{"id":"F2006L03505","name":"AD/CL-600/69 Amdt 1 - Horizontal Stabiliser Trim - Uncommanded Movement","slug":"ad-cl-600-69-amdt-1-horizontal-stabiliser-trim-uncommanded-movement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":61035,"registerId":"commonwealth-F2006L03505-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-600/69 Amdt 1 | Horizontal Stabiliser Trim - Uncommanded Movement | 13/2006 DM |\n| ------------------- | ------------------------------------------------- | ---------- |\n\n| Applicability: | Model CL-600-2B16 (CL-604), serial number 5301 through 5665. |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. If not previously accomplished, amend the Aircraft Flight Manual (AFM) by inserting Temporary Revision (TR) 604/21-1 dated 3 October 2006, or later approved changes to this TR. TR 604/21 dated 1 August 2006, which was installed under the original issue of this Airworthiness Directive, should be removed. |\n| | 2. Install circuit breaker quick identifier collars on the horizontal stabiliser trim control unit (HSTCU) circuit breakers in accordance with Bombardier Alert Service Bulletin (ASB) A604-27-029 dated 28 September 2006, or later revision approved by the Chief, Continuing Airworthiness, Transport Canada Civil Aviation (TCCA) |\n| | 3. Ensure all flight crew are aware that on the flight crew's first flight of the day, they are required to: |\n| | a. Review the location of the STAB CH1 HSTCU and STAB CH2 HSTCU circuit breakers, and |\n| | b. Check the stabilizer trim system as detailed in CL-604 AFM \"Normal Procedures\" section titled \"Flight Controls Trim Systems, Before Flight - First Flight of the Day\". |\n| | This may be accomplished by placing a copy of this Amendment in the AFM “Normal Procedures”. |\n| | 4. Install HSTCU, part number (P/N) 601R92301-15, (Vendor P/N 7060-10) or a higher Mod Number, in accordance with ASB A604-27-029 dated 28 September 2006, or later revision approved by the Chief, Continuing Airworthiness, TCCA. |\n| | Following installation of HSTCU Vendor P/N -10 or higher, it is permissible to remove the quick identification circuit breaker collars installed under Requirement 1 of this Amendment |\n\n| | Note 1: As called for in the AFM, it is recommended that Operators reinstate the functional check of the stabilizer trim system on the aircraft's first flight of the day. |\n| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| | Note 2: TCCA AD CF-2006-21R1 refers. |\n| Compliance: | For Requirements 1 2 and 3 - Within 14 days after the effective date of this Amendment. |\n| | For Requirement 4 - Within 12 months of the effective date of this Amendment. |\n| | This Amendment becomes effective on 27 October 2006. |\n| Background: | Transport Canada has received reports of uncommanded horizontal stabilizer trim motion on two CL-600-2B16 (CL-604) aircraft. In each case, the aircraft landed safely. |\n| | An investigation has revealed that a motherboard in the horizontal stabiliser trim control unit (HSTCU) had not had appropriate environmental protection applied during manufacture. The absence of corrosion protection and the accumulation of moisture during flight, caused short circuits that resulted in autopilot disconnect and trim system malfunctions. The trim problems included uncommanded trim, trim in a direction opposite to that selected, loss of trim position indication and, in one case, potential loss of trim disconnect capability. |\n| | This Amendment enhances the AFM stabilizer trim runaway procedure, mandates the installation of circuit breaker (CB) quick identification collars for the HSTCU CBs, and introduces some additional trim system pre-flight checks for the flight crew. The installation of a modified HSTCU with environment protection on the motherboard provides terminating action. |\n| | The original issue of this Directive became effective on 6 September 2006. |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n23 October 2006","sortOrder":0},{"sectionNumber":"AD/CL-600/69 Amdt 1","sectionType":"part","heading":"AD/CL-600/69 Amdt 1","content":"## AD/CL-600/69 Amdt 1","sortOrder":1},{"sectionNumber":"Horizontal Stabiliser Trim - Uncommanded","sectionType":"part","heading":"Horizontal Stabiliser Trim - Uncommanded Movement","content":"## Horizontal Stabiliser Trim - Uncommanded Movement","sortOrder":2},{"sectionNumber":"13/2006 DM","sectionType":"part","heading":"13/2006 DM","content":"## 13/2006 DM","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"This amendment expands and clarifies the original directive by replacing an earlier AFM temporary revision, mandating quick‑identification circuit‑breaker collars, adding a specified first‑flight stabiliser‑trim check for crew, and prescribing HSTCU replacement as terminating action. It also sets explicit short and longer compliance deadlines and references TCCA approval for revisions (Background; Requirements 1–4; Compliance)."},"complexity_factors":["Narrow applicability: applies only to CL-600-2B16 (CL-604) serial numbers 5301–5665 (Applicability).","Multiple action types: AFM amendment, temporary removal of prior TR, physical installation of identification collars, crew procedural changes, and eventual hardware replacement (Requirements 1–4).","Staged compliance windows: short 14‑day deadline for AFM/collar/crew checks and a 12‑month deadline for HSTCU replacement (Compliance).","Terminating action conditionality: replacement HSTCU (Vendor P/N -10 or higher) terminates need for temporary collars, requiring coordination of logistics and parts (Requirement 4).","Regulatory approvals and revisions: some instructions require later revisions approved by the Chief, Continuing Airworthiness, TCCA (Requirements 2 and 4).","Operational burden on crew: new mandatory first‑flight-of‑the‑day checks must be integrated into normal procedures; AFM insertion suggested method (Requirement 3; Note 1).","Technical root cause: investigation identified inadequate environmental protection on HSTCU motherboard causing corrosion and short circuits, underpinning both interim and terminating measures (Background)."],"plain_english_summary":"This amendment requires operators of Bombardier CL-600-2B16 (CL-604) serials 5301–5665 to insert a revised Aircraft Flight Manual page, fit quick‑identification collars to the horizontal stabiliser trim circuit breakers, perform an added stabiliser‑trim pre‑flight check on the crew's first flight of the day, and replace the horizontal stabiliser trim control unit (HSTCU) within 12 months. Operators fund parts, labour and paperwork; flight crews must change pre‑flight routine. The HSTCU replacement is specified as the terminating action. (Requirements 1–4; Applicability; Compliance.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is an amendment to an existing Airworthiness Directive (AD/CL-600/69). The amendment refines and enhances the original requirements but does not expand beyond the original safety purpose — addressing uncommanded horizontal stabiliser trim movement in CL-604 aircraft. The original directive required manual updates; this amendment adds physical modifications (circuit breaker collars and hardware replacement) as terminating action. The scope remains tightly focused on the specific trim system defect."},"complexity_factors":["Single, specific aircraft type and serial number range (narrow applicability)","Four distinct requirements with different compliance timeframes (14 days vs 12 months)","References to external technical documents (Alert Service Bulletin, Temporary Revision to Aircraft Flight Manual) that are not reproduced in the directive","One conditional provision (removal of circuit breaker collars permitted after hardware upgrade)","Standard aviation regulatory terminology (AFM, ASB, HSTCU, P/N) but explained through context"],"plain_english_summary":"This CASA Airworthiness Directive targets Bombardier CL-604 Challengers (S/N 5301–5665) to fix a moisture-vulnerable trim control unit in the horizontal stabiliser trim system that has caused short circuits and uncommanded or incorrect trim movement. It requires immediate operational mitigations — flight manual updates, circuit-breaker markings and pilot briefings — and mandatory replacement of the faulty unit within 12 months to prevent loss of control."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cl-600-69-amdt-1-horizontal-stabiliser-trim-uncommanded-movement","history":"/api/acts/ad-cl-600-69-amdt-1-horizontal-stabiliser-trim-uncommanded-movement/history","analysis":"/api/acts/ad-cl-600-69-amdt-1-horizontal-stabiliser-trim-uncommanded-movement/analysis","conflicts":"/api/acts/ad-cl-600-69-amdt-1-horizontal-stabiliser-trim-uncommanded-movement/conflicts","importantCases":"/api/acts/ad-cl-600-69-amdt-1-horizontal-stabiliser-trim-uncommanded-movement/important-cases","documents":"/api/acts/ad-cl-600-69-amdt-1-horizontal-stabiliser-trim-uncommanded-movement/documents"}}