{"id":"F2005L02383","name":"AD/CL-600/67 - Horizontal Stabilizer Trim Actuator","slug":"ad-cl-600-67-horizontal-stabilizer-trim-actuator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":36799,"registerId":"commonwealth-F2005L02383-current","compilationNumber":null,"startDate":"2026-04-01","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-600/67 | Horizontal Stabilizer Trim Actuator | 10/2005 |\n| ------------ | ----------------------------------- | ------- |\n\n| Applicability: | Bombardier Inc. Models:CL-600-1A11 - Serial numbers 1004 through 1085CL-600-2A12 - Serial numbers 3001 through 3066CL-600-2B16 - Serial numbers 5001 through 5194                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Accomplish the following in accordance with the applicable Service Bulletin (SB) listed below, or later Transport Canada approved revisions.a. Immediately prior to proceeding with the Horizontal Stabiliser Trim Actuator (HSTA) modification in paragraph 1.c below, carry out a special check of the HSTA lower gimbal pin for migration by measuring the clearance between the yoke and the lower side of the gimbal pinhead.b. If gimbal pin migration is evident, replace the HSTA before further flight. Within seven (7) days of the inspection, notify Bombardier of the failure by completing and forwarding the Feedback form provided with the applicable SBs.c. If there is no evidence of gimbal pin migration, modify the HSTA by installing the gimbal pin kit (Bombardier P/N 600K0720; Goodrich P/N52-210050) and re-identify the HSTA as per Goodrich VSB21207-00X-27-05; or replace the installed HSTA with a HSTA that has previously been modified with the gimbal pin kit (Bombardier P/N 600K0720; Goodrich P/N 52-210050).Applicable Service Bulletins.CL-600-1A11 - SB 600-0720, dated 31 January 2005CL-600-2A12 - SB 601-0555, dated 31 January 2005CL-600-2B16 - SB 601-0555, dated 31 January 20052. Replacement/spare HSTAs shall be modified with the gimbal pin kit (Bombardier P/N 600K0720; Goodrich P/N 52-210050) and re- identified as per Goodrich VSB 21207-00X-27-05.Note: Transport Canada AD CF-2005-20 refers. |\n\n| Compliance: | 1. Within 600 hours time in service from the effective date of this directive but not later than 30 November 2006, whichever occurs first.2. From the effective date of this Directive, prior to being installed on any aircraft.                                                                                                                                                |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Airworthiness Directive becomes effective on 29 September 2005.                                                                                                                                                                                                                                                                                                             |\n| Background: | Two failures have been reported of the lower gimbal primary pin of the HSTA. In both failure cases, each found during routine maintenance, the primary pin had not migrated to the extent that the operation of the HSTA was impaired. Analysis indicates that safety will be enhanced if additional pin retainer brackets are installed to mitigate lower gimbal pin migration. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n15 August 2005","sortOrder":0},{"sectionNumber":"AD/CL-600/67","sectionType":"part","heading":"AD/CL-600/67","content":"## AD/CL-600/67","sortOrder":1},{"sectionNumber":"Horizontal Stabilizer Trim Actuator","sectionType":"part","heading":"Horizontal Stabilizer Trim Actuator","content":"## Horizontal Stabilizer Trim Actuator","sortOrder":2},{"sectionNumber":"10/2005","sectionType":"part","heading":"10/2005","content":"## 10/2005","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with a focused, single-purpose scope: addressing a specific mechanical defect in a specific aircraft component. The scope remains tightly constrained to the HSTA gimbal pin issue as originally identified."},"complexity_factors":["Multiple aircraft models and serial number ranges requiring cross-referencing to determine applicability","Conditional logic: different actions required depending on inspection results (migration found vs. not found)","Specific part numbers and service bulletin references that must be matched exactly (Bombardier P/N 600K0720, Goodrich P/N 52-210050, Goodrich VSB 21207-00X-27-05)","Dual compliance deadlines (600 hours time-in-service OR 30 November 2006, whichever first)","Separate requirements for replacement/spare parts versus installed units","Reporting obligation triggered only if specific condition (migration) is found","Reference to external Canadian authority document (Transport Canada AD CF-2005-20) for context"],"plain_english_summary":"This AD requires owners/operators of specified Bombardier Challenger 600-series aircraft (CL-600-1A11, -2A12, -2B16) to inspect the Horizontal Stabilizer Trim Actuator (HSTA) for pin migration and, if needed, replace it or install a retention kit to lock the pin. Spares must be modified and any migration must be reported to Bombardier.\n\nThe action must be done within 600 flight hours or by 30 Nov 2006. It prevents potential loss of pitch control."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD is narrowly targeted to mitigate lower gimbal pin migration on the HSTA following two reported failures. It does not broaden regulatory goals beyond that corrective action: the directive prescribes inspection and a specific modification or replacement, requires modified spares, and points to model‑specific service bulletins. There is no evidence in the text that the directive grew beyond this original safety remediation purpose."},"complexity_factors":["Short, targeted directive focused on one component (HSTA) and one failure mode (lower gimbal pin migration)","Three-step requirement structure (1.a–1.c) with a simple conditional: inspect → if migration replace → if no migration modify","Two compliance timing conditions (within 600 hours or by a fixed calendar date)","Specific part numbers and re‑identification instruction references (Bombardier P/N 600K0720; Goodrich P/N 52‑210050; Goodrich VSB21207‑00X‑27‑05)","Cross-references to three Bombardier Service Bulletins (model-specific) and Transport Canada AD CF‑2005‑20","Applicability limited to three model groups with serial number ranges (clear but requires checking serial numbers)"],"plain_english_summary":"**What this directive does (mechanically)**\n\n- This Airworthiness Directive (AD) requires operators of certain Bombardier (Canadair) CL-600 Challenger aeroplanes to inspect and, if necessary, modify or replace the Horizontal Stabilizer Trim Actuator (HSTA) to prevent migration (movement) of the lower gimbal pin. (See \"Requirement\" paragraphs 1.a–1.c.)\n\n- Specifically, before doing the modification, operators must measure the clearance between the yoke and the lower side of the gimbal pin head to check for pin migration (Requirement 1.a). If migration is found, the HSTA must be replaced before further flight and Bombardier must be notified using the Feedback form in the applicable Service Bulletin (Requirement 1.b).\n\n- If no migration is found, the HSTA must be modified by installing a gimbal pin kit (Bombardier P/N 600K0720; Goodrich P/N 52-210050) and re‑identified per Goodrich instructions, or the existing HSTA may be replaced with an HSTA already modified with that kit (Requirement 1.c).\n\n- Any replacement or spare HSTAs must also be modified with the same gimbal pin kit and re‑identified before being installed (Requirement 2).\n\n- The AD lists the applicable Bombardier Service Bulletins that provide the technical steps for inspection and modification. Transport Canada approval is referenced for later SB revisions.\n\n**Who is affected**\n\n- Aircraft operators and owners of the specified Bombardier CL-600 Challenger models and serial number ranges listed under \"Applicability\".\n- Maintenance organisations and engineers who perform the inspection, modification or replacement, and parts suppliers who provide the gimbal pin kit (Bombardier/Goodrich part numbers are given).\n\n**When it has to be done (compliance)**\n\n- The inspection/modification must be completed within 600 hours time in service from the AD’s effective date or by 30 November 2006, whichever occurs first (Compliance 1).\n- Any replacement or spare HSTA must be modified prior to installation from the AD’s effective date (Compliance 2).\n\n**Why the regulator issued it (stated reason)**\n\n- The AD follows two reported failures of the HSTA lower gimbal primary pin found in routine maintenance. In those cases the pin had not migrated enough to impair HSTA operation but the regulator judged safety would be enhanced by installing additional pin retainer brackets to mitigate migration (Background).\n\n**Practical effects, costs and decision mechanics**\n\n- Who pays: aircraft operators bear the direct costs — labour for the inspection, cost of the pin kit (Bombardier/Goodrich P/Ns specified), and aircraft downtime while the work is done.\n\n- Who decides and how: the regulator (Civil Aviation Safety Authority delegate issuing the AD) mandates the inspection/modification; the Service Bulletins named in the AD set the technical method. Transport Canada is the approving authority for future SB revisions referenced in the AD.\n\n- Behaviour changes required: operators must add the special check to their maintenance work (measure clearances), replace any HSTAs with evident pin migration before next flight, modify HSTAs without migration with the approved kit, and ensure spare/ replacement HSTAs are already modified before fitment.\n\n- Effects on maintenance market and competition: the AD specifies manufacturer part numbers and re‑identification procedures, so operators will purchase the gimbal pin kits from approved suppliers (Bombardier/Goodrich). Independent maintenance organisations (MROs) can perform the work if they follow the SB instructions and any regulatory approvals, but the specified parts and re‑identification create concentrated demand for those parts and for authorised parts suppliers.\n\n- Opportunity costs and productivity: aircraft will be unavailable while inspected and modified, producing downtime costs for operators; there are also ongoing inventory considerations because spares must be modified prior to installation.\n\n- Compliance burden and implementation risk: the AD imposes a short compliance window (600 hours or a fixed date) that may force scheduling changes. There is a record‑keeping action (feedback form to Bombardier if migration is found) and a clear pass/fail measurement (clearance between yoke and pin head) but execution depends on maintenance staff correctly performing and recording the measurement and modification per the SB.\n\n**Trade‑offs and concentrated benefits**\n\n- The stated safety benefit is mitigation of pin migration risk (Background). The concrete trade‑off is operator cost and downtime against reduced risk of in‑service pin migration.\n\n- The AD’s explicit reference to Bombardier and Goodrich part numbers concentrates commercial benefit on those suppliers because operators must use the specified kit and follow re‑identification instructions (Requirement 1.c; Replacement/spare HSTAs paragraph). That commercial effect follows mechanically from naming the supplier part numbers.\n\n**Where to find the technical steps**\n\n- The AD requires compliance with the listed Bombardier Service Bulletins (SB 600‑0720 or SB 601‑0555 depending on model) dated 31 January 2005, and with Goodrich VSB21207‑00X‑27‑05 for re‑identification (Requirement 1 and Applicable Service Bulletins). Transport Canada AD CF‑2005‑20 is also referenced.\n\n(Effective date cited in the AD: 29 September 2005.)"},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-cl-600-67-horizontal-stabilizer-trim-actuator","history":"/api/acts/ad-cl-600-67-horizontal-stabilizer-trim-actuator/history","analysis":"/api/acts/ad-cl-600-67-horizontal-stabilizer-trim-actuator/analysis","conflicts":"/api/acts/ad-cl-600-67-horizontal-stabilizer-trim-actuator/conflicts","importantCases":"/api/acts/ad-cl-600-67-horizontal-stabilizer-trim-actuator/important-cases","documents":"/api/acts/ad-cl-600-67-horizontal-stabilizer-trim-actuator/documents"}}