{"id":"F2006L00751","name":"AD/DHC-8/117 - Rudder Trim Switch Wiring","slug":"ad-dhc-8-117-rudder-trim-switch-wiring","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":136774,"registerId":"commonwealth-F2006L00751-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bombardier (Boeing Canada/De Havilland) ","sectionType":"division","heading":"Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes","content":"### Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes\n\n| AD/DHC-8/117 | Rudder Trim Switch Wiring | 4/2006 |\n| ------------ | ------------------------- | ------ |\n\n| Applicability: | DHC-8 Models 401 and 402, serial numbers 4005, 4006, 4008 through 4016 and 4018 through 4058.                                                                                                                                                                                               |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. If not previously accomplished, carry out the following in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin (ASB)A84-27-13 Revision B, dated 12 January 2002, or later revisions, approved by the Chief, Continuing Airworthiness, Transport Canada: |\n|                | a. Modify the wiring for the rudder trim switch (2722-S2) by incorporating Modsum 4-126256; and                                                                                                                                                                                             |\n|                | b. Visually inspect all wiring on the back of the aileron/rudder trim control panel (P/N 82410608-001, -003 or -005) for chafing.                                                                                                                                                           |\n|                | Note 1: Aircraft modified and inspected in accordance with the Accomplishment Instructions of ASB A84-27-13 Revision A, dated 9 January 2002, also satisfy the requirements of this Directive.                                                                                              |\n|                | 2. Replace any chafed wiring found during the Requirement 1.b. inspection.                                                                                                                                                                                                                  |\n|                | Note 2: Transport Canada AD CF-2002-15 refers.                                                                                                                                                                                                                                              |\n| Compliance:    | For Requirement 1 - Within 30 days after the effective date of this Directive.                                                                                                                                                                                                              |\n|                | For Requirement 2 - Before further flight after the Requirement 1.b. inspection.                                                                                                                                                                                                            |\n|                | This Airworthiness Directive becomes effective on 13 April 2006.                                                                                                                                                                                                                            |\n\n| Background: | Transport Canada has advised that an investigation of an incident involving rudder trim runaway has revealed a discrepancy in the wiring of the rudder trim control switch on the aileron/rudder trim control panel. The wiring discrepancy in the rudder trim switch could potentially enable a single short circuit on the aileron/rudder trim control panel to cause a runaway condition of the rudder trim actuator |\n| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n2 March 2006","sortOrder":0},{"sectionNumber":"AD/DHC-8/117","sectionType":"part","heading":"AD/DHC-8/117","content":"## AD/DHC-8/117","sortOrder":1},{"sectionNumber":"Rudder Trim Switch Wiring","sectionType":"part","heading":"Rudder Trim Switch Wiring","content":"## Rudder Trim Switch Wiring","sortOrder":2},{"sectionNumber":"4/2006","sectionType":"part","heading":"4/2006","content":"## 4/2006","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The Directive implements the corrective actions described in Bombardier ASB A84-27-13 (and acknowledges ASB Revision A) and references Transport Canada AD CF-2002-15. It confines obligations to the listed DHC-8-401/402 serial numbers and to the specified wiring modification, inspection and replacement actions, and does not expand the applicability or introduce additional obligations beyond those referenced in the source material."},"complexity_factors":["Technical electrical modification (rudder trim switch wiring) requiring specific Modsum 4-126256 and adherence to Bombardier ASB procedures.","Narrow applicability: only DHC-8 Models 401 and 402 with specific serial numbers, requiring careful fleet identification.","Use of external documents: compliance depends on Bombardier ASB A84-27-13 Rev B (or later revisions) as approved by the Chief, Continuing Airworthiness, Transport Canada.","Operational urgency and timing: primary modification due within 30 days and any replacement of chafed wiring required before further flight, creating scheduling pressure.","Inspection requirement (visual inspection of back of control panel P/N 82410608-001/-003/-005) plus replacement if chafing found—introduces parts and labour costs.","Regulatory cross-reference: directive notes equivalence with earlier ASB Revision A and references Transport Canada AD CF-2002-15, requiring consistency across authorities.","Limited bureaucratic discretion: acceptance of later ASB revisions is subject to approval by the Chief, Continuing Airworthiness, Transport Canada.","Potential operational impact from removing aircraft from service for inspection/repair and ensuring correct wiring traces."],"plain_english_summary":"Requires owners/operators of specific Bombardier DHC-8-401/402 aeroplanes (listed serial numbers) to modify the rudder trim switch wiring per Bombardier Alert Service Bulletin A84-27-13 (Rev B or later approved revisions) and visually inspect the aileron/rudder trim control panel wiring for chafing, with any chafed wiring replaced before further flight. The directive responds to a wiring discrepancy that could allow a single short circuit to cause rudder-trim runaway, imposing short-term maintenance and parts/inspection costs on affected operators."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow Airworthiness Directive targeting a specific wiring defect in a specific aircraft model. The scope remains tightly focused on the original safety issue identified by Transport Canada — a wiring discrepancy that could cause rudder trim runaway. There is no evidence of scope creep; the directive does exactly what it says on the tin."},"complexity_factors":["Single, specific aircraft type and limited serial number range (approximately 50 aircraft)","Only 2 main requirements with clear sequential compliance deadlines","References only one external technical document (Bombardier Alert Service Bulletin A84-27-13 Revision B)","No nested exceptions or conditional logic — straightforward 'if not already done, do this' structure","Minimal defined terms (only standard aviation terminology like 'Modsum' and part numbers)","Short document (approximately 250 words of substantive content)"],"plain_english_summary":"This AD mandates owners/operators of specified Bombardier DHC-8-400 (Models 401/402, listed serial numbers) to correct a wiring defect in the rudder trim switch and inspect associated wiring, requiring prompt repair of any damage.  \n\nIt targets about 50 aircraft to eliminate a single-short risk that can cause rudder trim runaway—a serious loss-of-control hazard—by enforcing a manufacturer-developed wiring modification and inspections."},"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-dhc-8-117-rudder-trim-switch-wiring","history":"/api/acts/ad-dhc-8-117-rudder-trim-switch-wiring/history","analysis":"/api/acts/ad-dhc-8-117-rudder-trim-switch-wiring/analysis","conflicts":"/api/acts/ad-dhc-8-117-rudder-trim-switch-wiring/conflicts","importantCases":"/api/acts/ad-dhc-8-117-rudder-trim-switch-wiring/important-cases","documents":"/api/acts/ad-dhc-8-117-rudder-trim-switch-wiring/documents"}}