{"id":"F2008L03366","name":"AD/DHC-8/143 - Nose Landing Gear Electrical Harness","slug":"ad-dhc-8-143-nose-landing-gear-electrical-harness","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":120285,"registerId":"commonwealth-F2008L03366-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-8/143 | Nose Landing Gear Electrical Harness | 10/2008 |\n| ------------ | ------------------------------------ | ------- |\n\n| Applicability: | Model DHC-8-400, DHC-8-401 and DHC-8-402 aircraft, Serial Numbers 4003, 4004, 4006 and 4008 through 4184.                                                                                                                                                                                                                                                                                                                                                                        |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Replace the weight-on-wheels and steering harnesses by incorporating Modsum4-126401. Bombardier Service Bulletin (SB) 84-32-51, Revision B, dated 17 December 2007, or later revisions approved by Chief, Continuing Airworthiness, Transport Canada, provides approved instructions for incorporating Modsum4-126401.                                                                                                                                                           |\n|                | Note 1: Incorporation of Modsum 4-126401 in accordance with the original issue of SB 84 32 51, dated 16 August 2007 or with Revision A, dated 22 August 2007, before the effective date of this Directive is acceptable for compliance with this Directive.                                                                                                                                                                                                                      |\n|                | Note 2: Transport Canada AD CF-2008-22 dated 24 June 2008 refers.                                                                                                                                                                                                                                                                                                                                                                                                                |\n| Compliance:    | Within 2,500 hours time in service after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                                                   |\n|                | This Airworthiness Directive becomes effective on 25 September 2008.                                                                                                                                                                                                                                                                                                                                                                                                             |\n| Background:    | There have been several cases reported where the landing gear did not retract after take off. Subsequent investigation revealed this was caused by fatigue failure of the nose landing gear electrical harness. In conjunction with one engine being inoperable, this could, in certain operating conditions, affect continued safe flight and landingThis Directive mandates incorporation of new weight-on-wheels and steering harnesses that have a new conduit construction. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n6 August 2008","sortOrder":0},{"sectionNumber":"AD/DHC-8/143","sectionType":"part","heading":"AD/DHC-8/143","content":"## AD/DHC-8/143","sortOrder":1},{"sectionNumber":"Nose Landing Gear Electrical Harness","sectionType":"part","heading":"Nose Landing Gear Electrical Harness","content":"## Nose Landing Gear Electrical Harness","sortOrder":2},{"sectionNumber":"10/2008","sectionType":"part","heading":"10/2008","content":"## 10/2008","sortOrder":3}],"analysis":{"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":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive addressing a specific safety-critical defect in a defined aircraft population. The scope remains precisely limited to the identified wiring fatigue issue in the specified DHC-8-400 series serial numbers, with no expansion beyond the original safety purpose."},"complexity_factors":["Single, specific technical requirement with clear part numbers and service bulletin references","Limited applicability — only 4 specific model variants and defined serial number range","Simple compliance deadline: single time-in-service threshold (2,500 hours)","No nested exceptions or conditional logic — only one acceptable modification path with grandfathering note for early adopters","Short document (approximately 300 words) with minimal cross-referencing","Only 2 defined technical terms requiring explanation (Modsum, weight-on-wheels)"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of specified Bombardier DHC‑8‑400 (Q400) aircraft (serials 4003, 4004, 4006, 4008–4184) to replace nose-landing-gear electrical harnesses with improved versions using Modsum4‑126401 per Bombardier Service Bulletin 84‑32‑51 (Rev B or later) within 2,500 flight hours of 25 Sept 2008.\n\nIt affects operators and maintenance engineers and prevents metal‑fatigue wiring failures that have caused landing gear retraction/extension malfunctions and pose a serious in‑flight and landing safety risk."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive enforces the original corrective action (installing Modsum4‑126401) for the listed serial numbers and accepts compliance via the original or Revision A Service Bulletin issued before the Directive or later revisions if approved by the Chief, Continuing Airworthiness. There is no expansion beyond the specified fleet or the mandated modification; the Directive links to an existing Transport Canada AD but does not broaden applicability."},"complexity_factors":["Applicability limited to specific serial numbers (Applicability) — requires checking fleet serials to determine who is affected.","Mandated modification identified by Modsum number and executed using a manufacturer Service Bulletin (Requirement) — technical work and parts procurement required.","Acceptance of earlier Service Bulletin issues and of later revisions only if approved by Chief, Continuing Airworthiness, Transport Canada (Requirement/Notes) — introduces document‑version and approval tracking.","Fixed compliance window of 2,500 flight hours (Compliance) — creates scheduling pressure and operational planning costs.","Cross‑reference to Transport Canada AD CF‑2008‑22 (Note 2/Requirement) — regulatory coordination may affect interpretations and recordkeeping.","Safety‑critical technical cause (Background) — fatigue failure risk concentrates benefit of action on operators while costs (labour/parts/downtime) are borne by them."],"plain_english_summary":"Mandates replacement of the nose landing‑gear weight‑on‑wheels and steering electrical harnesses on specified Bombardier DHC‑8‑400 series aircraft by installing Modsum4‑126401 per Bombardier Service Bulletin 84‑32‑51 (or later Chief, Continuing Airworthiness‑approved revisions) within 2,500 flight hours. It affects operators of the listed serial numbers, who must fund and schedule the retrofit, and matters because harness fatigue has been linked to nose‑gear non‑retraction incidents that can affect continued safe flight and landing."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-143-nose-landing-gear-electrical-harness","history":"/api/acts/ad-dhc-8-143-nose-landing-gear-electrical-harness/history","analysis":"/api/acts/ad-dhc-8-143-nose-landing-gear-electrical-harness/analysis","conflicts":"/api/acts/ad-dhc-8-143-nose-landing-gear-electrical-harness/conflicts","importantCases":"/api/acts/ad-dhc-8-143-nose-landing-gear-electrical-harness/important-cases","documents":"/api/acts/ad-dhc-8-143-nose-landing-gear-electrical-harness/documents"}}