{"id":"F2007L02371","name":"AD/CL-600/79 - Aileron Power Control Unit Links","slug":"ad-cl-600-79-aileron-power-control-unit-links","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":67729,"registerId":"commonwealth-F2007L02371-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bombardier (Canadair) CL-600 (Challenger","sectionType":"division","heading":"Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes","content":"### Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes\n\n| AD/CL-600/79 | Aileron Power Control Unit Links | 9/2007 |\n| ------------ | -------------------------------- | ------ |\n\n| Applicability: | Bombardier Inc. Model CL-600-2B19 - CRJ-100/440 - serial numbers 7003 and subsequent. |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | Accomplish the following in accordance with Bombardier Alert Service Bulletin (ASB) A601R-27-130, Revision A dated 22 December 2003, or later NAA approved revisions:1. Conduct a detailed visual inspection of the four aileron PCU links for fractures/cracks and replace any fractured/cracked link prior to further flight.2. As part of the replacement of fractured/cracked links, perform the following:a. Record the torque value of the forward and aft attachment bolts for both PCU links for the applicable aileron; andb. Check for mismatch between PCU link and the PCU output fork; andc. Perform an eddy current inspection of the aileron PCU lugs, and if a crack is found, contact Bombardier in accordance with the above-mentioned ASB; andd. Record the information requested in Appendix A and Appendix B of the above-mentioned Bombardier ASBs.3. Aircraft that had the initial aileron PCU link inspection, and if necessary replacement, performed in accordance with ASB A601R-27-130, dated13 November 2003, meet the requirements of Requirement 1 and 2a, b and d of this AD. However, aircraft that were found with a fractured/cracked aileron PCU link and were not subject to an NDT inspection of the aileron lugs, are to have an NDT inspection of the applicable aileron lugs, required under Requirement 2c of this AD carried out.4. Forward the information requested in Appendix A and B of the above mentioned ASBs, or later NAA approved revision, and any associated fractured/cracked link(s), to Bombardier Aerospace at the address provided in the Bombardier ASBs.5. Repeat the inspection and checks of the aileron PCU links detailed in Requirement 1 and 2 of this AD. |\n\n| | Note: Transport Canada AD CF-2004-13 dated 20 July 2004 refers. |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | For Requirements 1 and 2:Unless previously accomplished, aircraft that have accumulated 2,000 flight hours or more upon the effective date of this AD; prior to accumulating 550 flight hours from the effective date of this AD; andAircraft with less than 2,000 flight hours upon the effective date of this directive; prior to reaching 2,000 flight hours or prior to accumulating 550 flight hours from the effective date of this directive, whichever is reached later.For Requirement 3:At the next repeat visual inspection of the aileron PCU link as detailed in Requirement 5 of this AD.For Requirement 4:Within 30 days of the initial inspection, unless previously accomplished.For Requirement 5:At intervals not to exceed 1000 flight hours. |\n| | This Airworthiness Directive becomes effective on 30 August 2007. |\n| Background: | Transport Canada has received reports of aileron power control unit (PCU) link failures on several in-service aircraft. Failure of one link is considered to be a dormant failure; failure of both PCU links to an aileron could result in reduced lateral control of the aircraft. |\n\n![](image.001.png) \nDavid Punshon \nDelegate of the Civil Aviation Safety Authority\n\n25 June 2007","sortOrder":0},{"sectionNumber":"AD/CL-600/79","sectionType":"part","heading":"AD/CL-600/79","content":"## AD/CL-600/79","sortOrder":1},{"sectionNumber":"Aileron Power Control Unit Links","sectionType":"part","heading":"Aileron Power Control Unit Links","content":"## Aileron Power Control Unit Links","sortOrder":2},{"sectionNumber":"9/2007","sectionType":"part","heading":"9/2007","content":"## 9/2007","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD stays within the original safety purpose: to detect and correct fractures in aileron PCU links to prevent dual‑link failure and potential reduced lateral control. It refines procedural detail (inspection method, bolt-torque recording, mismatch checks, NDT of lugs), adds mandatory reporting and part return to Bombardier, and sets repeat inspection intervals. Those additions do not expand the scope beyond the original safety objective; they clarify required actions and introduce administrative/tracking measures to support fleet-level analysis."},"complexity_factors":["Single-aircraft-type applicability limited to CL-600-2B19 serials 7003 and subsequent","Five numbered Requirements (1–5) with procedural and reporting elements","Cross-reference to Bombardier ASB A601R-27-130 (Revision A) and its Appendices A and B","Conditional compliance windows depending on current flight hours (>=2000 vs <2000)","An exception/clarification for aircraft inspected under earlier ASB (13 Nov 2003) that requires only the missing NDT if not previously done","Periodic repeat interval requirement (every 1,000 flight hours)","Reporting obligation (30-day deadline) and physical return of fractured parts to manufacturer","Technical requirement for eddy-current NDT (requires specialised equipment/personnel)"],"plain_english_summary":"**What this instrument changes (mechanical effect)**\n\n- It requires operators of Bombardier CL-600-2B19 (CRJ-100/440) series aeroplanes, serial numbers 7003 and later, to inspect the aileron power control unit (PCU) links and take corrective and reporting actions if defects are found. (Applicability: serials 7003 and subsequent.)\n\n- Specifically, it mandates a detailed visual inspection of the four aileron PCU links and immediate replacement of any link found to be fractured or cracked (Requirement 1).\n\n- When a fractured/cracked link is replaced, the operator must also:\n - record the torque values of the forward and aft attachment bolts for both links on that aileron;\n - check for mismatch between the PCU link and the PCU output fork;\n - perform an eddy-current (non‑destructive testing, NDT) inspection of the aileron PCU lugs and follow Bombardier’s instructions if a lug crack is detected; and\n - record the information requested in Appendix A and Appendix B of Bombardier Alert Service Bulletin (ASB) A601R-27-130 (Requirement 2a–d).\n\n- Aircraft previously inspected under the original ASB dated 13 November 2003 meet most requirements of this AD, except that if a fractured/cracked link was found but the lugs were not examined by NDT at that time, an NDT inspection of the applicable lugs must now be carried out (Requirement 3).\n\n- Operators must forward the completed Appendix A/B information and any associated fractured/cracked link(s) to Bombardier within 30 days of the initial inspection (Requirement 4).\n\n- The inspections and checks must be repeated at intervals not to exceed 1,000 flight hours (Requirement 5).\n\n- The AD refers to Bombardier ASB A601R-27-130 (Revision A, 22 December 2003) as the procedural source and notes Transport Canada AD CF-2004-13.\n\n**Why the instrument was issued (stated purpose)**\n\n- Transport Canada and CASA received reports of aileron PCU link failures in service. The stated safety concern is that failure of one link is a dormant (single) failure, but failure of both links on the same aileron could lead to reduced lateral control of the aircraft. The AD therefore requires inspection, repair/replacement, and monitoring to detect and prevent dual-link failure.\n\n**Who it affects and who pays**\n\n- Affected parties: Operators/owners of Bombardier CL-600-2B19 aircraft with serial numbers 7003 and later; maintenance organisations that service these aircraft; Bombardier (receives reports and failed parts for analysis).\n\n- Who pays: aircraft operators pay for inspections, replacements, NDT, downtime, and any reporting/admin costs. If parts are returned to Bombardier, operators also incur shipping/custody costs unless Bombardier arranges collection.\n\n**What behaviour changes are required of operators**\n\n- Schedule and perform the detailed visual inspection by the compliance deadlines (see Compliance timing below).\n- Replace any cracked/fractured link before further flight.\n- When replacing, perform bolt-torque recording, mismatch checks, and NDT of the lugs (and report results and return failed parts to Bombardier).\n- Repeat the inspection every 1,000 flight hours.\n\n**Compliance timing (practical summary of the AD’s conditions)**\n\n- For aircraft with 2,000 flight hours or more at the effective date: complete the initial inspection before accumulating another 550 flight hours.\n- For aircraft with less than 2,000 flight hours at the effective date: complete the inspection before reaching 2,000 flight hours, or before accumulating 550 flight hours from the effective date—whichever is later.\n- NDT required at the next repeat visual inspection if the earlier 13 Nov 2003 ASB inspection found a fractured link but no NDT was done.\n- Reporting to Bombardier must occur within 30 days of the initial inspection.\n- Re-inspection interval thereafter: every 1,000 flight hours.\n\n**Implementation, costs, and trade-offs (practical testing of the stated purpose against costs and incentives)**n\n- Direct costs to operators: labour for the visual inspection, potential downtime while inspections/repairs occur, parts and labour to replace any fractured links, and NDT equipment/time or outsourced NDT service costs. These are concrete and borne directly by operators (Requirement 1–2, 5).\n\n- Administrative burden: operators must complete the Appendix A/B forms and send them (plus failed parts) to Bombardier within 30 days. This creates a recurring paperwork and logistics task, especially for multi‑aircraft operators (Requirement 4).\n\n- Technical/implementation risk: the AD requires eddy‑current NDT of lugs. That requires trained staff and equipment; smaller operators may need to outsource this, which adds cost and potential scheduling delay (Requirement 2c).\n\n- Operational trade-off: an operator may elect to replace a suspect link immediately to return the aircraft to service quickly, rather than wait for extended diagnostic work; that substitution can raise parts costs but reduce downtime. The AD does not mandate a single supplier for repairs; approved maintenance organisations may carry out the work, so independent MROs can compete to provide the service (ASB referenced for procedures).\n\n- Concentration of benefits vs diffuse costs: the primary, concentrated safety benefit accrues to affected aircraft and their passengers/crew through reduced risk of dual-link failure. Costs are diffuse across operators of the affected fleet. Bombardier receives failed parts and data, which supports diagnosis and corrective action (Requirement 4). The AD’s reporting requirement channels information to the manufacturer for analysis.\n\n- Potential for unintended consequences: increased short-term maintenance demand for specific parts or NDT services could temporarily affect availability or lead to expedited parts orders. The AD itself does not impose parts-sourcing restrictions.\n\n**Decision and discretion**\n\n- Who decides: the Civil Aviation Safety Authority (via the AD) mandates the inspections. Operators decide when within the compliance window to schedule work and whether to use in-house maintenance or an authorised third-party maintenance organisation to perform inspections, NDT, and replacements.\n\n**References within the AD**\n\n- The mandated procedures are to be done in accordance with Bombardier Alert Service Bulletin A601R-27-130, Revision A (22 December 2003) or later NAA-approved revisions (Requirement section). The AD also notes Transport Canada AD CF-2004-13 as related material.\n\n"},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD maintains focused scope on aileron PCU link integrity. The requirements track closely with the stated safety purpose — addressing reported failures of specific components. The inclusion of reporting requirements and repeat inspections is standard for airworthiness directives and does not represent scope creep beyond the original safety intent."},"complexity_factors":["Multiple compliance deadlines based on aircraft flight hours (2,000 hour threshold creates bifurcated timeline)","Five distinct numbered requirements with sub-requirements (2a, 2b, 2c, 2d)","Conditional logic for aircraft previously inspected under earlier service bulletin (Requirement 3 creates exception for partial compliance)","Cross-reference to external Bombardier Alert Service Bulletin A601R-27-130 Revision A with mandatory adherence to specific revision date","Technical aviation terminology requiring domain knowledge (PCU, eddy current inspection, NDT, torque values, output forks)","Appendix references (Appendix A and B) contained in external document not reproduced in the AD itself","Nested conditions in Requirement 3 distinguishing between 'initial inspection performed' vs 'fractured link found without NDT'"],"plain_english_summary":"This Airworthiness Directive requires operators of Bombardier CL-600-2B19 (CRJ-100/440), serials 7003 onward, to inspect and, if needed, replace aileron power control unit (PCU) links after reports of cracking that could lead to loss of roll control. It mandates visual and eddy-current checks, torque/part verification, reporting broken parts to Bombardier, and repeat inspections every 1,000 flight hours.\n\nHigh-time aircraft must comply within 550 flight hours; others must inspect before 2,000 flight hours or within 550 hours, whichever is later."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cl-600-79-aileron-power-control-unit-links","history":"/api/acts/ad-cl-600-79-aileron-power-control-unit-links/history","analysis":"/api/acts/ad-cl-600-79-aileron-power-control-unit-links/analysis","conflicts":"/api/acts/ad-cl-600-79-aileron-power-control-unit-links/conflicts","importantCases":"/api/acts/ad-cl-600-79-aileron-power-control-unit-links/important-cases","documents":"/api/acts/ad-cl-600-79-aileron-power-control-unit-links/documents"}}