead it ties compliance to the Bombardier SBs or Transport Canada-approved revisions, which creates a process channel for acceptable alternatives via the Approving Authority.

The AD explicitly interacts with manufacturer service bulletins and a Transport Canada AD. It requires inspections “in accordance with Bombardier Service Bulletin (SB) 84-27-37” and SB 84-27-39, dated 5 February 2009, or “later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.” That wording creates a two-layer compliance structure: the technical procedures are contained in the Bombardier SBs, while any divergence from those SBs requires approval from a named oversight authority in Transport Canada. The AD also contains a note referring to Transport Canada AD CF-2009-25R1 dated 23 July 2009, affirming that there is a corresponding Canadian regulatory instrument. The AD is issued by the Civil Aviation Safety Authority, as indicated by the signature block showing James Coyne, Delegate of CASA. The AD therefore sits at the intersection of manufacturer technical guidance and domestic and foreign regulator actions.

The AD does not purport to modify contractual arrangements between operators and third parties, but it does impose constraints that will have contractual effects. For example, Requirement 3’s prohibition on installing valves with certain serial numbers unless they are inspected by the manufacturer and labelled “A” will affect supply contracts for spare parts, parts traceability documentation, and maintenance contracts. Operators who receive valves in the prohibited S/N ranges without the required manufacturer labelling will be unable to lawfully install them on affected aeroplanes under this AD. This may necessitate contractual renegotiation, return of parts to suppliers, or engagement with the manufacturer for post-sale inspection and labelling.

The AD’s reference to “later revisions approved by the Chief, Continuing Airworthiness, Transport Canada” creates an inter-jurisdictional approval step: technical update decisions for the service bulletins rest with a named official in another national regulator. That mechanism means that any procedural or methodological change to the inspection or replacement process will require intergovernmental or cross-statutory approval procedures to be applicable under this AD.

The AD’s text does not specify how compliance interacts with insurance policies, operator certificates or commercial aviation safety regulations beyond the reference to CASA as the issuing authority and to the Transport Canada approval point. The document does not set out appeals, exemptions, or review procedures in itself; any such processes would be addressed under the broader regulatory framework of the relevant aviation authorities.

The AD text includes limited amendment-history information. It cites Bombardier Service Bulletins 84-27-37 and 84-27-39, both dated 5 February 2009, as the procedural bases for inspection and replacement. The AD explicitly allows compliance by reference to “later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.” That clause establishes a formal pathway for later versions of the Bombardier SBs to become acceptable for compliance, subject to Transport Canada approval. The AD also notes a Transport Canada AD , CF-2009-25R1 , dated 23 July 2009, and the AD identifies a CASA delegate as the signatory with a signature date of 14 August 2009 and an effective date of 24 September 2009.

Beyond those elements, the document does not record any prior amendments to this particular CASA AD within the text provided. There is no internal amendment history listing multiple versions of AD/DHC-8/151. The AD’s reliance on later SB revisions and the need for approval by a named Transport Canada official means that amendment to the operational method would be effected by either: (a) a Bombardier SB revision that has been submitted and approved by the Chief, Continuing Airworthiness, Transport Canada and thereby accepted as an alternate means of compliance; or (b) a formal amendment of the AD by CASA, which would be recorded in a later AD document. The provided text does not include such subsequent ADs or an explicit log of changes.

Because the AD references a Transport Canada AD and service bulletins with a specific date, the present document functions as a snapshot that delegates technical details to the SBs and delegates approval of subsequent technical changes to Transport Canada. Any formal amendment to the AD itself, or the formal record of amendments, is not included in the source text provided.

The source document contains no litigation history, references to court proceedings, or citations of judicial decisions concerning AD/DHC-8/151. The AD references Transport Canada AD CF-2009-25R1 and Bombardier service bulletins as technical sources, but it does not refer to any appeals, enforcement actions, disputes, or litigation arising from the AD. The signature block indicates the AD was issued by a CASA delegate, but does not include subsequent administrative decisions, contested enforcement actions, or judicial review outcomes.

Given the absence of litigation references in the AD text, there is no basis in the provided source to describe any court interpretation or to summarise precedents. Any account of litigation or dispute resolution would need to be drawn from external material not included in this document. The AD’s internal structure,mandating inspection and replacement actions and tying compliance to service bulletins and Transport Canada approvals,creates regulatory obligations that could, in principle, be the subject of administrative reviews or legal challenges elsewhere, but the present source includes no record of such events.

Users requiring litigation history should treat the AD text as not containing such information and should consult the relevant regulatory and judicial records for CASA and Transport Canada to identify any subsequent administrative or judicial proceedings related to this AD or its implementation. From the AD alone, no litigation history can be reported.

Several concrete drafting and operational details in the AD are easy to miss and carry operational consequences.

• Serial number specificity and overlap: The Applicability and Requirements are serial-number specific and different across the two valve families. Requirement 1 applies to S/N 4105 through 4172 for the spoiler unload valves; Requirement 2 applies to S/N 4113 through 4179 for the rudder shutoff valves. Aircraft with S/N 4113 through 4172 fall into both requirement sets and therefore require both inspections. Operators must carefully check airframe S/Ns against the ranges before deciding which actions apply.

• Part numbers and serial-number ranges for installation prohibition: Requirement 3 forbids installation of Spoiler Unload Valves P/N 396000-1005 with S/N 0289 through 0424 and Rudder Shutoff Valves P/N 412700-1001 with S/N 0239 through 0384 unless those valves have been inspected by the manufacturer and labelled with an “A” suffix. The AD’s installation prohibition is tied to specific P/N and S/N ranges; maintenance staff should ensure that part tags and traceability match exactly, including any suffixes.

• Two-tier timeframes: The AD requires initial inspections within 750 flight hours and establishes two different replacement regimes: immediate replacement prior to further flight if leaking is found, and replacement within 6,000 flight hours where no leak is found. The “prior to further flight” language creates a hard, operational stop for aircraft with a detected leak. The “within 6,000 flight hours” requirement creates a long-term scheduling obligation. Tracking both timelines across a fleet requires accurate flight-hour accounting.

• Dependence on Bombardier SBs and Transport Canada approval: The AD instructs compliance “in accordance with” Bombardier SB 84-27-37 and SB 84-27-39, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada. Operators must use those SBs for procedure details and must obtain or confirm the status of any later revisions with Transport Canada; relying on other procedures without approval would not satisfy the AD.

• Manufacturer labelling as condition precedent to installation: Requirement 3 gives the manufacturer the role of inspecting and labelling valves with the “A” suffix. Operators and parts suppliers who receive valves without that suffix cannot lawfully install them on the affected aeroplanes under this AD. That detail can be missed in parts exchanges or inventory movements if suffixes are not recorded and tracked.

• Effective date vs signature date: The AD is signed by a CASA delegate on 14 August 2009 and becomes effective on 24 September 2009. The ten-day or multi-week gap between signature and effective date is a compliance scheduling fact that operators need to track. The initial inspection window (within 750 flight hours after the effective date) runs from 24 September 2009, not from the signature date.

• No explicit penalty language in the AD: The AD does not set out fines or sanctions in its text. However, the operational “prior to further flight” obligation and the AD’s issuance by a regulator imply mandatory status. Operators should not assume absence of penalty language means absence of enforcement; operational non-compliance creates safety and administrative exposure.

• Exact wording in the AD header: The AD text as provided contains several typographical oddities in headings (for example “Spoiler Upload Valves andRudder Shutoff Valves”). These typographical matters do not change the substance of the technical requirements, but maintenance staff should rely on the concrete requirements and serial-number ranges rather than the headings alone.

The AD’s text lays out precise steps. The following is a practical compliance checklist drawn from the AD that maps the obligations into operational actions. Each step should be completed with documentary evidence retained in the aircraft continuing airworthiness records.

1. Applicability check:

   • Verify the aircraft model and serial number.
   • Determine whether Requirement 1 (S/N 4105-4172) and/or Requirement 2 (S/N 4113-4179) apply to the individual airframe.

2. Obtain the referenced service bulletins:

   • Acquire Bombardier SB 84-27-37 (for spoiler unload valves) and SB 84-27-39 (for rudder shutoff valves), both dated 5 February 2009, or verify the status of any later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.
   • Do not substitute other inspection procedures unless an approved revision has been obtained and documented.

3. Schedule initial inspections:

   • Plan to carry out the inspections within 750 flight hours after the AD’s effective date (24 September 2009). For future reference, calculate how many flight hours remain in that window and schedule maintenance slots accordingly.
   • Ensure both left-hand and right-hand valves of each affected valve type are inspected per the relevant SB.

4. Perform inspections per SBs:

   • Follow the step-by-step inspection procedures in SB 84-27-37 and SB 84-27-39. Record findings, including whether any leaking or weeping was observed.
   • Record valve part numbers and serial numbers exactly, including any suffixes.

5. Action on findings:

   • If leaking or weeping is found during inspection, replace the affected valve prior to further flight as required by the AD. That replacement must be completed and documented before the aircraft is returned to service.
   • If no leaking or weeping is found, schedule replacement of the inspected valve(s) within 6,000 flight hours from the initial inspection date. Record the replacement due date in the continuing airworthiness records and in maintenance planning systems.

6. Parts sourcing and installation constraints:

   • Do not install Spoiler Unload Valves P/N 396000-1005 with S/N 0289-0424, nor Rudder Shutoff Valves P/N 412700-1001 with S/N 0239-0384, on DHC-8 Series 400 aeroplanes unless those valves have been inspected by the manufacturer and labelled with an “A” suffix as described in the relevant SB. Confirm manufacturer inspection and labelling documentation before installing any valves within those serial-number ranges.
   • Maintain traceability of all replacement valves, including manufacturer inspection status and serial-number suffixes.

7. Documentation and record-keeping:

   • Log all inspections, findings and replacements in the aircraft’s maintenance and continuing airworthiness records. Include the SB revision used, inspector names, dates and flight-hour counters at time of inspection and replacement.
   • Retain records of any manufacturer labelling or correspondence proving that a valve with a forbidden S/N has been inspected and labelled with the “A” suffix.

8. Coordination with regulatory authorities:

   • If a later revision of the SB is to be used, obtain written approval from the Chief, Continuing Airworthiness, Transport Canada, as the AD requires acceptance of later revisions only where so approved.
   • If there is any ambiguity about interpretation of the SB procedures or the AD’s requirements, seek clarification from CASA or the appropriate national continuing airworthiness authority.

9. Operational planning:

   • Prepare for possible operational disruption where leaks are found. Because replacement is required prior to further flight when leaks are discovered, maintain contingency plans for aircraft-of-grounding, flight reallocation and passenger accommodation.
   • Assess inventory of spare valves that are already manufacturer-inspected and labelled “A” to determine whether supply is sufficient to meet potential immediate replacement needs.

10. Ongoing monitoring:

• Track flight hours from the date of initial inspection to ensure replacement within the 6,000-flight-hour window where no leak was found.
• Monitor supplier and manufacturer communications for any SB revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Who pays and responsibility allocation:

• The AD places the duties on the aircraft operator and maintenance organisation to carry out inspections and replacements. That creates the practical cost burden of labour, parts procurement, and potential operational disruption for the operator. The manufacturer’s role is limited to providing the service bulletins and inspecting/labeling valves in the specified S/N ranges where those valves are to be made permissible for installation. The AD does not specify that the manufacturer must bear cost; costs are obligations that flow from the regulatory compliance duty.

Implementation risks and mitigations:

• Parts availability risk: Because Requirement 3 restricts installation of certain S/N ranges unless manufacturer-inspected and labelled “A”, operators should confirm availability of compliant spares and, where necessary, engage the manufacturer in advance to secure inspected spares or inspection and re-labelling services.
• Operational interruption risk: The “prior to further flight” replacement requirement for leaking valves imposes an immediate grounding risk for affected flights. Operators should pre-plan contingencies and carry or have access to compliant spares where practical.
• Procedural risk: Using unapproved inspection procedures or SB revisions not approved by the Chief, Continuing Airworthiness, Transport Canada will not meet the AD’s stated compliance path. Obtain approvals where necessary and document them.

Following the checklist above and maintaining documentary proof of each step will show compliance with the AD’s specific mandates as set out in the text.