{"id":"F2009L02862","name":"AD/DHC-8/149 - Spoiler Lift Dump Valve","slug":"ad-dhc-8-149-spoiler-lift-dump-valve","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":80203,"registerId":"commonwealth-F2009L02862-current","compilationNumber":null,"startDate":"2026-04-02","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-8/149 | Spoiler Lift Dump Valve | 8/2009 |\n| ------------ | ----------------------- | ------ |\n\n| Applicability: | Bombardier Inc. Models DHC-8-400, DHC-8-401 and DHC-8-402, Serial Numbers 4001 through 4237.                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Incorporate Bombardier Modsum 4 -113554 to add a Filter/Restrictor Fitting to the Spoiler Lift Dump Valve.Bombardier Service Bulletin 84-27-43, Initial Revision, dated 29 January 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada provides approved instructions for incorporating Modsum 4 - 113554.Note: Transport Canada AD CF-2009-26 dated 21 May 2009 refers.                                                                                                                              |\n| Compliance:    | Within 5,000 flight hours after the effective date of this AD.                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n|                | This Airworthiness Directive becomes effective on 30 July 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| Background:    | Several operators have reported cases of inadvertent single spoiler deployment during flight on the DHC-8 Series 400 aircraft. Investigation has revealed that the probable cause for this deployment is internal contamination of the Lift/Dump (L/D) valve and moisture ingress into the L/D valve armature. This condition, if not corrected, could cause uncommanded deployment of the spoilers resulting in increased drag and in combination with a loss of aileron, could result in a significant reduction in aircraft roll control. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n19 June 2009","sortOrder":0},{"sectionNumber":"AD/DHC-8/149","sectionType":"part","heading":"AD/DHC-8/149","content":"## AD/DHC-8/149","sortOrder":1},{"sectionNumber":"Spoiler Lift Dump Valve","sectionType":"part","heading":"Spoiler Lift Dump Valve","content":"## Spoiler Lift Dump Valve","sortOrder":2},{"sectionNumber":"8/2009","sectionType":"part","heading":"8/2009","content":"## 8/2009","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":3,"scope_assessment":{"changed":false,"description":"The directive's scope aligns with the stated safety problem and prescribes a narrowly targeted hardware modification for the affected serials. It does not broaden to other systems or fleets; it sets a defined compliance window (5,000 flight hours) and requires following an identified service bulletin or approved revisions, keeping scope consistent with the original corrective intent."},"complexity_factors":["Narrow applicability: specific models and serial numbers (DHC‑8‑400, ‑401, ‑402 SN 4001–4237) limits operational complexity.","Technical hardware mod required: incorporation of Modsum 4‑113554 to add a Filter/Restrictor fitting to the Lift/Dump valve.","Reference to external documents: implementation follows Bombardier Service Bulletin 84‑27‑43 (Initial Revision dated 29 Jan 2009) or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.","Compliance scheduling constraint: modification must be done within 5,000 flight hours, creating a medium-term maintenance planning burden for operators.","Regulatory linkage: cross-reference to Transport Canada AD CF‑2009‑26 and requirement for approval of later revisions introduces regulatory coordination and some administrative discretion.","Safety justification specific and technical (contamination/moisture causing uncommanded spoiler deployment), which narrows risk assessment but requires targeted inspection/installation capability."],"plain_english_summary":"This airworthiness directive requires fitting a filter/restrictor to the spoiler lift/dump valve on specified Bombardier DHC‑8‑400 series aeroplanes. The mechanical change aims to stop inadvertent single‑spoiler deployment traced to internal valve contamination and moisture ingress. It affects operators of the listed DHC‑8‑400/401/402 serial numbers and matters because uncommanded spoiler deployment can increase drag and, with reduced aileron effectiveness, materially reduce roll control."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a narrow, targeted scope addressing a specific mechanical defect in specific aircraft models. The scope remains tightly focused on the spoiler lift dump valve issue as originally identified."},"complexity_factors":["Single, specific technical requirement with clear manufacturer reference (Modsum 4-113554)","Limited applicability (only 3 specific models, serial number range 4001-4237)","Straightforward compliance deadline (5,000 flight hours from effective date)","No nested exceptions, conditional logic, or extensive cross-referencing","Short document with minimal defined terms (only standard aviation terminology)","Single background issue with clear causal chain (contamination → valve failure → spoiler deployment)"],"plain_english_summary":"This CASA Airworthiness Directive mandates owners/operators of Bombardier DHC‑8‑400/-401/-402 (serials 4001–4237) install a filter/restrictor on the spoiler lift dump valve to stop contamination/moisture‑induced, unintended in‑flight spoiler deployment. The required Bombardier modification (Modsum 4‑113554) must be fitted per the service bulletin within 5,000 flight hours of 30 July 2009. It’s safety‑critical—noncompliance grounds the aircraft from Australian airspace."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-149-spoiler-lift-dump-valve","history":"/api/acts/ad-dhc-8-149-spoiler-lift-dump-valve/history","analysis":"/api/acts/ad-dhc-8-149-spoiler-lift-dump-valve/analysis","conflicts":"/api/acts/ad-dhc-8-149-spoiler-lift-dump-valve/conflicts","importantCases":"/api/acts/ad-dhc-8-149-spoiler-lift-dump-valve/important-cases","documents":"/api/acts/ad-dhc-8-149-spoiler-lift-dump-valve/documents"}}